Can you use pressure treated wood inside a home?

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Posted by: from Barrie
2/11/2016 at 6:52:29 AM

Is pressure treated wood used as a baseplate around the framing of a basement within the building code?

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Harley from Harley Reed in Rodney
Date/Time2/11/2016 at 9:23:00 AM

Yes, only use pressure treated for the baseplate on a concrete floor. Don't forget the baseplate gasket or that you must use galvanized nails to fasten the baseplate to the studs.

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Date/Time2/11/2016 at 9:26:37 AM

Yes, pressure treated wood is a requirement wherever the framing rests on concrete.

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Justin from Court Renovations in Pakenham
Date/Time2/11/2016 at 10:09:50 AM

No, and I would not recommend using pressure treated inside of a home. SPF non pressure treated is fine as long as you speperate the wood from concrete like vapor barrier.

So if its a frost wall run tarpaper to the grade height outside, 2x4 wall insulate, make sure you have vapour barrier on the bottom of the plate you do not need pressure treated or sill gasket, the sill gasket will do nothing. If your worried about water in the basement I'd recommend you fix the problem before finishing it.

Check with local code as they may ask for a 2x6 frost wall if insulating with batts. I typically frame 2x4 frost walls and have them spray foamed to gain more space. Make sure you put the tarpaper up to or a little above grade and again make sure you have the vapor barrier under the plate!

If Framing a home I don't even use sill gasket, we wrap our plate in house wrap and grout underneath the sill as it full levels the plate, and fills any holes city of Ottawa requires this some places may not.

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Date/Time2/11/2016 at 10:55:44 AM

Hi Dale,

Yes you can use pressure treated wood in your framing, it is permitted in Part 9 of the Ontario Building Code, but having said that, it is not necessary and can prove to be problematic and/or increase costs unnecessarily.

Regardless of your choice always start a basement finishing project by taking the time to ensure that water is not an issue.

Water in basements can come from a number of sources. Water can migrate through the concrete foundation or travel freely through cracks or improperly treated form tie holes.

Another area that can pose problems for basement framing is from interior humidity levels.

As a first test, I suggest taping a piece of 6mil polyethelene vapour barrier to the basement wall with red Tuck Tape. Check it after a couple of days. If there is moisture on the vapour barrier then your humidity is too high in your basement and will need to be addressed. If the moisture is underneath the vapour barrier then you have an issue with water migrating through your foundation (or you did not seal the plastic properly and have to start again).

If the water is underneath you will have to diagnose the problem further before any framing begins.

As a general rule if there are no cracks and no running water (flowing trickles) you could start by painting your foundation walls from grade down with a masonry waterproofing compound like "Drylock" or similar products.

In any case, once you are certain you have dealt with any water issues start with a 1' roll of 6mil polyethelene vapour barrier (you can buy them in 1' rolls) on the concrete and then attach an SPF (regular framing lumber) atop that. Take the time to staple the excess up the front side of your wall where your new vapour barrier (after insulation) can be sealed with accoustical sealant to it or taped with red Tuck Tape.

It is important that you use 6mil polyethelene vapour barrier for these purposes and not "house wrap" or painter's plastic, they are absolutely not the same things.

Lastly if you choose to use the pressure treated base plate, you must understand that it requires different fasteners than conventional untreated lumber. The fasteners are much more expensive so you can either absorb the cost or take the time to swap out your fasteners everytime you switch to the top plate or any other framing.

Please note that if you do not use fasteners rated for "ACQ" treated lumber they will rust out very, very quickly to the point where they will shear off and no longer be attached to the studs.

As an example, I was cutting some pressure treated lumber on my large cabinet saw one time and left the off cut laying across the cast iron surface of the say while I finished my other cuts. In that short time frame (minutes) I had formed a line of rust 1 1/2" wide right across the top of the saw!

Having said all of this. If your area is prone to Termites, you will need to utilize the pressure treated material!

Hope this helps and good luck with your basement.

Jason Irving

Cedarfalls Building Consultants Limited

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Thomas from Trusted Trades in Mount Forest
Date/Time2/11/2016 at 11:04:31 AM

You can use it yes for a bottom plate should not be used anywhere else in the home.

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Date/Time2/11/2016 at 5:09:33 PM

On all of my residential contracts we have used pressure treated as a base plate. Now brown board. Remember to seal all ends you cut with the proper material. And we always run a roll of foam under the baseplate before we cut, fit and ram set the plates or wall section into place.

Hope that helps.


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Date/Time2/12/2016 at 11:36:01 AM

Wood pressure-treated with ACQ preservatives may be used inside residences as long as all sawdust and construction debris are cleaned up and disposed of after construction.

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James from Deckster Decks in Scarborough
Date/Time3/14/2016 at 11:47:44 AM

Yes you can. There are different classifications for pressure treated lumber.

There are several different chemical compositions in different types of pressure treated wood:

Use Category Brief Description

UC1 Interior Dry

UC2 Interior Damp

UC3A Exterior Above Ground, Coated

UC3B Exterior Above Ground,

UC4A Ground Contact, General Use

UC4B Ground Contact, Heavy Duty

UC4C Ground Contact, Extreme Duty

UC5A Marine Use, Northern Waters

UC5B Marine Use, Central Waters

UC5C Marine Use, Southern Waters

UCFA Interior Above Ground Fire Protection

UCFB Exterior Above Ground Fire Protection

More info here:

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