Damp proofing below grade foundation wall

[jmillican1983]

My shop foundation is going to be poured this week. I have on hand 10 gallons of a roll/spray on damp proofing coating, but I didn't realize the concrete needs to be fully cured before it can be applied. The foundation guy wants to backfill the exterior as soon as possible so he can finish the job. Do you guys think it's important that my below grade foundation walls get coated with damp proofing? I will be installing a footing drain as required, and the below grade portion of the wall is no more than 2 feet. I do live in Oregon where it rains a lot but I don't know if it's critical to apply the damp proofing on a shallow foundation wall. It's currently excavated with concrete forms in place and I haven't noticed any water issues, ponding, or seeping out of the exposed soil. Will I regret not damp proofing?

 

[Copymutt]

Make them wait, your calling the shots. It will pay big dividends.

 

[Kaizen]

So inside the garage is two feet into the hill? Dirt goes above floor?


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[johnnyradiant]

2' is more than enough to catch water. You might feel better with a dimpled high density Polyethylene plastic foundation membrane. It is heavily used around here, and it does work. The best thing is it can be applied right away. If it were my project I would damp proof and membrane, but the membrane is actually recommened to go on early because it is eaisier to 'nail' it on, or atleast that was what my product said when I did my own money pit 15+ years ago.

 

[larry4406]

Make them wait, your calling the shots. It will pay big dividends.

Agreed.

Strip the wall forms.
Spray the wall and seal the wall to the footing. Spray up to the grade line.
Rod out the footing weep holes to make sure they are clear.
Install draintile in 4" bed of #57 stone, cover with geotech fabric.
Backfill not sooner than 7 days.

Try to find real deal hot spray bituminous water proofing (hot tar) vs "damp proofing".

 

[ConCretin]

Damproofing is always applied right after the forms are stripped. I've never seen anyone leave a hole open for 28 days for any type of waterproofing. Either you have a very unusual product or you've got some bad advice. Congrats on the new project.

 

[jmillican1983]

Damproofing is always applied right after the forms are stripped. I've never seen anyone leave a hole open for 28 days for any type of waterproofing. Either you have a very unusual product or you've got some bad advice. Congrats on the new project.

Thanks! I did a lot of research on the application instructions for the products that are available for coating the exterior foundation wall. Some are liquid and some are a stick on membrane. I only found a couple that said they could be applied to green concrete, most require fully cured concrete and ambient temps above 50f. I can't find those products locally though. The stuff I have is called Henry 107, only because it's what HD had in stock. I am definitely open to another product that I can apply in temperatures below 50 degrees and immediately after removing the foundation forms. Any recommendations?

 

[Bighead38]

2' is more than enough to catch water. You might feel better with a dimpled high density Polyethylene plastic foundation membrane. It is heavily used around here, and it does work. The best thing is it can be applied right away. If it were my project I would damp proof and membrane, but the membrane is actually recommened to go on early because it is eaisier to 'nail' it on, or atleast that was what my product said when I did my own money pit 15+ years ago.

We call it mirror drain but it’s the membrane your talking about. I’ve done a lot of footing drains and have never been called back to a house for water issues. I’ve always dug around the house, washed the foundation clean, patched any needed areas, painted the foundation with tar or other waterproofing product, installed mirror drain, installed proper footing drains and leader drains, backfill and grade yard.

I posted a more in depth explanation recently in another thread.

 

[larry4406]

Damproofing is always applied right after the forms are stripped. I've never seen anyone leave a hole open for 28 days for any type of waterproofing. Either you have a very unusual product or you've got some bad advice. Congrats on the new project.

Agreed.
We pour and then strip the next day. Day after strip we apply hot spray tar water proofing.

 

[ConCretin]

Thanks! I did a lot of research on the application instructions for the products that are available for coating the exterior foundation wall. Some are liquid and some are a stick on membrane. I only found a couple that said they could be applied to green concrete, most require fully cured concrete and ambient temps above 50f. I can't find those products locally though. The stuff I have is called Henry 107, only because it's what HD had in stock. I am definitely open to another product that I can apply in temperatures below 50 degrees and immediately after removing the foundation forms. Any recommendations?

You mention a number of different products and applications. It's important to understand the difference between damp-proofing, which provides minimal protection against moisture in the soil from migrating from the soil into your concrete and water-proofing, which is is designed to stop liquid water under head pressure from getting through.

Damp-proofing won't bridge cracks, seams, etc and therefor isn't waterproof while sprayed on or membrane waterproofing will. These products might be more temp sensitive but they regularly applied to concrete that is less than fully cured. I'd probably just avoid a product that requires it. You can find plenty of products that don't.

 

[jmillican1983]

You mention a number of different products and applications. It's important to understand the difference between damp-proofing, which provides minimal protection against moisture in the soil from migrating from the soil into your concrete and water-proofing, which is is designed to stop liquid water under head pressure from getting through.



Damp-proofing won't bridge cracks, seams, etc and therefor isn't waterproof while sprayed on or membrane waterproofing will. These products might be more temp sensitive but they regularly applied to concrete that is less than fully cured. I'd probably just avoid a product that requires it. You can find plenty of products that don't.

I appreciate all the info. I really am having a hard time finding a product that doesn’t require fully cured concrete. Either the liquid membrane or the type that comes in a roll and sticks to the foundation like window flashing. Any recommendations for a specific product would be great.


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