Laying new slabs with a fall?

tellytv · 22 May 2014

Hi,
Need some advice, I'm replacing some paving slabs which in total is 22ft x 4 ft but was wondering about leaving a fall for the water to run off, is this easier enough to do and could you explain what I have to do?

Any help would be approached

Thanks

Ouch77 · 23 May 2014

A fall should definitely be part of the design, though how much and what direction depends on the type of slab and how you intend to deal with the runoff water.

there's a wealth of really good information on the paving expert website I'd highly recommend reading it, particularly the section on drainage.

tellytv · 23 May 2014

Would a digital spirit level work?

the slabs are 450mm square so how much of a fall would I need per slab?

Thanks

Ouch77 · 23 May 2014

what type of slab? smooth finish or Riven?

Read this

1:80 is good for most paving, but more may be required for heavily textured or riven slabs.

I've no idea if a digital spirit level would work, as I've never used one.

tellytv · 23 May 2014

the slabs are textured.

r896neo · 23 May 2014

For a DIYer i'd recommend a fall of at least 1:50 less than that if you get it a bit wrong you may get ponding.

Where are you trying to fall water to? a lawn/flowerbed should be able to deal will an area that small.

tellytv · 23 May 2014

thanks for the reply

how do I work out how much of a fall I put on each slab? the slabs are 450mm textured

the water fall will go onto the lawn

r896neo · 24 May 2014

you don't work it out per slab but over the whole area, you then use a string line to ensure the slabs follow this pre determined fall.

So i assume you are falling the shorter 4ft distance to the lawn with the 22ft edge along the house wall.

In this case from the house wall to the lawn your flags should drop 30mm over the whole distance.

1200mm (4ft) divided by 40 = 30mm so a 1:40 fall over 1200mm is 30mm.

Without a photo its hard to give you specific advice regarding setting up lines etc as i dont know your other considerations and levels.

tellytv · 24 May 2014

Thanks for your help much appreciated

Also what sand do I use for the pointing please?

and what would be the best angle grinder to cut 35mm thick slabs?

Thanks

WabbitPoo · 24 May 2014

Tell you what - read this

rbdrifter · 25 May 2014

tellytv said:
Thanks for your help much appreciated

Also what sand do I use for the pointing please?

and what would be the best angle grinder to cut 35mm thick slabs?

Thanks

Ideally you would use a 12inch stihl saw with dust suppression, you can hire them for a not a lot.

If not, use a 9inch grinder with a decent blade. Make sure you use protection

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Laying new slabs with a fall?

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