Using Rigid Exterior Insulation Under Hardishingle Siding

Bottom line is exterior foam insulation is a good investment.

Using rigid exterior insulation under hardishingle siding. Addition to my house. To secure the foam use two inch cap nails. How to install rigid foam under siding. 1 inch and 2 inch thicknesses are common.

Most homes in the united states are built with traditional wood frame construction with studs every 16 on center. Rigid insulation sheathing is made of a rigid plastic foam that is typically sold in 4 8 or 4 10 foot boards. Some people use roofing nails but if a strong gust of wind gets under the siding it may not hold. 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.

Rigid insulation provides thermal protection and it can also serve as an air and moisture barrier. The method works for both new construction and remodeling and doesn t affect siding and trim details very much. The nails have a plastic cap that keeps them from damaging the foam. I m an architect in wisconsin climate zone 6b and am planning to build a 300 s f.

Several manufacturers of rigid foam insulation recommend metal strap bracing as a structural solution for foam sheathed walls. 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. According to my calculations if i want to use rigid foam insulation on the outside of the 2x6 walls with r 21 fiberglass in the wall cavities i need at least r 11 25 in order to avoid condensation on the inside. Under driven nails can telegraph through to the fi nished siding and trim.

Building codes allow them as substitutes for 1 x4 let in braces. There are three primary types. I d like to side it in fiber cement siding to match the existing house. Many houses built today have a double wall type of insulation with fiberglass batts fastened between the studs on the inside and rigid foam board over.

When using continuous insulation foam sheathing avoid over driving fasteners which can result in dimpling of the siding due to the compressible nature of the foam sheathing. Fit the rigid foam insulation snugly and seal all. Always follow the manufacturer s instructions for installing rigid foam insulation. These irregularities should be corrected before the siding is installed.

So using 1 4 let in braces may not be an automatic solution when building foam sheathed walls metal bracing may not be the answer either.