Home Finishing With SIP’s
Foam Laminates of Vermont recommends the following products for covering all SIPS:
30# Felt paper:
We recommend 30# felt because it works great for protecting your SIPS. Builders have been using this for years. Often times siding is tore off 10-15 years down the road for additions and the OSB still looks brand new. The same cannot be said for products like Tyvek and Typar. Many times builders find rotten plywood with these products. Asphalt felt has a permeance rating of only 5 perms when dry, but a much higher rating of 60 perms when wet. The felt can soak up water that gets behind it and gradually dry to the exterior. Plastic house wraps are non-absorbent. Any water trapped behind them can only pass through to the exterior as vapor.
Home Slicker® is a product that creates an air space between your siding and your felt paper/SIP. This product will ensure that your SIP and your siding will dry out in the event that water gets behind the siding. This product is not needed for Vinyl siding. The air space created by this product will reduce the forces that draw water into your siding assembly. Water that does migrate into this area will drain away from the wall and allow the cavity to dry quickly.
Shiplap: We recommend adding furring strips to your SIPS for shiplap siding. This will increase the fasteners holding power. We recommend ring shank nails for application. Adding furring strips negates the need for Home Slicker because this will create an air space behind the siding.
Vinyl Siding: Home Slicker is not needed for this product. Vinyl is applied with roofing nails. See manufacturers’ recommendation for fastening intervals.
HardiePlank®: HardiePlank is a very popular siding choice by many of our customers. We recommend installing this product over Home Slicker®. Contact your Hardie Plank supplier for SIP fastening details.
Clapboards/Shakes: We recommend installing these products over Home Slicker®.
Typical installation is done with galvanized ring shank nails.
Cold Roof: A cold roof is achieved by adding strapping and another layer of sheathing over the SIPs. This is a pretty common procedure when using roof SIPS. This will create an air space over your SIPS which will allow them dry out if moisture escapes.
We feel a cold roof is not necessary if your roof SIPS are sealed properly. The cold roof can prevent rotting if you have heat escaping through your SIP joints. However, if your SIPS are installed correctly there will be no heat loss.
Many shingle manufacturers will not warranty their shingles over an unvented roof. It is worth looking into if you plan on applying asphalt shingles on your roof.
Metal roofing is commonly used over roof SIPS. This can be applied directly to the SIP or over a cold roof. We do not recommend an air space between the metal and the SIP. This can cause condensation under the metal which may cause rusting.