Concrete Slabs for upstairs floor - Hollowcore or Solid better?

Lemlin

I can get either an 8 inch hollowcore slab floor or a six inch pre stressed solid slab. Both are the same price. The manufacturer of the hollowcore reckons it will be easier on my walls etc.

Which do people think is better?

dCorbus

What do your engineer and architect reckon? What have they specified?

It's really all dependent on too many variables to say which is better.

Any particular reason you're going with concrete for your first floor slab?

You'll need to make sure all the engineering is up to scratch and you've got the ground floor supports in the correct locations. My advice is use your professional advisers and do not pay too much heed to the man selling one product or the other - You're not going to get much unbiased advice from that quarter.

soldsold

STC sound transmission rating for 150mm solid is 52, for 150mm hollow is 48, which is quite a difference, but for 200mm hollow should probably be close. I have 150mm solid which in my case didnt need a structural screed. I also had a maximum height to work within so the extra 50mm was helpful to have ie by sticking with 150mm solid.

Solid slabs also let less wind blow through, unless the holes in the hollowcore are plugged - in any case best practice is to wrap whichever one you use in roofing membrane for airtightness as it is being installed - roll out a 1m wide strip of membrane on the cavity wall, lay the slab on it, wrap the membrane over it so that you have half the membrane hanging down and half available to stick to the walls above and below the slab with either airtightness mastic or putting 4 inch expanding lath over it and plastering over it. The idea is to get continuous airtightness wrap around the slab.

S