Is fiber cement siding too risky on a house with no overhangs that gets little sun?
Homeowner in Long Island, ny. House currently has 40-year-old cedar siding with very little overhangs on a property with many trees, so the house doesn’t get much sun overall. Removing some of the cedar siding in a couple of areas revealed extensive rotting of plywood sheathing.
When it rains, water just pours down the corner boards and siding which get soaked because there is no overhang. Without a lot of sun, it takes long to dry. I would like to replace all of the cedar siding with fiber cement but it seems risky since fiber cement is a reservoir cladding that holds water.
I plan to use a wrb and a rain screen which should help, but I’m still worried that might not be enough long term with fiber cement. adding overhangs everywhere would be very expensive so it seems a safer option is wrb, rain screen and something like vinyl or cellular pvc that is not a reservoir cladding
I love the look of fiber cement but I don’t think I can take the risk without some overhang additions. any advice is greatly appreciated. Thanks!
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Having worked on Nantucket for a few years and in New England for most of my career, I'm a big fan of properly installed cedar shingles. The key is properly installed--the WRB needs to be nearly bulletproof in a situation like yours, with a rain screen gap and well-installed flashing. If you do that, I think unfinished cedar shingles will last as long as anything with a finish.
Fiber cement itself will last nearly forever, and the finishes on it generally last a long time, but yours is a challenging application for them and the finish would likely need to be redone every 5-10 years.
No cladding is impervious to stormwater, so it's just as important to have a good WRB and a rain screen gap with fiber cement as for shingles.
Thanks so much for your detailed response. Could you explain about what flashings I would need. I plan on using a high quality wrb with a dedicated drainage mate on top of that as a rain screen. What additional flashings would I need?
Also if cedar shingles aren’t an option for me due to the style of the house and fiber cement is not a good idea, what do you recommend for cladding? Thanks so much
Fiber cement might be ok, I really can't say as I rarely use it. I just don't think the finish will last. If you like the idea of real wood, I often use vertical boards in a shiplap or reverse board-and-batten style, or sometimes traditional, horizontal clapboards. There are now various products using wood treated to be decay-resistant, such as acetylated or thermally modified lumber.
Another option for you might be metal. It's relatively high in embodied carbon emissions so I rarely use it but it's very durable. It comes in different profiles.
Thanks so much. This is great. My final question is I currently have cedar clapboards on there now, and it resulted in massive damage to the sheathing. There was no rain screen when they were installed and the wrb was the black building paper.
Won’t the same painting issue with fiber cement be a problem with the clapboard. I guess I could leave them unstained?
As usual, Martin covered the topic of flashing here: https://www.greenbuildingadvisor.com/article/all-about-flashing.
Michael --
What is your preferred rain screen under cedar shingles? And WRB for that matter.
Ideally I like cross-strapping under cedar shingles; it's not as much work as it looks and it performs very well. But in almost all cases I just use Obdyke's Slicker Classic or another spun-bonded polyolefin mesh.
For a WRB, I usually spec Siga Majvest, Pro Clima Mento or similar. If the WRB isn't also performing as the air control layer and there is a deep rain screen, I'm also fine with Typar or even #30 building paper.
MikeonLI,
The downside of cement-based sidings is mainly that they are a reservoir cladding that can move water into the walls if they are not separated by a rain-screen and appropriate WRB. I've never heard that they were more prone to bulk water intrusion (leaks) that other types of siding.
As Michael said, they will need re-painting regularly, but I don't see how they would pose any greater risk to the underlying sheathing than other types of siding. I've used Hardie siding on several waterfront projects here on Vancouver Island that had small overhangs without problems.
Malcolm,
Thanks so much. I used the wrong term. I meant that hardie was a reservoir cladding. I’m worried about using a reservoir cladding with no overhangs. That’s why I was asking if a non-reservoir cladding (vinyl, cellular pvc) would be a better choice. I’m worried that fiber cement would hold too much water without overhangs and even with a rain screen it would risk the sheathing getting wet and possibly rotting. I plan to use a drainage mat as a rain screen on top of the wrb, not furring strips
It seems that you and Michael think that won’t be a problem. I guess the only disadvantage then is the more frequent painting that Michael mentions. Maybe that’s a reason to go for vinyl or cellular pvc. or metal, as Michael says