How To Insulate 2x6 Roof Rafters

It creates a breeding ground for mold and mildew and ruins the air trapping pockets that block heat flow.

How to insulate 2x6 roof rafters.

For rolled insulation place it between roof rafters. R 19 is made for 6 inch framing and if you installed the vent trays properly there should have been enough air movement in the cavities to prevent condensation on the back of your roof sheathing without nailing extensions to the rafters. If your attic rafters are 2 by 6 inch framing members i assume you used an r 19 batt insulation. Remember you ll need at least 1 air space above the insulation for attic ventilation.

Replace the floorboards and then spray more insulation on top of it. I have a 1925 bungalow in michigan climate zone 5. If you choose to use the 2x6 roof joists you ll only be able to fill the joist space up about 4 5. Although there are many different circumstances that may call for insulating roof rafters the means to determine the necessity for insulating rafters remains the same.

Look for water stains on the roof sheathing or damp or moldy spots on attic joists and existing insulation as a clue to where leaks might be. There are some unfinished crawl space areas in the corners on the upper floor. They are directly below the roof sheathing and are were insulated with fiberglass batts stapled between the 2x4 rafters. Water is insulation s enemy.

So your choices are 3 1 2 thick batt insulation for an r value of about r 11 9 or rigid insulation board for a r 20 to r 30 depending on the type of board. Box out light fixtures.