Open cell vs closed cell foam

16 years ago

I have had a few contractors come in and I am in a little bit of a confused state. My house is solid brick under renovation all walls open with 2x4 construction. I live just north of NYC. One tells me closed cell 2" and finish with fiberglass to get the higher R-value. The other tells me open cell full width of 2x4 with shave. What is the difference I have been told by both that there way is the best way. I know the closed cell will give me vapor barrior and the open cell will let the house breath more the contractor who wants to give me open cell staes that closed cell is not a good application for residential becasue it doesn't allow the house to exchange air. This all seems like I'm just being told whatever they want to sell. Any one have any opinions on this that may be helpful. Oh and if he open cell doesn't have a vapor barrior do I have to put one in? Thanks

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Comments (5)

oilpainter
16 years ago
Why are you going with solid foam in the first place. It is not the best insulator. I would go with bat insulation--check the R value when you go shopping for it-- or sprayed foam. Unlike it's solid cousin the sprayed foam adheres to all surfaces and fills every nook and cranny. If you use bat insulation don't forget behind electrical boxes too.

You need a vapor barrier no matter what you use for insulation. It goes on the side that is warm in winter. In most cases that is after the insulation is installed and on the inside of the house, just behind the plaster or drywall. All seams and around electrical boxes must be sealed with a special tape made for this. What the vapor barrier does is to keep moisture from the house from getting into the insulation thus rendering it useless for insulating.

You'd probably can have this confirmed by posting in the building a home or one of the home forums.
User
16 years ago
We used Icynene, a spray in foam as mentioned above, in our homes exterior walls six years ago and though this home is more than twice as large as our last home we spend quite a bit less on heating and cooling it. I'd seen it done on some home show while we were still in the planning stages so we investigated it along with other typical insulation and felt it was the best for our home. That doesn't mean it would be the best for yours. You'll have to do some research, but you might want to check out the link to what we used and see for yourself. Oh and it's a green product.
I have no connection with the company, just like their product.

Here is a link that might be useful: Icynene
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I am in south Louisiana. energy_rater_la, I have no problem with overfilling the walls. I need all the R I can get, and even though I give up R=1 for a 1/2" of air, I get R=1.9 for 1.2" of spray foam, and at $.16/in-ft^2, it still marginally makes sense. For the roof, as I will generally have 2x10 rafters (i.e., 9-1/4" deep), I do not need to have insulation all the way there (the optimal level from an overall cost benefits analysis is at 8".) energy_rater_la, are you saying that I do not have a problem with having some space between the foam and the ceiling sheet rock, unlike for the walls? It would not matter much if I did go all the way to 9-1/4", although I would be paying a little more for the insulation than I would get back in reduced energy costs (using my analysis of the cost of financing and energy cost increase and expected life), as well as not taking advantage of the air space R (value of 1). As for exterior insulation, in general, the costs of the material is so high, that once the wall is at R-12 (net), the total costs of the material and labor are higher than the reduction in energy costs. Actually the cost of material alone is OK, but the extra cost of labor pushes it into being too expensive. There is a new combined structural and insulation sheathing (Dow Styrofoam SIS?), but the material cost is even higher, and it only almost makes financial sense, but with the problems of "this is new, and how good is this going to hold up". However, since the east and west walls get more insolation (and therefore more heat gain), the numbers begin to work out for exterior insulation, and there is the added benefit that the local heat gain is less, which allows those rooms to have the same heat gain as the rooms with non-insolated walls, thereby allowing a more constant indoor environment. I will be putting in an extra 2" of insulation there (which makes integrating with windows easy as all manufacturers make jambs for 6" walls.) This leaves the question of what exact type of exterior insulation should I get. There are so many different types out there - this type of foam, that type of foam, fiberglass, etc. And the idea of vapor and water barriers, foil radiant barrier, with the open cell insulation has me very confused. Fortunately, the price per R is about the same, so I don't have to make a decision based on relative price, but only on what is proper. Here are some of the brands I have researched: ProPink Foamular R-Max R-Tech Which of these is better for my situation? Are there any others I should consider? Thanx again
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llaatt22
16 years ago
If you Google: Holmes on Homes Spray Foam

there are lots of sites to explain closed cell vs open cell.

BASF "Walltite" is a well known brand of closed cell spray foam.

The closed cell is much higher in R value which means less thickness is needed. Open cell takes up more room and may exert more curing pressure in areas of a structure where that isn't helpful.

Either one would be a good choice when compared to older methods and materials.

Here is a link that might be useful: a few facts in one place
jeff8407
16 years ago
Closed cell is the only way to go if it is appropriate for your applications--it think it would be.

We upgraded and used the closed cell spray foam in our current home, 2X4 exterior walls. Even though our home is nearly twice as big as our old home and our last home had 2X6 walls, plus an inch of sytro on the outside, our utility bills are now 1/3 lower even though the new home is bigger.

It is amazing stuff--you won't be disappointed.
thereddogruby
Original Author
16 years ago
Thanks for all the info I think we have made a decision we are going to use 2 inches of closed cell in the walls and beam ends and then use r-30 fiberglass in the ceiling I would love to spray the ceiling with open cell but its not going to happen the budget is to tight. along with the closed cell in the walls we will be adding r-8 in the walls to bring the R-value up a bit.

Open cell vs closed cell foam

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Open cell vs closed cell foam

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oilpainter

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