Insulating a difficult-to-insulate house
October 18, 2021 10:17 AM   Subscribe

We live in a virtually uninsulated 1905 Chicago worker's cottage (if you aren't familiar, think of a brick Cape Cod with the doors on the short end). We'd like to investigate insulating the roof with rigid foam sheets above the roof deck, but we're having trouble finding contractors who will even talk to us about it.

Our goals are making the thermally terrible second floor more comfortable in summer and winter (the second floor tends to be >90 F on sunny days in the summer and some rooms can dip to 40 F overnight in the winter) and reducing the house's carbon footprint.

The asphalt shingle roof is in decent condition but is probably 15+ years old, and there are a couple of other items on our to-do list we could roll into a roof replacement (replace aging flashing, fascia and gutters; demolish a now-unused chimney below the roofline; penetrations and mounts for rooftop solar panels), so we're interested in moving the thermal envelope to the roofline with above-the-sheathing rigid foam (as described here or here). But we're having trouble finding a Chicago-area contractor willing to do this, let alone one with experience.

So far, the quotes we're seeing fall into two camps: "rehab the top floor and add spray foam insulation between the rafters after gutting it to the studs" or "demolish the existing roof, add a bump-up addition, insulate the addition's new roof with spray foam." These both involve a significant amount of work we're completely uninterested in (a gut rehab/addition) just to add insulation. They're also probably outside our budget, and are additionally unattractive because they seem likely to result in a house that's unliveable for days or weeks--our bedrooms and sole bathroom are all on the top floor.

Moreover, my general philisophy of working with contractors is "don't ask them to do things they haven't done before or aren't comfortable doing," so we're really interested in finding someone who is actually excited by this sort of job. But it seems like we're striking out over and over again, and it's clear that everyone we've talked to so far is offering to do work that's squarely within their comfort/profit zone, the same thing they've done dozens or hundreds of times before. I'm also fairly sick of dealing with contractor FUD, stuff like "you shouldn't do this because insulating your house won't reduce your bills enough to break even [so you should renovate/add living space and a second furnace at the same time]," "that kind of insulation is illegal in Chicago," or even "insulation like that doesn't work in our climate"). To be clear, I don't think any of these things are true--well, maybe the first one, but our goal is to reduce our carbon footprint and maybe make the house more comfortable, not quickly recoup our investment via lower bills. I'd note we encountered similar BS responses while getting quotes for other new, unfamiliar projects: "Air-source heat pumps don't work in Chicago winters, so we don't install them," "you need at least 2000 square feet of open space in your basement for a hybrid electric water heater, so we can only put them in larger houses," etc., etc.

A couple of other notes: Our roof is Monopoly house-simple (though we do have a dormer). We know this makes the roof/fascia unattractively thick, and we aren't restrained by any sort of historical district, HOA, or sense of architectural or aesthetic decency. We're probably already way past the point of diminishing returns with air sealing and other cheap-and-cheerful measures. Likewise, the kneewall spaces have been insulated (fiberglass batt and loose cellulose) to relatively little effect. Longer term, we're interested in switching to all-electric heat, probably heat pump mini-splits with some sort of radiant backup, also for decarbonization reasons.

So, to turn this into a question: we're interested in specific contractor recommendations, but since that seems unlikely, if you dealt with a similar situation (doesn't have to be a roof, or even insulation, any green building retrofit will do) somewhere else, we'd like to hearing about your experience and strategies for locating contractors. And, of course, if you can make a compelling case for the bump-up addition, or explain why this actually is impossible/"illegal" in Chicago or anywhere else for code or climate reasons, I'm listening.
posted by pullayup to Home & Garden (11 answers total) 3 users marked this as a favorite
I notice that you link to a site that discusses preservation of these Workers' Cottages; have you reached out to them to see if they have a recommendation?
posted by EmpressCallipygos at 10:23 AM on October 18, 2021

Response by poster: One quick response and I'm out:

I believe the Chicago Worker's Cottage Initiative is fairly new, and I think all they can offer at this point is a referral to the older and more established Chicago Bungalow Association (which was, I believe, their inspiration).

The Bungalow Association's information is limited to referrals to local energy efficiency programs, which we suspect are how the air sealing and kneewall insulation were accomplished by a previous owner.
posted by pullayup at 10:31 AM on October 18, 2021

Find people via Green Building Advisor? Post there and hope to get lucky?

(ps they are right about HWHP: they make the room cold. If you put them in a room you are heating, you aren't getting any efficiency bonus. In a big unheated basement at least they can steal some heat from the ground.)
posted by flimflam at 10:52 AM on October 18, 2021 [1 favorite]

I suggest approaching the manufacturers or distributors to see if they can recommend contractors or know of people who install their products. They've got an incentive for you to buy so they may well be able to help. Smaller and more local manufacturers/distributors are more likely to be able to help.
posted by plonkee at 10:59 AM on October 18, 2021 [1 favorite]

I can't directly answer your roof question, but I've lived in - and gut rehabbed - a late 1800s workers cottage in Chicago, so I'm very familiar with that type of building. One thing that I'd recommend if you're doing a new roof - regardless of what else you do - is a well insulated whole house fan. It goes a long way to making early and late summer more comfortable at much lower power usage. Being able to exhaust hot second floor air into the small attic crawlspace and then out the attic vents, or even directly through the roof if that's all you have really helps when it's ~75 outside but 90 up on the second floor.
posted by true at 11:40 AM on October 18, 2021 [1 favorite]

search: chicago passivhaus retrofit contractors [ articles on several recent chicago projects with companies involved]

^ while you're not asking for Passivehaus, there are a lot of Passiv people who do retrofit, and they understand insulation deeply.

This page has a list of Illinois Passivehaus contractors:

I know from my own work here NZ that many builders are not interested in retrofit, and will try to push new build / major changes.
posted by unearthed at 11:43 AM on October 18, 2021 [1 favorite]

The problem with your idea of above-the-sheathing rigid foam is finding a way to make that layer of insulation continuous with whatever is going to be in the walls. Here's a page with an illustration showing how that can be done.

To achieve the effect in that illustration, your best bet might be to work with two contractors: (a) a roofer to apply the rigid foam and a new roof, and (b) a spray-foam specialist to add foam to the underside of the rafters and the inside of the wall cavities to achieve that continuous envelope.

This leaves the existing knee wall and ceiling insulation irrelevant of course. But if you go a different way in which you do rely on that insulation, or if you want an interim fix to make it more effective, understand that fiberglass kneewall insulation must have a solid layer behind it, which can be rigid foam, plywood, etc. Without that, the cold air in that kneewall attic just circulates straight through the fiberglass and negates any insulation value it may have. Illustration. AND, there must be an air stop below the kneewall between the joists that prevents cold air from migrating through the cellulose and into the hollow space below the floor of the second floor rooms.
posted by beagle at 2:16 PM on October 18, 2021

Response by poster: Responding to beagle:

The rub is our double-wythe masonry walls are currently 100% uninsulated (other than the R value and thermal mass of the brick itself, but we're neglecting this).

In a second phase we'd like to add rigid foam insulation to the exterior (per this, or this). At that point, the connection between the roof and wall insulation would be outside the masonry wall, similar to what I've heard referred to as a "chainsaw retrofit" (because on a frame building, you chainsaw off the soffits and have contiguous insulation/thermal envelope up the outside of the wall and over the roof...but this building never had soffits or soffit vents, the roofline just neatly intersects the top of the wall; I kind of assume the interstital space between the two courses of bricks serves a similar ventilation function to a soffit vent, but I'm honestly pretty ignorant about how 115-120 year old houses work). I don't think the fact that we don't currently have adequately insulated walls means insulating the totally uninsulated roof is futile, though.

But, like, this is a conversation I'd love to have with a builder. And we haven't even gotten to a place where we can do that.
posted by pullayup at 2:34 PM on October 18, 2021

Another idea: hire someone with the knowledge to be your liaison with any old local contractor. See this GBA story. The BSC consultants served that role. That person doesn't need to be a local.
posted by flimflam at 4:45 PM on October 18, 2021

Your plan sounds good. The way to have a builder take it seriously might be to have an engineer do up formal construction drawings for it, showing how it can be done in several phases. This would cost something (maybe $1,000?) but in the long run would save you money, because the builders would know precisely what you want and could bid accordingly. Also the engineer might come up with some wrinkles you're not thinking of, to improve the outcome.
posted by beagle at 8:34 AM on October 19, 2021 [2 favorites]

For what it’s worth the things the contractors are telling you about your proposed renovations aren’t entirely wrong (source - I am an architect). Heat pumps don’t perform effectively below 32 degrees - they do work but they work much harder to produce less heat. I myself have a heat pump in the PNW and I can say from direct experience it has to try REALLY hard whenever the temps are below freezing. Personally I would not recommend one in Chicago, given the climate - I don’t think you’d be happy with the performance.

For the roof insulation, while you can add rigid exterior insulation as a retrofit, it’s not something I see commonly done. The things your bidders are suggesting (spray foam from the inside) are far more common retrofit solutions because they generally are much simple to install to an existing building and perform quite well. Their point about interior renovations is just that once you take the drywall off, changing around studs and MEP systems that live in the walls becomes dramatically less expensive if you had any desire to do it because drywall installation is fairly expensive due to the quantity of material and labor involved. Obviously you’re not required to do this if you don’t want to though.

I think I’m unsure why you are so committed to exterior rigid sheets for your roof? While exterior insulation does perform better overall (it 100% should be the standard for new construction), it won’t be nearly as effective if it’s not continuous with exterior wall insulation, which it sounds like is infeasible for you to install. Is there a strong reason why you wouldn’t just do batts or spray foam between your rafters? If you need a new roof they could install it from the exterior if you need to replace the roof sheathing, if you’re looking to avoid interior work. There are also blown in insulation options that perform well and require minimal cutting and patching to install.

Long story short - while you can do what you want to do, neither of the projects you’ve noted are something I’d recommend as an architect. They are legitimate solutions, but from what I’ve heard i don’t think they’re going to do what you are hoping they’re going to do and there are better ways to achieve your goals (which your contractors are recommending).
posted by annie o at 7:22 AM on October 20, 2021 [2 favorites]

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