Insulating a 100 yr old home

[Learninggal]

NYC is HVAC climate zone 4. 100 yr old stucco home. Walls are lathe & plaster with 0 insulation. Attic has some old worn-out pink batts and rim joists in basement have nothing

I'm utilizing a govt. energy program so limited with choices. I've read many threads and do understand some perils if moisture gets in and stays there. So far, the few contractors I've called offer this. I asked about rock wool and the state program doesn't allow that

- Attic - open-cell spray foam on the floor of the attic. I have my HVAC furnace and condenser in there that serves the 2nd floor (not the best idea but I inherited it). However, this unit is barely used as the basement unit heats up the whole home and we barely use 2 weeks of air conditioning

- Closed cell spray foam after making holes on the 1st & 2nd floor between studs (actually it'll be either closed or open cell depending on how much space he finds in the walls)

- Basement isn't covered by the program so what insulation would you recommend for rim joists & basement walls? We plan to finish the basement next year and use it (not sleeping space but just want to use that space)

I guess the exterior of the house and roof matters here so I want to fix things up to ensure no moisture finds its way in. Roof replaced 5 yrs ago and in good condition. House painted 12 yrs ago and we do have stucco cracks developing all over so guessing it'll be a good idea to patch and repaint at the same time as the insulation or even before. Right?


Thanks

 

[Kaizen]

ten years ago i tried to get some guys to do that drill a hole and put it in the walls and none would do it. they were scared it would blow out the walls. maybe they made some advances.
spray foam on basement walls is controversial on old homes as moisture gets behind it and grows. I think the rim joists are fine. Mine is a foot thick and at two ends i have a 2 inch gap between the 2nd joist and the rock. Eventually i'd like to spray foam that whole area.
I only have clapboards on mine so i actually ripped off those and the sheathing and firred each joist out to accept 2x6 rockwool and did zipr sheathing. The difference in noise and temp is incredible.
can't they spray foam your attic roof to envelop the hvac unit? I'd go with rockwool in the cellar ceiling if you were going to do that.

 

[Learninggal]

Got it. So did you put rock wool on all the basement walls? My basement is 80% below ground and my main goal is humidity but a lot of humidity is also coming from the floor which doesn’t have a vapor barrier. It has tiles but no barrier below tiles

 

[kaymccampbell]

This is all MNSHO.

If your HVAC plant is in the attic, you'd be better to make the attic part of your conditioned space.

There's no way in hell I'd put spray foam in a closed wall space. I did spray foam in my entry, which had open stud bays, and after I ground it level, had to wait a while to grind it level again, as it expanded another inch. You would need a virtuoso foamer. There's probably a dozen in the country. Your guy won't be one of them. I'd blow fiberglass or borated cellulose in the walls.

For the rim joist area, I'd use spray foam. It makes a good air seal. I'd put an inch or so of foam sheets around the basement walls, then pin them in place with 2x4 framing. If you're trying to dry your concrete floor, then a sump pump might be the way to go.

 

[Learninggal]

Definitely putting 2 sump pumps because we've had water come in the past but it no longer does after doing the external waterproofing but to be safe, we'll identify 2 lowest spots of the basement to install a sump pump. However, without a vapor barrier doesn't humidity naturally enter through the floor?

For basement walls from floor to rim joists, do you mean something like this and do you think it's really needed if my basement is 80% below grade? https://www.homedepot.com/pep/Owens...Rigid-Foam-Board-Insulation-52DDNGX/315197962

 

[cannuck]

We are in zone 2 (moved here from zone 1) so have to pay a lot of attention to insulation. Didn't build this house, so had to retrofit to fix thermal bridging from 2x6 walls and joist headers. Have heard horror stories about trying to inject in walls. I used to build insulated (for floatation) gunwhales and that required an enclosure to hold skins flat that was far, far beyond the strength of any stud and lathe wall. I have seen analysis of "foam through a hole" walls and they seldom fill decently, and often fail. Here we stripped off our siding and moved the thermal barrier of the envelope outside of the existing walls using 1 1/2" polyiso rigid board. 2" would be far better in OP's case. Plastic siding hung on long nails, but coming down over floor joists to ground level. Another vote to use closed cell foam on attic roof and if basement wall can be exposed to spray foam up to top of wall, overlapping the outer envelope.

 

[billconner]

For walls I'd use dense packed cellulose. In many older homes including the 2 - 100+ yr ones I've owned - studies and top plate extend above attic floor. Perfect place to blow cellulose from, especially if balloon framed. Can pull baseboard and core there as well, or just core and patch.

Ceiling is tough with mechanical in attic but I'm not crazy about hot roofs. If you want attic finished, spray foam roof deck and then cellulose to drywall on rafters. Otherwise cellulose under attic floor AFTER you seal any penetrations: good of interior walls, light fixtures, above laundry chutes, around clues and chimneys and vents, and any place interior air can escape. Look for dirt build up in fiberglass where it's filtered interior air. Use foam in a can, flashing, caulk, poly, whatever works to stop air flow. A lot of air pressure from the stack effect on ceiling and upper walls. Guessing 2 story, neutral pressure plane around middle of 2nd story windows; positive pressure above, negative below. Then look a possibilities to enclose mechanical equipment.

Band silk either rigid foam sealed with foam in a can at perimeter of each piece or all spray foam.

If basement walks are stone, I think spray foam is answer, perhaps with studs off wall and cellulose. The foam is the vapor barrier and should be thick enough - 2" probably where you are - to keep the inner surface above the dew point and avoid condensation. I'd consider t&g on walls or something to that would allow cellulose to dry inward. People say vapor barrier on warm side, which is usually the higher moisture side, but often not in basement. Thats why you want interior surface to be very permeable.

I don't have a good answer for basement floor. I'd probably look for something that involved a thick coat of mastic to hold it. I might add an HRV un basement to be doubly sure no moisture build up.

 

[LWB]

Old basements (cellars) weren't designed to be insulated. There's no water proofing on the outside walls and water will come through the walls into the house and it dissipates. Put anything on those walls and you will trap the water behind it, likely to cause mold. Do anything to the floor and you end up the same. I have an old cellar with no insulation. I insulated the rim joists with R20 Roxul. Again, let that wood breathe and dry out if it gets wet. That's why these old homes are still standing with no mold issues. They can dry if they get wet.

Blow in attic insulation and good windows are you best bet IMHO.

 

[pcmeiners]

You likely have balloon framing. If you have a fire, flames could go from the basement to the attic in minutes, in 5 minutes a balloon frame house will be beyond saving, even the NYFD can not respond that fast . My parent's 120 year old home in Staten Island was saved due to the fire retardant cellulose insulation in the walls.

 

[dcg9381]

- Attic - open-cell spray foam on the floor of the attic. I have my HVAC furnace and condenser in there that serves the 2nd floor (not the best idea but I inherited it). However, this unit is barely used as the basement unit heats up the whole home and we barely use 2 weeks of air conditioning

- Closed cell spray foam after making holes on the 1st & 2nd floor between studs (actually it'll be either closed or open cell depending on how much space he finds in the walls)

HVAC and furnace will be a lot happier when they are not forcing heated/cooled air through uninsulated space. Roof insulation is best bang for the buck for that house regardless. You must be up north if you're only using upper AC 2 weeks a year.

Open cell if you have "room" for the insulation to expand. Otherwise closed cell. I have seen companies that will retrofit and "fill" walls from the bottom going up with a "straw", but have never done it that way...

Roof needs to be sealed if you spray foam. It's no longer a "vented" space. Soffits, roof ridge vents, etc, any "old plumbing" that puts moisture in the attic will need addressing.

- Basement isn't covered by the program so what insulation would you recommend for rim joists & basement walls? We plan to finish the basement next year and use it (not sleeping space but just want to use that space)

We have a place that's probably 100 years old. First problem in the basement is moisture. Without moisture control insulation is a problem. We have a sump pump, so it'll never really be a livable space.

When I built a basement in TX and waterproofed the walls, I chose not to insulate the walls (at all). We just put up 2x4 framing over the concrete. I actually want to take advantage of the ambient heating/cooling the ground as it's always moving internal temperature the right direction. YMMV.