Back wall (before cleanup)
Now that the back porch stairs are out of the way, the next step toward getting spray foam installed is installing the back sliding door. My initial plan was to install the new sliding door first and then remove the existing back door, but the two wound up happening concurrently, since there wasn’t anything left to hold the sheathing on. We started by taking off the siding on the outside (fortunately only one layer here). I started and Sarah finished it up.
Sarah removing siding
Once the siding was down I cut back the sheathing, which is when we realized we needed to take out the back door. Sarah did that while I ran to the store and picked up some supplies. We are fresh out of reclaimed 2x4s that are over 10′ tall, which is what we needed to re-frame the wall. That meant I needed to get 12′ 2x6s and cut them down on the table saw to the right thickness (~ 3⅞”).
With the back door gone and all of the sheathing removed, I framed in studs where the old door had been, sistering two studs next to each other to support the cripples above the door. Once that was in place I cut out the studs on the other side to make room for the new door.
The first step in framing the opening was to build a sill, since the balloon-framed house has a sill several inches below the floor. I sandwiched a piece of 1″ thick poly-iso foam between two cut-down 2x6s. That later proved problematic, since the screws that go into the bottom of the door lined up with the foam, so they don’t have any holding power. Ideally I would have put in wood blocks that lined up with the screws, but I don’t think it’s going anywhere. Next I added jack studs, king studs and a header, also sandwiched with foam. Finally I installed sheathing, using reclaimed boards from the house instead of plywood or OSB. It might be cheaper, but after all the screws I used, I’m not so sure.
So far this is all fairly standard. At this point the job gets a bit more complex, as we’re planning 2″ of rigid foam on the outside of the house. To account for this, all the doors and windows sit 2″ further out than normal so they sit flush with the outside, which makes for a simpler flashing detail.
Dean came over to help with the installation, starting with adding the 2×4 furring that surrounds the door. At the bottom we have the existing porch sill, so we cut back the porch flooring and built up the sill to the level of the door. Hopefully when we replace the porch that won’t cause issues. If not, we’ll deal with that when the time comes. Once the furring was on we carefully wrapped it with house wrap. When we eventually re-side the house, the wrap around all the windows and doors will get taped to drain wrap on the rest of the house. For now we left the rest of the sheathing exposed, since it’s inside the back porch.
Adding exterior foam and flashing tape
The next step was to put ½” foam over the 2×4 furring. The 1½” thick furring plus the ½” foam will sit flush with the 2″ of rigid foam. I then used the same flashing detail I’ve done on the other windows and doors, putting 4″ Weathermate tape down the side corners and a plastic sill pan at the bottom. I added a piece of sill gasket under the drain pan to further seal the bottom of the door before we add caulk.
Sliding door installation
The last step was to tip in the door and screw it into place. We wound up cutting custom wood block shims on the top and side to secure it properly, but everything was level and plumb for a change so it went fairly smoothly. I still need to add more Weathermate tape to the outside at the top and sides to complete the waterproofing, as well as Great Stuff and backer rod on the sides and top, but since this is in the porch there’s no particular rush.
Derek tries out the new door
The door looks great, and even though it only opens onto the enclosed back porch for now, we can tell it will bring in lot of light once the porch is gone. The relocated light switch is now pretty inconvenient, but I’m sure we can deal with that for the time being. Now we can finish up the fire blocking and get to spray foaming!
