Understanding The Limits of Vinyl Siding
Today as I was driving home for lunch I passed a new home under construction and witnessed something that really bothered me. A contractor was installing vinyl siding on a new home that was sheathed with OSB. However, there was one very crucial detail missing that really bothered me. The house had absolutely no type of house wrap, rain screen or even tar paper on it, just vinyl siding attached directly to the OSB sheathing.
All Vinyl Siding Leaks
Everyone needs to understand that vinyl siding leaks and allows water/moisture to pass through it and make contact with the house sheathing. While this may be a surprise to home owners it surely shouldn’t be a surprise to reputable contractors.
According to the Vinyl Siding Institute:
Vinyl siding has always been designed as an exterior cladding, not a water-resistive barrier. Vinyl siding is designed to allow the material underneath it to breathe; therefore, it is not a watertight covering. Because of its design and application, it provides a supplemental rain screen that enhances the water-resistive barrier system by reducing the amount of water that reaches the underlying water-resistive barrier.
So you can see why I might be a tad upset to see someone’s new home being built with no water-resistive barrier. At a very minimum a good quality house wrap or rain screen material should be installed. In addition, flashing around windows, penetrations and roofing transitions should be used. Unfortunately the house that I saw being built today will likely suffer from serious water damage in the next 5 to 10 years.
If you’re building a new home or having new siding installed be sure to insist on a proper water-resistive barrier. In the photo above you can see a house being built with vinyl siding, house wrap and proper flashing details. If you see bare wood with vinyl siding going up be sure to call a time out!
The most important details when using any type of siding are the flashing details. This is even more important when using vinyl siding. I’ve included links to some of our flashing detail articles to help you understand some of the basics.