The Brew Cabin

Posted: **Wed Feb 01, 2012 6:27 am**

Hi guys,

First post here but I've been using the site for a long time as my external works bible!

I'm planning a to have a bit of a specialist patio built with large-format (600 square) 10mm-thick textured Porcelain tiles (to match the same tile in high gloss indoors) for the inside-outside look.

Obviously this tile will need a completely flat (to falls) concrete base.

My plan is 100mm concrete on a 100mm+ well-compacted DTP1 base. Does that sound about right?

My main question is - what's the best way of getting the concrete completely flat?

It needs a 1:80 fall so I guess needs to be quite a stiff mix. What mix would you suggest? Can concrete be mixed semi-dry and laid as a screed?

Do I actually need concrete, or would a sand & cement screed be a better option as it's very easy to get this laid completely flat? I guess screed wouldn't be strong enough though?

Thanks in advance for your advice, great site.

Posted: **Wed Feb 01, 2012 7:58 am**

personally i would lay the type 1 and concrete to within +/- 10mm then add a 50mm screed
the screeders that we use can get screed to within +/- 5mm over 6m ,well within tiling tolerances
concrete can be laid very flat with screed bars and a dry mix and powerfloat,but to get it spot on screed is the way IMHO
LLL

Posted: **Thu Feb 02, 2012 12:32 pm**

if you put your shuttering in at the right level, there is no reason why you cant achieve the sort of level your looking for with concrete. One hit and it's done. Just get your slump right, a nice straight edge to tamp and screed, then your away.

Posted: **Thu Feb 02, 2012 2:35 pm**

I'm planning a to have a bit of a specialist patio built with large-format (600 square) 10mm-thick textured Porcelain tiles (to match the same tile in high gloss indoors) for the inside-outside look.

i wouldn't do that. the slightest bit of green and damp and its the easiest tickect to casualty when someone slips over. I have seen this time and time again. Whats inside does not suit outside ???

Posted: **Thu Feb 02, 2012 5:05 pm**

dig dug dan wrote:i wouldn't do that. the slightest bit of green and damp and its the easiest tickect to casualty when someone slips over. I have seen this time and time again. Whats inside does not suit outside ???

There are proper tiles for this purpose, generally referred to as "indoor-outdoor tiles".

The outdoor tile is tested and certified with a skid resistance coefficient of R10 and a slip resistance value of 2 (something from the Spanish building regs). I'm no expert, but the brochure basically says that they lube the tile with engine oil then put on an increasing slope and test at what angle the person slips over. Or something.

Anyway, these porcelain tiles ARE designed to be used outside, even when coated with some slippy stuff, and have been tested and perform relatively well.

Thanks for your concern anyway!

Posted: **Thu Feb 02, 2012 5:08 pm**

sounds like you have done your research. i stand corrected!

Posted: **Thu Feb 02, 2012 6:18 pm**

my 3 p worth
porcelain tiles are graded 1-5
1 being bathroom walls and 5 being commercial grade (think airport departure lounge)
you will need grade 4-5 for outdoors
a client dropped her iron on some grade 5 porcelain and the iron broke!!
LLL

The Brew Cabin

Best way to create a completely flat concrete base