FREQUENTLY ASKED QUESTIONS

Below, we have tried to answer the most common questions visitors to our Web site may have.

If you have any questions about our Installation Service or any of the Ardex screeds we have available, please don't hesitate to get in touch.

FAQ

Do you have any Technical Support, regarding mixing and laying of Floor Screed?

Call +44 (0)330 223 2364 to discuss your requirements with one of our friendly and professional team.

What are the drying times for floor screed

With regard to drying times, the British standards (BS 8204) state that a standard traditional screed will take 1mm per day, up to 50mm, and considerably more over that thickness to dry out.

Specially developed polymer-modified Ardex products can be ultra-rapid drying and be dry in a matter of hours. To discuss the best screed for your needs, give our professional team a call on +44 (0)330 223 2364

What type of floor screeding should I have in my new house/extension?

Ardex FastTrack Screeding range is the recommended floor screed for domestic use, as cost implications can be quite high for small areas done by flowing screed.

Ardex A23 screed is ideal for use in any home. It can receive tiles after only 48 hours, and resilient floor finishes can be applied 6 days after laying screed. So in just a few days your floor can be complete.

What are the advantages of using Ardex FastTrack Screeds over traditional forms of floor screeding?

With regard to drying times, the British standards (BS 8204) state that a standard traditional screed will dry 1mm per day up to a thickness of 50mm, and considerably more over that thickness. That would be in ideal summer conditions of 18c to 20c.

People often find they have 100mm of screed to lay and realise that they have well in excess of 100 days of drying time to wait before they can lay any floor coverings and turn on their new underfloor heating system.

When using System Ardex premium performance products, the screed can be dry in as little as 24 hours, regardless of thickness.

My under-floor heating system installer has told me that self-levelling ‘flowing’ screed is the best for UFHS, why is this?

Under Floor Heating System installers are basically plumbers; they don’t typically know a great deal about floor screed. Most tend to suggest this because they believe liquid screeds wrap around the underside of the heating pipe, giving better heat transfer. But let’s face it, where is the heat going to go anyway? With a good amount of insulation, that should be under the heating pipes, it won’t be going through the insulation. Therefore, this is a misleading sales pitch used by UFHS companies which aren’t major suppliers and installers of floor screed. Take into account that thinner screeds, such as flowing screeds, can cause undesired hot/cool spots between heating pipes, so a lower thermal transfer would be an advantage.

Ardex only manufacture cementitious screed products, as they can then control the recipe, the raw materials and the polymers going into it, to ensure utmost quality.
Liquid products, on the other hand, totally rely on operatives on site to have the knowledge and facilities required to conduct the mixing process according to strict standards.

By providing cementitious Ardex Screed products we eliminate this risk of error, ensure quality control and facilitate a high-quality finished result.

Flowing screeds will fully in case under-floor heating pipes, can traditional floor screeds do the same task?

Yes, there is a simple technique that will ensure traditional screeds do that too. But is it really necessary? We don’t believe it is, as it won’t actually achieve anything. It is something that the marketing people for flowing screeds came up with as sales pitch.

What reinforcing is the best option for an un-bonded floor screed?

Quite simply, polypropylene fibres in the mix with D49 wire mesh at any day joints. Some architects will specify that they want hex (chicken) wire, but everyone in the floor screeding industry knows that it is the least effective system.

What is the tolerance level on floor screeds?

The industry standard is 10mm across a 3m straight-edge. At FastTack Screeding we work to a minimum tolerance of 3mm or better across the entire floor screeded area.

What is the minimum depth for an un-bonded screed?

Un-bonded screed should not be less than 50mm deep for traditional screed.

What is the minimum depth for bonded screed?

Bonded screed can go to a 15mm in thickness screed, as long as it is bonded chemically (epoxy) or laid with SBR/PVA bond and SBR/PVA modified screed mix.

Recommended

ARDEX E 100 can also be used as an additive to:

• Improve workability without increasing the water content of mortars.

• Increase the compressive and tensile bending strengths of the hardened mortars.

• Improve the elasticity and reduce crack formation in mortars.

• Reduce surface dusting of screeds and renders while increasing their abrasion resistance.

• Enable the minimum thickness of the modified bonded Portland cement floor screed to be reduced to 15mm from the recommended 25mm minimum thickness for unmodified screed mortars.

I’ve heard about shrinkage cracking & curling in floor screeds, what are these and how do they occur?

Any material that has absorbed water, will shrink as it dries out. Sometimes, due to excessive drying, screeds will crack. If you try to artificially accelerate the drying times, then there is more risk of cracking. Curling is caused by the same conditions but normally manifest along day joints and internal angles. The thinner the screeding material, to be used, the more likely that curling can occur, due to time taken to dry it will be quicker on a thinner bed, than a thicker bed.

Recommended

ARDEX E 100 is an acrylic-based dispersion for use in screeding and rendering mortars in internal and external locations. The addition of ARDEX E 100 improves the compressive and tensile strengths, and elasticity and bond strength of the modified mortar. The workability and plastic properties of the mortar are improved without increasing the water/cement ratio, and early age crack formation is significantly reduced.

We have a screed that is weak, cracking, or badly dusting. Is it necessary to replace the screed?

No, but sometimes it may be the most commercially viable option. There are products that can be applied that will remove these problems, these are not cheap, but it may be the most viable option when you consider the cost of removal of the old screed and the cost of replacement.

Recommended –

Ardex PSRS
Ardex PSRS

ARDEX PSRS is an ultra low viscosity, solvent free, two component epoxy resin designed for strengthening and restoring poorly compacted and low strength screeds that do not meet the required in situ crushing resistance. ARDEX PSRS penetrates into the defective screed, filling voids resulting from poor compaction and consolidating loose particles to provide a high strength screed that can meet the highest soundness category given in BS 8204-1 for in situ crushing resistance.

  • Penetrates into the defective screed, filling voids resulting from poor compaction
  • Overnight renovation of screeds – rapid installation reduces overall construction times
  • Consolidated screeds meet the BS-8204-1 Soundness Category A requirement for floor screeds
  • Low odour and solvent free
What are granolithic screeds?

Granolithic screeds are very hard wearing, granite based aggregate, finished floors. They are used in industrial units, beer cellars & weight lifting areas etc.