How to fasten Hardie shingles or cedar shingles when using 1″ rigid foam and a rainscreen outside 2X6 wall?
cherilyn
| Posted in Energy, Heating & Insulation on
I am in the final steps of houseplan decisions, but need some advice. I was hoping to use 1″ rigid foam insulation outside our 2X6″ stud exterior walls and also use a rain screen as described in FH (3/8″ X 2″ strips run vertically to create a space between the housewrap and siding. When using vertical strips which is required for the proper air flow behind the siding how would attachment of Hardie shingles or cedar shingles be accomplished? Any ideas?
Replies
With shingle siding
vertical strips are going to be completely useless. You could consider nailng PT 1x3 or 1x4 horizontally across the wall to match the elevations of your shingles nailing. You might consider beveling the tops of the strapping outward from the wall. I think vertical airflow behind rainscreen siding is a very small part of the appeal, the capillary break is the huge attraction. Shingle siding (wood shingles, at least) breathe extremely well because of all the gaps between shingles. I would strap horizontally with absolutely no hesitation.
With shingle siding
I very much appreciate your opinion. Makes good sense I think. Thanks!
Better yet?
An even better solution would be to first nail on vertical battens and over them the horizontal strapping. Then the shingles. This buildup gives an unhindered vertical drainage plain between the cladding and the rainscreen material.
Yes, but
won't your windows be completely buried once you add that much furring? A lot of the windows I install are slightly buried when 1-1/2" thick trim is laid right over the nailing fins. If you install the windows to the plane of the foam, then install 2 layers of 1x, THEN install trim and siding, you'd better have a plan for how that's going to look... and of course there are probably ways.
Have you considered rain screen fabric?
I'm doing a job
with HomeSlicker and cedar shingles over it, but it's directly on plywood sheathing so the usual shingle fasteners (1-1/2" SS staples) can get their bite. With the added 1" of foam you would need some long fasteners for the shingles, probably 2-1/2" or longer.
Rigid foam and shingles
I'm currently working on a retrofit on an existing house with 2x6 studs and a layer of fiberboard sheathing on the exterior. The house also has a layer of 1" polyiso. on the inside surface under the drywall and fiberglass in the stud bays. I'll be removing the existing cedar siding, adding 2" polyiso. foam (not taped) and a layer of Zipwwall (taped) with 4" deck screws, Homeslicker, then cedar shingles. I feel it will be quicker to cover the entire surface with a good nail base layer. It will work for securing all the new windows and trim too.
Are you sure that you need strips behind Hardi singles? they dont need the same amound of air circulation as ceder shingles do.
I would just nail the Hardi to the rigid foam.
Why do you say the Hardi
doesn't need as much circulation as cedar? FC siding materials absorb an impressive amount of water. I would think a rainscreen behind them would be a great idea.
Does Hardi recommend using a rain screen and strips behind its products?
Seems like a rhetorical question.
Go ahead and read their literature, read current building science literature in general, look at where the building codes are headed, check into the things that failure analysts are finding, and draw your own conclusions. Perhaps you think that a rainscreen is not necessary, or is not wise under Hardie, in which case please explain. If you live in an arid climate, it may be less important, but that doesn't cover most of this country.