Steam insulation laying manual
Polyethylene films, working as steam insulations, are for covering constructions, and for building partitions thermal insulation, against water vapour inflow, which after condensation is the partition dampness cause. This partition could be a roof, wall, or ceiling. Tight steam insulation instalment is very important condition of its proper operation, because of water vapour high penetrative abilities. Leaving next steam insulation film layers unsealed increases significantly tributary and water vapour in thermal insulation remaining danger. On steep roofs insulation film’s laid on rafters at the loft side main task is thermal insulation protection against water vapour penetrating from usable rooms, and house interior. The film second function is warmth air escape by draught prevention. Even through very small roof gap, a lot of warmth air may escape, because temperature difference during heating season causes large pressure differences, and sudden air flows arising.
1. Steam insulations one lies after thermal insulation laying inwards horizontally or parallel to rafters depending on needs, and rafter framing construction complication extent. Irrespective of steam insulation spreading manner, one ought to lay it in light tension - tightening slightly.
2. In horizontal laying it is best to start from the top – from collar beam shield, or roof ridge shield depending on thermal insulation laying manner. Every another layer one must lay on overlap minimum 5 cm, and seal it by one-sided, pressure-sensitive adhesive tape outside the overlap, or by two-sided, pressure-sensitive adhesive tape inside the overlap, (Fig. 1) .
3. In along to rafters laying it is best to join steam insulation on overlap glued at rafter. Vertical joining beyond rafter must by made extremely carefully, and it is best to glue next layers with the help of rigid washer i.e. boards.
4. Steam insulation one fastens to the rafters by means of staples or two-sided, pressure-sensitive adhesive tape. We recommend mentioned tape to use, because one does not perforates the steam insulation. In staples usage one must glue mentioned perforations by pressure-sensitive adhesive tape pieces. It is best to drive in the staples by upholsterer or roofer ‘taker’.
5. On vertical components combinations like: elbow walls, chimneys, as well as gable or partition walls one should use special, combinations sealing pressure-sensitive adhesive tapes, (fig. 2). These tapes are especially good for these combinations because of its elasticity. It is important to leave appropriate allowances of steam insulation film at these places. For these combinations one recommends tightening battens usage, fixed to above-mentioned vertical components, (walls and chimneys).
6. In possible combinations with floor one ought to also use tightening battens, (Fig. 3).
7. At the roof windows and roof hatch combinations one must apply the manufacturer’s recommendations, in order to seal the combinations with window frames or other casings.
Attention!
Because of sheetrock characteristic in steam insulation laying, every loft room (not only bathrooms) should have efficient ventilation. In case of no such ventilation between sheetrock or at walls and plaster ceilings surfaces mould or fungus may appear. This threatens occupant’s health. This phenomenon also applies to unventilated rooms in every building’s place, and is not connected with steam insulation applying.
Present manual gives the most important, and basic recommendations, but does not includes information concerning all possible solutions used in roofs constructions. There are also situations,
were other solutions than described in this manual may be applied.
The manual was written basing on the building state of knowledge in June 2003