Insulating Basement Rim Joists With Roxul

We packed roxul rock wool into the end of every floor joist bay filling the area against the rim joist.

Insulating basement rim joists with roxul. Rim joists let in more than air. The common approach seems to be rigid foam with spray foam around the. I want to start upgrading the insulation on my mother s house and will be starting in the basement with the rim joists. The inflow of outside dry air more than offsets the outward diffusion of interior relatively more humid air outward toward the cold rim.

Because the air infiltration has been stopped the. In cold humid or mixed climates the foam board thickness needs to be 2 thick to stop the condensation in the rim joist area. If you have an unfinished basement you can properly insulate the rim joists in two or three hours. Now that i am finishing the basement want to insulate properly.

The roxul had stuck to the wood in the rim joist and caused mold in a few. You can tear off chunks and stuff them into the end of a joist bay and they will stay there. Insulating rim joists 11 18 2016 07 09 pm. This area is notorious for gaps and cracks.

I thought 1 rigid foam plus the roxul would be good enough but i just read this at the link below. Took it all out cleaned the mold and had it open ever since. Keep in mind that year it was very very cold like 25 so it was an unusual year. Another option for your rim joist.

Spiders bugs and even mice find the rim joist an attractive place to enter the home. Roxul is also fireproof so the packed area extended to the top of. This project will help lower your h. This will also block tiny passages where spiders and.

Use a box cutter to cut the insulation to length. The wooden rim or band joist area is where the house s wooden structure rests on the concrete foundation. Of rigid foam or spray foam. It s the simplest and least expensive basement area to insulate and will bring the highest return on your investment.

If the foam board is properly sealed additional fiberglass insulation can be added to obtain a higher r value. Fiberglass batts should never be installed near a rim joist unless the rim joist is first insulated with at least 2 in. In just a couple of hours you can seal and insulate your rim joists which are major sources of heat loss in many homes. It has a clay like consistency.

Thanks t the rigid foam must be sealed and i really would not add poly vapour barrier if you are using 2 rigid. It should be noted that using a porous insulation to insulate the rim joist area is less likely to cause a problem with moisture accumulation at the rim board in winter in cases where the rim area leaks air badly. Roxul is dense unlike fiberglass and inhibits airflow. Half of the basement is unfinished and the rim joists are stuffed with fiberglass bats that my late father may have put in there over the years.

The edges of each piece of rigid foam should be carefully sealed with caulk or canned spray foam. Insulating the rim joists rim board or header with r tech or owens xps foam board insulation along with great stuff spray foam.