How to insulate a finished attic.
How to floor an attic over insulation.
A finished attic should be insulated much like the rest of the house with insulation in the walls and ceiling.
With a finished attic insulation must help keep the attic areas comfortable.
Even easier you can also use a prefabricated attic floor kit designed specifically to raise the attic floor above the insulation.
It s an interesting exception.
Build up the height of the joists prior to installing flooring when the insulation reaches the tops of the joists.
Work from the perimeter of the attic toward the door or hatch so that you don t trample all over the insulation you just put in.
The joists for this riser should run perpendicular to the existing ceiling joists.
That means insulating the attic floor only not the walls and having vents in the roof.
Always cover the tops of the ceiling joists to make sure the insulation is deep enough to reach your target r value and to prevent thermal bridging the heat loss that occurs through the wood framing.
To give yourself enough space to ensure adequate insulation under the flooring construct a riser of 2 x 4 s in the attic over the existing joists.
However if you keep the storage weight to a minimum you may be able to build a storage platform above the insulation by attaching supporting beams to the sides of the trusses.
Place flooring over insulation to make your attic space functional.
Ensuring adequate insulation under the flooring.
This will make the installation of these new joists easier.
In zones 4 through 8 if you have full height insulation over 100 of the ceiling including the top plates as shown in your excellent guide here the iecc allows r 38 rather than the r 49 that is required if you can t achieve full depth insulation over 100 of the attic floor.
Attic insulation between roof trusses.
If blown in insulation is used control the height or thickness of the layers so boards can by laid over top without having to compact the filler.
1 put on work gloves safety glasses and a dust mask before entering the attic.
Attics are generally covered in batting or blown insulation.