Vinyl Siding Leaks – Period!

By Todd Fratzel on Siding & Trim

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!

Flashing Details

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.

About the author

Todd Fratzel

I'm full time builder for a large construction company in New Hampshire. I run their design-build division that specializes in custom homes, commercial design-build projects and sub-divisions. I'm also a licensed civil and structural engineer with extensive experience in civil and structural design and home construction. My hope is that I can share my experience in the home construction, home improvement and home renovation profession with other builders and home owners. I'm also the Editor-in-Chief and Founder of Tool Box Buzz. Please feel free to contact me if you have any questions, suggestions or you'd like to inquire about advertising on this site.

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  1. Wow. This is kind of scary to see. I have experienced a lot of water damage issues as a result of this kind of contractor neglect, and I feel so bad for the homeowner since they really have no idea what is under their siding, or more to the point, what is not. The local building departments should really get focused on this issue and make it code to put a waterproof barrier underneath vinyl siding to prevent future leaking issues that are almost guaranteed to happen.

  2. Ohio Home Doctor Remodeling says:

    That contractor was obviously incompetent and should be reported to the local BBB. This might have been avoided had the customer gotten at least 3 estimates with detailed job descriptions and details of their processes. Also if they had Goggled “steps for siding your home” or something similar, they would of had a clearer understanding of what to expect as they talked to different contractors to see just how much they knew about what they were doing.

  3. Brett says:

    That’s pathetic. I can’t comprehend how a contractor could knowingly do that. He must know that something has to be between the siding and the sheathing. But apparently house wrap or even tar paper cost too much for him and he doesn’t care about the home owner. This is even worse than a contractor that does install house wrap but doesn’t bother to tape the seams with the correct tape.

  4. Mr.Siding says:

    Vapor Barrier is code where I live. Installing anything over plain osb is insane, how can any one call them selves experts or installers if they do not even care of the results of there work 3 years down the road. Very nice article on what not to do!

  5. Leslie Hare says:

    Hey, this is a HUGE problem. Has anyone seen the Vinyl Siding Institutes position on this?

  6. Richard says:

    Todd, after reading your informative articles about foam board insulation and vinyl siding I have one question.

    I have a 2100 sq ft split level house which a basement and attic and is in dire need of new siding. The house was built in 1978 and has the orignal siding with only 1/4 foam boards. Next summer I was planning on replacing the siding with 2 inch foam board over the tyvak (I had a couple reputable siding companies to view the project and they said installing 2 inch boards is not a problem). My question is would you recommend this or do I need a water barrier coating over the foam boards and under the siding? I live in the Chicagoland area with brutal winters. Thanks, Richard

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