Comments on: Spray Foam Insulation – Insulating Ceiling With Polyurethane Foam

By: GB3RND

GB3RND — Thu, 08 Oct 2009 04:02:43 +0000

d1incharge
Please define professional. “Professionals usually recommend against foam, especially closed cell”
If professionals recommend against foam, why would well educated architects and engineers specify and design it into their structures?

By: d1incharge

d1incharge — Wed, 07 Oct 2009 02:54:25 +0000

The only “professionals” that recommend foam, are professional salesman.

By: d1incharge

d1incharge — Wed, 07 Oct 2009 02:52:58 +0000

And when the old plywood rots because it sees no vapor diffusion or fresh air,, you have to replace all that inslutaion with it. Professionals usually recommend against foam, especially closed cell, that is why it has been around for over 40 years and is being used in less than 1% of new homes.

By: d1incharge

d1incharge — Wed, 07 Oct 2009 02:41:03 +0000

how do you know those joist werent helping to support your ridge? most super old homes that have 2×4 rafers used the ceiling joist as collar ties. Just install rafters under the old ones so that you are left with more that 12″ and use batts…foam is a big con…….especially closed cell, which has had major moisture issues, among other things. Spending extra for foam to end up with the same r-value is a complete waste of money.

By: GB3RND

GB3RND — Fri, 04 Sep 2009 03:48:26 +0000

R-40 will require approx 7 inches of foam. This can be achieved by adding 2x4s on top of the existing rafters and attaching them with plywood on their sides. The foam then fills the space between.

By: fatmanmark

fatmanmark — Fri, 04 Sep 2009 01:24:08 +0000

nice video…i am renovating and wish to remove non structural ceiling rafters(formerly functioned as plater/lathe ceiling support)
local code calls for r40 ceiling
existing roof rafters are 2×4. any sugestions?thanks you