Patio Advice required

whitehaven · 28 Mar 2008

As I intend to relift them as previously mentioned & at present have just sharp sand down (1 tonne), can i therefore mix this as a mortar mix with cement & if so what ratio?
I have heard if I add a teaspoon of washing liquid to a bucket of mortar for wet pointing the joints this will provide flexibility & help reduce cracking!!

Like you say I don't want it lifting in a couple of years especially as this is a patio that was down when i bought the house.

I lifted it as the previous people had laid it above the damp course.. After 2 builders skips, depth of 1 ft x 16ft x 22ft of rubble & concrete dug out I don't want to ruin my hard work.

They are riven slabs with 1 middle, 16 segment on next outer layer then a final 16 outer layer, only 9 ft in diameter...now the best bit I have another outer layer which doesnt fit as the previous house owners bought the wrong finishing layer!!!
My local landscaping supplies can supply the final bits I need which will square off the circle to about 10ft across

WabbitPoo · 28 Mar 2008

Sounds like quite an adventure you've had!

If it were me I would lift the sand, and use it together with building sand and cement to make a wet mortar bed. A mixer would be useful. Make it in batches that you can use up without it going off.

Either way, pointing using a damp mortar mix, made with building sand and cement, 4:1, will be fine. You can use a plasticiser, but I can't comment on w-up liquid. I know brickies for years have been using it and some still swear by it. Not needed, IMHO.

Any idea what make the slabs are?

whitehaven · 28 Mar 2008

Damn that means I will have to put the sand back into the tonne bag & buy some builders sand aswell & hire a mixer. It's all been awkward with a 6month labrador & 3 yr old son at my feet aswell!

Don't know what make the slabs are.

Can i not get away with just doing a 4 & 1 with the existing sharp sand for the wet bed mix for the slabs & also for the joints?

leevis · 28 Mar 2008

Is it the general opion that laying slabs on a mortar bed, the mortar would be made up of 4 Builders Sand and 1 Cement?

WabbitPoo · 28 Mar 2008

leevis said:
Is it the general opion that laying slabs on a mortar bed, the mortar would be made up of 4 Builders Sand and 1 Cement?

No - use a mix of sharp and building sand. See earlier in post.

whitehaven said:
Can i not get away with just doing a 4 & 1 with the existing sharp sand for the wet bed mix for the slabs & also for the joints?

You could, though why not leave most of it where it is and just dig up the section you intend to do that day?

You need some softer sand in there for the ideal mix. Dont ask me the physics - something to do with how the cement needs smaller particles to bind with, and crack resistance, if I recall from uni - and have never tried just sharp sand. Dont think it would adhere to slabs very well.

whitehaven · 28 Mar 2008

Thanks rabbitpoo for your help, will get cracking (if you pardon the pun) as soon as weather,wife littleun & dog have cleared...lol

WabbitPoo · 28 Mar 2008

No problem, only its WABBITpoo, not rabbit. That'd be quite different.

As I live in Nottingham, you could always pay me to come and do it - my dog (Toby Barker) would like a visit with yours!

noseall · 28 Mar 2008

replying to an earlier comment:

the most noticeable difference between laying slabs upon solid concrete and upon mot, is the levels of suction or water absorbtion, within the substrate.

the excess water will have nowhere to go when laying upon the concrete, so it may bubble up through the joints and onto the slab face.

make the muck a little dryer for this part of the job.

Thermo · 28 Mar 2008

do not put washing up liquid in the mortar. it contains a high level of salt

maf20 · 28 Mar 2008

whitehaven said:
Damn that means I will have to put the sand back into the tonne bag & buy some builders sand aswell & hire a mixer. It's all been awkward with a 6month labrador & 3 yr old son at my feet aswell!

Don't know what make the slabs are.

Can i not get away with just doing a 4 & 1 with the existing sharp sand for the wet bed mix for the slabs & also for the joints?

I'm a few weeks away from laying a patio. I looked into hiring a mixer from HSS. It's going to take me at least three weekends to do, so by the time I priced it up I reckon it was easier to buy a cheap one from B&Q. They have them in for £99.99; got one last week. As soon as I'm finished I'll clean it out and whack it in the local rag to sell for a few quid. Will mean: -

1. Not under pressure to do it quickly with a hired mixer
2. Won't lose money on the hire if it chucks it down
3. Works out cheaper anyway of you're doing it over more than three weekends

Good luck!

WabbitPoo · 29 Mar 2008

Good idea. If you live near me I might buy it - my cheapo B&Q one has lasted 6 years and is in need of a replacement!

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Patio Advice required

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