Re-sarking during roof replacement
Roofer Sunshine Coast arranges roof re-sarking as part of roof replacement through independent local roofing contractors. When an old roof comes off, the roof frame is exposed for a short window. That is the practical time to lay new sarking or a roof blanket, because adding it later means lifting the roof again.
What sarking does on a Sunshine Coast roof
- Wind-driven rain. Storm rain pushed under tiles or flashings runs down the sarking into the gutter instead of onto the ceiling.
- Condensation. Humid air meeting a cool steel sheet at night forms water droplets. A blanket or suitable membrane stops that dripping into the roof space.
- Heat. Reflective sarking and insulated blankets reduce the radiant heat reaching the ceiling in summer.
- Dust and draughts. Tile roofs without sarking let dust, leaf litter and insects into the roof space, especially in wind.
- Embers. In bushfire-prone parts of the hinterland, sarking and sealing details may be part of the construction requirements.
Choosing the right membrane
There are two broad kinds. Vapour-permeable membranes let water vapour escape from the roof space while shedding liquid water, which helps in humid climates where moisture needs a way out. Vapour barriers stop vapour passing through and are used in particular situations. Roof blankets under steel combine a facing with insulation. Which one suits your roof depends on the covering, the ventilation of the roof space and whether the ceiling has insulation. Ask the contractor to name the product type and explain why it suits your house.
Getting the details right
Sarking only works if it is laid with the correct laps, drains into the gutter at the eaves, is not torn during installation and is properly finished around vents, skylights and pipes. Under tiles, the sarking should not be pressed tight against the battens in a way that traps water; counter-battens or a drape are used depending on the system. These details are invisible once the roof is on, so they belong in the written scope.
Related work
Re-sarking is usually done with residential roof replacement, tile roof replacement or a Colorbond re-roof. If you are dealing with damp or mould in the roof space, read mould and moisture under roofs first.
Signs the roof space needs attention
You do not need to be a roofer to spot the clues. Climb to the manhole with a torch on a dry day and look for:
- Daylight showing between tiles, which means wind-driven rain can get in too.
- Water stains or tide marks on rafters, battens or the top of the ceiling.
- Torn, sagging or dusty foil, or no membrane at all under a tile roof.
- Mould or a musty smell, often a sign of trapped humidity.
- Rust on the underside of steel sheets, which points to condensation.
- Black dust lines on insulation, showing where air and dust are blowing through.
If you see these, mention them when you book an inspection, and see our article on how poor ventilation affects your roof.