Anderson Floor Warming underfloor Heating may be fitted using Anderson Floor Warming System Board 30 for embedding in screed constructions. The system boards are made of EPS closed cell expanded polystyrene and shaped so that the laying of the underfloor heating pipe can be adapted to the heat requirements of the building. The design allows the underfloor heating pipe to be embedded in screed, while also being protected from contact with the reinforcement (if used). The systemboard provides 30mm additional insulation. We recommend the joints be taped prior to screeding.


We recommend that to achieve optimum efficiency of the underfloor heating system the use of weather dependent (weather compensation) flow temperature control, properly balanced and set in line with the design for adjustment of the primary and loop flow. We also recommend the settings are recorded for future reference.

Construction Outline

1. Insulation / Concrete floor
Insulation thickness must be designed to take account of underfloor heating needs.
2. AFW System Board 30
3. Pipe
Anderson Floor Warming Universal Pipe dia. 16mm.
4. Reinforcement (where required)
5. Concrete/screed
70 mm screed depth is recommended to allow proper function of the underfloor heating, i.e. in order to achieve the most even surface temperature possible (approx. 45mm required above the pipe). The minimum acceptable depth of screed is 55mm (i.e. 30mm above the pipe) where a liquid self-levelling (flow) screed is used. NOTE: increasingly “flow screed” depths are being specified less than 55mm, please ensure that full consultation is taken from the screed manufacturer and ensure that Anderson Floor Warming is aware as this may affect design.

Surface layer

Parquet, solid wood or laminated floor
Concrete surfaces are covered with a vapour barrier (DPM) and then, dependent on floor finish, with rag paper or cellfoam. The flooring should be installed in line with manufacturers instructions. Always consult Anderson Floor Warming for floor thicknesses above 34mm total and take advice from the flooring manufacturer.
Vinyl or linoleum flooring
Are laid according to the supplier’s instructions.
Ceramics or natural stone
Are laid according to the supplier’s instructions.

Drying out the concrete screed

It is extremely important that the concrete screed is sufficiently dried out before the floor covering is applied. RH measurement must be carried out in accordance with local building codes. The drying out time may be shortened by using the installed underfloor heater. The supply line temperature should in this case be kept around 5°C higher than the actual temperature of the concrete screed, though no higher than 30°C. Remember to take into consideration the curing time of the concrete or screedbefore using this method or cracks may form.

AFW Heating Circuit Manifold

The AFW Heating Circuit Manifold must be installed as shown in the design drawing. Please read the instructions enclosed with the manifold first.

Laying procedure, system boards

System Boards should be laid out from left to right according to the overall view. The boards have a joint system, consisting of overlapping locking edges. Start each subsequent row with the piece that was cut off at the end of the preceding row. This enables you to achieve a staggering of the joints as the floor is laid.

Laying the pipe

Lay the underfloor heating pipe out according to the layout drawing. Ensure the direction of flow in the loop is such that the supply line is closest to the outer wall. The pipe is mounted 50-100mm from the inside of the outer wall. Number and name the loops according to the drawing. The drawing probably shows various pipe distances in various spaces. An ’edge zone’ may also be necessary, e.g. if there are large window areas. It is very important to note differences in the pipe distances on installation.

A 180° pipe loop bend should be formed as shown in the diagram. This locks the pipe in place. If the pipe should slip out of place due to tension, use a Pipe Clamp, which is fixed down “angled” in one or more of the castellations the pipe is wedged against.

Pipes should be cut using pipe shears intended for PE-X.

Expansion areas

Large areas become ”expansion areas”. An underfloor heating loop must be laid within the same expansion area without touching a neighbouring area. Only supply and return lines may cross the expansion joint, these are then protected by a protective pipe.