The Brew Cabin

Hi all - great forum.
I have a problem with a 5 year old sloping block-paved drive. It was never sealed and I realise after reading here that it was never re-pointed with sand either (ie the contractors left once the paving was laid and it has never been touched since). The result is that there is a lot of moss, grass and weed growth in the joints.
I have 2 problems/questions.

1 - Generally the joints are quite tight, except at the edges where there are lots of part blocks. In addition to the weed growth, the paving is very grubby and so I have attacked it with a jetwasher. This obviously has the effect of pulling the sand out of the joints, but at the edges where the bigger gaps are it actually destabilises the blocks by eroding the sand from underneath.

2 - Some larger gaps have opened up in one area creating an open joint perhaps 10mm wide. Being in the centre of the paving it is not very practical to lever all of the blocks across to bring the gap back to the edging.

To remedy both of the above I am contemplating brushing in a kiln-dried sand and dry cement mix to stabilise the joints, followed (possibly) by a coaty of sealant. I have not seen this suggested or torpedoed anywhere on the forum, so I don't know whether it is a good idea or not?! All I do know is that if I only brush sand back into the newly cleaned paving I will be back to square 1 in 12 months time - I did this to a section of it last year and I may as well not have bothered...

What I want to achieve is a no/low mantenance surface which can safely be jetwash cleaned once a year or so without having to re-point constantly.

Any advice appreciated. Thanks.

Brushing in sand and cement is a massive no-no! It does actually state this on the main website, where I go to some pains to stress the fact that NO cement is used for the jointing. That's not how flexible block paving is intended to work and it will neither remedy your current problems, nor will it prevent recurrence in years to come.

The solution is to use cement-free jointing sand to refill the emptied joints. If there are large-ish gaps between the edges and the cut blocks, then it's best to replace those cut blocks with new pieces, following the rules for cutting-in which are given on the main website. You might be able to re-use some of the existing cuts, but it's quite likely that you'll need a few spare blocks to use for the cuts.

As for the 10mm gap in the centre of the pavement, the only real 'fix' is to lift and re-lay, but I'm more interested in why this gap has appeared and how far it extends.

You could, if you so desire, leave things more or less as they are, re-fill the joints with jointing sand, and then douse the lot with a stabilising compound, but there's no guarantee that this will remedy the movement. I see this as no more than a temporary patch-up and it does nothing to address the cause of the block movement.

If you replace the defective cuts, and re-lay the sections as required to eliminate the wide joints, then it's worth considering using a quality sealant to protect the paving and to eliminate the risk of losing jointing material during future jet-washings, but to seal a patched-up pavement, is, in my not so humble opinion, a complete waste of time and money. You wouldn't re-spray a car until the bodywork was perfect, so why spray on a sealant over your paving when the "bodywork" is still unsettled?

Many thanks for that - glad I asked now (and glad we have a had a damp week which prevented me from carrying out my dodgy plan !!)

In reply to your question, the pavement is built on a slight slope on a newly terraced section of garden. I suspect the retaining wall and backfill have settled a little causing the gap(s) to appear. The worst of the gaps runs for perhaps 1.5m.

Looks like I might have to bite the bullet and re-lay part of the pavement to close up the gaps then? I certainly want a permanent solution.

You have mentioned stabilising compound AND sealant - if I do as you recommend and sort out the fundamental problems, would you still recommend a stabilising compound? Also, could you recommend a suitable stabilising compound and/or sealant for this application?

Many thanks again
Mike

If you elect to use a sealant, then you don't need the stabilising compound, as a decent sealant will bind the jointing sand and protect the paving from stains and spills.

The only readily available stabilising compound is Keyfix from Marshalls, although there are others, if you want to spend a week hunting them down. As for a sealant, I'd suggest the Resiblock 22 or the Resiblock Ultra, although I know many contractors are particularly taken with the TechCon Supaseal - you can find contact details on the Sealant Links page.