Insulating a Brick Veneered Home – 4a – and “on my own”
Hi Guys,
I’m in the process of renovating/adding an addition onto my 1986 brick veneer home (standard size brick) home in Westchester NY (4a). My GC is very “old school” and my architect is essentially his great uncle in terms of “experience”. Both of have basically told me we’ll do whatever you want, but not willing to engage or honestly provide any opinions on how to do this right, or how they would do it. Architect is in the south of France now and says as my plan shows, it has adequate insulation. It says fully insulate walls and ceiling, and mentions fiberglass, my contractor says I need details…so uh trying to put this all together my self, here it goes.
Wall: Now framed out and already have bricks being relayed to close in the original garage doors. There is wood and tar paper and then about 1″ gap between that and the brick itself, here and there some mortar in between it. I’m not going to have any exterior sheathing as i’m matching the rest of the home and would start adding all this extra thickness, that and half the wall is already bricked. Inside is 2×6 framed walls. I’d like to use HD fiberglass but not sure if I should use faced, or just have them use unfaced and do a single plastic sheet across the entire side taped all appropriately as a vapor barrier and drywall over that. I want them to do a “air seal” package prior to doing the insulation, so as long as that’s all done well, and plastic is done on inside wall, would that be best practice? Should I do cut/cobble with foam board then fiber or roxul, something else instead? Opposite back wall is siding (3 sided brick veneer house), it has the paper type wrap on outside and then siding, no sheathing or anything. Same deal? Other 2 sides are interior wall so not concerned there.
Mansard Roof: Inside I have essentially a cathedral style roof with plenty of room to hit R49, no skylights or anything, full sofit around whole roof, but no ridge vent interestingly. I was thinking of doing closed or open cell foam but there are so many variables and read a ton on here about vented/unvented etc, so without an actual pro I feel like i’m risking too much getting it wrong, plud i’m honestly scared of spray foam :). I’m having my HVAC ran up and resting on the joists (just supply ducts, the air handler is next door in mudroom). Plan is to run the trunk and ducts up there, R8 wrapped ducts, then have them lay it directly on a 2″ rigid foam board, and create a 2″ rigid foam box around the entire ducts sealed with tape, then have them wrap the whole thing in R30ish on top but basically get me over R50 around the whole thing to try and combat extreme temp changes being in an uninsulated attic. R49 batts in the ceiling joists and sides coming down from the ridges. Sides running up from soffit to ridge will be about 2-3″ off the roof deck to allow the air to come in from soffits and up, and because we are redoing the roof shingles they’ll create a ridge vent on top to allow the deck to breath. Some would say just add the rigid foam exteriorly under the shingles if i’m doing that but I want to keep all the roofs and thicknesses the same (which hopefully isn’t a dumb idea). Again the question is, and the contractor said he has done this before, is do plastic underneath the fiberglass before drywall goes down as a vapor barrier but also to create a uniform airseal across ceiling.
Does all of this sound ok? I’m honestly so frustrated that I need to figure this out myself, but I see they’re just doing this to protect themselves – as long as it meets code, and it’s my instruction, they aren’t obligated – great model.
In conclusion, vented unconditioned attic/space, brick with breathable walls, plastic on the inside of walls and ceiling before drywall, allow everything to “breath” one way out? If I need to reverse this on walls and do sheathing against outside so that all breathing/drying happens to inside please note.
As always I appreciate everyone’s opinion and expertise on this forum, you guys are awesome.
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Replies
Alternatively on the roof/ceiling, I think i'd like to do this with either foam board around ducts, or spray foam 1.5-2" and cellulose instead of the fiberglass batts, I get the whole thermal bridging loss by just doing joists, so cellulose filled is probably going to be much better for the ceiling...
"Inside I have essentially a cathedral style roof"
Do you really mean cathedral? That means the ceiling runs parallel to the roof, the conditioned space extends to the underside of the rafters and the insulation runs along the underside of the roof. There is a GBA article, "Five Cathedral Ceilings That Work," that covers how to insulate them. But it sounds like you really have a vented attic?
"Architect is in the south of France now and says as my plan shows, it has adequate insulation."
I guess it depends on what the definition of "adequate" is. The 2021 IRC requires in Zone 4 that exterior walls have either R20 of cavity insulation plus R5 of continuous insulation; OR R13 of cavity insulation plus R10 of continuous insulation; OR R15 of continuous insulation.
Simply filling the 2x6 cavities with high-density fiberglass doesn't meet current codes. However, your jurisdiction may not have adopted the latest code, or may not require it for renovations. I assume that when he says it's "adequate" he's saying the local jurisdiction will accept it. If so, it's your call as to whether you want to meet current code.
The simplest way to meet current code would be to put 3/4" of Polyiso insulation between the studs and the drywall on all exterior walls and fill the cavities with R-20 or better. If it's carefully sealed it would provide a good air barrier and vapor barrier. It means the drywalls guys have to use longer screws, which is more work for them, and complicates the placement of outlet boxes and the trimming of windows and doors. It may also complicate the hanging of cabinets.
Hey thanks for the reply, looks like my town is using NY R402.1.2 , zone 4 says R20 or 13+5, so I think im good with R21 HD fiber.
Regarding the cathedral ceiling I don’t think that’s the right term for it. It’s a mansard roof and inside is now raised like rest of my rooms in house that have this high pitched and squared ceiling. So yea not cathedral now that I write it out 😆. Here’s a picture.
Does the air sealing with poly on inside make sense with this setup for both walls and ceiling/roof?
Thanks again
Why not just use faced batts?
Westchester is basically Zone 5. I'd use as much insulation everywhere that I could. It can get cold as hell there and you know it. I lived there my entire life.
Air sealing is critical to any good insulating job. Contractors aren't particularly worried about it, but you should be. Either advise them or all the subs that it's important to you or take it upon yourself to go around the house and make sure everything it truly tight, with caulk, seam tape and canned foam. Your town has an ACH number to meet their code. Find out what that is, find out how it will be measured (blower door test probably) and develop a plan with your GC to achieve better than that with the "air sealing package" you mentioned. The tighter the better as long as you install an ERV and provide make up air where needed.
Here on GBA people shy away from CCSF. It's expensive and there are horror stories about it being done poorly. I've had good luck with it. Just make sure you use a reputable company.
Good luck!
DC is right I think...faced batts, INSTALLED PROPERLY, would work.
Your architect is being less than helpful. His plans should show insulation details of how and where.
That roof appears to be set up for a vented attic. The soffit vents are a dead giveaway, but no ridge vent means there should be gable vents. That air has to get out of the attic somehow.
Thanks for this, agreed it does get cold here, was surprised to see I was zone 4. Curious what foam brand did you use? Do you have an ERV where it was done? If I just go right up against the rafters I feel like I need an ERV regardless otherwise where does this air go without one
Your build has progressed substantially based on the pictures, and your architect and contractor both seem less than helpful and even less informed.
You only get one chance to do this right. I would be inclined to find a local and REPUTABLE energy efficiency specialist (emphasized reputable) and employ them to give details and do field inspections. Maybe someone on this forum can give you a recommendation.
And your mantra needs to be air seal, air seal, air seal.
You will CONSTANTLY get feedback stating "I've done it like this for 30 years." Yeah. And all those buildings are uncomfortable. And 30 years ago my car had a carberautor. Today it has an electric battery. Things change as we learn. Unfortunately construction is an industry that has many people who do not learn about recent developments. Your arch & contractor sound like they are in that group. You need to get control of this and drive the air sealing.
Post here like you did; many knowledgeable people here will give you very helpful info.
Thanks, appreciate it. I have an insulation guy coming here Saturday morning , I want him to give me his plan, but yes I’m definitely getting the - I’ve done this for 40 years bs over and over. In any case whatever I do, I’m making sure air sealing is done , even if over the the top