zero clearance exterior material?
user-128080
| Posted in Construction Techniques on
In order to match up floors between an addition and existing house I had grade issues and so went with 2×10 PT rim joists and will be installing the foundation vents in them. Normally I cover the rim joists with the siding material (wood RBB T1-11 to match existing house in this case) but can’t do that because of ground clearance issues. I was thinking I would cover the rim joists with a belly board of some sort but am not finding a product that allows direct ground contact. (Hardiplank and Mira Tec both want 6″)
Any suggestions?
Thanks
Joel
Replies
Azek?
How many inches is the bottom of the rim off the ground?
if that rim joists is low enough where you can't cover it with siding, you have other issues such as too low to start or grade is too high at the foundation. You don't say where you are but that short path would be a favorite for termites (if termites are an issue.., yet). Water will have an easy splash from the ground into your vents.
This project is in Oregon. Just east of the Cascades precip about 18" /year- mostly in the form of snow. Termites not a problem here. Haven't back filled yet but I was planning on cutting sod back away from building about 6' to give me a slight slope away from addition. It still looks like I will be 2-3 ' into the rim joist. I was thinking sandwiching 6 mil visqueen between osb and siding at bottom of wall and extending it down over rim joist to footing. I was thinking of putting a 12" belly band of zero clearance material below the siding (directly outside of the rim joist) Someone suggested Azek - Local lumberyard can get me 12' piece of 1/2" x 11 and 3/4 Azek but it's $45 a stick- yow! I'd probably go with the Hardi as another suggested but I know the bottom 3" will be buried in the dirt and since it has wood fiber in it I don't like that option. any other thoughts?thanks
I just replaced two pieces of Hardi Trim that were in direct contact with the ground.
They lasted less than five years before disintegrating. The problem with fibercement is that it absorbs water which then freezes and blows the material apart.
I would stick with Azek.
- Rich
not sure what your code says there but there is a minimum of clearance between the sill and the dirt that's something like 6"-8" (can't recall the exact number). Even if no termites (West coastal region of OR is Moderate Termite country by the code books def) dirt as close as your planning is going to be an easier infil path for bugs. For your grade you should be dropping at least 6" in your first 10' or 5% if you can't PLs prevent you from going out 10'.
Bringing the dirt that high is a bad plan and now is the time to fix it.
Probably too late now, but you could have set the joists on the foundation and used smaller blocks to go up one more course. Not sure what this technique is called, and not sure if you'll even know by my explanation. Example. 8" cmu foundation wall with a 4" top course. Joists and sill bear on top of the 8" wall and subflooring runs to the edges. Walls are framed as normal.
See if they can get you 4x8 or 4x10 sheets of 1/2" for less and rip what you need your self. I've been getting 4x8x1/2 for about $95 a sheet.Often in error but NEVER in doubt!
1/2" @ $110 here
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Still cheaper then what his yard wanted for a stick.Often in error but NEVER in doubt!
Your problem with the Hardie is not wood fibre.It is that it will wick water up from ground contact, then freeze. That will end up making the product disintegrate in a few years from the freeze/thaw cycle.Go with Azek I guess, but there are other brands of cellular pvc too at less cost.you still have a major problem tho if you are going below grade with this. You will have water leaking into the house.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
I know Hardi says not to but I've used their 1" X 12" trim boards for years in that application and never had a problem. I only use it on existing situations that can't be changed. However, lately I've switched to AZEK which I like even better.
Copper
How about a short stucco skirt?
I've never done stucco- I assume you use a backer for it- could it go below grade?
Generally for skirting, around here, folks drive rebar into the ground and attach top part of rebar to beam with staples or bent over nails.
They then put up tarpaper and diamond mesh and tie wire to rebar. The tarpaper is adjacent to the rebar and the diamond mesh is to the outside. Your are ready to stucco.
It is not uncommon to have it 6" into the ground, but we do not have freeze thaw problems around here.
JLC has a great set of articles on stuccoing, and you can be premixed base stucco at most big boxes.
I usually do a three coat application with a slightly rough sponge texture on the final coat.