This old house general contractor tom silva and host kevin o connor demonstrate the proper way to insulate an attic.
How to properly insulate an attic bedroom.
Place planks 1 by 6 or 1 by 8 or plywood sheaths across floor joists to improve your mobility in the attic.
Because the simplest and cheapest way to insulate an attic is to add material to the floor.
Inappropriate mixture or application can result in suboptimal insulating results and hazardous fumes.
Preparing an attic for insulation.
1a attic access door.
Your attic also needs passive ventilation so that the attic temperature matches the outside temperature the way it should.
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.
Instead you should make sure your attic floor has sufficient insulation.
Plan to pull up the flooring and layer new insulation on top of the old.
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.
Installing a vapor barrier.
How to insulate an unfinished attic.
To install insulation batts and blankets.
Insulate across the top of flat attic.
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.
If the air distribution is in the attic space then consider insulating the rafters to move the distribution into the conditioned space.
To install loose fill insulation.
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.
Spray foam provides an air tight thermal boundary between your bonus room and the unconditioned air space in your attic.
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 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.
See below for a shopping list and tools.