I need to increase my floor depth by 100mm

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

Your question is:

“I have an existing concrete floor; the floor area is approximately 13 square meters. I need to increase the floor depth by 95 to 100 mm. What is the best way of doing this? The floor is used for a residential building, basically just for walking on”

Watch Andy’s video to find out his answer:

I think you have two main options. First of all, you could just screed the whole 95 to 100mm. You could place a screed, and it could be a traditional sand and cement screed, a fast-drying sand and cement polymer modified screed. You could even lay a liquid screed.

Potentially, the downside is that the thicker it is, the longer the drying times. It could be pretty significant if you are going up to 100mm of the screed.

There are quick, fast-drying, polymer-modified products, that would reduce the drying time. It is still quite thick as screeds go, however it is very doable and happens every day.

Void Former

The second option would be the way that I would suggest you go. It would be to use a void former below the screed. A void former would be placing some insulation to make up some of the depth. You could go for 50mm of insulation and then 50mm of the screed.

The cost is going to be about the same. What you save in the screed, you are going to spend on your insulation.

The price will be very similar, but what you will get is potentially a quicker drying screed. There are specialist screeds that will dry quicker regardless of the depth, however the thicker the screed the longer it will take to dry.

Better Thermal Performance

The other consideration, Ian, is you have some extra insulation in the floor make-up. The performance of the floor thermally/the resistance to heat loss is going to be better.

Using 50mm of insulation leaves 50mm of screed, and several screeds can go down to this depth. This is called floating construction. You do not have to worry about the strength of the screed at 50mm if you select a product that can go perform at that depth.

The overall thermal performance of the floor will be much better.

I think that’ would be my suggestion and the way forward.

I am looking forward to hearing what you think. Thanks for the question Ian!

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