Fanfold Behind Siding

Dupont has said on their website and product flyers that if using both fanfold and housewrap and committed to both put the tyvek housewrap over the fanfold but they actually recommend assuming the insulation is totally closed cell with very low absorption rate putting the insulation directly under the siding overlying dupont drainwrap which is designed to provide a better drainage path between the two than regular housewrap.

Fanfold behind siding.

Fanfold foam residing board. Foam insulation is often referred to as fanfold. Installing foam insulation under vinyl siding is a wise choice for homeowners who are seeking to protect their homes against moisture infiltration as well as improve energy efficiency. Also during this siding process you may also consider asking your contractor to add foam insulation between the vinyl and the house wrap for increased r value.

While fan fold has minimal insulation value it does even out wall defects and cuts down on drafts. Fan fold comes in foam sheets and is nailed directly to the sheathing. It also helps to level the walls so you get a better smoother siding job. I have not seen any studies that show how well tape adheres to foam over the long haul.

Like bob said it helps with sound insulation. If you have ever seen vinyl siding and the laps looked dirty all the time this is caused by heat buildup between the siding and the wall this heat excapes through the laps and causes stain. Generally referred to as rigid foam insulation this type of foam insulation is also called foam board foam plastic insulated. This creates a horizontal seam every 4 feet.

It also helps with wind infiltration through the walls. Fan fold is typically sold in 1 4 inch by 4 foot by 50 foot sections and is installed horizontally across the existing siding to level out irregularities before re siding with vinyl. Considering how effective house wrap is and how simple it is to install behind vinyl it is a good idea to ensure your contractor includes it when siding your home. When every penny counts you can rely on the performance of our most economical fanfold siding underlayment.

Foamular extruded polystyrene xps rigid foam insulation offers a comprehensive line of products in a wide choice of sizes thicknesses and edges with a lifetime limited warranty for the life of the home or building. Exterior insulation is a foam like layer that is applied under the new siding. It also serves as an air barrier. This is because some brands of foam insulation are stored folded and it unfolds like an accordion for easy installation.

Products can be used on wood steel framing or concrete walls. Fanfold foam residing board product data sheet pdf 783 kb. Generally the thicker the foam the greater the insulator. Fanfold board is worth the cost and effort to install behind vinyl siding.

Also it is a vapor barrior on boyh sides of the board.