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Cemfloor Liquid Screed
Cemfloor Liquid Screed
McGraths have teamed up with Cemexa Technologies of France to develop a new product for the production of cement based liquid screeds. Cemfloor is a high performance screed which complies with EN 13813.
During its 20 years of existence Cemexa Technologies has placed itself as a key player on the European market and one of the main active leaders of cement screed development.
There are 3 different products available in the Cemfloor range:
- C16/F3 - for domestic non underfloor heating
- C20/F4 - for domestic and underfloor heating
- C25/F5 - for commercial use
Cemfloor screeds are very responsive to underfloor heating; due to the fact that they can be laid in very thin sections and have a high thermal conductivity of up to 2.9w/mk.
Since Cemfloor is a cement based screed; floor coverings can be applied much faster than calcium sulphate screeds which require a final moisture content of 0.5% which can delay floor finishings by months.
Whereas Cemfloor can be tiled at a final moisture content of 5% and timber floors can be installed at a final moisture content of 2.8%; speeding up the entire build process.
Compared with other liquid screeds which generally need to be forced dried with underfloor heating; Cemfloor screeds can be used in non heated floors as it doesn’t require force drying to remove moisture.
- Thinner sections compared to traditional screeds. 25mm above underfloor heating pipes.
- Larger floor area without joints (up to 150m2).
- Exceptional Thermal Conductivity (up to 2.9W/m.k).
- Reduced drying times 10 days for tiling and 28 days for wooden floors in non heated floors, in heated floors 14 days for tiling and 21 days for wooden floors. This is dependent on drying conditions or “after suitable moisture test.
- Self-compacting – no voids around under floor heating pipes.
- Can be polished for final floor finish (consult technical personnel).
- All floor coverings can be applied with no need for surface sanding.
- More thermal insulation can be used in floors, compared to traditional sand cement screed which leads to a better u value for your building.
- Minimal Drying Shrinkage (<0.05%).
- Foot traffic after 24 hours.
- Can be applied in wet areas.
- Can be forced dried after 7 days.
- Compatible with all cement based tile adhesive, no priming of surface required.
- No Surface Laitance (Dust) after curing.
- Easy Installation; up to 1000m2 per day (Reduces time & costs).
- Lower Running costs for underfloor heating systems when using Cemfloor. This is due to the exceptional thermal conductivity of up to 2.9W/mk and the ability to lay thinner screeds over the underfloor heating pipes.
Cemfloor Screed is designed for use as a bonded thick levelling screed on concrete, as a floating screed over thermal or acoustic insulation, or as an unbonded screed on top of a plastic membrane.
Cemfloor is compatible with all floor coverings and cementitious adhesives and floor levellers.
Cemfloor screeds should be used in accordance with BS 8204-7:2003 ‘Code of Practice for Pumpable Self-Smoothing Screeds’.
To ensure a high quality screed it is recommended that application is carried out by a specialist screeding contractor. The freshly poured screed will need to be levelled using a dappling bar, ensuring to dapple the surface in two passes at 90 degrees.
- Technical Information
Cemfloor is produced in an ISO 9001 quality-controlled environment. Self levelling screeds produced with Cemfloor meet the requirements of EN 13813:2002 ‘Screed Material for Floor Screeds’.
Screed Specification EN 13813:2002 Compressive Strength >20 N/mm2 Flexural Strength >5 N/mm2 Minimum Thickness
Over underfloor heating pipes: 25mm above pipes
Shrinkage (28 Days) <0.05% Flow Rate 220-250mm Thermal Conductivity up to 2.9W/mk Fire Rating non-combustable Drying Time (5% MC) 10-15 Days (can be force dried after 7 days) Open to Light Foot Traffic 24 Hours Wear resistance "BCA" see website
- uValue Calculator
Liquid Screed u Value Calculator
Perimeter = (Length A + Width A + Length A + Width A) + (Length B + Width B + Length A + Width B)
Area = (Length A x Width A) + (Length B x Width B)
Before the screed can be installed the building should have the roof on, external doors and windows in place and be completely draught free and weather-tight.
Make sure the subfloor is laid flat and at the correct level to accommodate the insulation, liquid screed and the floor coverings. To help prevent leaks when the liquid screed is being poured, make sure all gaps and holes have been completely sealed. Remove all debris from the subfloor so that the insulation sheets can be laid flat.
Cut the first layer of the insulation around service pipes and fill in the gaps between the insulation and the pipes with a low strength sand & cement mortar. Place the second layer of insulation perpendicular to the first. When you walk on the second layer of insulation there should be no movement between the two layers and the surface should remain flat.
The edge strips should be as recommended by building control. Install the edging strip to the perimeter of all walls, abutments and columns, ensuring it is tightly secured. Pay special attention to the corners.
Plastic Tanking Sheet
Before the liquid screed is poured a water proof tank must be created on top of the insulation sheets. Lay 500 gauge polythene, without creases, on top of the insulation, with the polythene sheet joints overlapped by at least 100mm and secured with the appropriate tape. Tape the polythene sheet to the edging strip. Check all the joints are watertight and all protruding pipes are securely sealed to the polythene sheet.
Underfloor Heating Pipes
Once the tanking sheet is in place install the underfloor heating pipes, clipping them down every 300mm on straights and every 200mm on bends. Fill the heating pipes with water.
Expansion Strips & Reinforcing
All joints should reflect structural joints in the substrate and take into account the joint requirements in finished floor coverings. Place expansion joints across doorways between independently controlled heating circuits, between heated and unheated areas and in areas of high thermal gain. See our ‘Design Data’ sheet for the full guide to recommended bay sizes. Keep the expansion strips 5mm below the planned level of finished screed. Place and secure reinforcement fabric at external corners.
Hot Weather Protection
During a period of hot weather the windows should be blanked out to prevent excessive heat building up in the building prior to, during and after the liquid screed installation.
Pressure test the underfloor heating system and check for water leaks. Examine the polythene for tears and check all joints are properly taped. Confirm that all the areas prepared for the liquid screed are in a fit condition to accept the liquid screed, without leaking. Remove all loose material that could float to the surface of the liquid screed and spoil the floor finish.