advice sought: tiling roof terrace

[drsabrown]

Hi, My first floor flat has an exterior roof terrace which appears to be part of the original design of the house (built mid 1860's). The areas consists of two squares each approximately 2.5 metres wide, that overlap by about 90cm accross one corner. Currently the flooring is some kind of thick felt (not like flat roofing felt, it's smooth and appears to be quite thick). The floor is in bad condition, there is ponding, cracks, small lumps and it has become detached from the wall at various points. However the terrace as a whole appears to be solid and well constructed as part of the original house. My father has suggested tiling over it - applying 30cm porecelain tiles using a cement with the appropriate elasticiser directly onto the felt. Half tiles would go up the wall to an appropriate height, covering the damaged flashing and felt. Can anybody offer any advice or suggestions on this? would this work? Or any alternatives? Any help much appreciated.

Thanks and regards,

Simon

[Dave Plowman (News)]

The usual tiles for this sort of thing are called 'promenade' tiles - made out of GRP reinforced concrete. So thin, strong and light. But would normally go on asphalt rather than roofing felt.

I'd say it impossible to tile over a felt roof and end up with a waterproof result due to the movement. So the basic roof needs to be sound before tiling. Ie, the tiles are only to prevent wear and damage to the roof covering.

[rob]

I used a single ply membrane and then covered this with paving stones, but the roof was made to take the weight. It was not cheap but i dont think anything like this is going to be. I got a firm by the same name as the product. Rob

[Christian McArdle]

It sounds like the roof needs replacing anyway. Have you considered something like Polyroof 185, which will provide a walkable non-slip surface?

'm afraid the solution you've proposed sounds like it would just trap water against the broken roof, leading to water ingress into the building.

Christian.

[drsabrown]

Many thanks for all the responses, very much appreciated.

Does anyone know of a supplier of promenade tiles (possibly North London area or willing to deliver). I'll also look at the polyroof mentioned above.

Cheers,

Simon

[drsabrown]

Also, out of interest: If the cement and the grout were waterproof, would the original solution (using porcelain tiles) not provide a waterproof covering? How would this likely fail?

Thanks,

Simon

[Dave Plowman (News)]

Because the roof isn't rigid and will move with heat, etc. As will the tiles.

[drsabrown]

I see - and presumably minute cracks in the grout will allow water through(?)

Thanks again,

Simon

[Dave Plowman (News)]

You really need to quote the post you're replying to otherwise you'll get shouted at.;-)

IMHO, ceramic tiles need to be applied to a similar substrata if they're going to be waterproof. So like the concrete walls of a swimming pool, etc. Which is solid and waterproof to start with.

To try and use them to waterproof a moving thing like a roof covered in felt is IMHO a no no.

The promenade tiles I mentioned are merely to protect the substrata from damage - not to waterproof it. You don't grout them.

[drsabrown]

aha - understood. Many thanks again.

Sim> > > I see - and presumably minute cracks in the grout will allow water > > through(?) >

[Andy Luckman (AJL Electronics)]

Nearly, see if this helps: