Capillary Break Needed?
Chris_King
| Posted in General Questions on
I am about to start installing 1” of Roxul Drainboard on the exterior of my foundation and have plans to bring it up to my siding. The siding sticks out 1” and the Roxul is 1” thick, do I need to leave a gap between the Roxul and Vinyl siding or add some sort of break between them to keep the Roxul from wicking up water to the siding with the potential to hit the sheathing?
Thanks
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Replies
Chris, there should be little to no wicking, but to keep pests from using the Roxul as a highway into your structure, you should provide a metal "termite shield" flashing.
Has anyone experienced pests tunneling in Roxul? I would have thought it would be less hospitable than foam.
Vertical wicking in rock wool is weak, but still non-zero. If it's only in contact with vinyl siding the vinyl siding itself is the capillary break. If it's in contact with the foundation sill or wood sheathing that's another matter.
Using EPDM seam tape between the foundation sill/sheathing and the rock wool, lapped correctly to the housewrap, with another layer of seam tape formed as Z-flashing to direct bulk water coming down the housewrap to the exterior side of the rock wool will work without creating a big thermal bridge or gap.
Charlie,
No experience with the Comfortboard but I did have some mice build a nest in a batt of Safe and Sound I left lying around.
There was a GBA article saying a certain bird loved making its nest in roxul during construction
It may not be ideal but most insects and animals are adaptable, if its non toxic they will make a home in anything, so expect your roxul to get damaged unless protected.
I'll bet money an ant colony would do well in Roxul
Charlie,
Roxul states that per customer feedback pests don't like their product but they don't warranty for such. However I've heard one story (via video) where a squirrel(s) ate into some unprotected batts that were sitting in a garage.
Thanks everyone for the help, in regards to Alan's comments about birds liking to nest in it i found this GBA blog about covering the exterior of a house in Roxul and the bird problem.
https://www.greenbuildingadvisor.com/blogs/dept/guest-blogs/wrapping-older-house-rock-wool-insulation
Thats the one, so you have squirrels, mice and birds who like living in roxul, i think that proves its not pest resistant
Roxul drainboard against a foundation is very different from roxul batts lying around or in a cavity. Due to a long delay between renovation phases, i have had three layers of roxul drainboard exposed above grade for almost three years now. I haven't seen any pest damage of any kind. The only damage I've seen is some physical damage from myself or my dog, and where the gutter drain pipe drained directly onto the insulation for a period of time and the material sort of crumbled.
Having said that about the drainboard, I also have ~1900 square feet of comfortbatt in the attic floor. Before installing this, I had to remove the old insulation which was more mouse bodies and acorns than insulation. Since installing about 3 years ago, i've seen no evidence of the critters returning. Not making any claims, just relaying some experience.