Liquid Floor Screed in Widnes: Cost, Depth, UFH and Drying Explained

Liquid screed in a nutshell

Liquid screed (you may also see flowing screed, self-levelling screed or liquid flow screed) is a fluid floor mix that is pumped into the room and spreads to an even, level surface on its own. It goes over insulation or onto a concrete slab and forms the base that your tiles, timber or vinyl sit on.

Because it travels through a hose, a pump parked on the road can feed a room at the back of the house or upstairs, and a large floor can be covered in one go. In Widnes we see it used for everything from a single-storey kitchen extension to a full ground floor on a new-build plot.

What affects liquid screed cost per m2 and per m3

We do not publish a price list, because two floors of the same size can cost very different amounts. Any liquid screed price per m2 quoted online makes assumptions about depth, access and job size that may not match yours. The main things that move the price are:

Material is ordered by volume, so cost per m3 and cost per m2 are tied together by depth. Volume is area multiplied by depth in metres. For example, a 30 m2 extension at 50mm deep needs about 1.5 m3, and the same room at 60mm needs about 1.8 m3. Small changes in depth add up quickly over a bigger floor.

To get an accurate figure, tell us the approximate area, the planned depth if you have it, whether there is underfloor heating and how we get from the road to the room. Photos of the floor and the access are a big help.

• Size of the floor: bigger areas tend to be more efficient per m2
• Depth, which sets how many cubic metres are needed
• Anhydrite or cement-based, and any specific product the specification calls for
• Underfloor heating, which can change the depth and the product
• How far the hose has to run from the vehicle to the room
• The pour date and how it fits around other trades
• Whether the insulation, edge strip and membrane are already in

How thick should liquid screed be?

Liquid screed thickness depends on what is underneath and what the floor has to carry. Laid floating over insulation in a house, anhydrite screeds commonly start at around 35mm, going deeper for heavier loads and commercial use. Where the screed is bonded to a concrete slab it can usually be thinner. Cement-based liquid screeds generally need a bit more depth than anhydrite types.

With underfloor heating, the minimum is set as a cover depth over the pipes, so the overall depth is the pipe height plus that cover. Agree the finished floor height early in the job, because it decides how the new floor meets door thresholds and any existing room next to it.

Underfloor heating and liquid screed depth

Liquid screed is popular with underfloor heating because it fills every gap around the pipes. With no air pockets left behind, heat travels through the floor evenly instead of collecting along the pipe runs.

There is no single minimum liquid screed thickness for underfloor heating; the screed product and the heating system set it between them. As a rough guide, anhydrite screeds in homes are often specified at about 25mm of cover above the pipes, which usually works out at roughly 40 to 50mm in total on insulation. Cement-based products normally need a little more. Always follow the manufacturer's figures.

A thinner floor has less mass to warm, so the heating tends to respond faster than it would under a deep hand-laid screed. The pipes should be filled and pressure tested beforehand, and fixed down firmly, because a flowing screed can lift pipework that is not secured.

• System filled and pressure tested before pour day
• Pipes clipped or fixed so they cannot rise
• Heating left off while the screed is poured and in its first days
• Heating brought up gradually afterwards, following the screed manufacturer's schedule

Anhydrite or cement-based liquid screed?

Anhydrite liquid screed, also known as calcium sulphate screed, uses a gypsum-based binder. Cement-based liquid screed, sometimes called liquid cement screed, uses cement instead but still flows and levels itself.

Anhydrite is a common choice over underfloor heating, as it can usually go down thinner and passes heat well. It does not like persistent moisture, so it is not normally used in areas that stay wet, and the surface typically needs sanding and priming before some floor coverings.

Cement-based types cope better with moisture and tend to work with cement-based tile adhesives without the same surface preparation. Which one fits depends on the room, the finish, your timescale and the manufacturer's advice, and we are happy to talk it over before you book.

Liquid screed drying time

How long does liquid screed take to dry? You can usually walk on it carefully after a day or two, but that is a long way from dry enough for flooring. The real drying time depends on depth, the type of screed, the temperature, airflow and the season.

For anhydrite liquid screed, a widely used rule of thumb is about one day per millimetre up to 40mm, then slower beyond that. Keeping air moving helps, and many anhydrite products let you use the underfloor heating to help dry the floor after an initial period, following the manufacturer's schedule. Drying of cement-based liquid screeds varies more between products, so check the data sheet.

Test, do not guess. A moisture test confirms when the floor is ready, and both the screed and flooring manufacturers set the readings they will accept. Laying timber, laminate or some vinyls too early is a frequent cause of failed floors.

Getting a floor ready for liquid screed

Most problems on pour day come from preparation that was not quite finished. We go through area, access, the build-up, any underfloor heating and timing with you beforehand. This list covers what should be done before we arrive:

• Building watertight, with windows and doors fitted or openings sheeted
• Insulation boards flat, tight together and fully supported
• Edge strip fixed around every wall, column and fixed item
• Membrane down, lapped and taped so nothing leaks through
• Heating pipes secured, filled and pressure tested
• Finished floor level marked around the room
• A clear path for the hose from the road to the room
• Everyone on site aware the floor is out of bounds while it sets

Liquid screed compared with traditional screed

A traditional screed is mixed on site, carried in and levelled by hand. On a large floor that takes time, and the result relies heavily on the skill of whoever is levelling it.

Liquid screed is pumped in and finds its own level, so big areas go down quickly and the surface usually comes out very flat. It can generally be laid thinner, particularly over underfloor heating, and it surrounds the pipes completely. The trade-off is that the build-up underneath has to be properly sealed and the drying needs managing before flooring goes down.

Not sure which suits your Widnes project? Tell us about the room, the floor finish you have in mind and your timescale, and we will give you an honest view.

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