Best waterproof sealent between PVC pipe and concrete slab 3

[Bonypor]

Hi, we had to insert a 4" PVC pipe in a 5" thick concrete slab at the roof deck to insert the aircon cooper tubes, etc. We drilled 4" hole in the concrete slab and inserted the 4" PVC Pipe. The pipe is shaped 7 so the rain won't fall right in the hole center.

What is the best waterproof sealant that you put between the 4" PVC pipe and the 4" concrete slab hole that won't leak because we found out it was leaking yesterday when it was raining hard. We put sealant but it was not working. We just paint elastomeric waterproof in the bare slab. Thanks.

Top of slab.

Bottom of slab where it leaks rain from top roofdeck.

 

[hokie66]

Maybe a flashing like this? Installed properly, that will prevent water penetrating between the PVC sleeve and the concrete. But that won't keep the rain from falling straight down the pipe.

https://www.reece.com.au/product/ro.../dura-boot-roof-flashing-5-120mm-epdm-9503548

 

[Bonypor]

As I described, the pipe is 7 shaped or 90 degree angled on topmost so rain from sky won't fall into the hole.

In the reece product you mentioned, can it be directly applied on bare slab, or do you have to put membrane like asphalt torch on membrane on the entire balcony (or roof deck)?

Have you or anyone tried elastomeric sealant? Although I tried it, but it still leaked, why is that? Can you in principle put water tight elastomeric sealant between PVC pipe and concrete slab hole? (same diameter)?

 

[Tomfh]

That boot will be difficult to lap on and seal, plus the coolant lines are already installed.

Just cut a fillet into the slab around the top of the pipe using a grinder, clean the concrete and pipe with solvent, seal the fillet with sikaflex, and then paint on membrane lapping onto the slab, and up the pipe.

Alternatively you can seal the fillet with an epoxy product

 

[Bonypor]

I did't use any membrane in the top balcony because you need to put 2" of grout topping and it can become heavy. I only use the following Thailand made product on the bare slab. Any cons you can think of? So I can integrate it to the waterproof requirement between PVC pipe and slab hole.

 

[LittleInch]

Looks like you need something like this

https://pipe-equipment.co.uk/product/link-seals/

Or search pipe sealing concrete wall and loads of options come up.

Bit of a pity you didn't do it before putting the other pipes in place though...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Bonypor]

The aircon cooper tubes of the 4 HP split type airconditioners were already in place and it would not be possible to disassemble them. Need to waterproof 2 holes as my plain one component waterproof leaks.

Anyway. Don't you guys put any pipes in concrete slab? like storm drain for the rain or any drainage. Where do you put them? Outside in the exterior wall or in stairwells?

In case someone has actually use a sealant between a PVC pipe and concrete slabs. Please let me know what sealant you used that won't leak. I can't grind fillet because it can easily cut the PVC pipe and create bigger problems. And I can't put any link-seals because the aircon cooper tubes are already fully installed.

 

[LittleInch]

What's wrong with epoxy grout?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Tomfh]

If you don’t want to cut the concrete at all, at least make sure you clean the concrete and pipe.

polyurethane(sikaflex) or epoxy will both work.

 

[Bonypor]

What if I'd use epoxy grout or just pure epoxy and it still leaks? can you put sikaflex over the epoxy? it would be difficult to scrap cured epoxy adhesive.

What do you guys actually use? Or seriously. You don't put any pipes in concrete slabs at all? How do you insert pipes then? in the stairwell wall really?

 

[Tomfh]

I have sealed pvc pipes in concrete with both sikaflex and epoxy. Both work. If using epoxy use a thicker formulation. There are paste/putty type systems used for this purpose. It’s how they do pvc pipes in concrete pool shells

You can always add sikaflex to epoxy

 

[Bonypor]

I know epoxy has low viscosity and high viscosity. Low viscosity can reach tiniest gap. While high viscosity is thicker and can't reach tiny gap. Why should I use thicker formulation. Is it not the idea is for the epoxy to reach the tiny gap between the PVC and the concrete hole?

Also. For bare slab that is always exposed to rain. Is painting it with acrylic waterproof (Sista description as shown earlier enough?) Or do you really have to top the bare slab exposed to rain with membrane? We removed an old membrane because after years. The membrane cracked and you could't trace the leak anymore. So how do you put waterproof in roofdeck? Thanks.

 

[Tomfh]

If it’s too thin it will just drain out.

It all depends on the crack size really.

 

[Bonypor]

When the concrete slab was put, the 4" PVC was already placed. So the gap is very tiny. So I plan to plug the bottom with sealant and fill the top with low viscosity epoxy so it would reach all gap. Can this work? Using High viscocity epoxy would just cover the top without filling the gaps.

 

[Bonypor]

Concerning the above. Here is the photo of the technique. Before the 5" slab concrete was put, a 4" PVC stub out was placed. Then the stub out was hammered out to put either long pipe for storm drain or put any length PVC for aircon cooper tubes, etc.

Don't you use this technique? Why?

 

[Bonypor]

So would sealing the bottom with normal sealant and then using low viscosity epoxy above be able to fill the gap between PVC and hole? The orange stub out is just temporary. After the slab cured, the orange stub out is usually removed and replace with same diameter PVC enough for exact fit but still there is gap for water to leak from above. The balcony gets flooded during flash rain and it will become more common as climate change rules tthe weather. Thank you.

 

[Tomfh]

Was the hole drilled in the slab, as you originally said?, or was the pipe cast in?

 

[Bonypor]

Both. For the PVC tube with aircon cooper tubes inside. A temporary pipe was put and then replaced with a more permanent one. Same sized.

For others. The slab was drilled with additional holes for draining rain water. For example, with 2 inches hole, 2" PVC pipe is installed.

So they have same gap. So would sealing the bottom with sealant and pouring low viscosity epoxy above be able to fill the gap or not?

 

[Tomfh]

Yes provided you can create a seal at the bottom.