Nailing cedar board-and-batten siding to furring strips
Hello, I’m planning to replace tired and damaged vinyl siding on my house this spring and am looking for advice on attaching cedar board and batten siding as a replacement.
My plan is currently to install 1.5″ Comfortboard insulation, an artificial rain-screen drainage mat, then horizontal 1×4 furring strips to attach the Alaskan Yellow Cedar board and batten to. I have been unable to find a local building code that specs fastener penetration for cedar board and batten (3/4″ thick boards and approx. 7/8″ thick battens) however I did come across the Western Red Cedar Lumber Association specs that recommend a minimum 1-1/4″ fastener penetration for installation of board and batten.
I had been thinking that 3/4″ penetration with ring nails into the furring scrips would be sufficient but now I’m second guessing. Is there danger of this being not enough nail ‘hold’ for the siding?
Should I consider screws instead of nails?
Or thicker 2×4 or stacked plywood furring strips?
(With the wall thickness already increasing due to the addition of rigid insulation, any addition thickness creates a challenge.)
Any other recommendations?
Thank you for any feedback on this!
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Replies
We have had ZERO issues with 3/4 plywood or 3/4 pine/fir furring strips. So, either should work UNLESS you're coastal or in tornado alley. Even then tighter face nailing of siding is the main issue.
Hi Russel.
With the 3/4 inch furring strips, I assume you are referring to nailing the board-and-batten, but maybe you have done this over mineral wool. Have you specifically used 3/4 inch furring strips over exterior mineral wool? I've heard that thicker furring strips, mainly 2x4s, make it easier to keep the furring strips in plane for a flat siding install and that 1x material bends too easily and therefore compresses the insulation.
Hi there Russell and Brian, thank you for your replies. I appreciate the feedback.
Russell, do you just use standard ring shank nails?
Brian, that's a good point regarding the flex of the 1x4's, I have not worked with rigid mineral wool so hadn't considered compression being an issue. The furring strips will be installed over 2x4 wall studs that are 16" OC. I wouldn't expect much flex but definitely worth considering.
Hey Drew.
I recently watched a pretty instructive video on using string lines to get furring strips in plan for siding installation over exterior mineral wool. I'm not sure where I saw it, maybe over at Protradecraft.com. If I have some time this afternoon, I'll see if I can find it, but you might try YouTube.
Here's the video I was thinking of--right website; wrong insulation. But the technique will still be helpful with mineral wool, I would think (I've only done this myself with rigid foam). Anyway, I hope this is helpful: https://www.protradecraft.com/prepping-rainscreen-walls-siding
Hi there Brian, thanks for the link, very much appreciated! I had thought about some sort of method like this but this video really helps. Lots of great info there. I can see this being even more important over something less rigid such as mineral wool.
Seriously considering 2x4's for furring based on your point about 1x's moving too much.
Fyi..you don't need rain-screen drainage mat between the Comfortboard and the furring strips.
Comfortboard is hydrophobic so bulk water will just bead off.
Hi there John, thanks for the info! Do you know if mineral wool qualifies as a capillary break? I had planned to use a rain-screen mat to meet the 9.5mm drained and vented air space requirement by many building codes. If mineral wool satisfies this requirement, that would be a big bonus.
To clarify, my plan is to attach horizontal furring strips directly over the insulation without double-furring. Aside from the air space requirement, I was concerned that the horizontal furring could trap any ingress water and hold it on top of the furring strips. Is this unlikely with rigid mineral wool?
Yes it's a capillary break. Also mineral wool is vapor open which will readily allow drying to the exterior.
https://www.rockwool.com/a/s/understanding-vapor-diffusion/
I would think it's possible that bulk water could pool on top of the horizontal furring strips, but it's anyone's guess for how long.
Why not attached the siding directly to vertical furring strips at 16" or 24" centers? Normally B&B requires the vertical then horizontal then B&B as the best approach. (https://hammerandhand.com/best-practices/manual/4-rain-screens/4-6-horizontal-rain-screen-battens-vertical-siding/)
https://cdn01.rockwool.com/siteassets/o2-rockwool/documentation/technical-guides/residential/comfortboard80-installationguide.pdf?f=20180718133916
Thanks John, really appreciate the links! Very helpful.
As this is a renovation project, I'm trying to keep the wall thickness to a minimum. I haven't seen anyone use the double furring method in my area for B&B but I can definitely see how it makes sense, especially in areas with heavy rain. I had been taking a horizontal furring only approach in an effort to save time, materials and reduce wall thickness. Certainly worth considering the double furring method though.
With mineral wool, your WRB should be behind the rigid insulation. Because mineral wool is self draining, it doesn't need to be textured, regular house wrap is fine. The drainable WRB on the outside is not doing much.
For installation instructions, I would follow one of the pre-finished siding manufactures' instructions. Most ask for more than 3/4" of embed for board and batten.
https://www.maibec.com/imports/medias/pdf/en/installation-guide/maibec-installation-guide-regular-siding.pdf
Hi there Akos, thanks for the link, great info there!
As I mentioned above in my reply to John, do you know if mineral wool qualifies as a capillary break? I had planned to use a rain-screen mat to meet the 9.5mm drained and vented air space requirement by many building codes. If mineral wool satisfies this requirement, that would be a big bonus.
To clarify, my plan is to attach horizontal furring strips directly over the insulation without double-furring. I see in the link you provided that double-furring is a requirement in the east, I'm in Alberta and don't know of any such requirement. Aside from the air space requirement, I was concerned that the horizontal furring could trap any ingress water and hold it on top of the furring strips. Is this unlikely with rigid mineral wool?
Maybe it's a case of double-furring OR installing a rain-screen mat? I realize that only using horizontal furring presents some potential problems with trapping moisture that I may have to consider more carefully.
You would have to check with your local building official if mineral wool would be acceptable, I can't see why it shouldn't be. I'm not in an area where it is needed so I never had to look into it.
I'm not in a high precipitation area so almost any type of gaped cladding attachment is better than standard install. Horizontal strapping should work well enough over mineral wool, I can't see it trapping any water. You can always bevel the top to slope away from the siding as extra insurance.
The double strapping is to get the spacing to match the battens and get correct embed with that specific siding.
Our code specifically calls out furring and fastener sizes for wood siding and 1x4 with 2" nail is fine over insulation.
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Drew,
The code requirements here in BC for rain-screens are as you say for drained and vented cavities, not just capillary breaks. They do make provision for propriety rain-screen alternatives, but I've never seen mineral wool boards included in that. Practically though, building and Alberta, I'm not sure that's important. If your code doesn't require run-screens, I would omit the drainage matt and rely on the mineral wool with WRB behind.
Hi there Malcolm, Thanks for the info and recommendations! I don't believe that rain screens are a requirement in Alberta, I had been thinking of using one in an effort to build the highest functioning wall possible. With your feedback, and the feedback from others, I'm thinking now that a rain-screen is an unnecessary expense especially given that it's not required by code. It seems that the mineral wool will provide ample airflow especially given the relatively dry climate in Alberta.
Drew,
After building for a couple of decades here in Vancouver Island, a few years ago I went to Calgary to frame a house. A lot of the detailing - like embedding framing lumber in the top of the foundation - that would be disastrous here, works absolutely fine in your dry climate. I think the assembly you are suggesting will work well there.