Siding Clearance Above Finished Grade?
idahobuild
| Posted in General Questions on
Hey All,
For wood and/or Hardie siding, what is the code required clearance above grade. I found references that say “6 to 8 inches” but no indication as to when it is 6″ and when it is 8″.
Any advice on where to look for this in the code?
THanks.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
My opinion 6, 8 or zero just does not matter to the Hardy plank the stuff is essence waterproof and not going to rot.
The closer you get to the ground the more splash back from the ground you will get. The rain hits the dirt and splashes dirt up unto the painted surface of the Harty plank.
The distance above the dirt and you overhang will set your maintenance schedule for how often you will be washing the dirt off the house.
If you have zero overhang and want zero maintenance you will need to be about 24 inches above the dirt.
Walta
Hardie is not waterproof. It is not impervious to water damage. It is not rated for ground contact.
Besides the finish peeling off if it's left too close to the ground, the material itself can and will degrade over time with enough water exposure. It won't rot out as fast as bare untreated wood, but it will.
Last summer I had to pull the bottom row of Hardie off my friend's shed and replace it with Boral/TruExterior which is rated for that use. I've also seen Hardie turn to garbage when stored improperly.
Point is that there are materials intended and rated for use close to or even at ground that will work. Don't just put stuff there 'cause you think it's good enough.
idahobuild,
https://codes.iccsafe.org/s/IRC2015/chapter-3-building-planning/IRC2015-Pt03-Ch03-SecR317.1
See figure #5
Thanks Malcolm. Any idea what a "protected" siding would be --- as opposed to the "non-protected siding" mentioned in the image? Perhaps, similar to what WaltA100 says, they are talking about vinyl or hardie type sidings? Or are they talking about paint?
idahobuild,
I think "protected" is s synonym for "pressure treated". The title of that image is "non-treated wood siding. " meaning that just like the framing, you can't reduce the clearance unless it is pressure treated. This section deals specifically with wood siding. I don't think there are requirements for other types, but I'm not that familiar with your code.
I'm not an expert in codespeak, but I thought that "protected" meant covered or otherwise not exposed to weather. ie, the siding on a covered porch with a 12' wide roof overhang could be a lot closer to the deck than if it were not covered with a roof and exposed to rain.
andy_,
I've never seen any distinction in codes as to whether the siding was under an overhang or not. Wouldn't it lead to too many grey areas?
I took it to be PT because in our code it refers to "cladding that is adversely affected by moisture". That distinction makes sense as there isn't any interdiction against using cladding that isn't right down to, and below grade, as we do when covering exterior foam.
Both our code and the IRC make the distinction between the clearance required to the ground, and that to hard surfaces like decks, walkways, or patios, where it can be reduced to 2".
https://boabc.org/wp-content/uploads/2015/10/code_idx_980006.pdf
All manufacturers provide ground clearance, I would start there. Even if not specified in code, most default to manufacturer requirements.
ie Hardie, see P2:
https://www.jameshardiepros.com/JamesHardiePros/techdocs/d2w/installation/hardiepanel-single-family-hz5-ca-en.pdf
Even some of the clearances they spec I would question in snow country. You generally don't ever want to have any siding sitting in water or ice melt otherwise paint will start peeling on wood siding and fiber cement turns into mush.