Name:   Lifer - Subject:   spray foam Date:   12/21/2016 6:41:34 AM

There are a couple of options with foam. You can stay directly on to the ceiling which leaves the attic at outside temp or you can spray onto the bottom of the roof which keeps the attic at basically house temp. Either way you have to provide ventilation.  A Ridge vent or power turbine or a combination of both is still needed.  Also the foam does not go all the way to the point of where eaves meet roof line. They actually make a plastic channel that goes between the roof rafters from the eaves to about half of two thirds up the roof line to allow air passage from the eave vents to the peak vents. This allows air flow through but will maintain Temps comparable to the house if you spray the bottom of the roof and assures the eave vents aren't blocked by foam if spraying o  top of the ceiling. I think every situation is different but it basically comes down to personal choice. If you want to gain some use of the attic under the roof is best. I think directly on the ceiling probably provides greater efficiency.

There is also two types of foam, a closed cell and an open cell and once again specific application usually determines which is best for a particular situation.i am no expert but have done some reading on the subject. You can also order the spray and DIY. It comes in two tanks with a wand and mixes in a chamber in the wand. If you have some courage and basic skills you can save a ton of money o  installation. There are also YouTube videos to show step by step how to do it. It definitely is the best insulation method. A neighbor did an addition a few years ago and foamed the extension but opted to not retrofit the existing structure. Everyone advised to have the fiberglass removed and the entire attic foamed but he went cheap and didn't. Early in the 4first summer he had them back to remove the fiberglass and spray the older structure. There was such a difference in the attic Temps that it was condensing and "raining" in his attic.

As stated I am no expert and strongly advise you do some research before making any decision. There are some folks who are just showing up and sealing everything and not allowing for the house to breath, which is crucial even with foam. Hope this helps.