Category: Plans and Permits

We met with our architect yesterday and signed the paperwork so it’s official. We talked about the plans and started working some things out about how we’re going to renovate and live here at the same time. In an earlier post I mentioned that we’d decided to go with spray foam insulation instead of building a double wall so that we don’t lose square footage and still get a high R value. We’re also anticipating having to re-sheath the exterior, meaning we’d pull off all of the existing wood planks and put on new plywood, because they’re 115 years old and are probably water damaged and rotted. We don’t know this for certain, but we’re assuming the worst, given the condition of the rest of the house and the parts of the planks we can see, and we don’t want to assume it’s in good shape and then be surprised.

According to our architect, normally the exterior is done first.  We would replace all of the planks with plywood and then spray foam onto the new sheathing. It means everything seals nice and tight, plus we can install the new windows and flash them properly. However, it raises some problems. In order to re-sheath and re-side the exterior, some other things need to happen first. We’re planning to remove the second floor bump out, eliminate and move some windows on both floors, add sliding doors on both floors where the deck will eventually be, as well as remove the enclosed back porch and put on a front porch. We’d rather not make a mess of the second floor while we’re living in it, but even allowing for that we need to keep the back porch because it will have the only set of stairs once we’ve ripped out the front stairs, and we can’t replace the sheathing and siding while there’s a porch in the way.

That leads us to think it would be better to gut and finish the first floor first, followed by the second floor, and then redo the exterior. That’s been our intention all along since it gets us into the first floor sooner and pushes back the cost of re-siding for a few years. Unfortunately, if we spray foam first it will bond to the existing planks, making it impossible to remove them and re-sheath later. I spent a lot of time thinking about the logistics of trying to do the exterior first. Maybe we could replace the sheathing and siding one floor at a time? That doesn’t address the problem with the back porch. Finally I gave up and went back to the original plan.

When we demo the interior walls we’ll be able to inspect the planks and see what shape they’re in. If they don’t need to be replaced, then we don’t have anything to worry about and we can spray foam the interior. If they do need to be replaced,  we’ll put 1″ thick sheets of rigid foam insulation into the wall cavities against the planks, and then spray foam over them. That way the spray foam will bond to the rigid insulation instead of the planks, so we can still replace them later. It may not be a perfect solution, but it’s the best one we’ve come up with.

Model: Back of House

I’ve been dragging my feet, but we’re getting close to a decision about an architect. We’re waiting on a response to a question, and depending on the answer we’ll hopefully have it settled. The quotes were a lot more than we were expecting, but at this point it looks like we’ll be pursuing the Chicago Green Homes program. The price difference isn’t tremendous and it will likely pay for itself eventually. Also, we can’t go back and get it later, so if we’re going to do it now’s the time.

We haven’t spent a lot of time on the basement as of late. Last night I went through some more of our lumber pile, removing screws and nails so we can use it later for temporary supports, forms, and blocking. It’s really slow going and I’m questioning the value of it given the amount of time it’s taking. Even once we’ve got the boards cleaned up, nearly all of them will need to be cut down because one end is rotten, plus they’re mostly short, as in less than seven feet long.

This morning when I got up the house was about five degrees colder than the thermostat, which said the heat was “on”. I visited the boiler which was emphatically not on. The pilot was lit and everything looked normal. It occurred to me that yesterday I had flushed out the sediment, something the sharpie instructions  on the side of the boiler calls for “twice weekly” and I do more like “bi-weekly”. When you drain water (and sludge) the boiler refills from the cold water line. There’s a low water cutoff that had given us trouble before so I literally flicked the thing with my finger and the boiler kicked on. I honestly didn’t expect that to work, but I still got a bit of satisfaction and amusement from it. It was straight out of a movie.

Bump Out

One of the things we’ve been talking about for a while now is what to do about the second floor “bump out”. Despite our initial impressions, a survey of the attic shows this to be part of the original structure. Despite this, my inclination is to lop it off. Over the years it’s developed leaks and sags, and sealing it properly seems like a challenge. In addition, it goes right to the property line on the south side of the house, which will prove a challenge for getting zoning and permit approval to keep it. Its proximity to the neighbors house resulted in a broken window last summer during a hail storm because it ricocheted off the nearby pitched roof. While it brings in a lot of light in its current form, the floor plans for the second floor I’ve come up with put the bedrooms at the front, making it somewhat unnecessary. It adds a whopping 27 square feet of space, so it’s not exactly a big contributor to the size of the house.

However, my recent change of heart on double walls has raised the question of the importance of square footage. We’re eventually adding a finished attic, so we’re definitely not suffering for want of space, but keeping it with a bit of rearranging of room layout would increase bedroom sizes noticeably, and in the current plan they aren’t exactly generous. One of the architects noted that if we remove it, the city would never let us put it back, something that doesn’t really sell it for me, but it’s worth contemplating that reducing the size of the house in any dimension isn’t necessarily a smart move. Like so many other decisions, it isn’t an easy one.

Double Wall Section

We’ve met with several architects and we’re waiting for a couple of proposals. One of the common themes in talking with them is the suggestion that we should insulate with spray foam. We’ve been talking about building a double wall with rockwool insulation, and the architects are almost unanimous in saying that spray foam insulation in the walls is the way to go.

Now they are the experts, but I come back to the reasons we planned to do this in the first place: the insulation value of the double wall with rock wool is 25% better and costs less than half as much. There are other factors though: spray foam is an air barrier, and it would seal up gaps in our leaky old house. Not having to build the double wall would save a lot of work plus we wouldn’t be making an already narrow house even more so. On the other hand, we’re planning to replace the exterior sheathing after we remodel the inside, so using spray foam would mean adding some new layer to the inside before applying, so we don’t break the foam seal when we remove the exterior boards. When we do the exterior we’ll be using a house wrap and taping all seams, which should seal the house nicely, without the expense of spray foam.

I’ve been referencing BuildingScience.com, which has some R-Value Recommendations for walls based on climate zone. In Chicago, which is Zone 5, they recommend an R-30 wall. Closed-cell spray foam yields an R-value of  6 per inch. Filling the 3 3/4″ thick outside walls would give us R-22.5. In addition, we’re planning a 1″ layer of insulation on the outside of the sheathing, which will give us another R-4. Adding the minimal contributions of drywall and sheathing and we’re up to about R-28. Compare that to the double wall, as in the diagram. Each 3 1/2″ thick batt of rockwool provides R-14. Adding the exterior insulation and the rest of the wall brings that total to R-33 while also reducing thermal bridging. Of course, there’s another option that’s kind of the worst of both worlds: do both. We could spray foam the outer wall and then still build the inner wall, insulating it with rockwool. The insulation value would be a stunning R-42, but carries the highest cost by far as well as the most work.

Deciding the right course can often be tricky, but in this case it can be done with straight economics. Using houses on the market in our area today I can estimate the value of the square footage I would lose with the double wall. Then I subtract the extra cost of spray foam and the increased cost of heating and cooling. The numbers come out in favor of spray foam. So despite my inclination toward the double wall, I’m open minded enough to see the better decision and change my mind.