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Posted: Wed Feb 28, 2018 5:14 pm
by Meg99
Hi, I have recently had/am having a patio installed. The finish regarding the joint widths is very poor, some butted up against others, some 15mm wide. My installer says he’s going to cut along the joints with a cutter to make them all neat/uniform. He says he does it all the time, 8 can’t find anything of the sort by researching the internet’s.
Has anyone heard of this, or done this, is this even normal?! It sounds nothing but wrong to me.....?
Posted: Wed Feb 28, 2018 5:44 pm
by lutonlagerlout
if the stone is poorly sized then this happens ,but is more common with riven flags than sawn sandstone
if the stone is correctly sized the chances are he doesnt know what he is doing
cheers LLL 
Posted: Thu Mar 01, 2018 10:05 am
by Tony McC
Cutting modular flags to balance joint width? I'm with LLL - this installer sounds like an eejit.
Ther will nearly always be a bit of 'balancing' to do with modular flags (see this page) but it should almost NEVER involve cutting, and, when it does, it should be the last option, not the first!
If your man has flags butt-jointed (in direct contact with no effective joint), then he's laying incorrectly, and, with this particular type of flagstone, but joints almost always lead to spalling.
Do you have any photies?
Posted: Thu Mar 01, 2018 2:09 pm
by Meg99
Hi, thanks for replying. I can’t post an image, possibly because I’m on an iPad :-/
Apologies for that, as I have loads!
Basically, some joints are butted up against the next flag, and some are 10-15mm wide, despite apparently having used 3mm spacers.
This is only the start of my woes with this project, they have built up to my dpc and the fall works out to about 1:160.......
They want to ‘fix’ these issues by cutting a bigger French drain (currently 50mm wide and 80mm deep), but this is only against one wall, there are two other walls affected, one having a 10mm drop to paving with no feench drain, and the other having between 36-40mm drop and 55mm drop over 3.3m, hence the poor fall ratio.....
Although I can find the legislation of what falls and distances should be constructed with the patio, I cannot find much information on what would be an acceptable alternative/remedy, apart from the page on this site, but clearly I don’t want them to cut a 200mm drain in my beautiful new sandstone flags....still only against one wall 
Posted: Fri Mar 02, 2018 12:45 am
by lemoncurd1702
Some paving is literally in 150mm units, so if doing a random pattern it can be difficult/impossible to maintain a consistent joint width (try placing two 300mm slabs alongside a 600mm with a 5mm joint) so sometimes a cut is necessary. 15 mm is a bit wide of the mark though unless they are poorly calibrated/.Probably
I have had to butt slabs and calibrate the joint myself due to customers choice of paving.
I understand your concerns but does the overall job please you. If not post some pics so we can say yay or nay
Posted: Sun Mar 04, 2018 10:21 am
by Tony McC
Meg, you can send images to me and I'll upload them for you.
This is all beginning to sound very worrying. "French Drains" went out shortly after the Napoleonic Wars and are not a suitable method for draining paving, and paving up to DPC is usually a sure sign of a cowboy.
From what you tell use, I'd suspect these jackeens have no real skills and need to be thrown off the job, but, if you can, send me some photies so we can all take a look and advise you more fully.
Posted: Wed Mar 07, 2018 12:30 am
by lutonlagerlout
you would be surprised (not) Tony how often I still see *french * drains specified,have argued with council officers and architects over that fact that they really do NOT work , in the "150mm of gravel on mud format"
LLL
Posted: Thu Mar 08, 2018 12:53 pm
by Tony McC
When you see imperial units still being used on an everyday basis, 45 years after the building trade supposedly went metric, the fact that French Drains (aka shallow trenches filled with rubble) are still being specified.