New patio on old - Can i lay new patio...

legodickie · Post: # 59934Post **legodickie** Thu Feb 24, 2011 11:07 pm

My parents in law would like a new patio as their old patio is concrete slabs which some cracked and just looks old now. They would like a sandstone one. My question is of I remove old slabs will i possibly have a suitable base to lay new ones on or should i dig out hardcore and lay new sub base first. Thanks in advance.

local patios and driveway · Fri Feb 25, 2011 12:50 am

you run certain risks, how high will that leave you regards the damp course? do you know how well the base was laid originally? you say its cracked is that due to the base? its easy for me to say this but i would take it up everytime so i know that the work i have done is done right. there may be a different school of thought to follow

rab1 · Post: # 59952Post **rab1** Fri Feb 25, 2011 5:47 pm

for thie/costs involved rib up the old base and start again, at least then you will know its done correctly. :;):

dig dug dan · Post: # 59953Post **dig dug dan** Fri Feb 25, 2011 6:41 pm

can't you lift one slab and investigate what's underneath?

legodickie · Post: # 59958Post **legodickie** Fri Feb 25, 2011 7:30 pm

Thanks for the advice. I have lifted a couple and there is alot of mortar still stuck onto the back of them, so I guess they were laid on a full base of mortar and not five spots!! Mainly cracked due to age and possibly builders dropping heavy stuff by accident on them. I think it best to start again. Was just hoping that if I got the slabs up which brought most of the mortar I would have a good base to start with. Thanks again for your help.

dig dug dan · Post: # 59961Post **dig dug dan** Fri Feb 25, 2011 7:39 pm

it could be possible that a decent base was laid. the only way to tell, is lift all the slabs and bedding material, and have a look to see what it was laid on!

good luck

Pablo · Post: # 59963Post **Pablo** Fri Feb 25, 2011 7:43 pm

My guess is they have been laid on with the 5 spot method. A flag on a full bed will normally lift out free of the mortar base whereas the 5 spot will come away with the flag because it's not bonded with the rest of the mortar bedding. If the base underneath is at the right level and is at least 100mm thick then I'd just re-dress and whack the hell out of it. A patio on 40mm of full mortar won't shift. If the base is very fine then wait till it's dry before you compact it otherwise you will be starting from scratch.

Fri Feb 25, 2011 8:25 pm

you could lift the old ones and crush them with one of digdugdans crushers for a new subbase
its always hard to ascertain how good summat is from a keyboard
LLL

legodickie · Post: # 59976Post **legodickie** Fri Feb 25, 2011 8:37 pm

Can understand its not easy if a DIYER likes me describes something when I do not really understand all this sub base stuff. Put am looking to avoid lots of extra cost to inlaws if the base is good enough for a light use natural sandstone patio. Speaking of which anone no any suppliers who are not going to rip me off for said natural sandstone in the Rugby area, preferably in Rugby.

Fri Feb 25, 2011 9:37 pm

is rugby in bucks now?
LLL ???

Post: # 59985Post **seanandruby** Sat Feb 26, 2011 6:35 am

Dick' why don't you dig a try hole through the sub base, see how deep it is etc; then post a photo on here so we can tell you more. Strictly speaking if the sub grade is sound you don't necessarily need a sub base for a patio.

legodickie · Post: # 60015Post **legodickie** Sat Feb 26, 2011 9:39 pm

No Rugby has never been in Bucks, but its where they live and don't want to cart a load of slabs all the way up the A5. Will as suggested take pic and post it on hear for further opinions. Thanks all again.