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Insullation in old home. Worth it?

Posted by criticalmass (My Page) on
Tue, Aug 5, 14 at 13:19

We have a 1900 two-story + attic fixer-upper, and just got a new gas heater installed. Of course, the heating company told us that since the home is not insulated, we should look into it, and he suggested a place that can give us an estimate on spray-foam.

Bad thing #1) We're doing research on it, and it seems like we're looking at about $10,000. How long is it going to take before we make our money back? Fifty years? Just spent $14K upgrading from an old oil guzzler to a new HE gas heater. If we save $50/month on the heating bill, it will take about 16 years just to pay for the insulation.

Bad thing #2) We're reading a lot of bad things about harmful effects of spray foam insulation. Not to mention reports of "fishy smells" that may come from it in the heat. My wife absolutely hates the smell of fish.

Bad thing #3) We're not only hearing that an old house cannot "breathe" with insulation, but unless you have a vapor barrier in the wall (impossible with plaster & lathe), moisture from cooking, showers, dishwashers, etc, can get into the walls, causing condensation on the insulation, which attracts termites.

Bad thing #4) We're reading that when the spray foam expands in the walls, it can (and usually will) cause the wood lathe to expand, pop nails loose, and therefore cause the plaster to crack all over.

Question: Would installing fiberglass insulation myself in the attic do any good? We have no heat or air conditioning in the attic, so I don't know if it would do any good.

Question: We are leaning towards vinyl siding anyway. This, I'm sure will help, but will it be good enough?

Thanks in advance.


Follow-Up Postings:

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RE: Insullation in old home. Worth it?

Insulating truly old houses - those 100+ years old - will remain a contentious issue. I have no real desire to stir up this particular hornets' nest, but having lived in a 200 year old house for close to 40 years, I would offer the following:

The two most important places to insulate are the attic
and basement. Fortunately,these two areas are much
accessible than the walls and are much easier to deal
with. Yes, you can fiberglass the attic yourself and it
can make a big difference.

I share many your concerns about adding foam to the
walls. In addition to the ones you've cited, there is the
problem of access to the plumbing and wiring in the
walls. This is not a rare need in old houses.

The vapor barrier question is a real issue, but vinyl siding
is a really idea for an old house without one. Moisture will
make its way into the wall cavities where it will be unable
to exit because of the siding. Rot can ensue in an a very
short time.


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RE: Insullation in old home. Worth it?

Thank you for your response.

I assume you meant "...vinyl siding
is a really BAD idea for an old house..." by your comment. The problem is that we have asbestos shingle siding and missing a few shingles. Many of our neighbors on the block have new vinyl siding. We didn't consider the moisture issue.


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RE: Insullation in old home. Worth it?

There are many comfort-related things you can do ... and each one saves energy too.

Attic and basement insulation ... heat rises.

Stop air leaks and drafts:

Caulk around window and door trim, inside and out.
Add weatherstripping to openable windows and doors

$$$$! Add storm windows (period appropriate AND cheaper than replacement windows). Or make your own interior seasonal window liners.

Stuff non-degradable filler around all openings through the wall (I use plastic grocery bags) and then caulk the opening. BONUS: fewer pests coming in where pipes and wires enter.

Any time you have access to the wall/floor interface, caulk it. I caulked around the subfloor in the LR/DR in this house, between subfloor and baseboards and got an immediate benefit in fewer insects strolling around. Fewer drafts in the winter now, too. I'm continuing as I redo each room.


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RE: Insullation in old home. Worth it?

Bad thing #3) We're not only hearing that an old house cannot "breathe" with insulation, but unless you have a vapor barrier in the wall (impossible with plaster & lathe), moisture from cooking, showers, dishwashers, etc, can get into the walls, causing condensation on the insulation, which attracts termites.

as someone who tests homes for air leakage...believe me..
your house is breathing. older homes were built for ventilation
& the advent of sheet materials (sheetrock, plywood) didn't happen till much later. sheet materials make houses tighter..
but a lot needs to happen to make a 100 year old house
close to tight. a LOT!

air seal walls then have cellulose blown into walls.
air seal ceiling into attic space, then insulate.

can't comment on basements..but air sealing always
comes first...then any other work in that area...and
lastly insulation.

caulk is a great air sealer (not for hvac ductwork)
invest in a good caulk with a long life.
I like Dap's brand Alex 35 year and longer life.
personally I use the caulk that goes on white &
dries clear. too easy to grab white & use it in the
wrong place...

best of luck.


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RE: Insullation in old home. Worth it?

The good thing about retrofitting an old house for higher energy efficiency is that just about anything you do will improve comfort and save money.

You're right that foaming walls will not be cost effective.

Instead, spend some quality time with a caulking gun and hand held polyurethane foam, e.g., Great Gap. If you're installing batts in the attic, follow a guide for correct installation. Two layers at right angles to each other work best.

Here is a link that might be useful: US Department of Energy Guide to Attic Air Sealing


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RE: Insullation in old home. Worth it?

You need to understand that almost all technical information about insulation on the internet is the product of industry organizations that promote one kind over another.

The more internet articles you read the less you will know.

To advise you about insulating your house we need to know in detail how it is built.


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RE: Insullation in old home. Worth it?

Hmmm. Not wanting to hijack this thread, but I find this information interesting. We have all our plaster torn down in half our downstairs. I have been getting a list of spray foam insulation contractors started so I can have the open exterior walls insulated. I have read nothing but good things about spray foam insulation. Hearing what you saying is giving me pause though. I have never heard of the stuff being smelly, and that would be a huge concern for me. I also thought you did NOT need a vapor barrier with spray foam and that it did indeed breath. Now I'm confused. I really don't want to make my project take any longer than it already has. Where do I find good info on what to use to insulate my exterior walls??


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RE: Insullation in old home. Worth it?

As noted previously, a great deal of the information available about insulation, foamed in place and otherwise, is marketing driven. That doesn't mean it's completely unreliable, but recommendations vary widely, change frequently, and are often quite different from climate zone to climate zone. Your best source of information is probably your state university or state energy agency. Caution is necessary even here, however. Remember, not so long ago fomaldyhyde insulation was widely recommended and used.

Since your walls are open, a continuous poly vapor barrier would be pretty easy to install and not terribly expensive no matter what insulation type you employ. Remember, too, that wall insulation is not nearly as important as attic and basement. I personally would not use foamed in place n the walls of an old house - too many future difficulties in accessing plumbing and wiring, too much that can go wrong.


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RE: Insullation in old home. Worth it?

Hmmm. Just read that a vapor barrier is a no no in air conditioned homes. And you don't live in Oklahoma with out air conditioning, at least I wouldn't. We have no plumbing on exterior walls so that is not a problem. We insulated our attic years ago. It made a huge difference upstairs, but not for the main level at all. We have not insulated the basement, and we are a long ways off from doing that. The only way to insulate in our basement is along the gap on top of the stem wall, and we planned on that being spray foam also.


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RE: Insullation in old home. Worth it?

We got a lot of the information from a few different sources, but the biggest factor for my wife (on top of the helpful suggestions here) was one article from CBC, a Canadian TV station, who did an article about it, as well as the reader comments below it. I don't think I can post the direct link, but just search "Is Spray Foam Insulation Safe CBC" and you will find it.

In addition to the dangers and possible smell, is the cost, and how long it will take to "save back" the money that it costs to have done.


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RE: Insullation in old home. Worth it?

Closed cell foam does not need a vapor barrier. Anyway, vapor barrier installation is dependant on you climate. They go on the side that is mostly warm.

I used spray foam on the 100 year old wood frame side and 150 year old brick part of my house in the attic, gables and on the eaves. Also did some walls on first floor of wood frame side. Cost about $7000 for 50 x 20 attic and eaves and 20 x 20 first floor. Works great! Will be doing attic in 200 year old brick section and will probably use fiberglass because of cost. Spray foam seals out all air leaks, had great r value for thickness and adds structure.


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