Tuesday, May 25, 2010

ICF Construction and Housewrap

I've had a couple of people ask me why I am installing housewrap on a house built with ICFs.  It's certainly a valid question. 

Simply put, the main purpose of housewrap is to keep wind and water out.  Even though you may have exterior siding on your house (wood, vinyl, etc.), water can, and does, get behind the siding.  Housewrap will prevent that water from getting any further.  It also helps to prevent air intrusion around framing members in conventional construction.

When you build a house with ICFs, you don't need housewrap.  The outside layer of styrofoam serves as the moisture barrier, and the concrete does a fine job of keeping the wind out.

On my house, the only parts of the house that really need housewrap are the parts that are built using standard framing methods... the dormers and the tops of the gable end walls.  So... why would I install housewrap on the rest of the house?

When I rub my hand over the outside of the house, my hand gets covered in a very fine white powder... similar to chalk dust.  The styrofoam is starting to deteriorate from UV exposure.  It isn't anything to be concerned about at this point, but it is starting to happen. 

That's why I'm installing the housewrap.  I'd like to think otherwise, but realistically it'll be at least another year before I'm ready to install the exterior siding.  By installing the housewrap now, I'll prevent any further UV damage to the ICFs. 


  1. Thanks for the information you have a nice blog i learn a lot.


  2. I finished our ICF house about a year and a half ago. I hired someone to frame the inside walls, and asked them as part of the bid to wrap the house in Tyvek. They agreed, until the time came to actually do it. They fought like crazy to not do it, saying it was pointless, etc. etc.

    My concern wasn't as much the UV damage (although it will be a long time until you see the last of that dust) but more just cheap insurance. I used 'crinkly' Tyvek as an extra layer of water protection in the event that water did get behind the siding.

    Cheers for the great story and pictures.