Patio - ordering the supplies

chabsey

I'm planning on ordering the slabs / sand and cement for laying my patio today and was reading on this site:

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

where it says not to use building sand - "DO NOT USE BUILDING SAND - it is to soft and can become 'fluid' when waterlogged, consequently moving beneath the flags, causing settlement."

So, I was about to call the patio center I'm dealing with and order 1 tonne of sand...but I presume I've got to say that I don't want builders sand, but what is it I do want? Sharp sand? Or something else?

Anyone know?

Thanks!

Finneganjp

Sharp sand is recommended for laying slabs, however its a nightmare to work with it in a wet mix. My advice would be to use 6 sharp sand to 1 cement in a dry mix.

10-10-20

I'm glad you queried that. Normal sand has rounded grains which allows it to become mobile during movement in wet situations.
Sharp sand does not move as such and remains stable.

TKK

Surely if you're going to lay on a wet mix, which will set solid, it doesn't matter what type of sand you use? However if you're laying on sand alone you do need sharp sand.

Sonnenblumen

chabsey wrote:

I'm planning on ordering the slabs / sand and cement for laying my patio today and was reading on this site:

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

where it says not to use building sand - "DO NOT USE BUILDING SAND - it is to soft and can become 'fluid' when waterlogged, consequently moving beneath the flags, causing settlement."

So, I was about to call the patio center I'm dealing with and order 1 tonne of sand...but I presume I've got to say that I don't want builders sand, but what is it I do want? Sharp sand? Or something else?

Anyone know?

Thanks!

What slabs are you laying, if they are concrete based then sharp sand is fine but better as a dry mix with some cement mixed through. On the otherhand, if you are laying stone (natural) slabs then a wet mix is essential in which case you should use Builders sand.

A compacted hardcore base (at least 100mm - 150 mm) is required to provide stability for patio area.

chabsey

Sonnenblumen wrote:

What slabs are you laying, if they are concrete based then sharp sand is fine but better as a dry mix with some cement mixed through. On the otherhand, if you are laying stone (natural) slabs then a wet mix is essential in which case you should use Builders sand.

A compacted hardcore base (at least 100mm - 150 mm) is required to provide stability for patio area.

Gah! It's Indian sandstone, which is natural, so does this mean it's builders sand I should be using? And a wet mix, but to what ratio?

When I went to the patio place they said a tonne of sand and 4-5 bags of cement. Which works out at about a 10:1 ratio, does this seem strong enough for a wet mix?

And finally, with a wet mix can I prep an area of, say, 2 - 3 slabs and lay them, prep the next area and lay them and so on. Basically can I individually prep the area?

It's going on top of an existing concrete patio so that's my hardcore base.

Thanks for all the replies guys. Need to get this clear before I order the supplies.

Sonnenblumen

chabsey wrote:

Gah! It's Indian sandstone, which is natural, so does this mean it's builders sand I should be using? And a wet mix, but to what ratio?

When I went to the patio place they said a tonne of sand and 4-5 bags of cement. Which works out at about a 10:1 ratio, does this seem strong enough for a wet mix?

And finally, with a wet mix can I prep an area of, say, 2 - 3 slabs and lay them, prep the next area and lay them and so on. Basically can I individually prep the area?

It's going on top of an existing concrete patio so that's my hardcore base.

Thanks for all the replies guys. Need to get this clear before I order the supplies.

I'd recommend 5 or 6:1 as a good ratio and yes wet mix with builders sand. Not too wet, keep it firm !!

And yes you can prep as outlined. Ensure the concrete patio is reasonably stable, if uncertain break old slabs in situ.