Conservatory floor advice...

[ramrod]

Hi

Building a conservatory... 5m x 3m, .. stage now at - up to damp proof course with double brick wall, about to put down concrete base Question and advice please..

About 10 yrs ago I put in a block patio... put down scalping then sand ( plate vibrated it) more sand and then laid the block paving. The paitio is approx 150mm below the house damp proof course. The bricks are still with in the new conservatory foundations.

Question: can I lay sand on these.. then DPM, then 50mm concerte ...??? ..if so, it would save me having to get rid of the block paves .. and having to refill the void with concerte !!

This would also leave me with 100mm for insulation, screed and tiles.

Advice please on whether to leave the block pavers in situ... Thanks

R

[AJH]

If I am understanding you correctly all you need to do is lay a DPM over the paviours with edges lapped with your new DPC, then 70-100mm Celotex followed by your moisture resistant T&G decking boards which will provide a substrate for tiling. If you want to adjust the floor level up use a layer of soft sand blinding over the paviours.

[ramrod]

Hi Thanks for advice... but I want to concrete over the block paving ... so I would 1. lay some sand 2. lay DPM 3. concrete 50mm 4. 25mm celotex insulation 5. 50mm screed ... 6. under floor electric heating. 7. 20mm screed 8. tile

IS it OK to concrete over block paving ? would 50mm concrete be Ok ?

Thanks R

[robgraham]

Hi Thanks for advice... but I want to concrete over the block paving ... so I would 1. lay some sand 2. lay DPM 3. concrete 50mm 4. 25mm celotex insulation 5. 50mm screed ... 6. under floor electric heating. 7. 20mm screed 8. tile

IS it OK to concrete over block paving ? would 50mm concrete be Ok ?

Thanks R

If the blocks have truly settled - which I imagine they will have - then your plan seems to me quite OK. I've laid very thin flagstones (natural stone) which are only about an inch or less thick as a patio and they are on a bed of 1cement 10 sand 6 inches thick and I run a Ferguson tractor over it from time to time and none of them have cracked in 10 years. If you get the substrate right the rest will follow. Fail to do that and you have a continuing balls-up.

Rob Graham

Rob Graham

[Ron O'Brien]

Don't listen to him ramrod, that seems a rather extreme way of testing your conservatory floor to me :-)

[AJH]

I think there is no point in laying concrete + 2 screeds, also 25mm floor insulation is insufficient particularly with underfloor heating. The only definite things you need to do are 1) to lay a DPM and seal it to the existing DPC in the walls 2) lay an effective thickness of insulation (min 50, 70-100 will save your heating bills. Really beyond that all the layers will be whatever is needed to accommodate the UFH and the final floor finish at the right height. The heating pipe matrix will go on top of the Celotex, then screed over to a depth of

65mm and rienforce the screed with chicken wire to prevent any possibility of cracking.

[robgraham]

No, I've done the pre-testing for him.

Rob