Precast Concrete Waterproofing Solutions

[LongW8]

I have an ground level 1st floor outdoor patio poured over the spancrete (precast concrete) ceiling of my basement level garage. When wet/raining/snow, it leaks through the concrete patio and through the spancrete ceiling into the garage.

I feel that the most permanent way to solve the issue is to remove the existing concrete over the spancrete, put down a rubber membrane, pour a new concrete slab and then coat over the top with an epoxy coating of some sort.

Any suggestions for a contractor in the Milwaukee WI area that could seal this up? My first thought would be a parking garage contractor but they wont do residential.

Want to start a garage remodel next spring/summer and the leaking is the first step.

 

[larry4406]

Wow!

Can’t help you but that is a big ****.

Hope you can get a reasonable repair approach.

Following along.

 

[jrsavoie]

We were able to find a commercial contractor for garage planks that did the work on a weekend as a side job.
Might be harder for what you need.
How bad is the top concrete?
Is it good enough that epoxy injection and coating might save it?

I f they did a really poor job on the top layer it might not be terrible to remove. Just don't want to damage the planks now

 

[billconner]

There are bridge products - hypsum is one I used for a deck over living space and it worked great for over 25 years. I don't think it's still available any longer - can't find on Google - but suspect there are replacements. I find one called Nel-Dek by W R Meadows that looks similar. Made to go on concrete deck and be overlaid with concrete or asphalt. Much better than the much thinner membrane roofing products.

I think you may also want a positive slope under this to assure drainage. Don't know how much room you have vertically but the tapered foam they use for roofs might work.

Would love to hear what you end up with. Good luck!

BTW, at a building code hearing, I ran into a firm - architects and engineers - who only did this kind of design work. Those big plazas over occupied space. Talk about a speciality.

 

[LongW8]

We were able to find a commercial contractor for garage planks that did the work on a weekend as a side job.
Might be harder for what you need.
How bad is the top concrete?
Is it good enough that epoxy injection and coating might save it?

I f they did a really poor job on the top layer it might not be terrible to remove. Just don't want to damage the planks now

Top concrete isn't real bad.... I think, years ago, (we have lived here 30 years and didn't do it) the concrete on top cracked over some of the the seams in the spancrete. They came back later and cut out and filled with a rubber product of some kind. The cuts aren't over every spancrete seam but now there are cracks over the remaining spancrete seams.

 

[billconner]

ps - found this - similar

Waterproofing Solutions for Liquid Containment | CIM Industries

Explore premium waterproofing solutions including VOC-compliant coatings and membranes for engineers and contractors. Ensure reliable liquid containment.

chasecorp.com

 

[LongW8]

ps - found this - similar

Waterproofing Solutions for Liquid Containment | CIM Industries

Explore premium waterproofing solutions including VOC-compliant coatings and membranes for engineers and contractors. Ensure reliable liquid containment.

chasecorp.com

Thanks!!!

 

[billconner]

FWIW, when I bought the Hypsum - around 1995 - it was around $1/sf iirc. I was able to order at a local roofing supply house.

Out of curiosity, I looked for Mel-Dek (typo above - NOT nel-dek) the Royston product on line. Only found Mel-Dek - $334 for a 38 1/2" x 60' roll - so near $2/sf. Shipping added a lot but I suspect you can do better.

 

[strutaeng]

You sure there's no waterproofing between the spancrete planks and the concrete topping? By now, it already most likely failed.

Is there any slope? Where does the rainwater drain to? Two options I see are:

1. Remove the concrete topping, add slope (if not already), add waterproofing (add floor drains?) and repour topping. This is how balconies and terraces are built on the commercial side. Interior drains are similar to tile shower drains in that they collect the water down below the surface (secondary drainage.) Can you add drains below? I mean, do you have plumbing you can tie into? Adding slope may screw things up at doors, etc.

2. If you have good drainage away from from the walls maybe a traffic coating is an option? There are several out there and must be installed as a "system." Used on stadium concourses and parking garages. Needs to be detailed correctly at terminations such as against the walls.

BTW, those Spancrete planks are hollow core prestressed precast planks, correct?

 

[LongW8]

You sure there's no waterproofing between the spancrete planks and the concrete topping? By now, it already most likely failed.

Is there any slope? Where does the rainwater drain to? Two options I see are:

1. Remove the concrete topping, add slope (if not already), add waterproofing (add floor drains?) and repour topping. This is how balconies and terraces are built on the commercial side. Interior drains are similar to tile shower drains in that they collect the water down below the surface (secondary drainage.) Can you add drains below? I mean, do you have plumbing you can tie into? Adding slope may screw things up at doors, etc.

2. If you have good drainage away from from the walls maybe a traffic coating is an option? There are several out there and must be installed as a "system." Used on stadium concourses and parking garages. Needs to be detailed correctly at terminations such as against the walls.

BTW, those Spancrete planks are hollow core prestressed precast planks, correct?

Its sloped well towards the front walk. No standing water at all.
Any drains would have to run through the unheated garage.
I think the biggest issue with a coating is a good seal between the lannon stone knee wall and the concrete. Any thought?

Yes. Spancrete is a brand name for a hollow core prestressed plank

 

[billconner]

I thought there might be enough slope so drains were not necessary. I think if you can avoid drains and all penetrations, you'll be better off.

As far as walls it butts against, I'd bring the membrane up a few inches above top of finished patio and cover edge with counter flashing. I'd prefer metal cut into a grout joint but the surface applied with sealant may be pragmatic.

 

[strutaeng]

Yeah, agree on the base flashing/counter flashing at house walls and knee walls.

You need to determine if those knew walls are waterproofed all-around as well. Otherwise you'll get leaks there.

Waterproofing needs to tie into basement waterproofing.

In these things, it's at terminations and changes in vert/horiz. planes, joints, etc. the places were it's likely to leak.

 

[platapus77]

Can you just cover the patio with a roof?