Best way to insulate a block/stucco house
I am looking for some thoughts from the experts. I live in a uninsulated 1950’s cinder block house with stucco on the outside and on the inside is plaster with wire lath. The ceiling is well insulated. I live in NY and need to add some insulation. When it’s really cold outside we do have problems with condensation on the windows (which are double paned) and also on the upper portion of the north facing walls where the wall meets the ceiling. The house is small so I don’t want to tear down all the interior walls to insulate that way. I have looked in to vinyl siding and the company said that they can put up furring strips on the stucco then a 1-1/2” foam insulation board running vertically and then another 1-1/2” of foam board running horizontally (total 3” of foam) on the stucco and then put on the siding. I could also do just one 1-1/2” foam board that way the windows would not be set in so far. As it is now, the windows are set in about 3″. I am worried about compounding my present moisture/condensation issue and I don’t want to trap water anywhere within the wall/plaster or the block and foam.
1. Would just one 1-1/2” foam board be sufficient…meaning, help with the moisture and also make a difference in making the house warmer ? Would it be worth the expense of $10,000-14,000 (ballpark price)?
2. Should there also be Tyvek either in front or in back of the foam or because of the block it’s not needed?
3. Are there any other good options?
My options seem kind of limited. I greatly appreciate your input! Thank you.
Replies
I would first look at attic insulation. If that's light it's probably your best bang-for-buck, and the least disruptive.
If the stucco is in good condition I'd be very reluctant to put anything over it, especially vinyl. But if you do build out you should replace the windows at the same time, so the window openings are properly treated.
Cold wall insulation
It is perfectly normal for water vapor produced
inside the home to condense on the windows. They
are normally the coldest part of a room. WAter
vapor like heat always makes its way to the
nearest cold surface.
So what to do about those cold walls.
The way to deal with these is to stick one inch
thick sheets of polystyrene to these walls. And
to then stick sheets of drywall to the
polystyrene to protect it from knocks and
scrapes.
You can stick the polystyrene to the walls with
drywall adhesive and use the same adhesive to
stick the drywall to the polystyrene.
I first did this to a home some 45 years ago, it
worked well for the 28 years I lived there and
the new owners are well pleased with their low
heating bills.
The trick is to avoid heat bridges, which will
enable the heat to find its way through the
polystyrene, using adhesive means no heat
bridges and keeps the heat inside the room.
I did another home last year, now I use two inch
thick polystyrene, as heating costs are going
up. Instead of one inch thick polystyrene in the
ceilings, now I use 6 or 7 inches of
polystyrene. After you have done your walls, you
may like to rethink the amount of insulation in
your ceilings.
Insulating CMU wall
If your stucco is in good shape, your best money would be to insulate the inside. Interior finish is generally less expensive than weather durable exterior finish. It also depends on things you have on the exterior wall (e.g. plumbing, etc.) ... that might make it much less practical. You'd lose some floor space; how much depends on your insulation method/type.
As for condensation ... generally sounds like you may have a naturally tight structure ... or a lot of moisture generation. You need to insure you have good exhaust fans for e.g. baths and kitchen.
Why do you think you have to tear down INTERIOR walls to insulate the inside??
vinyl siding sounds horrendous, but I know nothing about the architectural character of your house or the neighborhood.
You could restucco the exterior if you went that route. Have you considered Dryvit synthetic stucco/insulation (exterior insulation finish system EFIS)?
Consider all your options ... you got one chance to do it ... pays to select carefully. It's a big expense with a long life.