Dodgy paving workmanship?

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JonnyB1984

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Hi all,

I would be grateful on getting some comments on a patio we had laid for us in June last year by a builder who was recommended by a family member. This builder had built a very nice (looking at least) extension to their house. But never laid any patios for them...

We had a quote from the builder which included:

1. Digging a sub-base, to be filled with hardcore then whacked down.
2. Patio laid on sand and cement.
3. Pointed with mortar.

We proceeded...

Our house is a new build in Cambridgeshire, so not great quality soil, clay and very compacted. The builders put turf on the clay before we moved in and survived remarkably well, considering the quality of the soil underneath!

The builder began by removing the turf, revealing the vary hard, compacted soil underneath. He then decided that a sub-base was not required and said that he would add aggregate to his sand and cement wet mix, effectively laying the patio straight onto our soil with a concrete layer, rather than just sand and cement.

I found this page at the time (https://www.pavingexpert.com/faq_subbas ... 20required.) which states that sub-base is occasionally required, and trusted his judgement/expertise...

However, we have since had various cracking in the jointing mortar (enough to fit a coin into) and now various slabs have moved, rock, come loose. One slab on the edge of the patio originally came loose and he re-laid it (saying "I probably stepped on that one before it had cured") and now that slab has come loose again! I even managed to lift it off of the patio yesterday, simply by placing a garden spade underneath it.

Looking back, I think he just wanted to cut corners for an easy life and now we are having to deal with a dodgy patio!

I've not since found any other sites that recommend using concrete and no sub-base so wondered what you all thought, if possible. Is concrete that much stronger that it would prevent settlement - I have my unknowledgeable doubts.

I'm considering getting a quote from a landscaper who laid another patio for us to come and look at it and get his opinion too, and a quote for lifting and re-doing it, which I will look to get covered in some way by the (lazy?) builder.

The way he laid the slabs was not a full bed, but rather a bunch of piles plonked quite close to each other. Some of the slabs sound hollow (movement/voids maybe?) and the way he pointed was to fill with sand first (to fill those voids maybe?) and then mortar over the top. Another lazy move to cut corners? Feels so, as some of the mortar that has come out is less than 10mm deep, when the slabs are 22mm deep.

He has blamed the cracks in the mortar because it was really hot when he laid it, but surely these are cracking because no solid foundation was laid?

Sorry for the long message. Looking for some experts advice please.

Thanks
:)
 
My patio was laid on a base on hardcore with 150mm concrete on top , slabs laid on bed of up to 100mm .
Sounds like his technique was no better than just dropping the slabs in the mud .
 
JonnyB1984 said:
found this page at the time (https://www.pavingexpert.com/faq_subbas ... 20required.) which states that sub-base is occasionally required, and trusted his judgement/expertise...
Click to expand...
Sorry but paving expert says

"Some paving types, block paving for example, nearly always need a sub-base,"

And also on their website it says at least several cm of MOT that has been compressed, (I know because I followed that last time I did a patio).


Their method of dots of cement on soil will always fail. Sorry again.
 
Bad job all round.

You may have got away with a full bed without a sub-base, but no way that dot n dab on soil would ever last
 
Thanks for all the replies. I've since had another patio done with a subbase and full bed - it's a great job, and also laid a patio myself - for a greenhouse, reusing the slabs that came with the house, using a subbase and full bed, also a good job (if I say so myself). These were both with sand and cement. The patio I did was just butting slabs together, and the other was using Sika jointing compound which still looks good now.

The main bits of advice I was after was whether anyone had any experience with the following points:

1. Use of concrete rather than sand and cement. Would this make it stronger? There are about 100 slabs of varying sizes (project Indian Sandstone) and perhaps 7 or 8 have some movement, yet some haven't moved one bit. I probably know the answer but I had some hope that these 7 or 8, he went a bit stingy with the cement hence the movement, but if he takes them up and redoes them with a full bed they may be ok - I guess like you say Mikeey84 we could get way with this if he redoes them...

2. I don't want to sound like I'm defending the guy, believe me, I'm very far from that! The way he laid was not 5 dots as I saw him do it. It was more a case of a bunch of piles with small gaps between the piles. So, imagine you had a 570mm square slab. He would do nine piles with a small gap between each pile. He said that when he mallets the slabs down the cement fills the gaps. My impression is that he got a bit sloppy with these 9 slabs and perhaps the gaps were bigger or less cement was used (or the cement has cracked and fallen down the holes in the soil!) My feeling is that he is quite old school (again, not defending him) Has anyone heard, or had any success with this method? - I am hopeful that the slabs that have so far stayed put, will do so for a few more years...

3. Method of pointing - any comments or more lazy-arsedness?

4. He has blamed the cracks in the mortar because it was really hot when he laid it, but surely these are cracking because no solid foundation was laid? Adding more to this - the pointing had started to crack back in September but none since. Does his reason hold any weight or is it just bullshit?
 
Last edited:
I missed the pointing method originally.

This is a half arsed way to do it. It should be mortar all the way down. It was always going to crack, as the unbound sand would shift, leave.a gap under the thin mortar, and hey presto, cracked mortar.

Sounds like a lot of corners were cut
 
There are 2 options, lift the loose and refit, and in about 5 years you will have probably relaid every slab, or get him back to sort
 
Did you say the mortar depth under the slabs is 10mm?
If so, it wants re-doing, it's never going to last.
 
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