Can You Insulate Floor Joists

If you choose to install insulation for floor joists it is best to first examine your floors and joists carefully.

Can you insulate floor joists.

When insulating from above right a loose fill insulation such as cellulose is breathable and will fit into every nook and cranny. Check that the joists supporting the floorboards are in good condition and don t show any signs of wet or dry rot. Aluminum sheeting can also be used to insulate between joists but this may not be the most efficient method for floors. It s easier to insulate if there s access to the floor from below and you won t have to disrupt the floorboards here left quilt insulation is pushed between the joists.

View of second story floor joists from below. It s even easier to insulate your timber floor if you have an unheated cellar or basement space underneath that you can get into. If you have an unvented crawlspace or basement you must insulate the walls instead of the floor joists. If the joists are okay you can fit insulation in between them and hold it in place with netting if necessary.

Fiberglass insulation batts or rolls are the most economical and easiest diy choice for insulating between the floor joist in a crawl space. The thickness of the insulation required is normally determined by the height of the floor joists so if the height of the floor joist is 160mm then we would recommend using 160mm of thermo jute insulation to fully fill the void. Insulating the space between the joists in a basement or crawlspace can help reduce your energy bills. The batts are optional.

The total thickness could be a combination of 100mm and 60mm thicknesses on top of each other. Here s how to insulate under a floor. There are two main methods depending on if you have access above the floor joists or below the floor joists. That means that as long as you ve done a perfect job air sealing the rim joist you can omit fluffy insulation between the joists assuming that you would be satisfied with r 16 performance.

Installation from above the floor joists the insulation boards should be installed before you start boarding the floor. Department of energy recommends r 11 3 insulation under floors in warm climates and an r 25 6 to 8 in cold climates. Cut the insulation to length using a square and sharp utility knife. Lay down a moisture barrier with sheets of 6 mil plastic if you have a dirt or gravel floor.