Jump to content

Housewrap exposure time


Danny Pritchard
 Share

Recommended Posts

Does anyone know if housewrap has an exposure time before it has to be covered.I have a client who is building a new home.She has been having trouble with the builder and because of that little work has been done on the house.The housewrap has been on the home for over 90 days.I have left a message with the manufacturers represenative but have not received a response as yet.

Thanks

Link to comment
Share on other sites

Originally posted by Danny Pritchard

Does anyone know if housewrap has an exposure time before it has to be covered.I have a client who is building a new home.She has been having trouble with the builder and because of that little work has been done on the house.The housewrap has been on the home for over 90 days.I have left a message with the manufacturers represenative but have not received a response as yet.

Thanks

Tyvek says 120 days.

Personally, I'd go with felt.

- Jim Katen, Oregon

Link to comment
Share on other sites

  • 1 year later...

Hi,

Danny didn't mention the brand. Some brands are limited to 90 days.

To contribute a little bit to the thread drift - a little building science explanation might be in order here. Kurt's comments about wrap are pretty much what everyone is experiencing. House wrap was never meant to be a moisture barrier - it was designed to be an air barrier.

Unperforated felt and wrap that's been properly applied perform similarly. However, when you introduce thousands of siding nails into the equation they're quite different. When water blows into siding with felt beneath, and water passes through thouse thousands of nail holes, the felt gets wet and it's perm rate increases, allowing air and water to more easily pass through it. That's the downside to felt. The upside is that, after the saturation stops, the felt allows the felt and underlying sheathing to thoroughly dry out.

However, when holes are punched through wrap and it's exposed to wind-driven water, the wrap's perm rate doesn't change. That's the upside to felt, it continues to do what it's supposed to do - prevent air infiltration. In fact, the only thing that changes is there are holes through it that will allow water to seep through. This is the downside. Though wrap is designed to keep out wind and is vapor permeable, it won't allow water molecules to to pass through, so any water that gets behind it through those thousands of nail holes becomes trapped between the wrap and the underlying sheathing, and this is what causes the sheathing, and ultimately the studs, to rot. Since there's really no way to effectively seal every single tiny hole and penetration through the wrap, thereby ensuring that absolutely no water can get behind it, the odds of trapping water in the walls are extremely high, no matter how carefully you apply it.

So, we're left with a choice, install a product that will probably only allow a little water through but will trap the water and promote rot, or install a product that will allow more water through but will allow the building envelope to more readily dry out, thereby preventing rot. Me? I'd choose the felt. It's been around for a century and there are a lot of old buildings still standing. I can't even begin to recount how many thousands of stories I've heard about rotting building envelopes that have been caused by wrap.

ONE TEAM - ONE FIGHT!!!

Mike

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...