patio (re-) laying

Save yourself a sh*t load of work & timber deck straight over it.

Err, not everyone thinks timber decking is wonderful.....

not really if there's been hardstanding there before, as in your case. If for example you were removing flowerbeds and lawns etc, then hardcore would be required, but whatever is under your patio now, isn't going any further down than it already is.

You work off the house, that is to say, your slabs run parallel with the brickwork of your house, and not a fence, shed or anything else - whether you decide to leave a gap near the house is up to to you, so long as the gap is exactly the same all the way along, then you can either fill in with pieces or fill with decorative stone

String is an absolute must.

solid beds of sand/cement (dry or wet) are required for vehicular traffic. for pedestrian use, blobs of fairly wet mortar, about 6 sand: 1 cement is adequate, five per slab, and don't step on any laid that day.

waste of time and money, for 16m you could mix enough by hand to last you a full day in one wheelbarow

the 600 X 600 ones cover a bigger area, and you can get them in 35mm, but it's your choice

I bedded our slabs on sharp sand and none of it has washed away in 20 years. Obviously the edges need to have mortar or be up against something solid. I laid them one by one, packing out as I went. Much easier than trying to level the whole area in advance as a pro would.

You may just need to properly compact whats there already and re-lay.

Paving upto the house carries a risk of causing or exacerbating damp in the house. A gravel border improves the situation.

the weakest mix that prevents washout is 12:1. However is that problem likely in your case? Lots of slabs are just laid on sand.

Are the ones you've already got no good? You could spend the money on a pressure washer.

Use something better than sand between the slabs in the gaps.

NT

In message , Fred writes

Excellent idea:-)

Depends what you find under the slab. For a *fresh* job on garden soil I excavated about 10" and put back 4" of crushed concrete.

Our soil level was high with regard to the slate damp course under the walls so I put a row of bull nosed pavement edging about 12" out from the house and filled the trench with shingle.

Drained to where? 1:40 is the minimum for underground soil pipe where you have solids to move. I think 1:100 would do to run off rainwater.

I used a 10:1 dry mix sharp sand/cement. The sand is unlikely to be

Pass. You can mix in a barrow or, if you have a level surface, you can mix the Egyptian? way: create a pyramid with your sand and cement and then move it twice.

Mine were 600x600mm but I was younger then:-(

regards

I'm certainly no pro, but levelling even a fairly large area is not difficult.

One thing I would advise is do not use sand in the gaps between slabs if it anywhere near a lawn. The grass and weed seeds will be in there in no time. Point all the gaps with mortar.

MBQ

It suited me to do a bit at a time though. With brick pavers you probably don't have that option but, with slabs, you can lay half a dozen and leave it for another day. Oooh my back etc.

I went for no gaps and, although we get the odd tuft of grass, it hasn't been a problem. We don't have a lawn though.

Well I don't know what is under the patio until I lift a slab to see. I'm not sure that whatever there isn't going to move any further because it obviously has: the patio is not level. Perhaps the patio has fallen as low as it will but OTOH how do I know that this isn't an ongoing process?

NT suggested it would prevent damp. I have concrete floor so there are no air bricks. I don't know whether that makes a difference? Would you put in a gap? Would 150mm be about right?

What fall do you use?

Thanks again.

Can they be lifted non-destructively? They have a pattern in them, which in theory would be good for grip in the wet but because they are "bobbled" it makes it impossible to get the chairs and tables not to rock because one leg is always on a "bobble" (in addition to the slabs themselves not being laid flat).

I used the calculator on the pavingexpert web site, that uses a 6:1 ratio but says that for 16m^2, I would need 1.2T of sand and 240kg cement to make a 50mm bed. That sounds like an awful lot to be mixing by hand to me, is it?

If you timber decked it you would only need 42m of 100 x 50 and 110m of

You don't. growing stuff and dying stuff are always shifting ground levels about.

less than 1:100

If they're laid on sand, they can be lifted easily. Just put a bar under one edge to lift a bit, then pick them up by hand. You could then either simply compact the existing sand, or pour on cement powder and mix in then compact, and re-place the slabs, maybe after pressure wahsing, and maybe the other way up.

If they're blob cemented down its less easy. You'll get a fair bit of breakage on lifting, you'll need some new bedding material and new slabs.

NT

If there's no damp problem now, odds are putting it all back as is wont create one. However it does up the risk having no gravel border. Its rather hard to make any certain prediction as to whether it wll or wont cause an issue, but presumably it hasnt so far.

NT

Yes, don't overdo the fall or you'll be having to remove too much when you get to the furthest point from the house. The bubble on the spirit level being ever so sightly off centre is enough IME

In message , Fred writes

I have my own ancient mixer so no recent experience. If you don't have a suitable flat surface its a non starter anyway. You might shovel 20 shovels of sand and 2 cement into a pile. You re-shovel it to a second pile nearby and then move it back. Then shovel it to your barrow. That is a lot of shovelling:-)

Big bag sand from my supplier is only guaranteed at 850kg. Presumably weighed moist and marked for trading standards purposes.

You might need to consider how close bags of sand can be dropped to your work area. Shovelling from bag to mixer might save a lot.

regards

Do you just lay joists on top of the patio and then lay "floorboards" perpendicular to the joists?

Does a decking require more maintenance? Does it need treating with preservative every now and again, like a fence would? If so, how do you treat all of it, without lifting the deck to treat the joists below?

Thanks.

None that I know of ;)