Posted: Mon Mar 07, 2016 9:50 pm
Hi everyone,
I need some expertise on building up and tiling over some shoddy concrete slabs.
So I had an idea: Build an extension, with the same tiled floor inside and out.
The interior tiled floor leads up to a bi fold door track, which has a slot drain butted up against the exterior face. Then there's a c.1.5m strip of concrete slab. Then another slot drain, then another c.1.5m strip of concrete, then lawn.
The first piece of concrete varies around 2" from end to end. However the second piece of concrete wasn't even shuttered ??? nope, they "used the edge of the lawn instead". Genius. Suffice to say that there's around a 4-6" tolerance at best, across this piece, which puddles, runs into the lawn, etc.
The next thing to say is that there's no DPM anywhere.
I've read the advice on here, and it appears I should have the following to tile outside:
1. Hardcore,
2. DPM,
3. Adhesive,
4. Tile,
What I currently have is:
1. Mud, with bits of hardcore squashed into it
2. Concrete, varying in thickness (a bit of a guess) from 100mm - 300mm
Questions:
1. Can I build-up the level of one or more slabs?
I looked at using a frost proof self leveller with crushed granite, but am not convinced it would last long. It's also extremely expensive for the volumes I'd need.
I noted that you can use a wet-lay method for tiles outside, on muck. My concern is a scenario where the frost gets onto the slab and blows the tiles (or what they're fixed to) in a few years time.
2. Should I bite the bullet and hire a breaker?
I'm tempted to rip out the worst of the two slabs (the one furthest from the house). I could also use an industrial floor grinder, to get the first slab within some kind of acceptable tolerance although I'd still need over 10mm of adhesive in places
I also have 3 x new concrete pads to build for sheds, a path, etc so I could just re-shutter it, order some readymix, and smash it out in one go.
3. Break-into the surface to give a key, and reduce the height so that I can get a decent 100mmm pour on top of what's there, using an SBR slurry, then more concrete (shuttered properly)?
4. A combination of the above, with a Ditra matting, to decouple the surfaces in case of movement/frost/etc.
The tiles we have are around 13mm thick porcelain, 600x600. I've used Ditra matting indoors everywhere.
5. What about a DPM - should I have one?
6. Any other options I've not thought of?
This is my project for the summer. I want to do this once, and do it right.
Any advice would be hugely appreciated, especially around the methodology and the specification of the concrete/slurry/mixes that I should be using.
Thanks!
I need some expertise on building up and tiling over some shoddy concrete slabs.
So I had an idea: Build an extension, with the same tiled floor inside and out.
The interior tiled floor leads up to a bi fold door track, which has a slot drain butted up against the exterior face. Then there's a c.1.5m strip of concrete slab. Then another slot drain, then another c.1.5m strip of concrete, then lawn.
The first piece of concrete varies around 2" from end to end. However the second piece of concrete wasn't even shuttered ??? nope, they "used the edge of the lawn instead". Genius. Suffice to say that there's around a 4-6" tolerance at best, across this piece, which puddles, runs into the lawn, etc.
The next thing to say is that there's no DPM anywhere.
I've read the advice on here, and it appears I should have the following to tile outside:
1. Hardcore,
2. DPM,
3. Adhesive,
4. Tile,
What I currently have is:
1. Mud, with bits of hardcore squashed into it
2. Concrete, varying in thickness (a bit of a guess) from 100mm - 300mm
Questions:
1. Can I build-up the level of one or more slabs?
I looked at using a frost proof self leveller with crushed granite, but am not convinced it would last long. It's also extremely expensive for the volumes I'd need.
I noted that you can use a wet-lay method for tiles outside, on muck. My concern is a scenario where the frost gets onto the slab and blows the tiles (or what they're fixed to) in a few years time.
2. Should I bite the bullet and hire a breaker?
I'm tempted to rip out the worst of the two slabs (the one furthest from the house). I could also use an industrial floor grinder, to get the first slab within some kind of acceptable tolerance although I'd still need over 10mm of adhesive in places
I also have 3 x new concrete pads to build for sheds, a path, etc so I could just re-shutter it, order some readymix, and smash it out in one go.
3. Break-into the surface to give a key, and reduce the height so that I can get a decent 100mmm pour on top of what's there, using an SBR slurry, then more concrete (shuttered properly)?
4. A combination of the above, with a Ditra matting, to decouple the surfaces in case of movement/frost/etc.
The tiles we have are around 13mm thick porcelain, 600x600. I've used Ditra matting indoors everywhere.
5. What about a DPM - should I have one?
6. Any other options I've not thought of?
This is my project for the summer. I want to do this once, and do it right.
Any advice would be hugely appreciated, especially around the methodology and the specification of the concrete/slurry/mixes that I should be using.
Thanks!