[drive surgeon]

been asked to quote a business forecourt consisting of around 760 square metres of blockpaving, its full of moss, not many weeds .  anyone any advice on such big jobs.?  the biggest job i have tackled was around 100 square metres.   i was looking at problems like drainage of water, getting rid of the sand /moss etc.

i hope the customer does not want it sealed as its too much hassle waiting for dry weather this time of year.

i have to include re-sanding too in the quote.
its going to be hard working out prices.

im wondering whether to include weedkilling too as i dont want weeds growing in his newly cleaned forecourt after a few days.  some forecourts i see seem to have something in the joints that stops this as they are not sealed. it must be some type of kiln dried sand  that stops stuff growing in it.
any ideas or help would be greatfull. i appreciate all advice on this forum . im still only a relative learner.  any help would be good .

[keith b]

If the joints in the paving are between 2mm and 5mm then use a product called "Keybond" from a company called Marshalls, if larger (over 5mm) then use "Geofix" jointing compound, but make sure the paving is bone dry before sweeping in.

To get rid of moss in the long term, use a product called "Lichenite".

[Roger Oakley]

Stop right there, Geofix is not for Block Paving, block paving is also known as flexible paving IE there is some movement, it needs kiln dried sand not a filler that will go hard , Geofix is for slabs etc, and in my opinion complete C**p I have used it, but have found far better products on the market.

[Ged]

resiblock 22 is used to stabilise jointing sand while retaining the flexible nature of the paving. it is called an elastomeric polymer. has minimal effect on the colour of the blocks.  used on airport aprons to combat sand erosion from jet blast and on other commercial applications such as sea fronts etc. speak to the technical bods at resiblock for details. you might do worse than to do their  day   course and learn all about sealing and get a load of freebies too.

[steve doyle]

Marshalls key bond is quite good and its what i often use.

its readilly available at builders  merchants but be warned, it doesnt go as far as the instruction say it will, but as it goes on with a watering can its easy to use.

[keith b]

Appologies Roger, I must have misread the posting, your quite correct geofix is more for paving slabs and not blockpaving - kiln dried sand alone is more than enough for the later!

[Roger Oakley]

Appologies Roger, I must have misread the posting, your quite correct geofix is more for paving slabs and not blockpaving - kiln dried sand alone is more than enough for the later!

That's ok Keith..... if you do use Geofix, you might want to try Marshall's M-Joint, it's about the same price as Geofix for 20kgs, but here is the best bit, it's a brush-in (like kiln dried) you then water it in, plus any that you don't use, just leave in the re-sealable container unlike Geofix which if you have any left over you have to throw away once it has been opened. Again this is only for slabs, Concrete, Yorkstone etc, and not Block paving.

[drive surgeon]

im just gonna use kiln dried sand as usual but i might put some weedkiller down after so the sand soakes it up, should help stop them grow.  im fully trained at laying resiblock 22 but dont want the hassle of waiting for dry weather as the boss wants it done quick this job .

[Roger Oakley]

If you have the time before you do the job, why not put something like Round-up down before, this would give you a fighting chance and should kill off some if not all of the weeds. Another thing I have done before now, is to put a weedkiller down straight after washing, IE all the joins, which has kept any weeds etc that you might miss at bay. On one job, the client said it was nearly 6-8 months before any weeds came back, which is not bad, but the product was expensive.

[drive surgeon]

cheers rog, thats what i would prob do but there are no weeds hardly, its just all moss, what im worried about is when i put fresh sand in the joints after it has been cleaned  that grass seeds and weeds dont start growing in the new sand as they seem to blow in with the wind.

[Roger Oakley]

cheers rog, thats what i would prob do but there are no weeds hardly, its just all moss, what im worried about is when i put fresh sand in the joints after it has been cleaned  that grass seeds and weeds dont start growing in the new sand as they seem to blow in with the wind.

The moss will come with washing, even just water, so you should have no problem there. Why not offer to come back say 4-6 weeks later and with a fine rose on a watering can apply a weed-killer, (charge extra) that way the sand will have had time to settle etc and you really shouldn't wash any sand out. Also at this time of the year, weed spores etc (Air-bourne) I would say are low, more chance of birds dropping seeds etc, which you can't really odds against.

[drive surgeon]

yes good idea , was thinking of using sodium chlorate over the entire area, but with a watering can is going to take a while, 760 square metres!   will it still be as effective on top of the sand rather than before sand to kill the roots underneath/

[drivewasher]

I can't see the problem here, seeds will not germinate in kiln dried sand it's sterile some people still call it steralised sand.
If the blocks are laid properly there will be no weeds underneath the blocks. kiln dried sand should be replenished by the occupier at least once a year, this has the effect of replacing the top few milimetres of sand that the weathar and insects have erroded away. If this is not done then the resulting channel (top of the 3mm sand joint) will fill up with atmospheric dust (soil) and the weed seeds and spores will germinate in this top few millimetrs

[drive surgeon]

your right in theory but i have seen grass growing in kiln dried sand in a week??    when drives are cleaned that have a lot of weeds growing in them we are just chopping the heads of in thoery but the root systems arew still under the blocks??  i think the answer is to put weed killer down after cleaning before the sanding and after sanding??

[allyoops]

I find that it is better to put the weedkiller on after cleaning and before sanding and if you are concerned about moss you can also put down a fungicide treatment

[Roger Oakley]

Agree with the answers since my last post,I was just trying to give you some ideas if you have to go the weed-killer route.  if this was me doing this job, I would chemical wash the surface, this would get rid of your moss problem in seconds, also give you a cleaner surface,  rinse, allow to dry out properly, then re-sand, job done. I know some don't like chemical useage, but that's how I would do it.

[allyoops]

What type of chemical do you use ? I have a 300 sq.m drive to do with a large moss problem,might be worth a bash,cheers Neil

[Roger Oakley]

Neil you have email.

[drivewasher]

your right in theory but i have seen grass growing in kiln dried sand in a week??    when drives are cleaned that have a lot of weeds growing in them we are just chopping the heads of in thoery but the root systems arew still under the blocks??  i think the answer is to put weed killer down after cleaning before the sanding and after sanding??

Yes, exactly, if the the sub base has soil in it or it's crap there can be roots growing in it. (a good job will be mot stone and a top layer of sharp sand, and no soil etc) these will grow up the sides of the blocks  and out into the air/sunlight to grow, you'll have to get the roots in that case. I use sodium clorate after a wash. So to recap if deep rooted and sand joints are kept full, then it's poor laying. If the weeds (as most are) are in the top few millimeters then wash em away, resand advise custy to keep joints topped up

[drive surgeon]

hey rog can you tell me the chemical wash you use please?? many thanks.

i normally get a good clean with the whirlaway and turbo but if chemicals do better i might try this on a business forecourt were there are no plants/grass. cheers