Concrete or screed for first floor ?

pajosjunkbox

Hi guys,

Anyone have any opinions on pouring concrete or screed for first floor. Rads will be heating first floor and precast floor is in. Blocklayers can plough on if screed I'd being used.
Is there much of a difference in cost. Thanks

Metric Tensor

Check if the hollowcore design relies on the shear keys being filled as this will be required first if so.

Your engineer will tell you based on the HC designer's information.

sydthebeat

Screed is concrete

I'm confused

pajosjunkbox

Hi Syd. I suppose the question is Pou concrete now before first floor block work goes up or pour it at a later stage.

sydthebeat

OK, well as MT says you first need to find out if a structural screed is required or not.

What's the story with the ground floor plumbing?

pajosjunkbox

Yes hollow core design means all shear key joints must be filled and cured. All rad pipes are in on ground floor. Nothing done upstairs yet. In the engineers drawing it requires mesh and 75 mm screed. Can I put this in now or am I better waiting until the a later stage of the build. Apologies for the lack of knowledge... Only learning as I go !

tradesman

sydthebeat wrote: »

Screed is concrete

I'm confused

Concrete is concrete ie stones sharp sand and cement mixed together. Screed is sharp sand and cement mixed damp not wet. I think this is what the OP meant. When the words "concrete or screed" are used like this that is what is being asked.
You can "screed" concrete which means to level.

Metric Tensor

If it's designed with a mesh in it OP there's a very high likelihood it is designed as "concrete" and also designed to go under the upstairs walls.

Ask your engineer but I'd say in your case it's almost certain that you will have to pour a concrete topping with the mesh before starting upstairs blockwork.

There's a lot of different ways of skinning the hollowcore cat so you really need to talk to two engineers - your own engineer and the engineer at the hollowcore company.

Metric Tensor

Tradesman has explained it well. In this context screed means a different thing to concrete despite screed actually being a subset of concrete.

Traditional sand and cement screeds tend to be mixed like site mixed mortar but structural screeds are usually ready mix from a lorry.

I've said "tend" and "usually" because it's a nuanced area.