Lumber in contact with concrete? 1

[Lion06]

Is there a provision in IBC that requires lumber in contact with concrete to be pressure treated? I thought there was, but I can't find it.

 

[MiketheEngineer]

Yes - I think it is in "Foundations"

 

[concretemasonry]

It applies to wood that is in contact with concrete that is in direct contact with the soil, where the source of moisture is.

Would you require treated wood in contact with concrete on the 40th floor of a concrete structure?

You may not find it in a blanket code requirement, but it well known based on good practice. If there is a barrier for moisture somewhere it is usually not a requirement.

Dick



Engineer and international traveler interested in construction techniques, problems and proper design.

 

[Lion06]

Does waterproofing on the outside of a foundation wall get you out of the woods with PT lumber on that foundation wall?

 

[Ron]

As Dick says, not required but a good idea. We usually think of preservative treatment as being for moisture and termite protection only. It can also help against the drying effects of concrete contact in dry locations.

 

[cdhse]

Check out IRC R319. The waterproofing does not solve your problem. You have to install an approved vapor barrier between furring and the wall.

 

[OldPaperMaker]

In the 2009 IBC, Section 2304.11-Protection against decay & termites, outlines where one should use "naturally durable or preservative-treated wood".

 

[msquared48]

Use either a PT plate or member, steel bearing plate, or a layer of building paper between the concrete and wood. No exceptions. None, Zilch, zero, period........................................!

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[Lion06]

I figured that. I always spec the end to be wrapped in a waterproof roofing membrane, but I was getting a hard time about it.

 

[msquared48]

If you are putting a wood beam in pocket inset into the top of a concrete wall, I would not wrap the end. Just bear on a steel bearing plate and leave a 1/2" air gap all around the end and side of the beam for ventilation. Wrapping here could cause a moisture problem as you are restricting ventilation.

You can also taper the top of the end of the beam to minimize the pocket size if needed.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[Ron]

Agree with Mike that you shouldn't wrap the end. Let it breathe. I would put a layer of felt or a coat of asphalt mastic on top of the steel or concrete at the bearing area.

 

[Lion06]

What if you don't have the ability to leave a gap? Say you are pocketing into an existing wall and the pocket is very rough and needs to be filled in with grout.

 

[Ron]

Fill the bearing surface with polymer modified grout and then use a piece of felt over the bearing surface. Sides don't need to be filled.