2x4 Attic Joists Upgrade Insulation

If you can see the floor joists boards about eight inches high spread a few feet apart across the attic floor you probably need more insulation.

2x4 attic joists upgrade insulation.

In order to create a deeper cavity for the insulation it will be necessary to attach wood framing to the existing rafters through a process called furring. Put insulation meant for 2x4 framed walls between the joists which will be the same height as the joists then lay a perpendicular layer of attic insulation maybe r 30 on top of them. The size of the joist determines how much insulation cavity space you can have beneath your floor covering in your case a 2x4 is 3 1 2 inches wide so in this instance your insulation cavity underneath your new proposed flooring will give you 3 1 2 inches for insulation. I m in the process of deepening the attic joists for insulation also.

If done right blown in cellulose insulation adds a lot of r value in all areas without doing too much work in regards to packing it in like batted insulation. In an older home a typical roof rafter can range between 2 4 s to 2 8 s. Some amount of thermal transfer will still occur through the joists themselves. Since modern two by fours are not 4 inches the true depth of the wall cavity is 3 1 2 inches.

I plan to attach new 2x4 s in parallel on top of the existing and screw on metal tie plates every 2 feet on each side of the joist staggered then roll out r25 and cover all with plywood for a storage surface. Just replaced the roof and tossed out what scanty old sodden insulation there was between the 2x4 joists. Whether you have batt insulation fluffy blanket like material or loose fill shredded material there should be enough to completely cover the joists. When using fiberglass insulation the pink stuff the attic roof rafter will need to be at least 16 deep.