Laying slabs in front garden using mortar?

I have a very small front garden in my house (100yrs old terrace). The area is about 4sq meters and I want to cover it with paving slabs. Currenty it is just soil.

One person has offerd to to do the work and when I asked about how he would do it he said he would compact the soil, then lay about 2inches of mortar and then lay the slabs on top. This would fix the slabs to the mortar as the mortar is wet.

He would leave a 10cm gap all the way round (with no mortar around the edges) to allow for drainage and to prevent damp on the house walls. This gap he would fill with pea gravel. I understand leaving the gap as I have read that you should not slab direct to a wall if there is a chance it will bridge the damp course.

I have never heard of this method of laying slabs. I thought generally they are laid on a bed of sand and are effectively laid sown not stuck down.

He says in his job (landscape gardner) they always do it this way.

Is this an acceptable method?

He has offered to lay them with sand but says in his exp this allows weeds to come up and the slabs are more secure this way.

I just want to know if there is something fundamentaly wrong in his approach or is it just another method that I have not come across so far

Many thanks

Bhupesh

Reply to
bp
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Reply to
pcb1962

If he is laying on wet mortar, then it is making hard work of it. I think he means he will be laying them on a dry mortar mix, which will set hard after a few days. That is the usual way of doing it. I use a weak mix, around 6 or 8 sand to cement, then when they are all down, go over the lot with a watering can. Perfectly normal in my opinion, so long as it is foot traffic only, if a car was parked on it, it may need a better sub-base. Alan.

Reply to
A.Lee

Mine has lasted 20+ years on just sand, with mortar at the edges. Not that cement is expensive, but mixing it takes time. I watched a pro laying block pavers, and he didn't use cement either. I wonder if it's anything to do with the new regs about soakaways on paved areas

Reply to
Stuart Noble

Generally speaking, there is no difference to the finished surface whatever they are laid on, the only difference with any paved surface is what is underneath it, and much crap is talked about all methods, with some people swearing by one method and ridiculing all the rest, while others proclaim their way is right and everyone else is a cowboy.

Block paving is always laid on sand because it's meant to be flexible, so all block paved drives, roads, pedestrianised streets and even carparks have nothing under the blocks other than sand on top of a sub-base.

For flags (slabs as you call them), you can either lay them on a solid sand and cement bed, blobs (or spots) of sand and cement or just sand, and there are pros and cons with all methods:

solid bed: pros: very few (if any) weeds in the joints, no need to try and point the joints as dry pavior sand can be brushed in, making for a neater job, less chance of any flags tipping, insects cannot undermine a solid bed Cons: uses more sand and cement, less drainage as it's one solid mass, expansion and contraction can cause the whole thing to crack if it's in full sun, cannot re-use the flags at any point in the future.

Blobs: Pros: easier to get level, uses less sand/cement, allows for proper drainage Cons: slightly hollow underneath allowing for insect infestations, weeds can easily take root in the joints, insects could undermine one or more blobs causing 'rocking', cannot re-use flags.

Sand base: pros: cheaper, allows proper drainage. Cons: allows weeds in joints, can be undermined, sand can be washed away over time causing rocking

personally I use blobs for foot traffic as a solid bed is overkill IMV, although I always use a solid bed for vehicular traffic.

NB, as a tip for anyone who uses blobs for flagging, instead of laying the 4 or 5 blobs in a 'dice' pattern, use the same amount of mortar, but lay it in a squre shape and one blob in the centre, so that the edges of each flag have mortar underneath them, then continue with the next row making sure there is mortar underneath every joint, this way you won't get any weeds establishing themselves (all weeds on paving come from *above*, not below as weed membrane manufacturers would have you believe)

Reply to
Phil L

Stay well away from spot bedding:

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previous occupiers of my house have spot bedded flags on top of builders sand and the (cheap shit) flags have cracked, some rock n roll more than Elvis on the bog and most of the sand underneath them has washed away. Oh, the pointing has all fallen out too. It's a disaster and looks terrible.

Reply to
Davey

I tried on sand, and couldn't get it to work for me, so ended up with a hardcore base, gravel, then laid on thick mortar. MOSTLY they are all OK..got one or two cracks where the thing is big and ends at a slope. and it was a bitch pointing.

Oh, and dont worry about weeds. I've got weeds growing out of solid pointing over solid mortar beds. They will grow anywhere a smidgeon of dirt can collect.

As far as paviors on sand goes, most drives end up rippled after a few trucks have been over. Awful.

I try not to dot and dab either after some rock and roll experiences, but the method above - a ring and a blob, is probably as good as it gets. Laying on solid mortar means that there either isn't enough, or it oozes up and needs cleaning off.

ON clay I do recommend a permeable substrate like gravel or limestone. Clay moves horrendously between wet and dry, and unless you actually lay a reinforced slab of concrete, there needs to be a bit of give here and there.

Reply to
The Natural Philosopher

That's why spot beding should only be done over compacted hardcore, sand should only ever be used under flags as a solid bed. On hardcore, the spots can't rock and the hardcore can't wash anywhere, or be undermined by ants.

Reply to
Phil L

I wouldn't like to try it with block pavers where you need to get the whole thing level in advance. Slabs you can pack out as you go, which is a doddle.

Reply to
Stuart Noble

block paving is easier than flagging:

Get surface ready, IE sub base in and whacked down, all nice and flat and well compacted.

Along one side, lay a length of 3X2.

Along other side, lay a length of 3X2.

Fill area in between with grit sand and drag a straight edge across so that you have an uncompressed bed of sand, which is exactly 50mm thick all over.

P-l-a-c-e blocks on, one at a time and don't lean on them or push them into the soft sand and don't walk on any.

When you've finished, whack over the entire area with a plate compactor three times.

Sprinkle silica sand over, brush in, whack again, re-sand and brush again.

Finished.

Reply to
Phil L

But the nice thing about slabs is you can do a bit at a time.

Reply to
Stuart Noble

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