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Treatment for 2x4 sill plate after installation?

Christopher Kirby

Registered User
Joined
May 5, 2019
Messages
11
Location
San Diego
So i have an as-built sill plate that is not pressure treated. Have you guys ever come across a product to treat a regular 2x4 sill plate with Borate or similar treatment after it has been installed? Conc Slab on grade foundation below, studs @ 16" o/c above.

Right now i cant find anything. It looks like we will have to replace it in total which will require a lot of demo to a wall with exterior siding already finished.

I was reading the code this morning and it sounds like if a sill plate on a foundation is more than 8" over grade it doesnt have to be pressure treated, but ive never gotten away with that on any of my plans so i dont expect that to work.

Ok thanks for reading, cant wait to see all the responces.
 
The key word with pressure treated lumber is the word 'pressure' used to describe how the wood is treated to ensure complete penetration of the preservative into the wood.

If you are not doing a demo and it is existing then why would you try to replace it? Does your specs require treatment or replacement?
 
I was reading the code this morning and it sounds like if a sill plate on a foundation is more than 8" over grade it doesnt have to be pressure treated, but ive never gotten away with that on any of my plans so i dont expect that to work.

R317.1, 2 (Less than 8-inches)

Also see number 3. sills and sleepers, allows an impervious moisture barrier, like seal sealer or felt paper.
 
Sills are usually treated as "forever" items. It will always be a potential "weak link" for vermin infestation.
What kind of underlayment did you use behind the siding?
At least it tends to be drier down your way.
Are you on a flat site?
 
The key word with pressure treated lumber is the word 'pressure' used to describe how the wood is treated to ensure complete penetration of the preservative into the wood.

If you are not doing a demo and it is existing then why would you try to replace it? Does your specs require treatment or replacement?
As-built non permitted detached storage bldg may be a problem for my client who wants a new addition to their living room. That's what brings me here. Looking for options to solve a potential problem.
 
Sills are usually treated as "forever" items. It will always be a potential "weak link" for vermin infestation.
What kind of underlayment did you use behind the siding?
At least it tends to be drier down your way.
Are you on a flat site?

The building site is flat but the property is on a hill. Idk what kind of underlayment they used, i will check next visit.
 
You could also try Borate lumber for interior sole plates, can be used and is usually cheaper the PT YP, just harder to find, not all yards stock it.
 
Here is a thought....if the person responsible for constructing this without a permit did not have the knowledge to use a treated plate, how many other issues are lurking that have not been found yet?

Might be simpler to do this right the second time and be done.
 
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Chris, are you above a flood plain? Up slope or down slope of the hill?
No flood plains. Middle of a small hill in East San Diego. Good site drainage.

I think being born in '85 makes me a millennial, idk. Lol. But my grey hair says otherwise! Thanks for the responces. LOOKS like termites already got this structure so it's a total loss.

Still, seams a sealant is the only solution to retroactively protecting a sill plate that is not PT. I will ask some plan checkers and report back.
 
'85 ehhh? So your east San Diego must be Rancho San Diego, not the East SD I grew up in near Euclid. :)
 
'85 ehhh? So your east San Diego must be Rancho San Diego, not the East SD I grew up in near Euclid. :)

No, we have the same east county. I grew up in alpine and went to school at Granite Hills. Probably just like you did, since its right near Euclid.

I've lived in Lakeside and El Cajon for years now. I might even be a tad more East County than you even, but that's not really something to brag about.

I was hoping to have some input for you guys on the sill plate subject, but I haven't heard anything yet. Stay tuned.
 
I have been down this road. There is no effective treatment that can be applied to lumber that has not been pressure treated. Cut ends and bored holes of pressure treated lumber are to be painted with a preservative but that lasts for only a few years.
 
No, we have the same east county. I grew up in alpine and went to school at Granite Hills. Probably just like you did, since its right near Euclid.

I've lived in Lakeside and El Cajon for years now. I might even be a tad more East County than you even, but that's not really something to brag about.

I was hoping to have some input for you guys on the sill plate subject, but I haven't heard anything yet. Stay tuned.

Chris, Yeah I ment Euclid avenue at University ave near 46th street. That used to be East San Diego! not East County San Diego. carry on
 
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