Spray foam provides an air tight thermal boundary between your bonus room and the unconditioned air space in your attic.
How to properly insulate an attic bedroom.
See below for a shopping list and tools.
Most codes require a specified minimum amount of headroom and it s tough to meet this requirement when insulating a finished attic especially since most codes require insulation equal to r 38 or more.
To install insulation batts and blankets.
Plan to pull up the flooring and layer new insulation on top of the old.
This insulation should only be installed by trained professionals.
How to insulate an unfinished attic.
Place planks 1 by 6 or 1 by 8 or plywood sheaths across floor joists to improve your mobility in the attic.
Your attic also needs passive ventilation so that the attic temperature matches the outside temperature the way it should.
Because the simplest and cheapest way to insulate an attic is to add material to the floor.
Preparing an attic for insulation.
If the air distribution is in the attic space then consider insulating the rafters to move the distribution into the conditioned space.
In the summer it will reduce the heat gain a bit in the knee walls although check to be sure it is not causing condensation against the roof in which case it should be removed.
Learn why it makes no sense to insulate the walls and ceiling of your attic if it is unfinished and you have no intention of finishing it.
Inappropriate mixture or application can result in suboptimal insulating results and hazardous fumes.
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.
Installing a vapor barrier.
To meet all three goals insulating your finished attic ventilating the roof and maximizing headroom use a combination of dense batt insulation rigid foam sheeting and air chutes.
In these designs take out attic floor insulation only below the finished space from knee wall to knee wall and insulate the knee walls themselves.
To install loose fill insulation.
This old house general contractor tom silva and host kevin o connor demonstrate the proper way to insulate an attic.
In unfinished attic spaces insulate between and over the floor joists to seal off living spaces below.
The insulation on the roof deck should have limited effect if the rest of the attic is well taken care of.