Block Paving Sinking - what action to take?

[CortinaV8]

I had a block paved driveway installed at the start of the year that has started to sink and crack the edges off blocks as it does, in the areas where the car wheels tend to end up.

I've had the installer back (eventually) and he claims to have rectified the few areas where it had dropped, It's still not totally level or looks as good as it did when it first went down.

I'm not really sure why it has happened, 150mm of type 1 sub base was used, and the rest of the construction looked fine from the bits I saw.

Just wondering what course of action you would take, the installer isn't interested in relaying the driveway, which is what I would prefer and is convinced I have had something really heavy on it. The only car I've had on the drive is a VW Golf.

 

[HERTS P&D]

Was this a 'cash job'?

Andy

 

[r896neo]

Either it wasn't compacted enough, the wrong sub base was used or the sand is much too deep or the wrong sand used. All of which lie at the foot of the installer. It is possible the underlying ground is very poor and unstable but unlikely. If he quoted for 150mm of sub base and installed that then there is not a lot you could chase him for.

I would guess the sand is too deep and too fine.

The sand should be between 20mm-40mm 50 at an absolute maximum and a consistant thickness. It should be a coarse free draining sand.


Is the sinking rutting where the car drives in or elsewhere on the drive? Or both?

 

[JohnD]

150mm of type 1 sub base was used

Was used?

or Was charged for?

How did he compact it?

 

[CortinaV8]

Not a cash job, nor the cheapest quote.

The sub base was 150mm of Type 1, the depth is correct as I saw it going in. The ground is fairly heavy clay.

The sand thickness sounds about right, not sure on the type of sand that was used, bit it is coarse.

The sinking seems to be where the tyres of the cars generally end up on the drive.

To be fair when he seemed to know what he was doing and the job looked good when done, but didn't expect I would start having issues within 6 months of it being down.

How would it be fixed, i'm guessing removing all the blocks/sand, adding/compacting more sub base if the sand is too thick and going from there?

 

[CortinaV8]

Was used?

or Was charged for?

How did he compact it?

That quantity went it, compacted in layers with a whacker.

 

[^woody^]

Post a picture. I'm not clear if this is rutting all up the drive or just at the front edge.

Generally you would need to do a one metre wide repair for ruts, and a concrete brace at the front of the drive stops dips there.

 

[London Mike 49]

When we had our drive done this year we went over the top on the spec but it is nice and solid.

We had a 150mm reinforced concrete sub base laid and the blocks were then laid on a sharp sand/cement mix directly onto the sub base. Paving sand was vibrated into the gaps and sealed.

The spec is similar to a garage forecourt.

http://www.pavingexpert.com/rigidbpv.htm

Lots of ideas on this site to help you decide what to do.

Mike

 

[John D v2.0]

Sounds like it was done properly to be honest.
Perhaps the sand was washed out/waterlogged? Ours is on a slope and I've had to top up the sand quite often near the top, and also get rid of a lot of ants nests built in the sand.

 

[Nige F]

Was this a 'cash job'?

Andy

What are you inferring, Andy ? Itinerant paving layers - whatever next.

 

[r896neo]

You need to lift a few blocks, ideally in the middle somewhere and check the makeup and depths to be sure.

If it is all legit as you say then it most likely wasn't compacted properly. Did they use a vibrating roller or pedestrian wacker?

Whatever the cause there is no fix apart from lift and relay.

As woody suggests I always lay the first few metres on compacted leanmix concrete instead of granular sub base to avoid rutting at the entrance.

 

[HERTS P&D]

If the job was not a cash job and is under 12 months old, which it is.
Then it is not fit for purpose.

Sue them!!!!

Start the legal paper work before the year is up.


Andy

 

[EddieM]

Not a cash job, nor the cheapest quote.

The sub base was 150mm of Type 1, the depth is correct as I saw it going in. The ground is fairly heavy clay.

The sand thickness sounds about right, not sure on the type of sand that was used, bit it is coarse.

The sinking seems to be where the tyres of the cars generally end up on the drive.

To be fair when he seemed to know what he was doing and the job looked good when done, but didn't expect I would start having issues within 6 months of it being down.

How would it be fixed, i'm guessing removing all the blocks/sand, adding/compacting more sub base if the sand is too thick and going from there?

How big is the drive? If Type 1 was used which is classed as impermeable and it is over 5 square m then you should have sought planning permission (same applies for a concrete base)

 

[^woody^]

The big unanswerd question is why have you got a Golf and not a Cortina?

 

[^woody^]

classed as impermeable and it is over 5 square m then you should have sought planning permission (same applies for a concrete base)

"Permeability" is not the criteria for when planning permission is required.

MOT 1 is not in impermeable in any case.

And the MOT is not on the surface either.