Using LP Smartside for Rainscreen Furring Strips
sstaberow
| Posted in Green Products and Materials on
Hi,
I found a good deal on Lp Smartside. I was thinking about ripping them into 3 inch strips and using them as furring strips for a rainscreen. I am going to use Fiber cement siding and am building in climate Zone 5b. I am wondering if it is a bad idea since it is an osb product. I am also wondering what side of the Lp Smartside would make the most sense to install toward the WRB (primed side or bare side)? Thanks for the help!
-Shawn
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Replies
Shawn,
I'll give your post a bump. FWIW. I think you can use a lot of different materials for spacing in a rain screen. But based on LP's technical docs, I don't think you could use Smartside as structural component.
Maybe Malcolm or another expert will venture an opinion.
Steve,
Thanks for the response!
Hi Shawn,
I suppose this is a question of risk. On the technical spec's from LP it is recommended to 'seal all exposed cuts' and the docs also spend a fair amount of effort making it clear that the siding shouldn't be exposed or installed on areas of large moisture content such as drying concrete, wet blown cellulose, plaster and green lumber among others.
Since it is an engineered wood product it is going to be less resilient than solid wood or plywood as the resins and binders in the product will make it less permeable and don't support as much hydric redistribution as you wood see in solid wood or plywood.
All of this said, the product will be protected from most UV and bulk water and it will be in a vented chamber which gives it good opportunity to dry. I would pay close attention to flashing and your WRB details-- as one should on any assembly. Be sure to allow for venting at the tops and bottoms of windows and punched openings to help ventilate this assembly.
If it were me I would probably defer to a solid wood product as it has shown to work over time. That being said, if you are open to taking on these potential risks the benefits of the rainscreen in general likely outweigh the cons of using this product.
Thanks for the help! Sounds like I better get out the credit card.
-Shawn
Shawn,
Right or wrong, I did something similar on my own small addition with some leftover LP trim, screwed through 3" foam with the primed textured side facing out. Didn't have to rip them, but did have to predrill the long screws to keep from splitting and cracking the primer. It worked well once I got the right length siding nails called for in the LP install manual for 'perfection shingles' on 3/4" deep furring.
I kept primed side out knowing that the vertical siding joints will likely see more water than the WRB or foam surface.
All that said, LP trim is thicker than the siding and holds a nail better. You'd likely need siding nails to reach back at least 1" deep into studs with any material thinner than 3/4" acting as furring.
I've had builders rip Zip sheathing, somewhat similar to LP Smartside in composition, into strips for rainscreen furring. We were surprised at how much they swelled in the rain before the siding went up, and not consistent swelling. I like Zip and Smartside for their intended purposes and I have no problem with using CDX or solid wood for furring.
Perhaps this will help ... https://www.youtube.com/watch?v=iJWvJkJEcs8