DIY spray foam / radiant heat / foil
From reading the posts, it looks like it is best to use a contractor for spray foam unless it is a small job like rim joist. Does anyone have a comparison for the best price for DIY closed cell foam?
A post by Riversong HouseWright suggests using the foil backed foam and seal around it. This makes sense for a room that has a wood stove.
I put a 60 watt light bulb into a 16″ cube blue foam 2″ thick cube. Within 35 minutes the temperature in side the box went from 52° F to 105° F. The next day I tried it again with aluminum foil inside of the 6 panels. The temperature went from 53° to 117° in 35 minutes. This was done in the basement where the temperature is 52° to 53°.
The foil made a 16% difference.
Does anyone have a good method to measure the radiant heat?
Because of the wood stove and this little experiment, I am planning on using spray foam for the rim joist and foiled backed insulation on the bottom of the beams.
bswanson
Replies
Riversong would undoubtable steer you towards cellulose.
There many other factors to consider beyond peak performance
when it comes to these products.
Flammability is one. Your wood stove is a serious consideration
in the material choices in that room.
Cellulose has One of the best fireratings.
It air seals much like the spray foams (which is one of there big
advantages).
It has a long track record, which none of the current man-made
products have.
Is completely non-toxic (a sticking point with all the others).
and has a low embodied energy. For the most part it comes from recycled paper.
Let us not forget animals and insects. Foams and fiberglass both have problems in this regard.
.
.
Foam has it's place, but don't assume it is always the cat's meow.
In order for something to be "the best" it needs to perform well
in all the situations that you (and it) will encounter. Time has shown
any one of these problems can bring the others to the end of there usefulness very quickly.
My plan is to start with the floor that the wood stove sits on. The area to be insulated is under the wood stove. It is basement with about four feet of head room over a concrete floor. The joist are 4 X 6 inch beams. The plan is to spray foam the rim joist and put the sheets of foil backed foam on the bottom edge of the joist that will look like a ceiling to the crawl space.
That sir is one of the instances that spray foam is indeed
a very good choice! I think stopping air movement is more important then the
radiant question though. Careful detailing will pay far greater dividends then any one
material over another.
The plan is to insulate under the floor that the wood stove sits on with the hope that the infrared heat that goes down will be reflect up. There are just a couple of wires feeding plugs in that space. This is the only know source of possible fire starter in that area.The details of the experiment can be found on the blog tab of http://www.sheilashomestay.com.
The foil foam showed better performance. If you used 2" in each case, you are proving one thing ... that R-14 is better than R-10. The Polyiso is R-14 maybe more. The extruded polystyrene R-10. Don't really count a lot on the foil in the product giving you much in terms of effective R-value. You only hint at what you might be doing with the insulation. Wall cavities?? For the foil to work, it needs to have a dead air space ... and it has to stay clean (which is a tall order in most construction).
Remember, both insulations will likely require a fire rated barrier. For sure on the Polystyrene. Polyiso is rated, but not sure if it is rated exposed. It is a urethane product, but the foil does provide a flame spread rating ... just not sure if it is enough to meet exposed requirements.