Paving slabs on gravel

[welshgaz]

I've just bought a new patio set and at the moment my patio area is 10mm gravel between 2 - 3 inches in depth bounded by a concrete path and a low wall.

Having thought about the chance of damaging the new furniture by dragging it through the gravel each time I use it, I thought it may be a better idea to put some form of hard surfacing in place. The option I was going for was to lay slabs over the area (planning on being around 3m x 3m).

When laying the new slabs, I want them to be level with the existing concrete path and in a bid to save a bit of cash, can I lay them on the existing gravel? Would I need to bed them on mortar to hold them in place better? I am debating what to use in the gaps between the slabs, and whether to have short joints of around 10mm and point it with mortar or to have 50mm joints filled with gravel held in with coloured mortar.

Obviously the cheaper option would be to have the larger gaps as it would reduce the number of slabs I need.

I do have a few existing slabs that I can use to lay on the ground to raise the level in the lower areas and then lay the new slabs on top.

I think that's it, what are your opinions of my plans? I know it's not the best way to do it, but is this going to work or likely to fail by Autumn?!!

Thank you!

 

[r896neo]

laying them on gravel will be nightmarish to get them level in the first place and will turn into a disaster.

Pressing gravel into mortar really doesn;t work that well either and it will crack up very quickly if not on a firm base with no movement.

In short, there is no sense pointing flags if they are layed anything other than a bed of mortar as the minute movement in a sand or gravel base will crack the pointing.

To do it properly you need to remove the gravel and then lay the paving on a bed of mortar. Ideally you want a sub-base of compacted hardcore too but for a small patio you could maybe get away with just a good 50mm mortar bed.

Check out paving expert for some good guides for various types of paving.

 

[welshgaz]

Thank you for the quick reply,

I thought that was what people would say, I was hoping that I was wrong and that it would be cheaper than I'd planned!!

As some areas are going to need raising up, could I lay the old slabs on the membrane sheeting (once the gravel has been removed) and then lay the new ones on these with mortar? I'd then look to put a 10mm mortar joint in between the slabs.

 

[r896neo]

i'd remove the membrane as it will have lots of rotting organic matter like old leaves etc on it.

You can use the old slabs to raise areas. Preferably you'd smash them up with a sledge hammer and pound them in a bit.