Mounting blocks for assemblies with exterior CI and rainscreen
Andrew_DePaoli
| Posted in Construction Techniques on
I am trying to come up with a good way to detail mounting blocks on an assembly that is lap siding, on 1×4 furring strips, on 2″ polyiso exterior insulation, on zip sheathing. If anyone has any suggestion or ideas I’m all ears. I want it to be sealed to the zip sheathing and to have also have some flashing. I like a lot of the pre-made mounting blocks that come with flanges (like the ones from studrimount), but none of them are deep enough to flash them to the sheathing and come out past the exterior insulation and 1×4. If anyone has any ideas I am all ears. Thanks
Replies
Have you looked at the Maine Deck Bracket? I believe it would give you slightly over 4 inches projection from the sheathing. Check out: https://www.finehomebuilding.com/?s=maine+deck+bracket
Hey Brian,
These look great, but I wasn't specific enough the application I am needing them for. I am detailing some mounting blocks for electrical and plumbing penetrations such as hose lines and exterior outlets and lights, etc.
How are you detailing your windows?
Your blocks are just smaller versions of the window. Treat the block bottom like a sill and tip it a bit. Then flash as you would your sash.
You probably don’t want to recess these blocks much as the lamps and even faucet works might be impeded.
Edit: there’s some nice in use, in the wall outlet boxes from Arlington that yoU won’t see a big box sticking out beyond the siding....
http://www.aifittings.com/catalog/inbox/
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Hey Calvin,
The windows are bucked out so the flanges lay on the face of the polyiso, and then the head flashing is deep, flashed to the zip sheathing.
So you think I should just fabricate extra deep mounting blocks myself as one unit, and flash like I would the windows?
I think I would give that some study. What’s the difference between the two? Window penetrations are bigger, but both penetrate the building envelope. I don’t know of any blocks that would mimic your situation so necessity is your mother.
And, it doesn’t hurt to ask because more than likely, someone has run into the same situation. Just not me.
Best of luck from a 71 y.o. Retired carpenter. A few aches but still 10 fingers.
Thanks Calvin. My thought exactly, someone else must have had to do this!
And Andrew, while I mention I’ve not probably done anything on your situation, I guess I mean, I don’t recall at this time.
A lot of water over the dam since ‘72......
I wonder if boral 1x glued into a box would work? I've never tested those glue joints for watertightness, but they might be. Easy enough stff to work with. Expensive, but one 16' board might take you pretty far.
I like the idea of making the box from Boral. Glue it up with PL 400, and you should be good to go. Flash it with Zip tape.
Thanks Dan and Andy. I'll try and let y'all know how we move forward with this detail.
Matt Risinger does a couple of youtube videos on his personal house hardie siding showing his use of pvc blocks for penetrations