Adding Screed Relevant for Load on Structure

Hi, welcome to cr4....

This is a multi-story structure, and you are somewhere above the first floor....You want to know if the floor can handle the extra weight of an additional 2" of concrete on a floor surface area of about 646 sqft....Is this correct ? If so, I think it would depend on the design characteristics of the slab, and current condition.....I think I would go with a lighter weight material....maybe wonder board and tile....

Is this hot water tube heating, electric? If water how big are the tubes and how much weight will that add.

If electric, much less to worry with.

SolarE

Ah the " and sqft's. but sounds about right. Floor is the one above the ground, i.e. the upper floor of a two storey building. Seems like the planned screed would be about 100kg per m2 wet and a bit less once dried, very evenly spread and non-moving. As I said, this is to be applied over a reinforced concret floor for a typical residential building. I just have no notion whether this is "much" or "peanuts". To me it's a good party attendance, and well before the music turns up to get all in swing.
The planned screed is already the minimum required. It has good density for the kind of heat storage/distribution desired. I guess screedless system possible but energy wise less efficient.

lyn

It would be a water UFH. Circulating water content < 100 litre. Electric system prohibitively expensive for this kind of surface/heat in UK.

Welcome aboard.

You maybe right in comparing that load to a party, but then when you have the party you will have that additional weight to considder.

I'd suggest you need to get a structural engineer to examine the current slab and confirm suitability. While he's (or she's) there, also get reviews on locations for your heater, pumps and other necessary components, the load bearing capability of the external walls (so that the future sundeck can be arranged) and any other relevant discussions in the one consultation.

Good luck.

In some instance you may find that your base already has insulation added on top of the DPM with a concrete slab laid over the top of this.

If this is the case then the pipework for your underfloor heating system is laid and fixed directly on top of the concrete base and then a screed is poured over this (normally this will be a 75mm screed).

Once the screed has cured you can then go ahead and lay your desired flooring on top of the screed.

From:

Water Underfloor Heating Installation - DIY Doctor

Zinga,

Have you looked into air-entrained concrete or light-weight aggregates? To minimize cracking, have you looked at the addition of polypropylene fibers into the aggregate? All of these are readily available in the USA and probably are also available in most places world-wide. With light-weight aggregate or significant amounts of air-entrainment, the weight/mass of the added floor material is much less and structural concerns are usually no problem.

--JMM

The screed thicknesses mentioned so far seem awfully high. In lyn's link, the screed shown containing the heating tubes is only as thick as the tube diameter, which could be around 15-20 mm. Also, what keeps the "screed" from being wood?