Styrofoam Only in Walls

[Guest]

I have a client who wants me to put Dow High Density Styrofoam into the walls of his balloon-framed turn-of-the-century house in Zone-4 (Vermont). He seems convinced that Fibreglas has health hazards.

I have always done Fibreglas bats and really wonder about his styrofoam-only idea. Would it work? Would it really give him an R-20 for a four-inch wall, slightly better than the R-19 Fibreglas? I told him about the additional expense, but he does not care. Should I do what he asks or try to convince him otherwise?

I read the Dow Styrofoam Project Planner, but it gives me only one side of the story. Anyone out there with experience in this kind of insulation? I would love to know!

Thanks!

Sam

[Guest]

Re: Styrofoam Only in Walls

Hi Sam,

I think it would be extremely difficult to do, unless you completely gut the inner walls or strip off 100% of the siding.

How about this? Why not shoot the walls with icynene, in order to do a good job of filling every nook and cranny, and then using the high density dow against the walls on the inside of the home? The combination of the two might get you the R-value he is seeking without the drafts that you'll get unless you can do an absolutely perfect foam board installation.

ONE TEAM - ONE FIGHT!!!

Mike O'Handley
[email protected]

[Guest]

Re: Styrofoam Only in Walls

Mike --

I guess I should have added that we have gutted the place already -- the plaster seemed in really rough shape, and he wants drywall rather than lath/plaster. Icynene insulation would come to $19,400.00 for the whole house, which scared him. The guy can spend money, but not that much all at once. I know I can save him a bundle over Icynene by either doing the styrofoam or doing Fibreglas, since I will put up the drywall, anyway.

So what do you think about styrofoam only? Would four inches give him an R-20? Any special considerations? Should I just stack four of the one-inch boards or would an airspace have any benefits? I would love a small How-To, since I have never done this.

Mike, I really value your opinion. I think you really know your stuff, probably better than anyone else out there.

THANKS!!!

Sam

[Guest]

Re: Styrofoam Only in Walls

Mike --


I guess I should have added that we have gutted the place already -- the plaster seemed in really rough shape, and he wants drywall rather than lath/plaster. Icynene insulation would come to $19,400.00 for the whole house, which scared him. The guy can spend money, but not that much all at once. I know I can save him a bundle over Icynene by either doing the styrofoam or doing Fibreglas, since I will put up the drywall, anyway.


So what do you think about styrofoam only? Would four inches give him an R-20? Any special considerations? Should I just stack four of the one-inch boards or would an airspace have any benefits? I would love a small How-To, since I have never done this.


Mike, I really value your opinion. I think you really know your stuff, probably better than anyone else out there.


THANKS!!!




Sam

[Guest]

Re: Styrofoam Only in Walls

Gosh...I guess we know our place then. Yeah...you can go down this path, but I'm not sure if the inital cost of the styro, which is pricey, particuarly in the sizes your talking, plus the labor involved in cutting it, fitting it, maybe caulking/foaming your runouts, plus feeding around wires and such, are going to make this an economically feasible alternative. Why not use a blown in cellulose? To begin with, I'd worry more about the whole effeciency of your wall assembly rather than just the R-value alone, and this product I'd guess would not only be cheaper in both mateiral and labor, but also give you good insulating and weatherization properties.

[Guest]

Re: Styrofoam Only in Walls

Sam:

Ditto what everyone else said. I have put rigid styro in a few walls out of necessity, but to build up a 4" cavity of the stuff would be very difficult to do, given the amount of trimming, fitting etc. I'm no expert on it, but blown-in cellulose or foam combined with stapping on the int or ext with styro sounds like the best solution you can offer your customer.
As an aside, don't worry about saving him abundle, just give him the best solution that you can make money at. (I have been reading S.Lyko's posts a lot)

Good luck
Andy

[Guest]

Re: Styrofoam Only in Walls

I have done this a number of times, and the studs are never perfectly parallel, or perfectly square to the wall. I ended up using a can of spray foam to seal the voids. You start out great, but as your frustration grows, you accept gaps to get the job done. If do this, tell me how you cut the board. Knife,or saw.

Dennis

[Guest]

Re: Styrofoam Only in Walls

Hi Sam,

Well, first let me say that, while I thank you for the compliment, I know better than anyone else around that I definitely DO NOT know my stuff better than anyone else around. Some of these guys have forgotten more about construction than I'll ever learn. That is the beauty of a forum like this, we can all offer certain strengths and by providing you alternative solutions help you to reach what, for you, might be the best solution.

Sounds like you have a client that tends to believe a lot of what he reads/hears in the media. The difficult type. Will you achieve an R20 with 4 inches of styrofoam? Well, yes you will - in a laboratory, but I'm not so certain you'll attain that in the walls of an old house, what with air movement, penetrations for wiring and plumbing, etc.. Besides, unless you have a true 4" deep wall cavity you won't even achieve the R20. So, maybe you cut panels to fit in the stud bays and use a Celotex product on the face of the interior walls and drywall over it. You'll end up spending a lot of time detailing and sealing joints with tape.

You know, it isn't designed for this type of application, but Dow also makes a foamboard called Wallmate that is designed to hold nailers in a rabbet at the overlap joint. I think it comes in a variety of thicknesses up to 4 inches. It was originally designed to insulate basement walls, but I suppose it could also be made to work in this application. How about filling the stud bays with conventional fiberglass batts and then lining the interior walls with a product like this Wallmate. Once you've installed it with tightly taped joints, rocked over it, applied a good CPVC vapor-barrier primer and painted over it, I don't see him being in any danger of exposure to the fiberglass.

That said, if icynene, which is a great air stopper, sound deadener and has a comparable R-value is not in the cards, I'd consider dense-packed cellulose as the next best alternative. You can still use a high-density close-cell foam layer on the inside walls to achieve the higher R-value and the foam can serve double-duty minimizing diffusion through the walls.

Dennis and Andy make an excellent point about trying to fit this stuff. About three years ago I labored for several days in extremely hot weather in a little cape where the owner insisted on using styrofoam to completely insulate the roof. Besides contending with fitting the blocks into every little space and working around old knob-and-tube wiring, I had to deal with nails protruding through the sheathing that caught on the panels when you tried to adjust them and the sides and joints were a b---h to seal. You go through a lot of cans of polyurethane expanding foam sealant with this stuff and then you have to contend with the mess the stuff makes. When you figure the time it takes to mark, cut, fit and seal this stuff, using icynene or blown in cells might actually end up being the cheaper alternative.

Let me ask you. When was the last time you visited Fred Lugano's website? He lives up in your neck of the woods and is well respected among insulating contractors. Did you know that his specialty is dense-packing cells in order to eliminate the need for ventilation and hours wasted air sealing? Check out his site at the link posted below. Also, stop by the Dow site, make your way to their insulation specification guide on the residential construction page, and spend a little time on their site studying the particulars of their products and deciding, once you've digested all of that, whether you still want to allow this client to proceed on the same path. Check out Dow at www.dow.com.

Lastly, has the client ever considered cotten or wool batting or the new recycled rag batting? These are other non-toxic alternatives to fiberglass that one might look at.

Good luck. I don't envy your task.

ONE TEAM - ONE FIGHT!!!

Mike O'Handley
[email protected]


The Weatherization Site

[Guest]

Re: Styrofoam Only in Walls

My two cents for what it is worth - I have done this several times with excellent results for some clients.

Here is how:

buy 2" 4 x 8 sheets of Dow EPS(R10) - cut them into 12" strips using a circular or table saw. Tack them into the 16" space leaving 2" on either side.

Call Foam-Tech in VT. and have them come in and seal the edges and coat the foam board with 1" of closed cell urethane foam (R7/in) resulting effective R value is nearly 19 and you avoid these problems:

1. trying to make exact fit cuts in an irregular stud bay.

2. dealing with the hassles of foaming edges to seal (this is an absolute must!) from a can that you buy at the store.

You get the benefit of cheap foam r-value (Dow) with reduced labor costs on your part and the speed and effectiveness of a superior bond and added r-value from the closed cell foam. Everyone is happy - this will be pricey but most likely significantly less expensive than Icynene...

Special bonus - w/ no offense to Fred L. - you get to work with one of the most innovative foaming companies in the entire US! (how do I know - I use to work for them...)

Good luck


http://www.foam-tech.com/index.htm

[Guest]

Re: Styrofoam Only in Walls

Now that is a slick idea. Bravo Bill.

This is what I like about this board. People are civil to one another. They take time to discuss a variety of options without dissing one another and going WAY off-subject and viable solutions are often the result.

Sam, I think you and Bill should hook up offline to discuss this in more detail, 'cuz it sounds like he has a workable solution to your customer's quirky requirement.

ONE TEAM - ONE FIGHT!!!

Mike O'Handley
[email protected]

[Guest]

Re: Styrofoam Only in Walls

Thanks for the kudos...

BTW - I have used the Wallmate product (in an unconventional way) on my own house when I built it.

I built a 2x4 wall with no plywood on the outside instead I used 2" of the wallmate product that you describe above. Then I sprayed 3" of closed cell foam on the inside for a 2x6 thick wall with an R-30 value! A little known fact is that after the foam cures it provides greater racking strength than plywood. In essence I am creating a field applied stress skinpanel. I then vertically strapped the outside of the foam and hung Shakertown cedar panels from it creating a ventilated rainscreen.

I did the same thing on the roof with the Wallmate and then screwed plywood to it before adding my shingles. My walls are vented but my roof isn't! Sprayed closed cell foam on the inside and then added open cell to the inside of that for an R50 roof here in NH. My heating bill for a 3000 sq.ft. house is $500 of propane but from the outside looks like a conventional house design.