Will it wick?"

[TBA]

Any thoughts on the prospect of the PWF plywood wicking in the attached image, where the plywood extends 6" over the foundation wall and would be at or very close to grade, the sill plate would also be PWF.

Anyone have some experience with this? Could the plywood wick and eventually affect the wall system?

Thanks for any insight.

[jraabe]

If I understand the diagram correctly you have a PT sill and plywood with standard wood studs.

That would be a better than average wall and while there may be some wicking up into the PT ply if you are actually in wet soil you could have a moisture barrier on the first say 24" of the studs so that moisture wouldn't wick into the untreated framing. The ply and sill should not have problems with occasional wetting.

[peg_688]

I see two issues with that system

#1: You mentioned almost to grade , will your siding be wood ? That would be a code violation and a rot problem , and yes then wicking of moisture would climb the studs . Remember drawing water up the tree / stud is what the norm  is for wood so I'd say if your siding is wood you might be setting your self up for failure.

#2: The second issue which works on paper , but seldom in real life /the field is your foundation , slab on grade / concrete would need to be perfect to allow that lap . You could kick your lower plate out say a 1/2 " or so to insure your squaring up of your wall / boxsill / framing would allow that detail without putting a huge flair , bows out that WILL be in your foundation . So again your drawing a detail that will be hard / inpossible to follow .

Kicking the plate out the 1/2" would also cure the wicking up the back side of the sheathing as well as allowing your idea , slightly modified as above , work . You would still have a problem if your siding if wood , or something  like LP . If it's Hardi / vinyl/ metal although I wouldn't recommend burning metal , but just close to the grd. it should be OK .

You must be a Architect  Just kidding John , sort of    

[TBA]

It's actually the pony wall over my ICF foundation. I need a way to protect the blue skin and Styrofoam that's above grade, the 4x8 PT plywood sheets would act as the sheeting as well as the protection, the pony wall is 3' 4" leaving 8" to cover the blue skin etc. I'd most likely put a mortar or stucco type treatment over tar paper and wire attached to the PT.

But if it will wick, then scratch that idea.

Thanks.

BTW: the sill will overhang 1/2" all the way around.

[peg_688]

Oh that sort of different , could you use a sheet Hardi?

Or run your felt up the back side , maybe use a 12 1/2" wide rip of felt 6" up the back , 1/2" across the bottom , 6" up the face ,so it would create a  "U" . Then over lap the "normal" felt so that bottom edge is "sealed" by the felt? Just thinkin outside the box , might be over thinking it    

If your stood of the 1/2" I think it would be fine just as you stated in the (your) second post.    

[TBA]

Hmmm, sheet Hardi. Does it have the same sheer strengths/values as plywood? If so, that might be the best bet.

Thanks.

[peg_688]

Hmmm, sheet Hardi. Does it have the same sheer strengths/values as plywood? If so, that might be the best bet.

Thanks.

No not quite the same , run it by your local inspector , it is a pony wall in a crawler you could pick up your shear on the inside , maybe with a metal strap / diagonal. You'd need to look into it a bit more for shear strength / code compliance.

Not knowing where your localed as in earthquake / hurricane/ etc country this advise is a shot in the dark sort of deal.

Keep us posted ;)G/L PEG  

[TBA]

Decided on offsetting the sill 1/2", other than the odd 1/4" wave (inward bow) on the foundation walls as determined by stringing, then butting the sheeting to the foundation - then felt and wire over entire cripple wall and ICF to grade - then parge coat and then finished with light concrete fake rock.

No wicking.