slabs on solid concrete base

[drewIOW]

Hi everyone,

I've read so much about the different approaches to laying flagstones onto a mortar base; but obviously everyone's situation is slightly different to the next.

Im just looking for some confidence to actually make a start with the patio.

Here are the facts :-

* Sandstone Project pack (18.5m2)
* 25m2 Solid concrete base (been down 3 years)
* retaining wall on 3 sides
* drainage channel on the 4th

Now I love the idea of a dry mix, or even just sharp sand and the slabs laid onto that. But I read a lot of "I only use 6:1 full mortar bed" which is slightly worrying me about anything laid on a dry mix.

Not all of the slabs will be touching the retaining wall, so I would use a mortar base for any that don't.

Is it easier to lay on a dry screeded base? is it safer to just go with a mortar base? how dry is a dry mix?



Any help would be great

 

[wrathkeg]

full mortar bed just means that the slab is supported by, well, a full bed of mortar as opposed to the old 5 blobs of mortar approach:

http://www.pavingexpert.com/layflag1.htm

You would still need to use a mix of sharp sand and cement. It could be dry with no water added at all (in which case moisture round and about sets it hard in time) or slightly wet:

http://www.pavingexpert.com/layflag3.htm

You will want to have a look at this in your situation:

http://www.pavingexpert.com/faq_layover01.htm

 

[r896neo]

you will not be able to use a screeded bed, the tolerance of the flags will not be good enough so you will have to use an individual bed for each flag.

don't use a totally dry mix either make it semi dry or wet.

i prefer a wet mortar as its faster to get the bed right becuase it spreads as you tap it down.

A semi dry mix will not flow under a slab so you need a very accurate bed and if its not right you need to lift and add more/ take some away.

I use 6:1

The main advantage of dry mix is its cleaner but its not really an issue in my opinion.

 

[drewIOW]

Ok thanks guys,

6:1 wet it is, the difference in height for each slab means. Ease over clean!

Starts tomorrow, if it tips it down Saturday, will that be enough time not to worry? Considering the heatwave and all

 

[wrathkeg]

you'll need to make sure you keep it damp if it gets as hot as they say, and all the more so if it's in the sun. a light but regular hosing down or watering can should do it. and keep them covered with some polythene or similar.

search paving expert for weather for more info.