I am thinking of adding insulation to our attached garage wall, to increase the insulation between the living space. Is adding Dow styrofoam board or something similar a good idea, or worth the cost? (It's more flammable than the 5/8 fireshield)
For example, the Dow 1" stryofoam board would add R5 to my wall, which is only 3.5" with R-11 fiberglass.
Thanks guys!
If when you stand in the house near that wall, you feel colder than another exterior wall or if the wall feels cold to the touch, it may be worth it. One cannot give an objective answer to the question as posed. Going from R-11 to R16 seems like a small step but if the wall is cold, it may make the difference you want.
If you are just looking for ways to randomly cut your energy budget, you want to more carefully consider the costs. At best you will see less than
10% savings over total. Making up optimistic numbers: Lets say your heating bill is $200 per month in the winter (5 months) and you save 5% by installing the insulation that comes to $10 per month or $50 per year. How much is that insulation going to cost you?If you are trying to improve the comfort in a certain part of your house, it will be worth the cost even if the payback is long.
Exposed foam is a fire fuel looking for an ignition source. Please provide the source for this foam board. with 1" equals R-5... I bet you did not read the whole listing. This rating is part of an assembly.
More insulation in the attic seems a better bet. I added R-30 this summer and cut the a/c bills in half from July to August and more than 40% since.
Nope extruded board is 4.92
The OP may want to look at this too
Why not both?
: > For example, the Dow 1" stryofoam board would add R5 to my wall, which : > is only 3.5" with R-11 fiberglass. : >
: > Thanks guys! : : Exposed foam is a fire fuel looking for an ignition source. Please provide : the source for this foam board. with 1" equals R-5... I bet you did not read : the whole listing. This rating is part of an assembly. : : More insulation in the attic seems a better bet. I added R-30 this summer : and cut the a/c bills in half from July to August and more than
40% since. : : No, he's apparently looking at the "blueboard" type stuff, or pink, whichever. Codes here do say it needs to be covered though, which makes sense anyway; being exposed leaves most anything susceptible to damage. In fact, that's stamped right on the blueboard - I just looked at a leftover piece on the porch.While I'm thinking of it; the OP should also beware the possibility of the foam boards, creating a second vapor barrier - shouldn't let that happen - easy to remedy if the wall's are going to be opened at all.
Hmm, good point on the vapor barrier... What would I do?
I was thinking of blue board, then 5/8" fireshield on top of it. I just finished insulating my attic! It was woefully under-insulated, I live in NY and only had 3.5" in most of the house.
Thanks for all of the replies guys!
: > : > For example, the Dow 1" stryofoam board would add R5 to my : > wall, which : > : > is only 3.5" with R-11 fiberglass. : > : >
: > : > Thanks guys! : > : : > : Exposed foam is a fire fuel looking for an ignition source. : > Please provide : > : the source for this foam board. with 1" equals R-5... I bet you : > did not read : > : the whole listing. This rating is part of an assembly. : > : : > : More insulation in the attic seems a better bet. I added R-30 : > this summer : > : and cut the a/c bills in half from July to August and more than : > 40% since. : > : : > : : > No, he's apparently looking at the "blueboard" type stuff, or : > pink, whichever. Codes here do say it needs to be covered : > though, which makes sense anyway; being exposed leaves most : > anything susceptible to damage. In fact, that's stamped right on : > the blueboard - I just looked at a leftover piece on the porch. : >
: > While I'm thinking of it; the OP should also beware the : > possibility of the foam boards, creating a second vapor barrier - : > shouldn't let that happen - easy to remedy if the wall's are : > going to be opened at all. : >
: >
: Hmm, good point on the vapor barrier... What would I do? : : I was thinking of blue board, then 5/8" fireshield on top of it. : I just finished insulating my attic! It was woefully under-insulated, I : live in NY and only had 3.5" in most of the house. : : Thanks for all of the replies guys!
Basically, just damage the previous vapor barrier. Slash it up, whatever, so air/moisture can get thru it. Kind of depends on the situation.
Pop
Doh. What will be difficult, is that the vapor barrier would be on the wrong side - the blueboard would be on garage side (non-living space side). Will that be a real problem?
Owens Corning Super Tuff-R is my insulation board of choice. It is R 6.5 per inch with a foil shield on each side. Although it is the highest R value of the commonly available sheets, it is also the cheapest. I just covered my new 2 story addition with it. It is very easy to work with and cuts a lot easier than the Foamular products.
Owens Corning has a very nice FAQ on their web site covering most questions about their products. Tuff-R is approved for use on the inside or outside of a wall. It does not pose any problems from a moisture barrier standpoint.
Since I had different walls in different stages of construction right now (northern Ohio), it is interesting to see how the condensation differs.
On walls where I have only R13 fiberglass with stapled kraft paper barrier, there is some moisture collecting underneath the insulation (on the inside of the outer osb wall).
On the walls that also have 1/2" Tuff-R on the outside, there is no condensation, since the osb is far warmer.
Dennis
... : >
: > Basically, just damage the previous vapor barrier. Slash it up, : > whatever, so air/moisture can get thru it. Kind of depends on : > the situation. : >
: > Pop : >
: >
: Doh. What will be difficult, is that the vapor barrier would be on the : wrong side - the blueboard would be on garage side (non-living space : side). Will that be a real problem?
Unfortunately, I'm the wrong one to be able to give a reliable answer to that one. My guess is, yes, it could be a real problem because two vapor barriers will collect moisture between them which cannot escape. As a result, mold and wood rot might get a good start, plus freezing/thawing effects depending on a lot of things.
I think DT in the next post has a pretty reasonable alternative if you can afford it. I do know you have to avoid multiple vapor barriers but in your case I have no assistance I can offer. It would definitely be better to go to something that's not a vapor barrier in and of itself.
Pop
I live in central NY and I think you should bring your attic up to an R38. This can be done by either fiberglass or cellulose blown in insulation.
Is your garage wall colder than other exterior walls? It shouldn't be any worse than other exterior walls if you keep your garage door closed. You may think this is a silly statement but I've heard a few insulators grumble because they get calls from disgruntled homeowners but when they check on the situation they find that many of them leave their garage doors open for extended periods of time.
If you install Dow Styrofoam or Dow Tuff R both must be covered by 5/8 type x drywall for two reasons. 1) Both products have high flame spread/smoke developed characteristics and must be covered by code. 2) Your garage wall is probably a one hour fire rated wall and will lose that rating if it doesn't have firecode drywall on both sides of the wall.
Section =A7RR318.1.2 of the NY State Residential Code requires 1/2" gypsum board over all foam. There's no mention of anything thicker or that it must be Type X.
Section =A7302.3.3 exception 2 of the Building Code of NY State requires
5/8" Firecode for the garage ceiling if there are habitable rooms over the garage, if not, then 1/2" drywall is acceptable for the walls and ceiling. RI was under the impression that the wall(s) between the house and the garage had to be a one hour fire-rated wall. Perhaps this isn't true.
In MA I believe the house-to-garage door must be rated at 2 hours.
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