Patio height advice

[surreygooner]

Hi,

I think I've made a bit of an error on my patio height. As you can see from the pic the concrete base is 2 brick courses below the DPC and 1 below the aide brick - I was hoping to reuse some riven slabs but once bedded they'll come up to 1 and1/4 bricks below DPC and 1/4 brick below airbrick - will this be ok or should I look at thinner slabs/other suggestion.

Thanks



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[surreygooner]

Sorry just realised pic is upside down!

 

[r896neo]

Your finished height should be 150mm below dpc as you know. I would say that 100mm may still be ok although definately not recommended and will be picked up by a survey. Less than 100mm is asking for trouble.

At the end of the day the choice is yours, you know the possible risks and have to weight that up against the work of removing the concrete and re-doing the sub base.

You will not get slabs thinner than 20mm calibrated stone.

You could use tiles which would be laid on tile cement and could be as little as 25mm for tile and adhesive but your concrete would need to be ultra flat and high quality or they will crack easily.

 

[surreygooner]

Thanks r896neo my other thought was to put a drain against the house to run to a soak away then slab from there onward, making sure from there onwards the slabs angle away from the house to the soak away I've dug?

 

[r896neo]

If your happy with the compromise what often happens in this scenario is to forget the drain, just fall the paving away from the house and leave a gravel strip 6 inches wide and a fraction below the paving to deal with any possible splash back.

As i said, it just a question of risk versus extra work

 

[surreygooner]

That's a great help thanks, I was thinking of something similar but in addition setting a channel against the house to move any standing water to either side and a natural soak away - that way standing water won't be a problem and splash back shouldn't be either as it is a very sheltered garden as the majority of the weather hits the front of the house.

Thanks again

 

[r896neo]

Don't bother with the drain, there will be no standing water if you fall the paving away from the building.

Plus rain will just as easily bounce up off a linear drain grating as a paving slab so it defeats the purpose of having it.

If you do go for gravel strip you'll need to break out a channel of the concrete so any any water can soakaway through it. In fairness you'll need to do this too if you go for a drain because an aco channel is about 4 inches deep and needs bedded on some concrete.

 

[surreygooner]

Could I just drill a series of holes for drainage?

 

[r896neo]

Yes as long as you do lots of them.

You may struggle if you dont have an sds drill. Also be careful to check for services central heating pipes from a garage etc.