Recommended home insulation r values.
Attic rafter insulation not deep enough.
When using fiberglass insulation the pink stuff the attic roof rafter will need to be at least 16 deep.
It is important that the insulation be evenly distributed with no low spots.
In order to create a deeper cavity for the insulation it will be necessary to attach wood framing to the existing rafters through a process called furring.
Installation of attic or rafter insulation.
To see how to add insulation out to the eaves see installing rafter vents.
Even if you already have insulation in your roof you may still be losing heat if there is not enough.
But if the floor is covered in plywood you can t stuff enough insulation beneath it to do the job sufficiently not even in warm climates.
Use care when reading the above linked un sourced handbook.
The higher the r value the better the thermal performance of the insulation.
One obvious solution would be to screw lengths of wood along the rafters to increase the depth.
Mark the desired level on different roof trusses around the attic before you start photo 4.
For example 2x4s would do but that is a lot of extra work.
Insulation level are specified by r value.
Because it s hard to insulate these areas many capes leak heat at the eaves a recipe for ice dams.
If the rafters are deep enough however it s more cost effective to work from the interior.
I might be minimized if i only screw pieces of 2x4s from place to place just to support the drywalls.
When you re blowing insulation it can get dusty and hard to see whether you ve got it deep enough around the entire attic.
Because the simplest and cheapest way to insulate an attic is to add material to the floor.
If your attic insulation covers your joists and is distributed evenly you probably have enough.
Attic rafter insulation is generally the most cost effective of any energy efficiency upgrade made to a house considering the potential cost savings that can be achieved on the monthly heating bills.
If you cannot see any of the floor joists because the insulation is well above them you probably have enough and adding more may not be cost effective.
R value is a measure of insulation s ability to resist heat traveling through it.
The ideal solution especially if the rafters are not deep enough to allow for code minimum cavity insulation is to add rigid foam above the roof deck.
In addition to some of the structural considerations mentioned earlier furring can further reduce your existing attics head room.
Pick up the blower and insulation cellulose blown in ceiling insulation is a good choice for diyers.
Install baffles against the roof sheathing between rafters so insulation does not seal up these avenues of air circulation.
If there s still not enough room you can always add a layer of foam board or closed cell spray foam to the top of the roof topped by sheathing or other protective layers.
In an older home a typical roof rafter can range between 2 4 s to 2 8 s.
