GENERAL INSTRUCTIONS

Protective clothing is not required when handling Silver.

Silver may be installed either way up

Bare electrical wiring must not be allowed in contact with Silver. PVC coated electrical wiring to normal domestic items such as light fittings may come into contact with Silver.

If electrical cables are surrounded by insulation they may need to be de-rated and guidance should be sought from a qualified electrician

INSTALLATION PROCEDURE

Silver is unrolled above or below the rafters in horizontal layers, parallel to the eaves. The product should be installed from ridge to eaves, and over- or under-lapped to ensure that any water inside the rafter space runs down and does not penetrate the insulation or the rafter space. As the Silver is unrolled across the rafters it is fixed in place using nails or staples of at least 14mm depth. The next roll of Silver must overlap the preceding layer by at least 50mm, and the overlap should be sealed along the entire length using the specified adhesive tape.

When installing Silver, try to retain the full width (with two seams) whenever possible. For the bottom layer, it is better to use a complete layer, and increase the overlap with the next layer up, rather than cutting along the Silver to maintain a 50mm overlap.

Silver should be permanently held in place using wooden battens fixed with nails. Battens may run either parallel or perpendicular to the rafters.

Plasterboard is fixed to the battens. If insulation material such as glass wool rests directly on the plasterboard, a standard plasterboard is acceptable. If insulation material such as PIR is separated from plasterboard by an air layer then foil-backed plasterboard should be used.

A breathable roofing membrane is fitted above the rafters following the manufacturer’s instructions. Tiling battens and tiles are then fitted.

CUTTING

Silver can be cut using a sharp knife with the Silver resting on a board, or with scissors. When cutting Silver, always retain as much of the welded seam as possible. Where Silver has been cut and the layers are exposed, the cut edge should be taped together.

Pieces which have been cut should be stapled and battened as soon as possible, and should not be left only partially secured overnight.

Awkward shapes (such as triangular pieces for dormer cheeks) should be taped up, stapled and battened immediately.

Any tears or holes should be repaired with the specified adhesive tape.

TAPING

It is important that Silver is securely taped at overlaps and junctions with walls or windows. TLX tape or Henkel All-Purpose Duck tape are recommended as a suitable tape. Other tapes should not be used unless they have been shown to have equivalent bonding to Duck tape.

Silver must always be taped together when the surfaces are clean and dry.

AIR LAYERS

Unventilated air layers form an important part of the Silver Insulation System. If the air spaces are omitted, whilst there is no danger of condensation, the overall thermal performance of the structure will decrease, and the U value will be higher. Additional insulation may be needed to achieve the desired U-value for the roof.

ADDITIONAL INSULATION

Install additional insulation according to the manufacturers’ instructions.

Provide for air gaps between additional installation and Silver as instructed.

STORAGE

Silver rolls must be stored on a flat dry surface, protected from the weather and direct sunlight.

Make sure when installing Silver that it does not come into contact with heat sources above 80°C.

VAPOUR CONTROL AND VENTILATION

Where Silver is fitted below rafters it also performs as an effective vapour barrier, preventing water vapour from the house from penetrating the roof structure and possibly condensing on a cold surface. No additional vapour barrier is required.

Where Silver is fitted above rafters, then it is necessary to install an additional vapour barrier below the rafters. Foil-backed plasterboard where joints between boards are well sealed or 500 gauge (0.12mm) polythene sheet may be acceptable vapour barriers.

Ventilation of the rafter space is not needed if a breathable roofing membrane has been used. If a non-breathable (or 1F type) membrane is in place, then a 50mm ventilated air space beneath the felt is required.

Ventilation of the space between the membrane and the outer roof covering is not required for air-open coverings such as clay or concrete tiles and natural slates.

If in any doubt about possible harmful condensation, contact Building Control for guidance.

ACHIEVING BETTER U VALUES

U-values lower than those given in the examples may be achieved by using a second layer of Silver, or a greater thickness of additional insulation.