Patio Stone - help needed

[PinterandPirandello]

We’re fitting a new patio (never had one before) but are clueless about patio slabs. Can anyone recommend what material/slabs would be good for a patio that doesn’t get sun all day please and that can be jet washed. Not too keen on very light colours, thinking more of a mid grey or darker beige colour. Where would we look for slabs?

Builders have quoted Indian sandstone at £27 a sq mtr. Is that a good price?

Thanks

Sandstone is quite attractive, but jetwashing will gradually wear away the surface it is not hard or strong. If it is damp it will be stained with black mould. My neighbour has it, laid flat so rain and puddles linger until there is enough sun to dry it. It is black with mould and accumulates dirt. I have it, and mine was laid with a good fall so rain runs off the edges onto the lawn. IiRC it has one inch per yard. If you put a ball on it, it will roll off. Mine is pretty clean.

A few things to bear in mind:

Slabs need to be laid on a firm foundation, MoT1 is the name of crushed stone product meeting the specification for roads. Any quarry or builders merchant can supply it. Cheaper alternatives are available that are not as good. It is bashed down flat and level with a vibrating plate, and should then be as firm as concrete. The slabs should be laid on a full bed of mortar, and pointed with it as they go down. Dabs of mortar, or a bed of sand, are cheaper but not as good.

The finished surface must be at least two bricks below your DPC. A bodger will lay a patio on top of the old surface, so it ends up higher, often resulting in damp. A proper job requires the ground to be dug up to at least the depth of the slabs plus base. This will be at least six inches. Paving companies have a diagram of correct construction. Bodgers will charge you for it, but not do it.

The edges of the patio must be strong so that it does not spread sideways. My preference is for an edging of paving bricks (they are dense and hard to resist frost damage)

Pics with edging. This isn't mine, but it's the work of a very fine builder I know, and I copied his style.

Thanks @PigletJohnfor the tips. Will check the builders are laying correctly with the right mortar. I did speak to them about laying beneath the damp proof course. What is the stone in your first picture please?

Indian sandstone. I don't think its concrete. It might be dusty. The pattern and colour show up more when wetted. Mine seems to have more variation.

limestone always looks lovely but not sure of cost

Don’t ever power wash. It will ruin all your concrete pointing. Wet n forget is the best! (and cheapest, and easiest!)

@PigletJohn any tips for getting the black staining off? I have Indian sandstone and under plants and trees there are terrible black patches. I wondered if it was resin or saps based on where it accumulates. We have a good run off.

A mould and moss remover such as "wet and forget"

I'm told there is a similar stronger chemical but I can never remember the same of it.

And do your best to keep it dry, for example if there are drainage or gutter faults, or if you can reduce shading and get more sun on it.

I don't know about resin or sap. I'm told the sticky residue that falls on cars is due to sap-sucking insects in the trees above.

Whatever you do, don’t get limestone. We have it and it’s bloody lethally slippery when wet, also needs jet washing quite often, much more than the bog standard concrete it replaced.

"I'm told there is a similar stronger chemical but I can never remember the same of it."

Sodium hypochlorite, ttd active Ingredient in bleach. Should be watered down and plants / beds nearby given a good soak in advance.

OP you could consider outdoor porcelain which is not porous and not damaged by power washing. It must be primed with an adhesive slurry prior to being laid for this reason and comes in multiple colours and textures

But it’s so pretty 😭😭😭

We have patio cleaner attachment for our pressure washer, can we use that on sandstone?

It will wear away the surface

So a no then!

If we get a patio cleaner solution, how do we apply that?

Watering can or garden sprayer

Can you then use a brush?

Only a soft one. The chemical kills the mould, and once dead and dry, it loses its grip. It is not like a bleach, more like a soapy solution.

Thanks all, very useful information.

Popped back to say I scrubbed my black spots under plants/trees with a brush and fairy liquid, it's come up really well. Probably 95% gone. Hard work though 💪
Still plenty of washing up liquid left too....good old fairy 😅