Insulation and OWB ownership.

[Flying Dutchman]

I originally purchased an outdoor wood boiler because I was heating a some 4000 sq ft, leaking falling down home that I inherited from my grandfather. I was heating it with an ancient indoor forced air stove because I couldn't afford the $3000 a year it took to heat it conventionally with propane.

I set the house on fire on two different occasions with that junk furnace. I got out of college and was dirt dirt poor for many years but finally got a decent job and was able to get a loan for the outdoor wood boiler.

3 years later, I am rebuilding and rehabbing that home. Quite extensively. I have bare stud walls, and bare ceilings to fill with insulation. Ripping the second story off, changing rooflines, layouts, wiring etc.

Many people...home OWNERS... are encouraging me to have closed cell spray foam installed in the entire home.

My contractor and brother in law... people who WORK on homes, are trying to steer me away from it, due to:

-moisture mitigation issues (house needs to breathe)
-downline cost from requiring upgraded HVAC to deal with moisture and air stagnation issues in the home
-possible moisture issues on the OUTSIDE of the home (studs sheets rotting, nails rusting off etc)
-difficulty encountered when changing or repairing anything in-wall
-initial cost

The difference between spray foam and traditional insulation and fiberglass is potentially going to be 6-10,000. Fiberglass seems easy... Cheap, easy, conventional, tried and true. But the hours and hours of research I've done point to spray foam being such a superior insulation that there is no competition even.

I intend to live in this home for many years, perhaps forever, and I have an "inexpensive" method of heating the home, but I can never catch up cutting wood and am burning alot of unseasoned wood, construction scrap, paper etc (whatever fits in the door). I understand that better efficiency means less wood consumption. IN general, it will take much longer for the spray foam to pay off for me than it will for someone with a conventional fossil fuel or electric furnace, making it harder decision to make.

Any one have any input on this? What did you do during this design decision.

 

[grader]

the idea that a house needs to breath is just nuts. the house should be as air tight as possible and you control the air changes with an hrv. you dont have to use only spray foam to fill the wall cavities, just one to two inches gives you the air sealing you need and the rest can be fiberglass or cellulose. this can save you money compared to full foam fill.if you do the insulation right this time, it will pay you back for the rest of your life. with the house gutted now is the time to install ductwork for the air exchange system.

 

[Coal Reaper]

x2 on the 1-2 inches of foam. i had them do only a coating in my boiler room to seal out for air infiltration and i am amazed at how warm that room stays.

 

[maple1]

the idea that a house needs to breath is just nuts.

now is the time to install ductwork for the air exchange system.

If you would install an air exchange system, then the idea a house needs to breathe isn't quite so nutty.

Are you re-doing the siding?

I have lost touch with up-to-date building practices & code requirements since we built 18 years ago. But basically, if I was doing it again, I would get the house as tight & insulated as possible, and put in an exchange system (they do have to breath some) using a HRV ventilator, same principle we used. When we built, that meant meticulously sealed vapour barrier on the inside, 6" of fiberglass, then Tyvek on the outside. Nowadays, I'm not sure what the exact recommended recipe is, but it might be more like air barrier on the inside, cellulose in the cavity, then a layer or two of foamboard on the outside under the sheathing. I don't think I'd do the spray foam, except maybe for certain spots like the joist/sill area. But in a retrofit like yours, you might be better off doing the 1-2" against the outer sheating (that would leave space for wiring etc.), then cellulose the rest. Or fiberglass, but that seems to have become less favourable. But I don't think you'd want to end up with a case of vapour barrier on both sides of your wall, which would be the case say it you have spray foam on the outside, and traditional vapour barrier on the inside.

Pay very close attention to air sealing on the top side, the stack effect can really pull the heat (and moisture) out thru into your attic with just a few air breaks up there.

 

[aka.bugle]

Sprayed foam is a pretty toxic product. More so if it ever burns (ask a fireman). You can airseal and better insulate a home with "Dense Packed Cellulose" and not have the moisture issues possible w/ foam. See http://nationalfiber.com/

 

[Lapeer20m]

+1 on an inch or two of foam then filling the rest of the space with less expensive insulation.

Even "regular" insulated walls should have a vapor barrier installed which would prevent the wall from "breathing"

I really like cellulose insulation vs fiberglass. It has superior r value, is non toxic wont make you itch, works when compressed, works when wet, has a tendency to dry itself out, and has superior sound dampening properties. A contractor can spray it on the open studded wall before you drywall, or you can go with the conventional method of adding it to the cavities after the drywall is in place.

 

[mole]

Another choice would be a Mooney Wall. Look it up on builditsolar.com. It looks like a great balance of cost and performance, especially if you do the work yourself.

 

[Fred61]

Although I do recommend making the house a tight a possible one thing you have to bear in mind is that those old buildings made a lot of moisture because they might have stoned up basement walls and no vapor barrier on the floor. You will more than likely need an HRV but one other thing that will help is to NOT have a vapor in the ceiling. What you're trying to accomplish is a healthy indoor environment free from mold producing moisture.

I have also seen homes that had real good vapor barriers in the basement and no vapor barriers in the ceiling that actually caused the wood trim to crack and the furniture to fall apart in the winter while the occupants had to walk around the house with a quarter in their hand to ground themselves before touching any doorknob to prevent arcing to their fingers. What I'm saying is that there is no blanket right or wrong on insulation. Each case is different.

 

[arbutus]

Sprayed foam is a pretty toxic product. More so if it ever burns (ask a fireman). You can airseal and better insulate a home with "Dense Packed Cellulose" and not have the moisture issues possible w/ foam. See http://nationalfiber.com/

Dense pack cellulose impressed me the few times I have seen it. Spray foam has been great in three houses owned by relatives. You could go with an inch or two of open cell foam, get the air sealing effect, allow some vapor travel, and insulate with cellulose in the rest of the cavity too.

 

[Yankee]

I'm currently in the same situation, 200 year old farmhouse. The insulators I've talked to say not to do the "Flash and Bat" (thin spray foam and fiberglas). I guess what is occuring is the frost line develops at the inside foam line, creating a moisture issue in the wall.

 

[maple1]

I'd say that's because the foam acts as a vapour barrier, so if you also have real vapour barrier on the inside - that's a vapour trap. Maybe they're talking closed cell - and if you used open cell you'd be OK? I haven't got this stuff all figured out. There's lots of reading to do on it on greenbuildingadviser site, but there's also more than enough back & forth on there to make my head spin.

 

[newbieinCT]

Great thread - I acutually hopped onto Hearth.com to read what others had to say about insulation since we are in the process of fixing up our 1894 farmhouse (with "modern" additions from the 1980s). I feel like I've read every website on the topic b/c each contractor we have had come in have a different option (because they are selling something different).

A few thoughts (again - I am not an expert, there are a few things I've been struggling with and thought they might be worth mentioning)

Since you are down to the studs, sounds like you don't have to worry about the moisture issue with the cellulose, If you have plaster and lathe walls (like we do in half of the house) I think the moisture issue is a bigger issue. There are many a sites saying one of the big cons of cellulose is a mold issue b/c there is no vapor barrier. The other con that keeps coming up is: settling. People say their walls are filled and then, due to settling, there are cold spots. Has anyone else heard of this or is this a rare but possible con?

Also- I've been reading about off-gassing with the foam insulation. A little scary b/c of the toxicity and smells...but I am so tempted b/c of the high R value. Others have said the foam blew out the drywall or plaster and others have said it shrinks and doesn't stay as cold.

Thanks for the tip on the Flash and Bat. I had a contactor suggest it - I will do more reading on it. F&B seems to make so much sense...of course there has to be an issue with it
No easy answer with insulation!
Meg

 

[BoilerMan]

You want the vapor barrio on the warm side of the wall. Fiberglass on it's own is nothing just a filter, and a thin spray of foam will not be warm enough on the inside surface for the vapor not to freeze. If I were in your shoes, I'd consider spraying the inside of the foundation walls with 2-4" of closed cell foam.

On the open stud walls, I'd consider Roxul with a foil-faces foam board on the inside over the studs and then strapped with the drywall applied to that. This way thermal bridging is elimated through the wood framing, and a metal vapor barior is on the inside, just be sure to seal the foam very well with a quality tape.

This is how I built my house, and have had very good results...........just don't cheap out on the tape.

TS

 

[Fred61]

Blanket insulation in those old houses can end up with a lot of leaks because of stud spacing. Regardless of how good your insulation is, if there are gaps your insulation project will be a failure.

 

[Flying Dutchman]

Part of my house is new construction, but in the end It will have all new siding, sheeting, tyvek.

The entire roof will be new, with scissor trusses (making an 11 ft vault) which poses an insulation challenge in and of itself. That part of the house was so bad I had to tear it down to the ground and start over. So SOME of it is new 2x6 construction. The REST of it will be uneven 2x4 stud walls due to multiple additions. Some of the basement is rock foundation and as old as 1830. Some of the house is above dirt with a criawlspace. These areas are definitely going to need spray foam, but for the bare studs and ceiling, there are so many choices that I'm overwhelmed.

It will cost approximately 5-6000 to spray foam the the new part, about 1500 for fibergalss. The contractor wants to seal it all up, roof vent and all, spraying the foam directly against the back of the roof sheeting and against the wall sheeting, R20 in the walls and R49 in the cieling. He wants to spray foam in the floor joists behind the in floor heating tubes, I dont know if I want that.


TONS of great suggestions. I really like the Mooney wall concept. I think that will work awesome for the old part of the house in the walls.

Found this too, this seems legit?

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[MarkW]

From what I've found, foam runs right around $1/board ft. So, I'm not sure how that's a "Poor man's spray foam" job. If you're a diehard DIY'r, I guess it's one route.
I've got dense pack cellulose in part of my home and there's no settling what-so-ever, for those concerned about that. You can even take the siding or wallboard off and the stuff won't move.
If I'm able to build this summer as planned, I believe I'm going to go with the Mooney wall concept and dense pack cellulose. Vapor barrier over that, of course.

 

[maple1]

If I was going to use spray foam, I would get it done professionally by someone with a good rep. There are horror stories out there about foaming gone bad that led to very bad off-gassing & an unliveable house. So don't think I'd try it DIY - too much at stake.

 

[newbieinCT]

If I was going to use spray foam, I would get it done professionally by someone with a good rep. There are horror stories out there about foaming gone bad that led to very bad off-gassing & an unliveable house. So don't think I'd try it DIY - too much at stake.

I second this one! I've been reading the horror stories of people who are living in hotels while they re-gut the house

 

[newbieinCT]

From what I've found, foam runs right around $1/board ft. So, I'm not sure how that's a "Poor man's spray foam" job. If you're a diehard DIY'r, I guess it's one route.
I've got dense pack cellulose in part of my home and there's no settling what-so-ever, for those concerned about that. You can even take the siding or wallboard off and the stuff won't move.
If I'm able to build this summer as planned, I believe I'm going to go with the Mooney wall concept and dense pack cellulose. Vapor barrier over that, of course.

Thisis great to hear! On line you read the horror stories - it's good to know it isn't all bad I think on the proposal they gave us, it was going to be dense pack in the attic under the floorboard (it's a finished attic) but he didn't specify on the walls. it just says "borate cellulose) that they say will be fire rated, mold proof and "will not settle"
I guess I need to clarify is that is loose or dense pack in the walls...
thanks for the info!

 

[Fred61]

I think the horror stories came from the urea-formeldehyde foam and not urethane.

 

[newbieinCT]

I think the horror stories came from the urea-formeldehyde foam and not urethane.

You are right - I should have said that, urea-form not urethane. I have heard some concerns about which foam is truly a urethane not a urea - I haven't looked into it too much. We have to decide on the walls: cellulose or foam. It's a tough decision. Newer construction we will insulate but probably not the older part until we rip off plaster and start fresh with new drywall. Fun fun fun
trying to decide on new pellet stove too - too much information running around my head right now

 

[Fred61]

I'm a fan of cellulose, either loose or dense packed. Both fiberglass batts or blown fiberglass are out of the picture in my opinion.

Flying D,
If you can furr out some of the walls to make a deeper cavity, now's a good time to think about it since you're down to studs. Sometimes it needs to be done in these old places simply to get the wall straight.

 

[Flying Dutchman]

How do you do cellulose in a scissors truss?

My spray foam contractor claimed it was impossible and would not net adequate r value at the pinch points along the rooflines.

 

[MarkW]

How do you do cellulose in a scissors truss?

There's a mesh product that can be applied to the trusses, then the cellulose is blown in at numerous points through holes made in the mesh. Obviously, the mesh in fine enought to retain the insulation yet allow the air to escape in order to achieve density desired.

http://www.menards.com/main/buildin...ssories/insulweb-4-x-1500/p-137249-c-5776.htm
I think there's a product that works as vapor barrier, as well.

 

[B-Mod]

It will cost approximately 5-6000 to spray foam the the new part, about 1500 for fibergalss. The contractor wants to seal it all up, roof vent and all, spraying the foam directly against the back of the roof sheeting and against the wall sheeting, R20 in the walls and R49 in the cieling. He wants to spray foam in the floor joists behind the in floor heating tubes, I dont know if I want that.
/quote]

You don't want the foam sprayed on the heating tubes or alum. plates if you use them. You want a 2" air gap before any insulation. If you want foam, I would use a product like reflectix first, with the shiny side up, 2" below your tubes. Then either spray foam on the bottom of the reflictix, or just use fiberglass batts.