How Long Does a Screed Floor Take to Dry?

Screed floors are usually safe to walk on in about 24 to 48 hours but take at least 28 days to be up to full cured strength.

Liquid screed is commonly used as a layer over concrete flooring, forming a thin top layer that can cover underfloor heating with a smooth flat surface.

The even screed layer is suitable for tiling, carpeting or laying floorboards over, but waiting for the screed to dry can take a significant amount of time.

It's wise to wait until the flooring is absolutely dry and cured through before you think about laying your final flooring materials.

Factors in How Long a Screed Floor Will Take to Dry

The freshly poured screed must be undisturbed for the first 24 to 48 hours, with the room completely shut off to ensure nobody walks on the liquid screed until it has set on the surface.

Ideally, you should avoid walking on screed for two to three days. However, light traffic and occasional walking are normally fine. 

If you need to move any heavy equipment or furniture, you should use wooden boards to avoid causing deep grooves or indents.

Panels used to protect uncured screed need to be removed quickly to ensure they don't restrict ventilation and delay the curing process.

Tips to Cure a Screed Floor

• During the first two days, close windows and doors to ensure the moisture in the screed doesn't evaporate too quickly.
• Close off any direct sunlight where possible, drawing curtains and shutting blinds.
• If the property doesn't have doors or windows yet, you should use boarding.
• When the screed is dry enough to be walked on (carefully!), you can open these again to help the full curing process begin.

If your new screed floor becomes damp during the first two days due to rain or leaky windows, you should dry out the water as quickly as possible.

Provided the screed doesn't stay wet for prolonged periods, it should dry to the normal strength once you've soaked up any excess water.

Typically, a normal 40 mm screed will dry to about 0.5% water content in around 40 days, but multiple variables could mean that it takes a lot less - or longer.

Conditions That Impact How Long a Screed Floor Needs to Dry

There are many different screed types, some designed to dry quicker, and others such as bonded screed suitable for thinner flooring layers and used as a bonding primer.

Other relevant factors include:

• The humidity in the room.
• Ambient temperatures.
• How quickly and often the air changes.

Generally, unbonded liquid screed takes one day per 1 mm to dry out, up to the first 40 mm deep. Thicker screeds need one day for each 0.5 mm beyond that to become fully cured.

However, that's assuming that the room is about 20 °C and has a standard humidity. If the room is warmer and the humidity lower, the screed will cure faster.

Additives to Speed Up Screed Floor Drying Times

Depending on the type of screed you're using, the function of the room, and the kind of building, you can modify the screed application or add supplementary materials to the solution to alter the drying time.

Some of the most common additives are:

• Hydraulic binders, added to the screed to improve the strength and speed up the drying time.
• Plasticisers reduce moisture levels, which means the screed doesn't need as long to set.
• Aluminium-based cement sets quicker, but there are potential pitfalls, and this material can be very expensive to repair or replace.
• Polypropylene fibres are a reinforcing additive that helps prevent the screed from cracking and binds the flooring for a smoother finish.
• Polymers such as PVA can be used to make the screed stickier, which is resistant to water, and often means the screed can be a little thinner.

A lot depends on how thick the floor is because a denser screed across a large floor will inevitably need much longer to dry out than a thin screed in a small space.

Recommended Depths of Floor Screed

Let's run through some of the types of screed and the minimum depth you'll need to aim for:

• A fully bonded screed should be 25 mm deep at least.
• Unbonded screed needs to be 30 mm depth or more.
• Screed over insulation must be between 35-40 mm thick.
• Underfloor heating screed should be 30 mm deep from the top of the pipework.

As we've explained, traditional screed sets in 24-48 hours, but a fast-set screed can be fine to walk on in as little as two hours.