Key Features

• Produced to a controlled flowable consistency to fully encompass heating pipes.
• Elimination of voids resulting in uniform heat transfer and maximised thermal efficiency of the underfloor heating system.
• Reduced screed depth when compared to traditional sand cement screeds minimising heat storage, resulting in a floor which responds rapidly to user requirements.
• Extremely low shrinkage - can not curl and minimises the risk of cracking.
• Does not require reinforcement.
• Increased productivity - 500-1000m2 per day can be easily achieved.
• Heating systems can be commissioned in accordance with BS1264:2001 - 4 clause 4.4, as early as 7 days after application of the screed.
• Minimal thermal expansion (0.012mm/Mk).
• Excellent thermal conductivity (2.2W/Mk).
• Environmentally friendly.

Key Installation Points

• The area to be screeded must be made water tight to prevent leakage.
• The polythene slip membrane installed over the insulation must be overlapped and sealed to prevent loss of screed.
• Pipes or cables must be securely fixed to prevent floatation and lifting during application of the screed.
• Best practice is to fill pipes prior to application of the screed to check for leaks, this also reduces the risk of pipes floating whilst the screed is being poured.
• Ideal flow is 230-250mm measured using the DIN1060 flow ring.
• Minimum cover to pipes or cables must be 30mm.
• If required surface laitance must be removed prior to commissioning of under floor heating.
• Heating should be commissioned in accordance with BS1264:2001 - 4 clause 4.4 to accelerate force drying of the screed prior to application of the floor finish.
• Screed moisture content must be a maximum of 0.5% and 1.0% respectively prior to application of subsequent impermeable and permeable floor coverings.

Drying Times

Screed Drying Times

Under ideal drying conditions (a warm, well ventilated room) a Gyvlon Screed dries at a rate of 1mm/day up to a maximum thickness of 40mm and then at a rate 1/2mm/day for thicknesses above this:

Example

50mm Gyvlon Screed Drying time: (40mm*1 day) + (10mm*2days) = 60 days (2 months)

Drying times can be improved by the provision of good ventilation, open windows and doors in good weather, removal of laitance as recommended, the use of dehumidifiers and by force drying of the screed using underfloor heating.

Assisted Drying

Laitance removal: During the hardening process a friable film may form on the surface of the Gyvlon screed slightly reducing the rate at which moisture can escape from the screed prolonging drying time. Removal of this film 1-3 weeks after application using the recommended equipment will open the surface assisting the screed to dry.

Dehumidifiers: Dehumidifiers can be used as early as 7 days after placing of Gyvlon Screed to assist with drying. It is important that a closed system is employed to ensure that any moisture extracted from the environment during operation is removed whilst the warm air dries the screed. Failure to seal the water collection vessel will result in the moisture being recirculated delaying drying times.

Forced Drying

Force drying of a Gyvlon screed can be accomplished by commissioning of underfloor heating systems in accordance with BS1264: 2001 Part 4 clause 4.4 as early as 7 days after the screed has been placed.

Raise system water temperature in 4-5 degree C increments from ambient to 20-25 degree C, maintain for a minimum of 3 days and then gradually increase the temperature again in 4-5 degree C increments to maximum operating temperature which should be maintained for a further 4 days (water temperature should not exceed 55 degree C for a calcium sulphate screed), prior to returning to ambient temperature in readiness to receive floor finishes.

Please note that it maybe necessary to commission and run the U/F heating system for greater than the 7 day commissioning period to enhance the drying. The time that is required for force drying is directly proportional to the age of the screed at the time of commissioning. In all cases it is important to remember that adequate ventilation is required to maintain good drying conditions.

The screed must be dry before application of the floor finish and failure to follow this procedure prior to the application of subsequent impermeable floor coverings such as vinyl is likely to lead to failure of the floor finish at a later date.

Subsequent to drying the screed by one of the above methods the residual moisture content must be determined using one of the approved test procedures to demonstrate suitability for acceptance of floor finishes (0.5% for impermeable finishes such as vinyl, and tiles and 1.0% for carpets.

Once proven to be dry it is important that the surface of a Gyvlon screed is protected from accidental spillages and leaking fixings (central heating pipes etc). Should these occur the exposed screed will require further drying to attain the required moisture content and in the worst case, full saturation of the screed drying times will be as with freshly placed screed leading to possible delays in the construction schedule.

The information provided above is given in the best faith as a guide to drying of Gyvlon screeds and can be greatly influenced by individual site conditions.