Best Joist Insulation For Pier Floors

There are many ways to insulate raised floors.

Best joist insulation for pier floors.

If you want to insulate a floor assembly by leaving the joist bays empty and installing rigid foam on the underside of the joists here are a few things to keep in mind. Fiberglass insulation is usually the best option though handling fiberglass can be dangerous and it is not the most eco friendly option in some cases. One tactic is to place rigid insulation panels between the floor joists. This is to prevent the joist.

The insulation should press right up against the floor between joists. But for it to be effective you need to stop air leakage from the crawl space to the living space insulate the floor and then stop air movement through the insulation from the crawlspace. Wall insulation systems require that the band joist area of the floor frame be insulated. Adding insulation mitigates the problem but there are some considerations to keep in mind.

A pier and beam home built on top of sturdy supports typically has an open crawl space between the floor of the house and the earth. These stiff boards are placed close together on top of the floor joists. At least 25mm of the joist must be left exposed to ensure air circulation. According to the 2012 irc the minimum r value for floor assemblies is r 13 in zones 1 and 2 r 19 in zones 3 and 4 r 30 in zones 5 and 6 and r 38 in zones 7 and 9.

The insulation should be pushed tight to the underside of the floorboards. Underfloor insulation will help eliminate drafts in homes that are raised above the ground those that have a crawlspace or are set on piers. An uninsulated floor allows heat to escape making the house less energy efficient. A semi rigid material is generally best as it can be cut very slightly oversized and squeezed in between the floor joists thereby ensuring no draught causing gaps.

Any compromised floorboards or joists can also be replaced as part of the retrofit project. When air moves over or through insulation it robs it of its insulating value. Wall insulation shall begin 3 inches below the top of the masonry foundation wall and shall extend down to 3 inches above the top of the footing or concrete floor 3 inches above the interior ground surface or 24 inches below the outside finished ground. Insulating under the floor will prevent drafts from entering via the gap between the floor and the ground.

In some cases if the floor is accessible from below it may also be possible to partially insulate the joists from underneath which offsets thermal bridging through timber members but this is not often the case. Fiberglass rolls can be placed between joists but the fiberglass itself will need to be cut to fit properly between joists.