Roof Insulation For 2x4 Rafters

So at 16 oc each joist is 2 2x4s together.

Roof insulation for 2x4 rafters.

For light load roofs 24 o c. Visit the roof framing page for more information on cutting roof rafters and visit the roof pitch calculator for determining rafter lengths based on rise and run. Rafters must be strong enough to hold the roof sheathing and the shingles. Install a timber stop batten across the rafters as shown in position c with the batten equalling the thickness of the quinn therm insulation.

They are directly below the roof sheathing and are were insulated with fiberglass batts stapled between the 2x4 rafters. It s already a low ceiling 78 ceiling on the low side and 87 ceiling on the high side. If your local building authority has a rafter spacing code you may not space rafters wider than required by code. If you get premium kiln dried lumber then you could span 10 5 with the same size of lumber and.

For instance 2 grade 2x4s at 16 on center will span just over 9. We just had rebuilt repaired the roof of a flat roofed addition to our house due to a roof leak and resulting breakdown and mold problems. There are some unfinished crawl space areas in the corners on the upper floor. 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.

Let s say you ve 384 sqft of ceiling to cover. If your rafters are only 2x4 either you ve got about 400 sqft or you ve reinforcement load bearing partitions beams somewhere. The rebuild was done the same way. Moving to 16 on center you could span your spf 2x4s up to 6 for heavy loads and 9 for light loads which would still work with a 12 12 gable shed.

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. Spacing your 2 4 shed rafters at 24 on center limits the width of your roof. 2 4 rafters can span up to 7. The original roof ceiling was framed with doubled up 2x4 joists for extra strength.

Rafter span tables use these tables to determine lengths sizes and spacing of rafters based on a variety of factors such as species load grade spacing and pitch. A drywall sheet is 32 sqft. Lay quinn therm qr insulation boards above the rafters butted tightly against the stop batten and supported on both sides by the rafters. It s easy to say oh yeah just put 1 2 drywall on your ceiling forgetting that it weighs over 50 pounds.