Structural Issues at the Restaurant and Apartment Project
This week, I was working on developing some demolition drawings and minor new construction for project 3x30 – restaurant and apartment for my friend. At our meeting a few weeks ago, we decided to remove all of the interior partitions on the second floor and the exterior wall that encloses what used to be a light well. Due to the existing condition of the building, I decided to head out for another site visit to get some more detailed information about the structure of the building.
Existing Architectural Drawings
Just like any renovation project, I asked my friend to obtain the existing architectural drawings for his building from City Hall. So he made a few phone calls and they were able to find a small two page set that was either submitted for a renovation and addition back in the mid 1900’s. Needless to say, the drawing set was not helpful and it looked like a two minute napkin sketch.
Basement and Ground Floor Structural Issues
Once we arrived at my friend’s building, we walked through the small basement and first floor to investigate the existing foundation and primary supports. If you look at the photograph below from an earlier post, you can see the condition that the space was in when my friend purchased the building. The 2x4 stud wall with vertical pipes at the center of the space used to be a structural wall that held up the floor joists of the second floor.
The moment I saw the splintered 2x4 at the left of the photo, I immediately knew that the building wouldn’t last another month. With more investigation, you can see that the 2x4 horizontal supports below the joists were cut so that a drain pipe could be installed. This led to a significant slope towards the center of the building on the second floor. There was also a significant amount of water damage at the back of the building where the old waste pipe cracked.
As we continued investigating the space, we found that the floor is composed of wood joists and concrete planks that appear to have been cast in place. We also found that the shear wall is supported by a concrete foundation and the drain/water pipes follow this foundation. On the other side of the shear wall, there’s a large hole in the floor from a structural failure.
In a search for answers, we decided to investigate the existing floor joists for the ground floor and discovered 2x11 joists that were notched and inserted into the old CMU and brick walls. Since the building has been abandoned for some time, the constant moisture and changes in temperature weakened the wood and eventually led to it collapsing.
Second Floor Structural Issues
With a better understanding of the structural issues on the ground floor, we made our way to the second floor to continue our investigation. We realized that the sloping wall adjacent to the light well was from a shift in the floor joists as it sloped towards the failing structural shear wall on the first floor. The exterior walls enclosing the light well also contributed to the floor joists sloping towards the center of the building because a portion of the roof load was distributing down these walls, which are attached to the floor joists.
With some additional investigation of the light well, we discovered that it was covered by the existing roof. We decided that the light well will be demolished and the opening in the brick wall will be filled. To bring natural light into the space, we’ll put a large skylight where the existing light well is located. We’ll also remove the roof joists that currently bear on the wall of the light well and we’ll replace it with joists that bear on the new infilled brick wall.
The last major structural issue that we discovered on the second floor was that the roof joists were beginning to slope towards the back of the building. In the first photograph, the joists are just starting to cross one another instead of being parallel and level. This is because of the shifting floor joists below that have been dropping from the compromised shear wall on the ground floor below. The joists in the bathroom are also collapsing between the vent stacks, which caused a tear in the roof membrane.
Exterior Wall Construction and Insulation
Due to the age of the building and the old construction technology, the exterior walls are two wythes thick with no air gap. The interior spaces were lath and plaster, which was placed over thin furring strips. So we decided to build typical 2x4 walls along the exterior shell of the building to add some insulation to the spaces.
With a better understanding of the building, we’re now calculating column and beam sizes that will replace the old shear wall and be anchored to the existing concrete foundation. Once the columns and beam are in place, we’ll have contractors move into demolishing the interior partitions on the second floor, the exterior walls at the light well, and replacing all of the 2x4 shear wall supports at the center of the building with metal studs. We’ll also have the contractor fill the brick wall, restructure the roof, and have a new roof installed with skylights.
However, it will take lots of time and finances to get to those next steps. We’re definitely looking forward to moving the project along and getting the building in a stable condition soon!