Attic Insulation 2x4 Rafters

Insulating the roof above the rafters is known as warm roof insulation as the rafters are brought into the insulated envelope of the building.

Attic insulation 2x4 rafters.

How to increase the interior ceiling joist for r38 insulation. For roofs that won t experience heavy snow loads a gable roof can span up to 22 with 2 4 rafters. You can use either 2 6 or 2 4 rafters for roofs with a 3 12 pitch or greater but it depends on the overall size of your shed. We love our diyers so take up our incentive to improve your attic insulation situation yourself.

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. Blown in insulation is installed using blowing machines. Ceiling joists are the horizontal boards that span the width of the house resting on the outer wall plates and possibly on. Shaded or north facing roof pitches would be the most susceptible but with only 2x4 rafters and likely r13 or less the roof deck runs warmer drier than if it were insulated to current code min.

Whether there is a real hazard or not depends primarily on your local climate climate zone as well as your shingle color type and shading factors. This over rafter insulation method also reduces thermal bridging giving an airtight continuous layer of high performance insulation and results in a well insulated attic space. Get a free 24 hour blown in machine. By installing high density 8 inch fiberglass batt insulation the rafters will then meet an r 30 roof insulation standard.

Water is insulation s enemy. It creates a breeding ground for mold and mildew and ruins the air trapping pockets that block heat flow. Box out light fixtures. For instance if the roof has 2 by 6 rafters and you want r 30 insulation which is standard in many communities you can add a 2 by 4 which will give you an 9 inch rafter space.

For roofs that will experience heavy snow or wind and will span the same distance use 2 6 rafters. They are directly below the roof sheathing and are were insulated with fiberglass batts stapled between the 2x4 rafters.