What’s the Liquid Screed Drying Time Before Tiling?
How long does liquid screed take to dry? This is the question we’re constantly asked by contractors and developers. Drying times are key to efficiency savings when it comes to sub flooring and wet underfloor heating installation. So we thought we’d devote a blog to the subject.
The first thing to say is that every installation and environment is slightly different. Liquid screed can be relied upon to deliver high quality flooring wherever it’s poured, but there will be adjustments to be made according to the atmospheric conditions of the site.
Curing the Screed – 24-48 hours
Once the screed has been poured it must be left to dry until solid. This will normally take 24-48 hours. This is known as the curing period during which it’s important to maintain the moisture levels in the screed. Doors and windows should be kept closed throughout this drying period, and all efforts should be made to avoid direct sunlight on the flooring.
Water Ingress and Screed Non-Forced Drying Times
Spillages and water ingress will weaken the screed so it needs to be dried out. This is achieved using natural cross ventilation on site where possible (after the initial curing period).
The standard timing for drying liquid screed on a 40mm depth would be 40 days. If the screed is deeper you can add a further 0.5mm per day. This drying time is based on atmospheric conditions in which the average temperature is 20ºC and the relative humidity is 65%.
Before tiling is laid, the screed needs to have dried to the approved level. The code of practice value is stated as 75% relative humidity which equates to 0.5 % moisture content by mass.
Drying Times Using Force Drying
Liquid screed can be force dried, starting 7 days after installation. This involves the use of the underfloor heating system, and dehumidifiers.
- Step 1. Set UFH water temperature at 25ºC for 72 hours.
- Step 2. Raise water temperature to maximum value (55ºC) for 96 hours
- Step 3. Ensure the cross ventilation is activated throughout this process (unless using dehumidifiers).
- Step 4. Continue force drying process until a moisture content of 0.5% is achieved. Normally this would take around 4 weeks.
Use of Dehumidifier for Force Drying Process
The use of a dehumidifier (or several, dependent on the size of the installation) aids and accelerates the drying process. If a dehumidifier is employed than you’ll need to keep the doors and windows closed in order for it to do its work to maximum capacity.
RB Liquid Screed Employs Screed Specialists for Installations
At RB Liquid Screed we take pride in the consistent quality of our products and the expertise of our screed experts. Contractor clients appreciate the fact that they have direct access to screed expertise, right from the start. This allows for effective preparation of the site, prior to the pour, and for high quality aftercare. Our screeding specialists assess the atmospheric conditions and provide guidance right up to tiles being laid.
If you’re planning a UFH installation, using liquid screed, call our screeding specialists today on 01842 659498 / 07498 964984 to find out how we can support you.