Exterior insulation / ran screen fastener recommendations
southern_water
| Posted in Construction Techniques on
Am adding 2″ foam to house exterior sheathing (Zip). 1x rain screen would then go on top of the foam and siding on top of that. Am seeking recommendations on fasteners/fastener systems. I have seen 3″ screws with some sort of plastic cap for the insulation then longer screws into the studs for the rain screen. Any recommendations from those who have done this before?
Thanks
Ben
Replies
For the rain screen 1x4 boards I used Fastenmaster Headlok screws for basically the same wall assembly that you are describing. These are approved for this application. Google this "TER 1009-01 HeadLOK Rigid Foam to Wood Framing". or try this link:
https://d3g5z6m6vcoqo2.cloudfront.net/resources/HEADLOK-TER-No.-1009-01.pdf
I believe you'll want minimum 3/4"board+2"foam+2" penetration = 4.75" minimum screw length.... so either go with 5 or 5 1/2". But confirm this for your own application with the document in the link provided. You'll also need to lookup the appropriate screw spacing for your application.
For the foam you can just tack it in a few spots to hold it in place with washers or whatever is available. I used a minimum number or 1x4 scraps to hold the foam on until the rain screen 1x4 was attached. Then remove or leave the scrap pieces and put some liquid flashing into the holes from the inside (In your case leave them). Or you could be more fancy and use some of the large plastic washers designed for this purpose.
Best of luck.
Thanks.
Based on that and the anticipated cement board siding weight I'm looking for a 5 1/2" lag screw (3/4 Zip, 2" foam, 3/4 furring, 2" penetration) that will affix the furring strip every 16" vertically. And I'll just find some construction screws and washers for the foam.