Home Insulation Made Easy!
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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.
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.
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.
The only “professionals” that recommend foam, are professional salesman.
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?
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