Hello All
I am building a patio around our house.A few months ago when we were going to be using paving blocks I asked Tony how to get the fall to work out going around a corner.
But the family have now said they would like slabs instead. So the gradient will be more. From the main site and books I see that the fall for slabs should be 1 in 60 . I have set some strings up but since the patio will be about 30ft out from the house (see blue arrows on the photo ) and 50 ft along the house this fall seems a lot.
1 Can the fall be reduced from 1 in 60. The slabs we plan to use are like an Old English Yorkstone made by a firm in Kent. Scott Paving (anyone used this firm and if so what are the slabs like??)
2. The Red arrow on the photo points to the front of the house where the patio will be about 10ft wide. How would you turn the corner with a 1 in 60 fall without having to mess the slabs up by mitre cutting them.Or any other ideas?
3 The green lines on the photo are where I plan to have drainage channels. Do you think this looks ok or would you follow the channels all around the edge of the patio .The retaining wall will end up about 18" above the patio height.
Riven or riven-effect flags have a nasty habit of retaining rain and other water in the nooks and crannies of their surface, which is why they are best laid to a 'generous' fall of around 1:60. You could reduce that to, say, 1:80, as long as you accept that water will hang on the surface and therefore the risk of algae, moss, and ice is increased. Although 1:60 can seem excessive when seen on a taut string line, when the flags are actually laid, you'd hardly notice - honest!
When it comes to dealing with the corner, the flags can be laid as full (ie: not mitred) units and the change in direction of fall accommodated via the jointing. It's difficult to portray this without a 3D drawing, and I just don't have the time just now to knock up such a drawing.
However, when it comes to laying, use a spirit level to check each flag as it is laid to ensure there is fall in one direction or another. The flags aginst the house on the rear patio will fall directly away from the house. as you move towards that corner, the flags in the area around the interface between patio and side path will have their fall heading at 30º-60º, away from the corner roughly along what would be a mitre line, and then, once you;re past the corner an on to the side path proper, the fall is at 90º to waht it was on the patio - towards that free edge. Summat like this.....
As for the drainage channels, I can't see a real problem but you could simplify matters by using a dished channel and just a couple of point gullies.
Thanks Tony for you help.
While I still have the photo available on the site, one other question
When I lay the slabs do I start by running parallel to the house or way from the house.
Also at what point on the patio would you start to lay them.
If you're doing a random layout, some of the flags will be parallel and some will square - have a closer look at the idealised layout in the drawing I posrted earlier: you should be able to identify some sequences where the flags are parallel (at the corner running to the left) and other sequences where they are square (from the large brown-coloured flag at the corner running 'south').
There's no set point at which to start laying - the best place to start varies from project to project, but a good rulke-of-thumb is to start at a corner on the longest straight line. This ensures you have a good base line from which to work and it also minimises the amount of cutting that's necessary. Looking at your photo, I'm guessing that the house wall on the left side of the image is longer than that on the right, so I'd probably start from that corner in the middle of the photo, working towards the left (as you look at the photo) and then work my way around to the right-hand side.
