Attic Insulation In 2x4 Ceiling Joist Space

I have a 1925 bungalow in michigan climate zone 5.

Attic insulation in 2x4 ceiling joist space.

Find your zone on the map and then use the chart to determine the level of insulation you need to properly insulate your attic walls floors and crawlspaces. Work from the perimeter of the attic toward the door or hatch so that you don t trample all over the insulation you just put in. They are directly below the roof sheathing and are were insulated with fiberglass batts stapled between the 2x4 rafters. Some amount of thermal transfer will still occur through the joists themselves.

In an older home a typical roof rafter can range between 2 4 s to 2 8 s. That s a big size and strength difference between the two types of attic joists even if the joist spacing is the same. Purchase rolls or packages of insulation that will fit in the spaces between the ceiling joists. When using fiberglass insulation the pink stuff the attic roof rafter will need to be at least 16 deep.

Ceiling joists are typically 2 8 lumber floor joists are usually 2 10 or 2x 12 lumber. Achieving greater r values in attics the higher the r value the better the thermal performance of the insulation. Current insulation code requires r 49 insulation in the ceiling. If your attic joists won t bear the weight necessary to finish out a living space but the engineer cleared them to support floor decking for light storage you can install inch plywood or.

The second layer which should be. Install one r 19 batt or roll in every joist space with the paper side facing down and add a second layer of r 19 on top perpendicular to the first layer. There are some unfinished crawl space areas in the corners on the upper floor. The standard width for joists is 24 inches.

Since this insulation will be 12 inches thick the top will sit above the joists but will not cover them. Put standard fiberglass insulation that s appropriate for the climate probably r 38 between the joists. Set up a stepladder tall enough to work comfortably from.