DC Rowhouse Renovation - Focusing on the inside: getting from floor to floor by Gregory Upwall

View showing the main “stringers” in place

View showing tread support angles and secondary stringers in place

Welders working late into the night

The complete steel structure for the stairway with the temporary treads in place

With the house now protected from the elements we can start to focus on the inside. A first priority was getting the new interior stairs built so we can get from floor to floor without climbing ladders (finally). Since the stairway is designed as a focal point in the new house we spent time considering different options for the right material, evaluating each in terms of time required, appearance and budget. In the end, in order to achieve the look we wanted, we decided to use a custom fabricated steel design for the structural portions of the stairway and hardwood stair treads for the steps that will combine to give a modern look while the wood stairs will still give a warmer more residential feel to the stair. In order to keep fabrication and material costs from getting excessive (which can easily happen with custom steel fabrication), we chose to detail it with more readily available steel shapes, and detail the parts in a way to keep the fabrication and material costs lower than other similar custom steel fabrications.

 This is detailed and time-consuming work that requires focus and accuracy since each piece of steel must be cut and welded to the correct size and configuration in order for the stair to function properly and meet code requirements. From our three-dimensional BIM model of the house, we were able to develop detailed drawings with very precise dimensions that our steel fabricator used to build the stairs from.

 With the steel frame in place we have installed temporary wood treads for now that will remain in place while the remainder of the heavy construction gets completed. The temporary steps are a great strategy since they don’t need to be protected during the remaining construction phases. With this strategy the temporary stairs can take a beating and we don’t have to worry about them. The temporary wood treads don’t need to be precise or fine quality wood since they will eventually be replaced with the final hardwood treads that we will finish to match the hardwood flooring in the house. Once we get to the finishing phases of the project we will have the steel finished and painted and the final hardwood treads and handrail installed and sanded and finished. Can’t wait to see the finished product!

DC Rowhouse Renovation - Focusing on the inside: The new basement slab by Gregory Upwall

Laying the under-slab insulation over the drainage gravel

Notice the white radiant tubing in-place above the steel bars

Now that we can turn our focus to the inside of the house we can start to think about the quality of the indoor environment that we aim to create. An important early consideration is in the design of the very floor that will separate our living space from the earth on which the house sits. As we prepared to install the new concrete slab in the basement there were important considerations in what went in place beneath the slab. After the old concrete floor was broken up and removed we had the contractor lay down a layer of gravel to cover the exposed soil. The gravel remained in place in the intervening months while we were focused on the rough framing and on getting the rest of house dried-in. But now with those important steps complete, we could finally focus on getting the new slab in place. 

 In years past concrete floors were poured directly on top of the soil, but today we have learned that this is not a good idea. Since concrete is a porous material and not a good insulator, both moisture and heat can pass through the slab, and need to be addressed in order to keep the house comfortable and dry. We were lucky in this location since the site is well drained and we did not have any issues with groundwater in this part of the city.

 As a side note, we cannot emphasize strongly enough the importance of addressing groundwater issues if they do exist, before installing any new interior concrete slabs or finishes. If you are in a location with high water-table or where signs of any prior flooding or water seepage have been witnessed, these need to be addressed and corrected, otherwise water and moisture can become a recurring problem that can lead to mold and mildew forming inside the house. Groundwater issues are generally best addressed by a civil engineer with experience in dealing with site drainage and groundwater issues. Commonly applied techniques for preventing water from entering basements and foundations include installing foundation drainage trenches and piping below the slab, and the installation of a properly sized sump pump. You should consult with a civil engineer if any ground water issues are present on a project.

View showing reinforcing steel bars (“re-bar”) and vapor barrier installed over the foam insulation

View showing foam insulation along edge of slab

 Since water was not a problem on this project we were able to install the new concrete without any foundation drains or sump pump. But even without active groundwater issues moisture is present in the soil and the temperature of the soil is considerably colder than our indoor temperature will be in winter. To address the moisture in the soil, our continuous layer of gravel will serve to percolate moisture away from the bottom of the slab. And to address the heat loss we installed a three inch layer of high-density foam insulation board (making sure that it was carefully fitted to create a tight and continuous layer) over the top of the gravel. Then we installed a layer of heavy mil plastic film over the top of the foam to help keep any moisture from passing through from the ground into the interior of the house. 

 We also had our plumber install the flexible tubing for radiant hydronic heating of the slab. It is important for this tubing to be laid in a uniform pattern to ensure uniform distribution of heat in the slab. With all of these measures in place the contractor could finally order the concrete and pour the slab. In this case they chose to mix the concrete directly on site since the access to the site was too narrow to bring a ready-mix truck in, and also because we developed our own custom mix for the concrete. For this project we plan to leave the concrete exposed as the final finished floor in the basement, and we wanted something a bit more distinctive than a common concrete slab. So we purchased special white colored Portland cement and a smaller washed gravel for our concrete mix. During the final finishing phases of the project we will have the surface of the slab ground and polished with a special floor sander and then sealed with a clear sealer. We have installed a similar floor on other projects and it has turned out nice. But since each mix and batch of concrete can vary we will not know that exact appearance that we’ll get until the end when we have the floor sander on site. We are excited to see how it will turn out and hopeful that we’ll be pleased with the result!

DC Rowhouse Renovation - “Dried-in” (at last) by Gregory Upwall

view from alley: old windows are being filled in and opening for glass block is being prepared

The guys un-packing the windows during the window install

view showing the alley side wall partially re-pointed and the new opening for the glass block being prepared

view from the rear showing windows and doors installed and building wrap (base layer) in place

view from the rear during window installation

Looking up the new rear wall while building wrap and windows are being installed

view showing the glass block installed

view showing the alley wall fully re-pointed and the building wrap on the upper addition

It’s official. We are “dried-in”. While this term would make a high school grammar teacher cringe, it is a common term that is used loosely in the construction world to indicate the point when - although still a long way from finished - we can finally keep the elements out of the building (!). The main accomplishments required to get from “rough-framing” to “dried-in” are: a.) installation of the exterior doors & windows, b.) installation of the “weather resistive barrier” or “building wrap”, and c.) installation of the roofing membranes. In our case this phase also included the installation of the glass block into the new large vertical opening in the brick wall facing the alley.  Since weather is hard to predict most construction projects get rained on a few times before they are officially dried-in. In our case, we did not make it to dried-in before getting some rain, so the framing and sheathing did get wet a few times. But thankfully, we had some nice dry and windy days between storms so the building was able to thoroughly dry. And since we chose AdvanTech for the floor and roof sheathing we could rest a little easier since the products are designed to withstand moisture during construction. 

The glass block installation required careful planning and execution since the opening is twenty three feet tall so any deviation would translate into the block being out of level or plumb from the bottom of the opening to the top. Luckily our masons did a great job in preparing the opening and in installing the block and the finished result is something we are very happy with.

 Since this old DC Rowhouse in the Pleasant Plains neighborhood still had the original wood frame, single-pane windows, we decided to replace all of the exterior doors and windows in the project. The product we chose for this project is Weathershield’s Contemporary series. We love this manufacturer and these windows in terms of the look and the quality. The Contemporary series offer more modern narrow exterior frame and sash profiles which is perfect to complement the more modern character of the new portions of the building (additions).  The eight-foot-tall triple-sliding glass doors, and the large four foot by seven foot fixed glass window at the top of the glass block opening were very heavy so moving them to the 3rd floor and maneuvering them into place required an experienced (and strong) crew. We are very happy with the large glazed areas that will bring lots of natural daylight into the space.

 The weather-resistive barrier and flashing tapes that we have selected are manufactured by Pro Clima (a German company) and sold by 475 High Performance Building Supply. We selected these products since they are vapor open and will help to provide a weather tight enclosure that still allows moisture to escape through the envelope from the interior to the exterior. (We should note that currently we have only installed a base layer of Typar, a common building wrap, to cover the exterior walls, the Proclima membranes and flashing tapes (we’re using the Adhero & Solitex UM) will be installed over the Typar when it is time for the installation of the exterior metal cladding (stay tuned for more about this in a future post).

 For the roofing we chose TPO (short for “thermoplastic polyolefin”) for the upper roof and torch-down membrane roofing for the balconies (since they will eventually be covered with floating pavers). TPO is considered to be the roofing material of choice for flat roofs today in terms of durability and maintenance. Since the pavers will ultimately absorb the vast majority of the UV light (the part that is destructive to building products) we decided that the TPO was not necessary for the balcony waterproofing. 

DC Rowhouse Renovation - Rough Framing: the building takes shape by Gregory Upwall

The first shipment of framing lumber and plywood is delivered

The day that the old roof came off

The new upper 3rd story addition taking shape

View of 3rd-story addition from the front

The new rear additions taking shape at the 1st and second stories

Interior walls framed within the new 3rd-story addition

The additions framing nearly complete

View of 3rd-story addition from the front (the addition is barely visible above the original architectural rooftop features)

During the early portions of a renovation project patience and a good dose of faith are sometimes required since progress often seems slow and is less evident to the observer. But things finally seem to speed up once the portion of the construction referred to as “rough framing” begins. Why do we refer to this phase as “rough” framing? The framing part is pretty obvious, we are building “framed” portions of the building envelope with wood studs, joists and rafters. The rough part is a reference in contrast to “finish” carpentry, which refers to the trim, moldings, cabinetry, etc. that will come later. The rough framing or rough carpentry is referred to as “rough” since it is the structural portion of the carpentry that can be left rough since it will eventually be covered up by other finish materials. The rough framing is a pretty exciting time since it is the portion of the project when things move quickly and when the shell of the building really takes shape. 

Here in the North America (mostly US and Canada), where commercial forests are relatively abundant and soft-wood lumber is plentiful and cheap (relatively speaking), wood framing is the most common type of construction for homes and smaller residential buildings. Wood framing is particularly well suited for building additions onto older masonry buildings since it is relatively lightweight, yet strong and ductile, and also creates cavities that can be insulated within the walls and roof assemblies. Wood framing is also notable in it’s adaptability. Since wood members are cut and fastened together on site with relatively simple hand-held tools, it lends itself to creating custom sizes and configurations for walls, roofs and window openings.

With the newly framed rear and upper level building additions in place the size of our project has significantly grown in area, especially when viewed from the rear (something the neighbors have certainly noticed). With this project we are pleased with the resulting proportions and sight lines. In fact, due to the set-back of the new upper addition from the front wall of the original building, the upper-story addition is not even visible from the sidewalk in front of the house, and just barely visible when viewed from across the street. The volumes of the rear additions were designed to step in and out with balconies and are topped with an overhanging roof. The result is that the building feels less bulky when viewed in context with the neighboring houses.

 We have designed several projects that included either “pop-up” and “pop-back” type additions here in DC. These types of additions are somewhat controversial since many examples lack proper consideration to proportion and detail, and are often built in the place of traditional architectural features that have been removed. As we described in our earlier post “Design Approach” from August 10, we worked to place the volumes of the additions for this project in ways that fit within the new restrictions of the 2016 Zoning Regulations and within our own design criteria of hoping to conceal the additions. Based on the early glimpses of the framed building additions, we feel confident that our design objectives for the building additions -  that they are visually and proportionally complimentary to the original row-house – should prove to be successful. Now that the framing of the building envelope is complete, the next objective will be to get the exterior doors and windows installed, the roofing membranes installed and the building wrapped with a weather-resistant barrier so that we can keep the moisture from entering the inside of the house. At that point the house can be considered dry on the inside and we can actually start turning our focus to the interior finishes.

Sustainability Matters: Air Barriers by Gregory Upwall

On September the 26th, UDC hosted a Green Building seminar on air barriers. This was the last in a series of seminars organized by DCRA. If you are interested in attending any, they will resume in the spring of 2019. These seminars are free and open to the public so they are usually well attended and presented by people who are passionate about their subject.

Air barriers are defined as a “material or materials assembled and joined together to provide a barrier to air leakage through the building envelope. An air barrier may be a single material or a combination of materials”.

Air barriers stop the uncontrolled flow of air through a building’s exterior envelope. Airflow is caused by air moving from high pressure to low pressure. This moving air carries both heat and moisture. It can carry 50 to 100 times more moisture than diffusion alone. This is a huge consideration in a climate zone with high humidity such as ours; here in DC an air barrier becomes an even more essential component of any wall assembly.

Air leakage through a building’s envelope (walls, slab and roof) is generally caused by one of the following three phenomena:

a) Wind – on the exterior of a building creates positive pressure on the windward side and negative pressure on the leeward side which draws air through the building.

b) Stack Effect – warm air rises and cool air sinks.

c) Mechanical Pressurecaused by supply and exhaust imbalances.

We’ve all had the experience of standing beside a window and feeling cold. This is a common air barrier failure, and is an example of infiltration which is often caused by poorly sealed joints between adjacent building components. An example of exfiltration happens when a positively pressurized building has holes in the wall assembly. The pressure forces warm air through the insulation and into the wall cavity which cools causing condensation within the wall cavity.

High pitched roofs allow for passive ventilation (through the stack effect). Attic vents, dormer windows, vented soffits create heat differentials that allow for warm, moisture-laden air to rise and exit the building and cool air to enter.

Historically, buildings were not constructed to be airtight. They were drafty and poorly insulated but that also meant they had a lot of drying potential. But construction has changed, moving from masonry walls to the modern cavity wall. Interior finishes became more sensitive to relative humidity, residential HVAC proliferated increasing the need for more airtight homes. In response, the International Residential Code (IRC) adopted requirements for a continuous vapor barrier in 2009 following the International Building Code’s 2006 requirement.

In traditional masonry buildings, the air barrier is the wall itself. The thickness of the brick, paint on plaster, taped drywall or just paint on a brick wall all act as air barriers. Still, air leakage is quite common in these buildings. It is very difficult to make these layers continuous around the entire perimeter of the building envelope. When retrofitting older masonry buildings a lot of extra attention and detailing are required to eliminate gaps or leaks within the air barrier.

With the addition of air barriers, vapor barriers and proper thermal insulation, it becomes very important to take into account the unique hydrothermal properties of masonry walls. Misapplications can result in harmful effects like spalling since brick is designed to dry to both sides. Also the historical character of the building or neighborhood should be taken into consideration in any retrofit of a masonry building since it could result in changes to the exterior of the building.

The most important thing to remember about air barriers is continuity! A simple rule of thumb is on a drawing you should be able to put your finger on the air barrier and trace it around the entirety of the building perimeter without picking your finger up.

 Air barrier products may take several forms:

Mechanically-attached membranes (also known as housewraps),

 

self adhered membranes (peel and stick).

fluid applied membranes

and spray applied foam.

and spray applied foam.

There are several methods that are commonly used to measure the air-tightness of houses and buildings today. Blower door tests are used to help identify problem areas. A blower door is a powerful fan that mounts into the frame of an exterior door. The fan pulls air out of the house, lowering the air pressure inside. The higher outside air pressure then flows in through all unsealed cracks and openings. These tests determine the air infiltration rate of a building.

Blower Door Test

Thermal Imaging

Infra-red cameras can give real-time thermal images of the whole or parts of your home. When the blower door test is paired with a thermographic inspection, they can show exactly where cold air is flowing into your home. These tests must performed by professional energy auditors. It is important to employ these measures intermittently during the construction process since these tools are the best way to determine whether the assemblies are air-tight. They need to be carried out during construction while the building envelope components are still accessible (so that problem areas/leaks can be identified and fixed).

If you are renovating, building an addition to your existing house, or building from the ground up, you should familiarize yourself with Table 402.4.1.1 in the International Energy Code(IECC). In DC the Green Building reviewers at DCRA will check to make sure that this table and the components of the air barrier are properly identified in the drawings when a building permit is under review.

Air sealing also makes a big difference to indoor comfort. If you have an older leaky home and don’t want to spend the money on expensive retrofits you might want to spend some time on simple air-sealing efforts like caulking around window frame perimeters and electrical outlets and checking wall/ceiling joints for leaks. Ensuring that windows properly lock and seal and adding door sweeps also make a big difference. Weather-stripping, the process of sealing around doors, and windows, is another simple and cheap way to mitigate leakage without breaking the bank.

In single family homes, leakage areas are typically found in these areas:

·       Recessed lights

·       Duct connections

·       Attic connection between top-plate and drywall in the interior of building.

·       Corners

·       Rim joists

·       Attic Hatches

·       Chimneys (without dampers)

·       Poorly built additions

·       Ill-fitting door and window frames (in older homes)

With an airtight house you will have lower heating bills, fewer drafts (i.e. more comfort), reduced chance of mold and rot because of moisture, and a better performing ventilation system. Now that’s a wrap!

DC Rowhouse Renovation - Rebuilding the Old Garage with Masonry & Steel by Gregory Upwall

View from the rear of the old garage when we purchased the house

When we purchased the house the one-car garage attached to the back was perhaps the scariest part. The side wall was severely sagging inward and the steel beam supporting the roof looked like it consisted of more rust than actual steel – both looked ready to collapse at any moment. Suffice to say that we felt no hesitation about tearing it down, and of course, we decided to re-build it stronger and better than before.

The masonry that we chose is a special “ground-face” CMU (aka: concrete masonry unit). A quick aside on CMU: most people call this material “cinder block” and think of it as common and ugly. We admit that the standard product that is used most commonly is not much to write home about. But the ground-face block is a whole different breed. First off, the cement and aggregates come in a range of colors (we chose a slate grey). And secondly, after the exterior faces have been ground smooth in the factory, this block is smooth to the touch and has the appearance similar to terrazzo. (We really like the product and hate it when people write it off as just cinder block…).

As was mentioned in our post about foundations (see Strengthening the original: part 1) we installed new reinforced concrete foundations around the perimeter of the garage. From the foundations vertical reinforcing bars (re-bar) were extended vertically up from the foundation so that as the block wall is built with the bars extending up through the hollow cells in the center of the blocks. As the block is laid the cells are filled with a solid grout mixture that encases the re-bar. Once the walls have fully dried they form a continuous structure from the foundation to the top, tied together by the steel reinforcing bars.

The roof of the new garage was another design challenge since it will also support the small walk-out deck off the kitchen at the main floor level above. We spent extra time detailing the construction of the garage roof to allow for it to step down from the interior floor level and still leave room for the decking boards. With this detail, the finished decking will be flush with the interior floor and the water-proofing below the decking will be concealed from view. To achieve stepped-down area on below the decking we needed to come up with the thinnest possible roof structure over the garage since we could not afford to sacrifice ceiling clearance in the garage below (otherwise there would not be enough ceiling clearance for my beloved 1990 VW Westfalia Vanagon).

After considering several options, we chose small 4” deep steel wide flange beams. These compact beams are very strong compared to wood framing and will provide the needed support for the decking above. Our contractor cut slots in the top of the masonry wall to set each beam into, then grouted them in place. Once the wood blocking was in place and fastened into the sides of the masonry wall the plywood sheathing was fastened to the blocking to create a rigid surface that ends up stabilizing the tops of the walls and tying them together into one cohesive structure.

view of the CMU blocks being set on the foundation with the steel reinforcing bars extending up through the hollow cells

View of the masonry walls under construction

View showing step-down in the floor over the garage that will allow for waterproofing to be concealed and deck boards to bet set flush with the floor inside

view from above showing the CMU block on palettes and the top of the foundation wall with the vertical reinforcing bars ready to set the masonry onto

view showing the this steel beams with the roof decking installed. The overall depth of the beams & decking is only 4.5”!

Section drawing through garage showing step-down in floor above garage and custom roll-up door at garage opening

For the back of the garage we will have a custom roll-up metal door fabricated and installed that will yield the maximum clear opening width and height for the garage door opening when fully opened. We are working with Door-Serv Pro, a garage door installer from West Virginia, to design, fabricate, and install the door. In order to maximize the vertical clearance at the garage door opening, we have decided to mount the coil for the rolling door above the garage mounted to steel posts. At the completion of the project we plan to build low cedar walls around the perimeter of the deck that will conceal the roll-up door housing.

Wall Section through custom roll-up door at garage opening

These details are all custom and require special attention, but they are necessary when building within a tight confined area such as this house. We feel confident that they will seem well worth all the effort once the project is complete.

DC Rowhouse Renovation - Strengthening the Original - Part 2: Floor Framing by Gregory Upwall

While the steel fabrication crew was busy installing the steel frame, our general contractor was able to work on reframing the existing floors. This is the other major type of re-strengthening work on a renovation project like ours. With the removal of the old interior walls, the original floor joists are effectively left unsupported in the middle and the distance that they “span” is now the full width of the house. Also as part of our new design, the stairway is being relocated from it’s original location to a new location along the alley side wall at the rear of the house. In order to move the stairway an entirely new opening in each floor has to be created for the stairway to fit into. All of this reframing was installed in accordance with the structural engineer’s framing plans and details.

In areas where the span distance of the original floor joists has been increased by the removal of interior walls the structural engineer has called for new wood floor joists to be “sistered” along the side of each existing joist. Sistering is a term that refers to connecting a new joist into the old joist by installing equally spaced screws through the side of the new joist into the existing joist for the entire length of the span. With the new joist “sistered” to the old the two effectively act as one stronger joist.

In certain locations (such as the perimeter of the floor openings for the new stairway) stronger wood beams are needed to carry the larger concentrated loads that occur from attaching the stairway and the adjacent floor areas. In these locations engineered lumber is typically used instead of standard framing lumber since it is stronger. The term engineered lumber is used to describe a variety of different products, but all engineered lumber products are made from wood fibers, veneers, or layers that are bonded together with adhesives in a factory. While the manufacturing of engineered lumber does come with a variety of factors that can increase it’s overall sustainability as a building product, a major advantage comes from the fact that engineered wood does not require the harvesting of large mature trees since the wood fibers used in it’s production are generally from smaller and younger trees. is For our project the engineer called for “LVL” beams (LVL stands for laminated veneer lumber) in these locations.

Removing a section of the old subfloor to create a space for installing the new beam in the floor framing

Measuring the opening for the new stairway opening

Lifting the new beam into place

Setting the new beam into place

The new beams forming the opening for the new stairway

Our framing crew had to remove sections of the old floor framing and cut “pockets” into the old masonry walls in order to insert the new beams. Once all of the new joists and beams were installed the original subfloor boards were removed and a new layer of “Advantech” floor sheathing was installed. Advantech is a great new plywood flooring and wall sheathing product that has greater moisture resistance, stiffness and fastener holding characteristics than typical plywood. The Advantech sheathing also has a “tongue & groove” profile along the edges of the panels allowing them to interlock for greater strength.

Now that all of the interior floor levels have been re-framed our contractor can turn their attention to re-building the garage at the rear of the house. Once the new garage is in place they will be able to start framing the new rear walls and then the new addition at the top of the house – very exciting!

A view of the newly re-framed upper floors (looking up from the 1st floor)

Floor framing and steel posts in place

A view below the 1st floor showing the new LVL beams, Advantech sheathing, and the new steel posts place

View from rear alley with scaffolding removed showing steel frame in place and new floor framing in progress

Sustainability Matters: Achieving Net Zero Energy Buildings by Gregory Upwall

On September 5th 2018 we attended the “Achieving Net-Zero Energy Buildings Workshop” organized by the New Building Institute (NBI) in collaboration with two DC Government agencies: DCRA & DOEE. The conference was held at The University of The District of Columbia’s impressive new student center and was very well attended. The conference started by emphasizing several troubling statistics to those of us in attendance as a reminder of why this topic is so important:

·       74% of carbon emissions come from buildings,

·       While the US comprises only 4% of the world’s population, we produce 15% of all greenhouse gas emissions.

Washington DC, the city we call home, has striven to be a leader in sustainability. In 2017, DC was named the first LEED Platinum city in the world. In this spirit, DC has committed to becoming a carbon neutral city by 2050. The built environment will play a critical role in mitigating the effects of climate change. Tommy Wells, the director of DOEE, opened the workshop by saying, “We don’t tear down a lot of buildings in DC. So new buildings must be rock-stars, and we need to learn how to retrofit the existing stock” in order to address global warming, climate change and issues of resilience.

So what is net zero, you might ask? The Net Zero Energy or Zero Net Energy building (ZNE) is defined as:  an energy-efficient building that produces at least as much energy as it uses in a year, when grid-supplied energy is accounted for at the source (including primary energy for generation, transmission and delivery to the site).

A study conducted a decade ago revealed that NZE buildings were possible in every climate zone in the US, and today there are many are examples across the country.

 Schools are currently the most common NZE buildings by type, followed by offices and multifamily construction.

 The main benefits of these hyper efficient building are: reduced greenhouse emissions, increased productivity and well-being of occupants, and Savings (Utility bills).

 

American Geophysical Union Building in Washington DC

 One of the case-studies presented at the workshop was The American Geophysical Union building, currently under construction right here in DC (200 Florida Ave, NW). This is a conversion of an old building into an exemplar of energy efficiency and modern amenities. The new facility will boast a solar array, a roof garden, a green wall that runs the height of the interior space, dynamic glass shading, radiant cooling ceiling panels and a sewer heat exchange to name a few. The USGBC will be holding tours of the building on October 24th so sign up!

 If you happen to be in Virginia, you might want to visit one of VMDO Architects’ pioneering high-performing projects. They gave a presentation on their award-winning net zero elementary school, Discovery Elementary, a recently completed in Arlington, Virginia.

 

Discovery Elementary School

For more examples, NBI has a database of North America’s most advanced energy efficiency commercial projects including zero and ultra-low energy projects.

So what goes into achieving a net zero building? All the presenters at the conference stressed the importance of engaging stakeholders and setting target performance metrics early in the design process (and to define them in the RFP). Once the design team is put together and everybody is on board, owners, occupants, and the design team members should come together to brainstorm potential strategies and technologies in what are called Integrated design Charettes. Iterative energy modeling is critical for hitting those targets. Monitoring building and occupant patterns will ensure that you not only design to net-zero but that your building actually performs at net-zero.

 In an effort to be sustainability leader, DC has set some ambitious goals for the future of our city. Clean Energy DC is DC’s Climate Mitigation Plan. It includes DOEE’s Sustainable DC 2032 climate and energy targets. By 2032 all new construction in DC will be (required to be?) Net Zero. Greenhouse gas emissions will be reduced by 100% by 2050. DOEE’s 50/50/50 challenge seeks to cut energy use by 50%, increase the use of renewables by 50% and reduce greenhouse gas emissions by 50%. DCRA will be adopting codes that mandate new residential construction to be net zero by 2020 and new commercial construction by 2026.  They also announced that in the coming months they will be introducing “Appendix Z” – an incentivized, voluntary net zero building program for residential and commercial buildings. These objectives together are conceived of as a grass roots effort, driven by the community to encourage early adopters to lead the way and prime the industry for the city’s net-zero goals. 

 For more information or technical and financial support, the DC government encourages residents to refer to the following resources:

DC Pace

DC Green Bank

Solar For All

DC Rowhouse Renovation - Strengthening the Original - Part 1: Foundations and Structural Bracing by Gregory Upwall

To determine the depth and size of the existing foundations test pits were dug.

Now that the demolition work is done, we have reached the point in the project where the new construction can begin - and the new work starts with the foundations. To most eyes, the foundation work can seem to move very slowly and the improvements can seem somewhat imperceptible and/or unremarkable. But to be sure, this phase is probably more important than any that will follow.

The depth and size of the existing footings are critical information for the structural engineer in determining whether new foundation work will be required to accommodate the new portions of the project.

If the foundation work is inadequate, the building could settle or shift, causing cracks and structural issues in the rest of the house. At the time that this house was built (nearly 100 years ago) the importance of the foundation work was not fully understood as it is understood today. Although the craftsman who originally built these houses were very skilled in the arts of masonry and carpentry, the foundations that they placed the buildings on were often inadequate compared to today’s standards. Fortunately, there has been much progress over the years in understanding the importance of well-constructed foundations. Foundations are to buildings what roots are to trees, they are the un-sung heroes of all good construction. For without them, the parts of the building that we see and occupy would be greatly compromised.

Remember that our project falls under what we would consider an “intensive renovation”, meaning that our goal is to replace and upgrade as many of the components and systems (to meet modern standards) as possible while retaining the original exterior walls and architectural features of the house. Since we have removed the entire rear wall of the original house to make way for the new expansion of the house, our structural engineer determined that most of the new fortifications were required in that area of the house.

Our foundation work was started by documenting the size and condition of the original foundations below the existing house. In order to see and measure the original foundations test pits were dug during the demolition phase and a soils report was prepared by a geotechnical consultant following the directives of our structural engineer’s drawings and specifications. Many readers of this blog may have heard of “under-pinning”, which is a term that is commonly used to describe the process of excavating below existing foundations in order to install new reinforced concrete foundations below them. This is usually done in order to create higher ceilings in low basement or crawlspace areas. This work can be very slow and expensive since the new foundations have to be installed in short segments, one section at a time. Thankfully in our case, since the existing foundations were low enough, we were able to lower the basement slab by a few inches without triggering under-pinning on this project, which was a big cost savings!

Foundations require digging, and since we are building them under the existing house, most of the digging must be done by hand. Our contractor and his crew actually broke apart and removed the original concrete floor in the basement and several inches of the soil beneath. All of the debris was piled up in the basement and then hauled by hand out of the basement into a truck. This work is painstaking and we have a great appreciation for the workers who do this hard work.

Soil and concrete had to be dug by hand and piled within the basement before being hauled away.

This photo shows the large pit dug at the rear corner of the original house which extends completely underneath the original foundation.

Once the concrete was removed, large pits were dug at both rear corners of the house for the two new large foundations required in these locations. Since we had removed the old garage and will be rebuilding it entirely, a trench was dug around the entire perimeter of the garage for the new garage foundations. The other places where new foundations were required are at several interior posts that will support the new stairway, and below the new/re-built rear wall of the house. Reinforcing steel bars (or “re-bar”) were laid in the holes and extended vertically prior to pouring concrete. After the concrete is poured, it “cures” over the next several weeks before reaching full-strength. 

Pits dug for new footings that will support the new stairway on the interior of the house.

New trench for Garage foundations (ready for concrete to be poured).

 

Structural engineer’s drawing showing new foundation and steel frame.

Trench for the new garage foundation wall ready for concrete to be poured (with steel re-bar installed).

 

New steel frame installed at basement level. The bolts have been set into the old brick wall with epoxy to create a stronger bond with the old brick.

Since the rear wall and portions of the floors were removed for the new stairway, the existing alley side wall was left unstable from the engineer’s point of view, so a structural steel frame was required in order to stabilize the wall and to stiffen the house against lateral forces (such as wind and seismic forces). Since the side wall faces the alley and is not against another rowhouse, it has increased bracing requirements which in this case were addressed by the internal steel frame. The steel frame was erected on site by a steel fabrication contractor and was fastened to the brick by a series of bolts that were drilled into the brick and set with epoxy to help them bond with the old brick. The steel frame has been designed to fit along the interior side of the brick and will actually be concealed behind the drywall once the project is finished. With the foundations and the steel frame in place the we can now turn our attention to the wood framing. The next step is reconstructing the existing floors to strengthen them and to create the opening for the new stairway……

View of new internal steel frame (looking down from 1st floor)

View of new internal steel frame (looking from rear yard)

View from rear alley showing scaffolding during installation of steel frame.

Steel fabrication contractor on site installing steel frame.

Steel fabrication contractor on site installing steel frame.

Steel fabrication contractor on site installing steel frame.

DC Rowhouse Renovation - The Demolition Phase by Gregory Upwall

View of interior after removal of walls and finishes

View of interior after removal of walls and finishes

The first phase of any renovation project is demolition, or more accurately, “selective demolition”. We typically prepare specific demolition drawings which indicate specific parts of the building to be removed in order to accommodate the new design. The removed components usually include walls, roofs, floors (or portions of them), windows, doors, cabinetry, plumbing fixtures, etc. For this project the demolition was significant. In order to accommodate the new rear addition, all 3 stories of the original rear brick wall had to be completely removed. To make way for the new 3rdfloor addition, the original roof will be removed entirely. On the interior all of the original walls, cabinetry, radiators, plumbing, electrical wiring and fixtures were completely removed. Even the original stairways were removed since they will be in a different location in the new design – this is what is typically referred to as “gutting” the house.

2nd floor after interior demolition

2nd floor after interior demolition

2nd floor after interior demolition

2nd floor after interior demolition

While the housing stock here in DC spans several centuries, the majority that come into our office as renovation projects were built between 1890-1930. Homes of this era can often contain old layers of lead paint and asbestos (which was used widely in many different building products from flooring to insulation to siding). These materials are hazardous and should be removed by professional abatement contractors who are trained in the proper removal and disposal of these materials. Another common concern comes from the very dust that is produced when removing old building materials since it commonly contains significant amounts of mold and other contaminants that can cause respiratory problems. These materials and conditions should not be overlooked and proper measures should be taken during the removal and disposal of materials that are to be removed from the building.

Another consideration that we recommend to our clients during the demolition phase of the project is the opportunity to salvage certain materials that are being removed for re-use or recycling. This is commonly referred to as “de-construction” and can help to divert significant amounts of waste from ending up in the landfill. It is generally advisable to consult with a de-construction contractor prior to the start of demolition work in order to identify which materials, if any, are candidates for salvage. In most municipalities today construction waste is required to be sorted and hauled to different facilities. Metals such as copper and steel are good candidates for recycling. The goals should always be to a.) dispose of all materials properly, b.) salvage or donate any worthy materials for re-use, and c.) minimize the volume of material that will end up in the landfill.

Another concept that is worth mentioning whenever we discuss demolition is that of temporary “shoring”. This refers to any temporary measures or construction that will be required to support the building in the time between the removal of the existing components until the installation of the new structural components. Shoring often includes temporary posts and beams that must be securely installed by the contractor prior to removing portions of the existing building. In this project since so many walls are being removed and new openings are being created within the walls and floors (for new windows and stairways accordingly) it was necessary to install a temporary bearing wall at the basement and 1stfloor levels in order to support the existing floor framing during construction.

View of original stairway (before it was removed)

View of original stairway (before it was removed)

Demolition often goes quickly once started so this is often a time when it appears that a lot of progress is being made, which can be very satisfying (especially after months of waiting for permits to be approved). It can be both scary and deeply satisfying to see the old, worn and dilapidated parts of the building being removed to make way for the new construction to come. This is also the phase when you get to see the real “bones” of the building and to identify areas in need of repair. This is generally the time when we remind ourselves of the common saying  that “it’s going to get worse before it gets better”.