Frequently Asked Questions
What is the drying time of the screed?
Drying time depends on the depth of screed, site conditions, and ventilation. As a general guide, liquid screed dries at approximately 1mm per day up to 40mm depth, then slows to around 0.5mm per day beyond that. Under ideal conditions — good ventilation, temperatures between 5°C and 30°C, no direct sunlight or draughts — light foot traffic is typically possible within 24–48 hours of pouring.
What depth of screed do you recommend?
Recommended minimum depths: fully bonded 25mm, unbonded 30mm, over acoustic or insulation matting 35mm for domestic use and 40mm for commercial areas, over underfloor heating pipework 40–50mm. Always follow the manufacturer's data sheet for the specific product specified.
I have heard that underfloor heating takes a long time to heat up and cool down — is this true?
A well-designed system with intelligent controls will allow you to pre-programme heat-up times. Modern smart controls use historical data to build a pattern of your heating requirements, including cooling-down periods, so the system anticipates demand rather than reacting to it. With liquid screed correctly installed at the right depth over the pipework, thermal performance is excellent.
Can I have underfloor heating if my floors are in place but I want to do a refurbishment?
Yes — there are systems designed specifically for refurbishment projects. You can even extend the system at a later date. Getting the design right at the outset — correct pipe centres for your heat source, manifold locations, balancing and pressure testing — saves money in the long term and avoids the need to re-open finished floors.
Can I fit underfloor heating myself?
Underfloor heating is a specialist installation. Our engineers know exactly how to install pipework at the correct centres for your heat source, with properly positioned manifolds, balancing and pressure testing carried out before screed is poured. Errors at this stage are expensive to correct once the floor is down — you only put your floors in once.
I have a joisted timber floor — can I have underfloor heating?
Yes. There are underfloor heating solutions for every type of floor construction: screeded floors, fully floating timber floors, battened and joisted floors, and floor builds that incorporate acoustic components. The correct system depends on the floor construction, heat source, and insulation specification — we will advise on the right approach for your project.
What is the difference between anhydrite screed and Cemfloor screed?
Anhydrite screed uses calcium sulphate as its binder — ideal for large floor areas, underfloor heating, and anywhere a fast, flat finish is needed. It must not be used in permanently wet areas such as bathrooms. Cemfloor is a cement-based liquid screed that is waterproof when properly sealed, making it suitable for bathrooms, wet rooms, and external covered applications. Both are self-levelling and significantly faster than traditional sand-cement screed.
Can liquid screed be used in bathrooms?
Standard anhydrite screed is not suitable for bathrooms as it can soften when permanently wet. Cemfloor screed is the correct choice for bathroom and wet room applications — it is cement-based and can be fully waterproofed with a suitable tanking membrane or liquid waterproofing system applied over it.
Does liquid screed crack?
Liquid screed is engineered to minimise cracking through its self-compacting nature, but correct installation is essential. Perimeter expansion strips must be fitted around all walls, columns, and upstands before the pour. Bay joints are required for larger areas. The screed must be protected from draughts, direct sunlight, and rapid temperature changes during the first 48–72 hours. When these steps are followed, cracking is rare.
How do I know when the screed is ready for floor coverings?
Screed must reach a relative humidity (RH) of 75% or below before most floor coverings can be applied — and 65% for timber and engineered wood flooring. Test with a calibrated hygrometer placed on the screed surface and sealed with a hood. Do not rely on drying time estimates alone — always test before laying any floor covering.
Do you supply screed only, or supply and install?
London Flow Screed provides a full supply and installation service. We do not supply screed only. Our service includes delivery by pump, the pour itself, and finishing to datum level. All work is carried out by our own experienced crews.
What areas do you cover?
We cover Greater London and the surrounding counties: Surrey, Kent, Essex, Hertfordshire, Buckinghamshire, Bedfordshire, Berkshire, Oxfordshire, Hampshire, Sussex, Suffolk, and Cambridgeshire. Visit our coverage page for full details of areas served.
How do I get a quote?
Call us on 07730 584 748, use our contact form, or message us on WhatsApp. We provide free, no-obligation quotes and will beat any like-for-like written quotation from a competitor.