conservatory sub floor

[robo]

I know this subject has been discussed before on this forum but I cannot find an answer to my question.I intend to build the floor like this=100mm compacted hardcore then 30mm sand blinding=120g DPM=100concrete=polystyrene slab=chipboard floor,in that order.Do you thik this would be OK.By the way its a conservatory floor i am doing.

 

[legs-akimbo]

Ok me thinks..... except what about a 75mm screed.

 

[robo]

Legs, do you mean screed on the dpm instead of concrete

 

[legs-akimbo]

No,onto your polystyrene slabs, unless this is a solid slab you can simply lay chip board to which i would not be familiar with. My floors I screed over the jabberlite insulation bats at 75mm as it is classed as an unbonded screed. Though I actually prefer to lay the insulation above the d.p.m. and below the concrete, less hassle this way.

 

[shaggy]

My personal choice is chipboard on top of polystyrene just because it's easier to do. It does give a good floor but I do recommend the V313 moisture proof. The other thing is to make sure the concrete slab is flat before laying polystyrene, otherwise the floor will deflect at the dip. Any dips can be filled with dry sand and ruled off.

 

[robo]

Ta for all the answers.

 

[robo]

Legs andShaggy can I just get this right,!00mm Hardcore,30mmSand blinding,Dpm,75mm Screed ,Polystyrene,18mm Chipboard floor in that order.Would that be ok,sorry to be a nuiscance.

 

[shaggy]

You're not a nuisance robo, we want your floor to work. With your latest suggestion you've missed out the concrete. Legs has suggested a 75mm screed on top of the polystyrene, which is on top of the 100mm concrete, instead of the chipboard. He also said that he preferred to put the insulation below the concrete, in which case you could finish the floor with 50mm screed on top of the concrete. I don't disagree with any of that but I personally find screeding hard work and have had a lot of success with V313 chipboard.
I agreed with your first post but added that I would use the moisture resistant chipboard, the V313. Legs also said ok to that but he suggested a 75mm screed instead of the chipboard. Either is ok.
(I think you mean1200g for the dpm)
Recap then:
1)Hardcore;sand blinding;dpm;100mm concrete;polystyrene;chipboard
2)Hardcore;sand blinding;dpm;100mm concrete;polystyrene;75mm screed
3)Hardcore;sand blinding;dpm;polystyrene;100mm concrete;50mm screed

 

[robo]

Now all is clear,cheers Shaggy.