Ask Andy “Minimum Screed Depth Over Acoustic Insulation”

I’m Andy Parkin Managing Director of the Multi-Award Winning Speed Screed. Thank you very much for your question, Alasdair.

Your question is:

“What would be the thinnest screed, fibre, reinforced or otherwise, that you would recommend for a flat interior to be cast over an acoustic isolation layer within a floor build-up?”

Watch Andy’s video to find out his answer:

When we’re talking about acoustic insulation, it is something used for sound deadening. What we want to do is we want to stop the transmission of sound around the building.

It would be classed as insulation, the construction type “floating“. It is floating construction because the screed sits on top, “floating”. It is not in contact with the substrate. There’s something in between, and that is the acoustic insulation.

Even though it may only be five or six mm thick, it is still classed as floating, as there is a certain amount of give which leads to flex within the screed. The screed needs to be able to resist that movement.

You need a certain amount of screed density if you are looking to meet RobustDetails. If you are following a particular system such as EFC4, (IsoRubber), you would need to place 65 mm of sand and cement screed or 40 mm liquid screed. These are minimum screed depths for EFC4.

If you are not looking for a certain amount of density, and you just want the minimum screed depth (not looking to pass any sound testing).

The minimum thickness possible for a “floating” screed is as follows.

Domestically 35 mm, 40 mm for a commercial for liquid screeds.

35mm for specialist sand and cement.

A traditional sand and cement screed, would be 65 mm.

The two considerations for minimum screed depths are:

1. Minimum screed depth/density to comply with RobustDetails
2. Minimum screed depth of the product.

I’m sure you’ve got other questions which I’d be delighted to answer.

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