Why Put Fanfold Polystyrene Under Siding

However another important consideration is what to put under your siding.

Why put fanfold polystyrene under siding.

It provides an r value of 4 per inch of thickness and is the cheapest type of foam board insulation. Fanfold foam residing board. This is the same stuff your disposable coffee cup and is made out of and it s used to protect fragile items in their packaging. The house has wrap under the siding.

Fanfold foam residing board is a thin perforated extruded polystyrene foam board faced on one side with a plastic film facer and combines proven xps foam technology with a unique design to enhance the application of new or replacement siding. By glenn hooper june 2 2015. Will this cause any condensation issues. And even though some manufacturers call it rigid foam insulation for the purpose of vinyl siding it basically has the same insulating value as a piece of plywood.

This foam board insulation is the rigid pink or blue panels that can be found at home centers in many different thicknesses. This creates a horizontal seam every 4 feet. I get asked if this or that in the in the cavity works as well as foam under the siding. I am having the siding removed from our house and 2 foam board but under the siding.

The windows are being removed and moved out the 2 to line up with the foam board. I have not seen any studies that show how well tape adheres to foam over the long haul. Eps is used under roofing over foundation walls and beneath siding. As many things in building science go you my dear reader have to learn something.

It also serves as an air barrier. Why insulation under the siding is important. In reality rigid foam board which sometimes comes in fanfold usually only has an insulating factor of r 1 and does not add any appreciable insulation effect to your home. The house was build in the 19970 s 2 4 walls and pink insulation between the studs.

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. Let s take a look at each. 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.