13 Feb 2010, Posted by Shawn in Live Work, Sustainability, 7 Comments, Short-URL:http://portlandbuilt.com/mkh4b
Live/Work Video Update: Siding!
With the roof finished, our crew moved on to the task of siding the project. Our initial plans called for a rain screen, but (for many reasons) we decided to forgo this measure. Instead, we opted for several layers of weather resistance including Tyvek and XPS (pink foam).
Working outward from the plywood siding, the wall is composed of:
- A Layer of Tyvek ship-lapped over the lower layers of pink foam board
- 1″ layer of pink board to mitigate thermal bridging (click the link for more details)
- 1/4″ Hardi-board (cement-fiber board)
My contractor, Rory Read, has an excellent article discussing the pros and cons of this wall system. He also details the thinking behind each decision point – it’s an excellent read.
Here’s a time lapse video of the Tyvek installation, followed by a video of the siding on the building’s north face.
7 Comments
February 14, 2010 11:24 pm
Patti
Wow! Thanks for the show. I’ve been waiting to see the results. Like the “ta-da” too.
March 9, 2010 4:01 am
scott owens
I would be curious on why you skipped the rainscreen ?
I am re-siding my house which currently has stud/celotex/stucco to go to
stud/wrap/foam/air_gap/hardie
and the ability to have the air gap ( probably provided by Car-A-Vent products ) seems a very valuable addition.
There is also a new product from DOW called SIS that gives sheathing and closed cell insulation in one sheet that might save labor by only installing 1 item instead of 3.
March 09 2010 10:18 am
Shawn
Hey Scott,
The rainscreen was eliminated for two reasons: First, cost. While it seems a relatively minor expense, adding the screen creates downstream issues in terms of wall thickness, window details, etc. Second, we have two layers of weather resistance - Tyvek and XPS (pink foam). We felt that this double-skin approach significantly limits the threat of water intrusion, and if water does get in, there's a path to exit at the belly bands. I'm putting the finishing touches on a video that details this system.
In Portland, rain screens are going to be code-mandated (this summer, I believe) so it's a bit of a moot point now. I do think that if money were no issue, then I'd do the air-gap/rain screen as you've planned.
Tell me more about this Dow SIS system...I'm curious!
March 9, 2010 12:14 pm
Scott Owens @Twitter Name
Here is a link –
http://building.dow.com/na/en/sis/
I am not entirely sure how window rough opening is handled.
It is pricier than OSB/wrap/foam but the trade off I think is labor saving from the single product installation and the R3 from an overall thickness of 1/2 inch for those with spacing issues. This is less thick than the standard 5/8 OSB and provides thermal efficiency as well and might easily allow rainscreen walls without dramatic differences in wall thickness over “stock” construction.
.
March 09 2010 13:43 pm
Shawn @ShawnBusse
Thanks, Scott! I'll check it out - this is just the kind of information our readers are looking for.
The thickness issue can be a real factor, so I'll be curious to see if Dow has an answer for window detailing. That was a real pain for our stud-wrap-foam build-up. It's surmountable, but a lot of labor.
September 1, 2010 3:23 pm
Richard Burchett – Siding Repair Katy TX
I too was wondering why you left the rain screen out but it was cleared when you explained the cost consideration and the two layers of protective skins.
Though since it will be code mandated not to do away with it then I guess people will just have to do away with the savings starting this summer right?
Great video by the way
Thanks!
September 01 2010 15:57 pm
Shawn
Hey Richard,
Yes, I think code will really drive the decision-making going forward. That said, I have already seen lots of rainscreen options at all sorts of price points. Even though we skipped the screen, I think it's probably good to have it code mandated. While we paid a lot of attention to detailing the building envelope, many builders skip this step and cause all sorts of havoc for homeowners.
At the end of the day, I think your best protection is working with a builder who knows what (s)he's doing, and understands key vulnerabilities (ie windows/doors). The best rainscreen in the world won't help if your window flashing drains back into the wall!
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