Screed Thickness Over Underfloor Heating

I’m Andy Parkin Managing Director of the Multi Awarding Winning Speed Screed.  Today I would like to talk about Screed Thickness Over Underfloor Heating.

Why Does The Screed Thickness Over Underfloor Heating Matter?

When we talk about Underfloor Heating in this example we are talking about “wet” underfloor heating screed depth.

All the following information is based on 15mm pipes, other than 10mm pipe with the low-profile system.

Screed thickness over Underfloor Heating minimum should be based on the “high spot” in the building, assuming that a level floor screed is required, and not a profile of the substrate.

The “low spot” will mean an increase in depth.

When considering screed depth with Underfloor Heating Systems, are you looking for a quick responsive system, where a thin screed will heat and cool quickly?

Or thicker screed where the screed takes longer to heat up due to the pure volume of the screed, however will store the heat in the screed more effectively?

Generally, responsiveness is a main consideration, however when running air/ground source heat pumps that run on lower water temperatures, the extra thickness of screed acts as a storage heater.

Screed thickness over underfloor heating is generally about the minimum depths as most screeds can go to required thickness (always check with each individual project).

Below we have an overview of minimum thicknesses:

Liquid Screed Depths (calcium sulphate).

• 35mm to 45mm total depth of screed inclusive of pipe (dependant on product chosen).

Low-Profile Systems

• 22mm total depth of screed

Traditional Sand And Cement (1:3 & 1:4)

• 65mm total depth of screed

Hydraulic Binder Screed (Fast Drying)

• 55mm total depth of screed

Retanol Extreme (Fast Drying)

• 45mm total depth of screed

That covers the major types of screed.

I hope you now have a better understand of screed thickness over Underfloor Heating, if you have any other questions please contact us. We love to help!