Sagging Addition in Rental Property

So….we bought our third rental property and planned to do the standard cosmetic and insulation upgrades. However, we had a slight ‘slant” in the kitchen and began to wonder how to fix the problem. To begin we identified that this section was not accessible from the basement; and therefore was an addition to the main house/foundation. We tried to get underneath from the outside and quickly discovered that the small addition sat on a wooden foundation (much like a deck). The 4×4 posts in each corner had begun to rot and sag downwards. This was causing our slant and needed to be rectified before we rented the home to someone.

Let the FUN BEGIN!

I call this face….”I’m not happy about how big this project became.” We see it often.

Me and my business partner Caleb discussed different “hacks” we could perform to make this job easy. We flirted with the idea of using an automobile jack outside at each corner to add a new 4×4 for support. This way no demolition would be needed on the interior. However, it would not allow us to solidify the floor joists and that seemed silly given that we didn’t want a tenant to fall through our kitchen floor.

We decided to cut a small hole in the sub-floor and take a look at the joists. They were in semi good condition for being 50 years old, but they seemed undersized for the job. We wanted to make sure that this project was done correctly and ripped up the floor to expose our work area.

The strategy here was simple.

First; support each corner with a new 4×4 post. I hand dug the dirt floor until I reached the brick “foundation”. I then cut a slightly oversized treated 4×4 and fit it into position using a lift up and hammer in method. The bottom would rest on the bricks and the top would support the wall section.

Second; We added new 2×6 joists along each existing joist. This method called “sistering” would insure that the wood holding up our tenants was sized correctly for the job (probably oversized).

Third; We placed new cross supports running perpendicular to the floor joists. These ran underneath the entire length and were supported by 4×4 posts sitting on concrete blocks.

Fourth; We changed the crawlspace area to be part of the home’s insulation envelope (previously it was an un-insulated and un-vented crawl space…bad!). I used 2″ rigid foam along the exterior walls. It is sealed with spray foam at all the seams which thoroughly locked the rigid foam into place. These foam panels were purchased from Lowes in 4’x8′ sheets and cost about $40.00. We required two sheets to fully insulate and seal the crawlspace walls. Further, we required 4 cans of spray foam purchased for $4.50 each. I then attached R-13 batt insulation to cover the foam and further prevent heat loss from the crawl space area to the outside. My goal is to keep the crawlspace dirt floor from becoming frozen and therefore prevent “flexing” between the seasons. Insulating the crawl floor would be the correct way to bring this fully inside the envelope. However, two of our supports are not dug below the frost line and therefore they would naturally change height as the ground changes between hot/cold. This is why the floor is now a big heat sink. Bad for energy efficiency but hopefully the home condition will keep this area at a steady temperature throughout the year.

Fifth; I went back outside and changed the gutter run off locations. The original addition had rotted posts because water had made its way underneath this area. I tried to insure that rain water directed itself naturally away from the home. Included in this strategy is concrete pavers added around the exterior that are sloped/graded away from the home.

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