Slate tiles for patio

gripper · Post: # 11814Post **gripper** Thu May 04, 2006 12:58 pm

Hi tony and pals !
what a great site, i almost feel like i could pave the whole street ! i am about to lay slate tiles that are 300x300 and 30mm thick onto a class 4 mortar mix (as per your advice) but i need to know about the base. at the moment the existing surface is concrete with what i think is hardcore underneath. when i remove the concrete and reveal the hardcore will i then need to whack down the hardcore and will that then be a good enough surface to spread the mortar mix on ?
thanks in advance for your help

Post: # 11824Post **Tony McC** Thu May 04, 2006 1:29 pm

Yep.

It would be better to have a concrete substrate on which to place the mortar bed, but if levels won;t allow this, then laying the bedding mortar over thoroughly compacted sub-base is a good second best.

gripper · Post: # 11835Post **gripper** Thu May 04, 2006 3:15 pm

coolio tony thanks and should i hire a vibrating plate thingy rather than hurting my little hands to whack it all down ?

Post: # 11850Post **Tony McC** Fri May 05, 2006 1:07 pm

Depends on how big is the area. Anything over 20mÂ² is definitely better done with a plate compactor.

AndyF · Post: # 11859Post **AndyF** Sat May 06, 2006 12:58 am

I'm laying 15mm slate on concrete as you advised in my drainage post. I have a 3.5x5m area adjoining to about 1.5x6m area (L-shaped). Reading your section on expansion of concrete slabs, will it be necessary to incoorporate some expansion slots, especially as the concrete is, in places, bounded by 3 walls?
I am keen to keep a water-tight seal between paving and building walls, as the DPC comes down almost to ground level.
Thanks again.

Post: # 11862Post **Tony McC** Sat May 06, 2006 9:06 am

A crack control joint should be placed at the hunction of the two sections, and a second CCJ halfway along that 6m path. Other than that, I'd be tempted to use an expansion joint against the walls that surround the larger area, and have them topped off with thioflex or a similar polysuphide waterproof, flexible joint sealant.

AndyF · Post: # 11933Post **AndyF** Sat May 13, 2006 10:01 am

I will be laying a hardcore base, partly to raise levels, and partly because I have a good quantity of brick and concrete rubble that can go back down again. Use of a wacker plate will be available.
Should that be ST4 grade concrete? What would be a minimum thickness for light traffic/patio use?
Thanks again.

Post: # 11985Post **Tony McC** Tue May 16, 2006 9:46 pm

ST4 min 100mm thick

AndyF · Post: # 12195Post **AndyF** Tue May 30, 2006 10:02 am

Hi again,
with regard to my first post in this thread, I have found another source for the slate which is said to be between 17mm and 24mm thick. Reading the manufacturer's laying guide, they suggest a 100mm well compacted hardcore, over which there should be 40mm compacted sharp sand.
The slabs are a mixture of 600x600, 600x305 and 305x305, and the guidance is to lay them with a slightly wet motar mix of 1 cement to 5 building sand, on average 25mm thick.

In view of your suggestions for my previous scheme in this thread, and that of Gripper's, do you think that this one is a viable option? It's quite a departure from your own recommendations.

For a number of reasons, the idea of not laying concrete is a bonus.
Thanks again.

Post: # 12248Post **Tony McC** Sat Jun 03, 2006 5:36 pm

My recommendations are my recommendations. I don't give a Donald Duck what "manufacturers" (who are probably just retailers) say. You can choose to follow my advice, or choose to follow theirs, but don't expect me to change my mind just because some glorified shopkeeper tells you summat that sounds easier.