Patio advice

[Invader75]

Afternoon all. 

 

I'm looking to replace our old patio with some Brazilian slate. The existing patio was extremely heavy concrete slabs that must've been down for 50 years. They've been removed and it looks like there's a hardcore base underneath, a gravel/sand type. 

Would this be ok to lay on top once it's been whacked? Is it cheaper to do cement/sand wet mix or buy slab mix? Factoring in the hire of a cement mixer, lugging sand cement, etc. 

[CC45]

Did the old patio move at all?  if not crack on.  Sharp sand in bulk bag out the front, cement safely locked away somewhere (valuable stuff) & mix in a wheel barrow.

[Invader75]

13 hours ago, CC45 said:

Did the old patio move at all?  if not crack on.  Sharp sand in bulk bag out the front, cement safely locked away somewhere (valuable stuff) & mix in a wheel barrow.

No, old patio was down for as long as I can remember and no movement. Although the slabs were extremely thick and heavy. The new Brazilian slate slabs I have are about half the weight (same size) and half the thickness. I'd been advised to lay them on a mortar mix as they're not quite as heavy. 

[CC45]

Good advice.  I'd just run a whacker over it to level it all and then crack on. 6:1.

[Invader75]

On 07/07/2021 at 21:24, CC45 said:

Good advice.  I'd just run a whacker over it to level it all and then crack on. 6:1.

 

Do you know how I would work out quantities of sharp sand and cement?

[markc]

38 minutes ago, Invader75 said:

 

Do you know how I would work out quantities of sharp sand and cement?

Work out the area, multiply by average thickness to get approx. volume and then multiply by weight of sand and cement.

P.S. regular sand/cement screed is 1800kgs per cubic metre

Edited July 16, 2021 by markc

[CC45]

just laying mine now - ended up using 5:1 in the end, SBR the back of all slabs then lay them down on the mix.  I've used a 10mm tiling trowel this time - seems easier to get a light fluffyish bed to lay the slab onto.  Few whacks with a rubber mallet and you're sorted.

 

Damn hot out there today.

 

https://www.toolstation.com/vitrex-notched-adhesive-trowel/p76594?store=FU&utm_source=googleshopping&utm_medium=feed&utm_campaign=googleshoppingfeed&mkwid=s_dc&pcrid=515847200306&pkw=&pmt=&gclid=EAIaIQobChMIuNT_8IDr8QIVVOvtCh3vAQLrEAQYBCABEgJXWvD_BwE&gclsrc=aw.ds

 

[Invader75]

Cheers guys. I'm flying blind on this. A friend is helping me lay it, but he's away. I'm in charge of ordering everything! ??‍♂️ If the area we need to patio is 21.60m2  and I need 1” Full bed, wet mix sand and cement (this is what's recommended by the slate suppliers), How much sharp sand and cement do I need to order?

It is sharp sand I need right?

[Invader75]

Update. Took a while but got it all done. Only issue was after checking with slate suppliers, they don't recommend having a fire pit on them as they can crack. I wondering if there were any other options that people have used to avoid slate cracking? 

[markc]

Slate doesn’t cope well with direct heat, if you sit the fire pit on something insulating like a few layers of cement board it should be fine, assuming it’s a raised metal type

[CotswoldDoItUpper]

49 minutes ago, markc said:

Slate doesn’t cope well with direct heat, if you sit the fire pit on something insulating like a few layers of cement board it should be fine, assuming it’s a raised metal type

We had a skate hearth under a 5kw wood burner in our last place. Seemed ok for the 3 years we used it! 

[joe90]

1 hour ago, Invader75 said:

I wondering if there were any other options that people have used to avoid slate cracking? 

Legs !