patio over concrete

[AndyBill]

just outside our conservatory is a patio made of concrete,
could i put patio slabs on top of this or should i take it all up?

if i can should i put sand under the slabs or just mortar?

 

[noseall]

provided you have the tolerance, i.e. the finished slabs are no higher than 150mm below d.p.c, then go ahead.

the only problem with laying mortar bedded slabs onto impermeable surfaces is lack of suction. the water in the mix will have no where to go and may run over the slabs if mixed too wet.

otherwise give it a stiff brushing and leave the existing concrete down.

 

[Thermo]

if the existing concrete is stable enough then as noseall says, its fine. Always best to give it a good clean off and brush a neat cement slurry over it first to help adhesion of the mortar

 

[AndyBill]

thanks chaps ,
sorry but what is a neat cement slurry?

 

[noseall]

thanks chaps ,
sorry but what is a neat cement slurry?

mainly cement mixed with water, though a handful of sand helps.

 

[Thermo]

you literally need a bucketful of it, few large trowelfuls of cement mixed with water in the bucket, and brush it over the patio.

 

[crazycanuck]

must be nice , in canada we rip concrete out or frost in winter 3-4ft deep will heave it up
hello walton on naze

 

[Thermo]

i thought you must be, with all the depths etc youve mentioned! thats a big problem over there isnt it. Ive watched holmes on homes a few times and been amazed by the construction used, but in those conditions doesnt surprise me.

 

[WabbitPoo]

I too have seen Holmes. Glad to see its not just this country that has cowboy builders....

 

[mlb3c]

must be nice , in canada we rip concrete out or frost in winter 3-4ft deep will heave it up
hello walton on naze

how is the weather there now?