Patio problem

[buzzyb]

Morning all,

I wonder if someone can help me.

In June the builder laid a new patio - bout 3m x 3m. Slabs are York stone of three different sizes. The ground was leveled followed by a good 3inches of sand and cement before the slabs were laid. The grouting was done about a day or so later because the weather changed.

Within a month the grouting started to shrink and crack. By the beginning of this month the slabs in two differnt parts of the patio have risen plus several others are loose. One area of loose and risen slabs equate to about a quarter of the patio area which has to be dug up and relaid and the other area is about 1.5 m x 1m plus a few random slabs.

There is no problem with root damage as the builder had a good dig around, if anything there is a load of hard core about 12 inches down.

The builder is unable to say why this happened and has said if it happens after this repair it's our problem.

Is there anyone who can offer any advice as to why this has happened?

Many thanks

B

[landscaper2]

You say 'the ground was levelled' and this could be the clue. Just 'levelling' ground will not give a good enough sub base and the ground has started to move, taking your patio with it. If it was very dry at the time of installation, then as the ground rehydrates, it will expand and rise. If the ground under the patio was not consolidate well enough, then it will sink. Either way you will get the movement you describe.
With Indian sandstone(which you may have) which is usually not much more than 25mm thick, we would lay a 100mm concrete base in one hit, then bed the slabs on a sand/cement mortar bed before pointing.
We have laid directly as you describe on occasions (due to cost) and have had exactly the same problem with movement on 2 projects.

[buzzyb]

Am I right in assuming the builder has got it wrong. He should have used cement only and not a mix of sand and cement?

The builder is convinced the land has moved ie subsidance which we say is not possible because there is no evidenace any other part of the garden or fencing has moved. He believes we should get a land surveyor.

We did notice when he dug up the slabs and concrete in the large area the grouting and the sand & cement came up easy. The smaller area requried more effort.

Can you advise what we should do? We paid a lot of money to have the patio laid and now I feel we have wasted our time and money.

Many thanks

B

[landscaper2]

With any building work, the job is only as good as the foundations it sits on and your builder should have taken the ground conditions into account when the prep work was carried out and clearly this is not the case.

So, where do you go from here bb? I would guess you probably paid £850ish for the job. You have £180 worth of slabs that could probably be reclaimed by the sound of it, so do you want the hassle of a court case, if there is one to answer? As hard as it seems, it may be worth putting this down to experience, saving some pennies and having it done properly in a couple of years and maybe with a bit more style.

I would always recommend that garden work be carried out by a reputable landscape contractor as they would have come across all types of terrain and will carry out the job accordngly. Hope that helps

[AlBags]

It wasn't packed down well enough.
Best hand-pointing hard into the paving joints. Best for lasting effect.
So many folk just brush some in and water it. Quick, easy and not very good.
Crushed stone is a good base on top of rubble. Then sand and mortar dabs.