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The common train of thought that Anhydrite Screeds take longer to dry for floor finishes compared to their Sand/Cement Traditional cousins has had manufacturers searching for the Holy Grail of a “Faster Drying” solution for years. This statement, is not altogether true as a traditional screed will require in the region of 10-11 weeks at 50mm thickness, whereas Anhydrite would be similar at 10 weeks, they both come with the caveat of “ideal drying conditions”. These conditions are watertight build, 20 degrees C temp, and relative humidity of 65% – something we don’t get a lot of in the UK over the course of the year! You can of course get additives for traditional screed to decrease the drying times, but we are talking about 2 different types of floor here anyway, particularly in relation to Underfloor Heating Systems and their performance. You also, can’t force dry traditional, which is not the case for Anhydrite which can be done after 7 days. The graphic below gives a brief overview of the 2 products.

In recent years, we’ve also seen the arrival of the Fast Drying Cementitious Screeds. A welcome addition to the Flowing Screed product list , this is seen more as a contender to the Sand/Cement market, in particular commercially where large areas can be installed daily all at SR2 accuracy, releasing work areas back to Site Managers earlier. These however, come with their own small print when it comes to UFH. Whilst they are no doubt faster drying, they do still require a full commissioning and cycle of the UFH system before being confirmed as dry for floor finishes. Put both flowing screeds up against each other in the same conditions, with the same requirements on cycling the UFH system, and you will be seeing virtually the same results. 

“We pride ourselves at Niche on pushing the boundaries to find a better products and services for our customers, including our new Speed Dry temporary boiler service.”

We are approved for the major players in the market

We regularly use Lkab and Anhydritec from the Anhydrite sector, and both Longfloor and Cemfloor from the cementitious, all good, quality products. All of the faster drying versions have the added bonus of not requiring Laitance Removal according to their product data (although as we have found – this isn’t always guaranteed). Results, from our own test however have proven varied to say the least. During the Summer Months, on 2 occasions we had 50mm Anhydrite screeds reaching 75% RH in an impressive 17 and 19 days respectively, whilst more recently a 40-50mm screed not achieve the required RH at 56 days. As in all walks of life, consistency is what we all aim to achieve.

What can we conclude from this?

We live in the UK. It’s cold and damp. Whilst there’s no doubting these products have a place and continual improvements will only make them better, there is no substitute for following the correct Post Installation Guidance. Here at Niche, we have a 5 page Guidance Document which accompanies every estimate, and Years of experience for our customers to draw down on. Sadly this isn’t always paid attention to. By following the steps you can have your flat, high performance, heated screed floor ready for floor finishes much quicker than you think. FORCE DRYING is the way to go. Removal of your Laitance after 7-10 days, introduction of heat through your UFH system, and placement of dehumidifiers is the only year round, tried and tested process.

Why Choose Niche?

• Delivered direct & installed to your site with no fuss

• 100ltr Buffer tank and 2x 6kW Immersion Elements

• Operates like a conventional boiler in supplying the heat to the UFH System

• High Flow rates from a Grundfos circulation Pump ensures heat transfer

• Low Weekly cost to hire with an initial set up fee and collection charge

• Easy to use thermotstat for optimal efficiencies

• Ergonomic Handles ensures easy manoeuvring around sites

• Male & Female Blue 3 Pin Plugs Supplied

• Pressure Relief Valve Fitted for Safety

• Expansion Vesesel Fitted

• Consumer Board with Individual Fuses to Safeguard the Property