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.