pressure treated sills

[bill1952]

@Glenn
Glenn has a great article in JLC on this but it seems that, at that time, the IRC was not really clear. So I'm asking.

Existing ICF stem wall - 12" thick. Top is minimum 16" above ground. Existing 2x4 wall on a pt 2x6 sill, no visible sill sealer. I'm planning - actually got permit yesterday - to finish space including a non-load bearing wall flush with inside of stem wall. Would you permit that I need sill to be untreated on a foam sill sealer?

As Glenn points out, lots of exceptions to the general rule of decay resistant material on a slab on ground.

Related, is a 2x4 sill on an ICF - 2" foam - 8" concrete - 2" foam - a problem (non-load bearing)? Probably why existing is a 2x6.

Thanks!

 

[steveray]

Sill sealer is an energy code requirement...If it is a sill on concrete floor the exception to non-PT would be an impervious moisture barrier....

 

[Beniah Naylor]

What if you used a plastic sheeting under the untreated wood? 16" seems to be a long way off the ground for water to wick up into the wood.

 

[mtlogcabin]

R317.1 Location required.
Protection of wood and wood-based products from decay shall be provided in the following locations by the use of naturally durable wood or wood that is preservative-treated in accordance with AWPA U1.

1. Wood joists or the bottom of a wood structural floor where closer than 18 inches (457 mm) or wood girders where closer than 12 inches (305 mm) to the exposed ground in crawl spaces or unexcavated area located within the periphery of the building foundation.

2. Wood framing members that rest on concrete or masonry exterior foundation walls and are less than 8 inches (203 mm) from the exposed ground.

3. Sills and sleepers on a concrete or masonry slab that is in direct contact with the ground unless separated from such slab by an impervious moisture barrier.

Asphalt Felt paper should work.

 

[ICE]

Exception #2. Wood framing members that rest on concrete or masonry exterior foundation walls and are less than 8 inches (203 mm) from the exposed ground.

Your foundation stem wall is 16" above exposed ground.

 

[bill1952]

Thanks. I assumed to he 16" above ground on a stem wall got me put. No help on the bearing, half on the ICF foam?

 

[Inspector Gadget]

There's Code, and there's best practice.

I leave with an essential wisdom by my better half, who knew this truism long before I dreamed of doing this inspection thing for a living:
"Water always wins."

Build accordingly.

 

[Beniah Naylor]

Thanks. I assumed to he 16" above ground on a stem wall got me put. No help on the bearing, half on the ICF foam?

We had a house that was bearing on the ICF foam all the way around, a 2x4 sill that was half on concrete, half on foam. We wrote it up, the engineer later specified to remove the foam under the sill plate, and support the sill plate with a thick steel angle bolted to the concrete.

 

[jar546]

@Glenn
Glenn has a great article in JLC on this but it seems that, at that time, the IRC was not really clear. So I'm asking.

Existing ICF stem wall - 12" thick. Top is minimum 16" above ground. Existing 2x4 wall on a pt 2x6 sill, no visible sill sealer. I'm planning - actually got permit yesterday - to finish space including a non-load bearing wall flush with inside of stem wall. Would you permit that I need sill to be untreated on a foam sill sealer?

As Glenn points out, lots of exceptions to the general rule of decay resistant material on a slab on ground.

Related, is a 2x4 sill on an ICF - 2" foam - 8" concrete - 2" foam - a problem (non-load bearing)? Probably why existing is a 2x6.

Thanks!

Termite area?

 

[bill1952]

Termite area?

No. Way too cold. (Chipmunks and mice are a big problem though. )

 

[jar546]

No. Way too cold. (Chipmunks and mice are a big problem though. )

Yeah, you are just out of the moderate/heavy map and even out of the none/slight area. That must be pretty darn cold up there along the St Lawrence.

 

[bill1952]

Yeah, you are just out of the moderate/heavy map and even out of the none/slight area. That must be pretty darn cold up there along the St Lawrence.

Yes it is in winter (though balmy in comparison to the year I spent very near artic circle!)

It is just supporting an inner wall. I was wrong above, they used a 2x8 as still for exterior wall, and it doesn't leave room for a 2x6 under inner wall. A 2x4 plate with 2" on foam and 1 1/2" on concrete is probably ok but not thrilled.