Under Floor Heating System for Solid Floors

Polyplumb floor heating in solid or screeded floors incorporates the unique Polyplumb screeded floor panel. The light weight plastic floor panels nest for easy storage and carrying.

The floor panels are simply cut to the room shape. They form a simple grid for the quickest possible pipe laying and form a precise guide for minimum bending radius. They set the pipe at exact centres and hold the
pipe against movement when screeding. The floor panel holds the pipe above the insulation allowing full screed surround. Optimum screed depth is 65mm from panel base, i.e. 40mm from the pipe top. Insulation below and at the edges of the floor screed is required by Building Regulations. Edge insulation also acts as an expansion joint.

Note : Rooms packs are supplied with pipe at 100mm centres (100m coils) and House Packs with pipe at 200mm centres (80m coils).

Solid Floor Installation Diagram

Pre-installation requirements

The sub floor must be swept clean and be free from mortar residues.

Insulation

Insulation should be laid in accordance with the requirements of Building Regulations.

Edge insulation strips

Edge insulation strips permit the free expansion of the floor screed and need to be installed around all surrounding walls and fixed constructions, such as columns, steps and access doorways. (installation
pictured top middle).

The edge insulation must also be used to separate areas where either the total area exceeds 40m² or lengths less than 8m exceed a length x width ratio of 1:2.5, eg corridors. Edge insulation is bent at 90º near to the base, to form a double-sided self-adhesive strip, which bonds the floor plates to the floor insulation.

Edge insulation is laid in addition to perimeter insulation required by Building Regulations.

Floor panels

The floor panels are laid above pre-installed insulation and are overlapped at the edges.

Note that the 1/2 castellation overlaps the 3/4 castellation; the first panel is therefore laid with the 1/2 castellation edge nearest to the wall. The panel can either be cut using a saw or snips, or simply overlapped to the nearest fit. The floor panel should not be used at the base of the manifold, as pipes need to be closer together than the floor panels permit.

Pipes around this area should be retained by pipe clips, which may also be used intermittently to secure the clip plate to the insulation.

Pipe

When the floor to be heated is covered by floor panels, pipe can be installed at the pre-designed centres. Unwrap the pipe from the coil completely and take pipe from the outside of the coil by unrolling the pipe in the direction that the pipe is being laid.

Pipe laying

The floor panel ensures that pipe is laid at the pre-determined spacing. 15mm pipe is laid at 100mm or 200mm centres as required; 18mm pipe may also be laid at 300mm centres.

The minimum bend radius is ensured by encircling two castellations for a 90° bend or three castellations for a
180° bend (see diagram below).

Pipe laying - Step one

All circuits to be laid at 100mm and 200mm centres must be laid in a spiral configuration. The first loop of pipe should be laid around the perimeter of the area to be covered by that circuit. The next loop should be laid either 200mm from this pipe for spacing of 100mm, or 400mm from this pipe for spacing of 200mm.

Pipe laying - Step two

Continue the loop of the pipe to the centre of the panels, leaving enough space to form a double return
(“s” shape in the centre of the loop).

Pipe laying - Step three

Continue working out from the centre by filling the space between the two pipes on the primary circuit,
therefore leaving pipes at the required spacing centres.

Where 300mm spacing is required (18mm pipe systems only) a meander pattern can be used. The pipe
simply crosses the room from one side to the other encapsulating three castellations at each return bend.

Conduit pipe

Conduit pipe should be used around heating pipe where the pipe passes through edge insulation strips, ie room, or through expansion joints within the floor. A section of conduit 400mm long should be applied. Conduit is also used where the pipe leaves the floor adjacent to the manifold. This is normally threaded down the pipe after the pipework has been installed.

Screed cover

Screed should only be laid over the pipe that is pressurised to 6 bar, as this prevents pipes being crushed during the screeding process. Sand and cement screed should be laid to a depth of 65mm minimum (40mm cover over pipe minimum).

Screed significantly greater than this thickness will delay initial heating times.

Timber - suitable for Polyplumb solid floor and suspended floor systems

Although many people are concerned the effect of heat on a timber floor, much of this concern is misplaced.

Of more importance is the floor moisture content. Timber floors should be laid at moisture content of 10% to 11%, which during the heating season will reduce to 8% to 9% and cause a very small amount of shrinkage.

The floor will re-absorb some moisture when the heating is not operating and the moisture content will increase to 12% to 13%

Application of Timber floors over Solid floor systems

Where traditional oak flooring is to be laid on a solid floor, joists can be used at 1 metre spacings to provide a fixing point for the boards.

Insulation, floor plate and pipe can then be laid between the joists and screed laid level with the top of the joists (see diagram).

Individual circuits of pipe are laid between each set of joists and care should be taken to ensure that the screed is completely dry prior to the wood board covering being laid (see diagram).