Laying Paving slabs on concrete base

DublinDilbert

Hi All,

I was wondering if anyone had any links to web-sites for laying paving slabs? I've been doing some googeling and reading up.

I'm looking to lay paving slabs ( bog standard 40 x 40 ones ), to form a patio for light use.

There is already a concrete base ( > 6 inches of concrete ) where i want to lay the slabs, it's nice and smooth + has a run off on it... I've been debating whether to put down 1" of sand + compact it then lay the slabs, or to motor the slabs down with say approx 10-15mm of mortar under each slab so they are nice and level.

Using mortar would be fairly simply, like tiling, but it would leave voids under the stones which would be an issue with water freezing ect... Laying them on sand wouldn't be too bad either...

If i go down the sand route i was going to mix 1 part cement to 5 parts sand, is this over kill?

I would be interested to hear peoples opinions / advice.

Anyone know anywhere good to source the paving slabs + sand around Dublin 7 / Dublin 15?

Sonnenblumen

DublinDilbert wrote:

Hi All,

I was wondering if anyone had any links to web-sites for laying paving slabs? I've been doing some googeling and reading up.

I'm looking to lay paving slabs ( bog standard 40 x 40 ones ), to form a patio for light use.

There is already a concrete base ( > 6 inches of concrete ) where i want to lay the slabs, it's nice and smooth + has a run off on it... I've been debating whether to put down 1" of sand + compact it then lay the slabs, or to motor the slabs down with say approx 10-15mm of mortar under each slab so they are nice and level.

Using mortar would be fairly simply, like tiling, but it would leave voids under the stones which would be an issue with water freezing ect... Laying them on sand wouldn't be too bad either...

If i go down the sand route i was going to mix 1 part cement to 5 parts sand, is this over kill?

I would be interested to hear peoples opinions / advice.

Anyone know anywhere good to source the paving slabs + sand around Dublin 7 / Dublin 15?

Best to lay slabs on a 10mm wet mix (5:1). Avoid sand jointing, problematic and good weed growing environment, best to seal joints with wet mix also. Eccellent range of stone paving available from Natural Stone Yard (Ashbourne), also open Sats 9-1.00 and del service available. Well worth a look.

tradesman

Lay slabs on 5 dabs of mortar. use a 3" x 2" to keep them level and flat. Point in between with a damp( just wet enough so it leaves a slight stain in your palm) mix of sand and cement 2 sand to 1 cement. Pack this into the joints and then get an off cut of hose pipe and rub the joints smooth.

Gurgle

Sonnenblumen wrote:

Best to lay slabs on a 10mm wet mix (5:1). Avoid sand jointing, problematic and good weed growing environment, best to seal joints with wet mix also.

Carefull now.
If you're sealing the joints with a wet mix, make sure theres enough of a slope for water to run off the patio. Otherwise you'll be in puddle city for half the year.

De_man

hi ya

see www.pavingexpert.com


a pint of plain is yer only man

DublinDilbert

Hi Guys,

Thanks for the replies... I like the idea of mortaring them down, as it's just like tiling then... I'll make sure everything is all square before i start and I'm going going to run off in one direction at an angle...

I guess the only up side to bedding them onto sand is if i mess up, it might be easier to correct...

Thanks again.

Boggles

Don't use the 5 point method as advised, lay the slabs on a compete cover of mortar, it eradicates weak points and will only cost a small bit extra, use wet mix for the joints. Take your time and since you already have a flow with the existing concrete you don't have to worry about that. Good luck with it.

jimzy

I'm in a similar situation.

I have flagstone I want to lay as a patio at the rear of my house. I've been doing a fair bit of research into this but cant seem to find any answers to this.

Basically, I don't have a concrete base, but have a fairly compact bed of smallish stone ( fine stone and inch size stuff - you know the stone that is put as an bed to tarmac, etc. )

I have tried to level that out and give a fall of a few inches away from the house. I had intended on laying the concrete bed for each flagstone directly on top of this stone.

Will the patio be ok on the stone, I don't really want to have to pour a concrete bed for the entire patio as the space im looking to cover is very large, and would probably add a lot of cost to the job.

Any feedback or thought would be appreciated!

Bubbles09

Hi I would like to put paving stones on my foot path out the front of my house but my boyfriend is making the job into a massive 1 saying i'll have to dig up the foot path that is there first before paving and all this I just want to know is it advisable to put paving stones down on to concrete or would you be better off digging it all up?

De_man

are you talking about paving stones or paving slabs?

you need a minimum of 150mm from the top of slabs to your damp proof course (DPC) on your house (normally you'll have this) this is min requirement for building regulations and prevents dampness.

smartassname101

tradesman wrote: »

Lay slabs on 5 dabs of mortar. use a 3" x 2" to keep them level and flat. Point in between with a damp( just wet enough so it leaves a slight stain in your palm) mix of sand and cement 2 sand to 1 cement. Pack this into the joints and then get an off cut of hose pipe and rub the joints smooth.

Hi, Not trying to offend you but your method is the worst of all possible methods save for just throwing them down without any bedding because it leaves voids beneath the flags, making them more likely to fracture when loaded even light traffic,
the voids can allow surface water to accumulate, leading to subsidence or instability,
the voids provide a ready-made home for invertebrates, particularly ants, which love to mine an unbound bedding and/or sub-grade,
the solidified mortar spots settle differently causing the flag to 'rock' when trafficked,
correcting any rocking flags requires the old mortar to be broken out and disposed,
it does not comply with any Code of Practice (BS7533: Part4) which requires bedding to provide "uniform support".