Flat tiled roof : Any Tips for leaks ?

[SurinBeach]

Hi,

 

I've got a shophouse building with a concrete flat roof, it used to be tiled but leaked.

I had the tiles removed, roof sealed with Lanko ensuring it went up the side walls too, re-tiled, and guess what same leaks in same places (lowest point where water flows to I guess)

I've installed a tiled skirting board last year, no difference ...

 

Pics attached.

 

I'm thinking of painting a 5-10cm cm border with a rooftop waterproof paint ie on tiles at the edge of the walls and the side walls.

 

Should I re-grout. the new tiles went down 3 years ago...?

Due to height restrictions I can't install an additional metal slanting roof...

Can I spray the tiles with a clear nano sealant ?

etc

etc

 

Cheers for any advice ...

SB

 

Ps And Don't buy the Philips EXTERIOR lights as in the photos, the plastic tops cracked and leaked with 2 years !

 

 

 

[simoh1490]

We had the same problem with our house in Phuket, it was all about expansion and contraction of the horizontal and vertical surfaces, as you're probably aware. What we did was to focus on the joint between the horizontal and vertical using lead flashing and flexible sealer - any other through roof fittings need to be inspected and treated also. Any flashing needs to be bent back at 90 degrees and the edges of it sunk into the concrete and sealed - it did work and the leaks stopped.

[MaeJoMTB]

I would suggest a corrugated slanted 'sun roof' above the flat roof (foam and silver insulated underside).

Not expensive, it will keep the rain off (mostly) and provide you with a nice shaded area during the day.

 

Your roof and views look really nice.

[SurinBeach]

4 minutes ago, MaeJoMTB said:

I would suggest a corrugated slanted 'sun roof' above the flat roof (foam and silver insulated underside).

Not expensive, it will keep the rain off (mostly) and provide you with a nice shaded area during the day.

I would but I cant due to height restrictions ...

[SurinBeach]

11 minutes ago, simoh1490 said:

We had the same problem with our house in Phuket, it was all about expansion and contraction of the horizontal and vertical surfaces, as you're probably aware. What we did was to focus on the joint between the horizontal and vertical using lead flashing and flexible sealer - any other through roof fittings need to be inspected and treated also. Any flashing needs to be bent back at 90 degrees and the edges of it sunk into the concrete and sealed - it did work and the leaks stopped.

Thanks Simoh1490. Could you PM me the contractor's details please ?

[simoh1490]

5 minutes ago, SurinBeach said:

Thanks Simoh1490. Could you PM me the contractor's details please ?

I did the work myself using an angle grinder to make the half inch deep cuts into the concrete, the flashing and sealant are easily sourced from Homepro or similar. Use four inch flashing or wider and make the cuts into the concrete at a slight downward angle, mark it all out beforehand do that part carefully, the rest is simple work - pre-bend the flashing before installation using a steel beam as a straight edge and pack the area into which it is placed with sealant. Also, make sure the roof surface is down to concrete without any tile coverings etc, you can always tile over the flashing if you have to or simply box it in/hide it. If you get everything prepared before hand, flashing bent and cut, lines cut into the concrete, you can do the installation process quite quickly, two people or three, start at sun up not sundown, do over two days if you can't finish before the sun/building gets too hot.

[BEVUP]

They need to learn to put a water proof coating down prior to the tiles being laid

& also need goo grouting ( All that crocodile / ect still falls apart )

I would of used Epoxy which would actually hold the tiles together instead of having a corner crack of due to their laying techniques 

[SurinBeach]

3 hours ago, BEVUP said:

They need to learn to put a water proof coating down prior to the tiles being laid

& also need goo grouting ( All that crocodile / ect still falls apart )

I would of used Epoxy which would actually hold the tiles together instead of having a corner crack of due to their laying techniques 

Lanko is the manufacturer of the water proof coating we put down before the tiles were laid ....

Yeh maybe I'll re-grout....

[simoh1490]

The leaks on flat roofs like yours come from the joint where the floor meets the walls, regrouting the tiles on the floor isn't going to accomplish anything, IMHO.

[SurinBeach]

1 minute ago, simoh1490 said:

The leaks on flat roofs like yours come from the joint where the floor meets the walls, regrouting the tiles on the floor isn't going to accomplish anything, IMHO.

Thanks Simoh1490, I'm planning on doing the floor/wall joints ASAP...

[RichardColeman]

[Aussieroaming]

Find a contractor with a poly sprayer. 

[Sir Swagman]

Lanko make a flexible grout/paste, I cannot recall the number (292?) I used this with fiberglass matting strips to seal sectional 1m concrete pipe water storage that was buried in clay. As the seasonal drying and wetting of the clay caused movement, it kept leaking at joints. That fixed it though.

[Tofer]

On 17 May 2018 at 8:23 AM, SurinBeach said:

I would but I cant due to height restrictions ...

Check with your local Aor Bor Tor, I don't think a timber structure would be a problem as it is considered a temporary structure, i.e. easily removable. That's the case in our area, but then we pay extortionate "fees" here for the privelage of building anything, even compliant designs. Also a timber structure (framing) could look very attractive if designed well.

I would suggest the corrugated polycarbon roofing sheets, more attractive than corrugated steel / aluminium, which again give more of an appearance of a temporary structure.

[canopy]

What about the new Sikalastic 501 product? Pay careful attention to the flashing pieces and all other installation details.

 

 

 

 

[simoh1490]

That's certainly something the OP should consider, my problems with it have to do with durability and the potential need to keep redoing the work every few years. For me personally, a lead flashing secured by sealant is likely to be more successful and have a longer life than a paper flashing secured by several coats of sealant and the cost/effort involved in both options is very similar.

 

 

[canopy]

Can you even find lead flashing in Thailand? I believe it could be used with Sikalastic since it also bonds to metals. But I am not sure durability would increase. Fiber flashing embedded in elastic sealant might allow better differential movement without shearing much like adding steel rebar in concrete. Sika is a very reputable brand and their products are not cheap. If they recommend fiber flashing I would be confident it would be long lasting.

 

[simoh1490]

You may well be entirely correct, I don't know. It would be interesting to understand the amount of differential movement involved in flat roof construction here since that might help determine the strength needed in the flashing. I'm guessing when I say that the combination of vertical movement emanating from the foundations/footings and the lateral movement resulting from thermal expansion and contraction, might be significant....dunno.

[SurinBeach]

Thanks Tofer

Thanks Canopy

 

I'll give one or both of them a try, maybe start with Simoh's suggestions in the edges with the Silkalastic first go ....

[thailand49]

You noted tile?  These look like wood pranks (hardwood floor looking material ) not tile? 

You be surprise, just from the first picture I already noticed a few area stair and corner of wall that that might cause the leaks. Regardless of it being cement under if the grout even a bit it will start to leak. I have a roof area much smaller and pretty much try all the stuff mentioned and none works for long period. It drys up and sooner or later it cracks and regardless how small it starts to leak.

Even the top of your walls it is pourous and can cause a leak, to each his own but this is too large a expose area, I would seriously try to cover it as suggested regardless of the code and even that it might still leak.

Best way is to tear it all up, put a cover over the cement, seal, dry and wait for it to rain before tile etc.. 

[simoh1490]

Tile on a flat roof is cosmetic rather than functional, with regard to water penetration, water tends not to penetrate concrete that has been cast as one piece but instead to penetrate where two pieces are joined/meet or where through roof fittings penetrate the concrete. Tile and grout that sits on a concrete surface may make the roof look nicer and make it easier to clean but it really doesn't act as a water barrier any more than the concrete roof already does so. Regrouting, therefore, is of no real value unless the tile has been used to hide cracks/gaps in the concrete, in which case the underlying problem of water ingress has had a band-aid put over it and that will fail eventually.

[superal]

How were the tiles laid i.e. on a 50 mm bed of cement which is the typical Thai way or by way of combed tile adhesive ? You also mentioned re grouting but if the tiles are laid the Thai way there will be next to no gap between the tiles to secure a grout . There is a clear  liquid sealer on the market  that is brushed over the area to form an invisible seal but cannot remember where I saw it , not cheap and from a reputable manufacturer . Easy fix if it works but exposure to the hot sun may pose a problem  .

I assume there is a fall to an external perimeter drain point that  is not shown and if so does the area drain quickly or are there pools or puddles when the rain stops .         Exactly where do the leaks occur in the house , mid span of room or ceiling to wall join , just at one end of the house ? as you say you are getting same leaks in the same place which sounds a bit odd considering that you have carried out a complete reworks . If me before I would carry out any flash sealing which is not a small job I would use a easy fix temporary perimeter seal either by a small  up-stand  to see if that works .

[simoh1490]

With my house in Phuket I was able to remove an access panel in the ceiling from within the living space to find the source of the leak, if you don't have one already it might be worth making one so that you can be certain where this leak (and future leaks) are - my ceilings were suspended wallboard so it's an easy and small task to cut and make a hatch. The risk, of course, is that you seal the edges of the roof but the leak is found to be elsewhere, around a through roof fitting perhaps such as a soil pipe or similar, my inspection through the roof hatch clearly showed the water coming in at the edge and running down the wall so I was able to proceed with the fix with confidence.

[SurinBeach]

4 hours ago, thailand49 said:

You noted tile?  These look like wood pranks (hardwood floor looking material ) not tile? 

You be surprise, just from the first picture I already noticed a few area stair and corner of wall that that might cause the leaks. Regardless of it being cement under if the grout even a bit it will start to leak. I have a roof area much smaller and pretty much try all the stuff mentioned and none works for long period. It drys up and sooner or later it cracks and regardless how small it starts to leak.

Even the top of your walls it is pourous and can cause a leak, to each his own but this is too large a expose area, I would seriously try to cover it as suggested regardless of the code and even that it might still leak.

Best way is to tear it all up, put a cover over the cement, seal, dry and wait for it to rain before tile etc.. 

 

These are Cotto CERAMIC tiles, quite expensive too ! Cover seems the way to go !

 

[SurinBeach]

3 hours ago, simoh1490 said:

With my house in Phuket I was able to remove an access panel in the ceiling from within the living space to find the source of the leak, if you don't have one already it might be worth making one so that you can be certain where this leak (and future leaks) are - my ceilings were suspended wallboard so it's an easy and small task to cut and make a hatch. The risk, of course, is that you seal the edges of the roof but the leak is found to be elsewhere, around a through roof fitting perhaps such as a soil pipe or similar, my inspection through the roof hatch clearly showed the water coming in at the edge and running down the wall so I was able to proceed with the fix with confidence.

 

I considered a hatch when this was "fixed" a few years ago ...and decided on ONE BIG HATCH ie I took the whole gypsum suspended ceilings down and painted the I-beams gunmetal grey  !

My 2 leaks are by the walls on both sides of the building about where the bed headboard is ...

 

[simoh1490]

An excellent idea! It looks like there's no doubt.

[SurinBeach]

3 hours ago, superal said:

How were the tiles laid i.e. on a 50 mm bed of cement which is the typical Thai way or by way of combed tile adhesive ? You also mentioned re grouting but if the tiles are laid the Thai way there will be next to no gap between the tiles to secure a grout . There is a clear  liquid sealer on the market  that is brushed over the area to form an invisible seal but cannot remember where I saw it , not cheap and from a reputable manufacturer . Easy fix if it works but exposure to the hot sun may pose a problem  .

I assume there is a fall to an external perimeter drain point that  is not shown and if so does the area drain quickly or are there pools or puddles when the rain stops .         Exactly where do the leaks occur in the house , mid span of room or ceiling to wall join , just at one end of the house ? as you say you are getting same leaks in the same place which sounds a bit odd considering that you have carried out a complete reworks . If me before I would carry out any flash sealing which is not a small job I would use a easy fix temporary perimeter seal either by a small  up-stand  to see if that works .

 

My British builder did the roof tiling, it was LANKO'd then tiles laid but cant remember on what ! And yeh the grout is not as wide as I would have liked !

I've heard about a clear sealant but wonder how long it would last with the Phuket UV.

There is a reasonable fall to drains at the rear of the building, and an overflow pipe too. No pools or puddles.

Leaks are on both sides of the walls about where the bed is at ceiling to wall join.

 

Many Thanks for the advice, will try a perimeter fix...

 

 

[thailand49]

5 hours ago, SurinBeach said:

 

These are Cotto CERAMIC tiles, quite expensive too ! Cover seems the way to go !

 

I'm no expert, but the guy is talking the building is a shop house and the way they are build and I have one build that I rent out. They use these cement pranks that are laid over creating a walking ceiling most likely the same for the roof.  That being said between the pranks unless it is seal completely top and bottom water can leak between the pranks and also along the walls. As I've found even the smallest of a crack water will find it way into the crack even if hairline! 

Most of these shop houses don't use their roofs in such a manner and certainly don't sheet rock their ceilings under those cement prank roofs, thus the complain most likely sheet rock is now molded.

Regardless of the expensive tiles sitting water will get through the grout sooner or later since the building will settle and shift and the pranks will move creating cracks under the tiles and when that happens leaks.

If you were to rip the tiles off, caulk seal with what you want and let it sit for six months after time you will see what I mean.

My opinion the large area it might be impossible to stop any leak no matter what you use. Personally, I would lay another thin layer of cement smooth it out put a hard sealer over it when cracks start to show up just fill them in and seal the area again yes constant maintenance.

Good luck!

[SurinBeach]

11 hours ago, thailand49 said:

I'm no expert, but the guy is talking the building is a shop house and the way they are build and I have one build that I rent out. They use these cement pranks that are laid over creating a walking ceiling most likely the same for the roof.  That being said between the pranks unless it is seal completely top and bottom water can leak between the pranks and also along the walls. As I've found even the smallest of a crack water will find it way into the crack even if hairline! 

Most of these shop houses don't use their roofs in such a manner and certainly don't sheet rock their ceilings under those cement prank roofs, thus the complain most likely sheet rock is now molded.

Regardless of the expensive tiles sitting water will get through the grout sooner or later since the building will settle and shift and the pranks will move creating cracks under the tiles and when that happens leaks.

If you were to rip the tiles off, caulk seal with what you want and let it sit for six months after time you will see what I mean.

My opinion the large area it might be impossible to stop any leak no matter what you use. Personally, I would lay another thin layer of cement smooth it out put a hard sealer over it when cracks start to show up just fill them in and seal the area again yes constant maintenance.

Good luck!

 

It was a shop house in the old days (20 years ago) but then gutted 10 years ago, concrete planks are used internally. Roof in question is a concrete slab.

 

I'm thinking Sikalastic Roofseal the edges all the way around and see how it fairs over the next 6 months !

If not OK then yes I'll be ripping up the newish (expensive) rooftiles, thin layer of (waterproof ?) cement then sealant such as Roofseal ...

 

Just wish there was a Contractor who specialised in this !

 

Cheers

SB

 

 

[simoh1490]

Rather than rip up the entire tile floor, perhaps just remove a one foot strip all around, it might even be possible to re lay that one foot strip to cover the Sikalastic?