Roof space – insulation is wet

Cause

A leak through roofing, around a chimney, flue or other roof penetration, from an inadequately flashed parapet or an overflowing internal gutter

Repair

  • locate and repair the leak. Where it is suspected that leaking is extensive or the leak cannot be found, engage an experienced building surveyor for advice

  • remove any insulation that is wet or where there is mould present. Wear protective clothing and a disposable mask

  • allow the ceiling space and framing timber to dry out

  • install new insulation into the dry space, covering the whole ceiling area (but not the top plate)

  • where the roof space is fully accessible, fit bulk insulation between and over ceiling joists, with no gaps or folds

  • where the roof space is only partly accessible and segment or blanket-type insulation cannot be fitted by hand, consult an experienced specialist contractor to install blown-in, loose-fill insulation

Cause

Leaking pipes or water tanks in the roof space

Repair

  • locate the leak and make a permanent repair, or call a licensed or certifying plumber to make repairs

  • remove any insulation that is wet or where there is mould present. Wear protective clothing and a disposable mask

  • allow the ceiling space and framing timber to dry out

  • install new insulation into the dry space, covering the whole ceiling area (but not the top plate)

  • where the roof space is fully accessible, fit bulk insulation between and over ceiling joists, with no gaps or folds

  • where the roof space is only partly accessible and segment or blanket-type insulation cannot be fitted by hand, consult an experienced specialist contractor to install blown-in, loose-fill insulation

Cause

Moist subfloor air moving through brick veneer cavity where the cavity is open to the roof space and to the subfloor space 

Repair

  • identify the cause of the subfloor moisture and address it. If it is caused by a leaking pipe, make a repair, or call a licensed or certifying plumber to repair it

  • if surface water is flowing under the house, lower the ground levels around the building and slope the ground away from the house. Install channels or sub-surface drains and discharge into a stormwater drain or soak pit 

  • lay polythene sheeting at least 0.25 mm thick to cover the ground under the house. Ensure that the ground is shaped so no water accumulates on the polythene. Polythene sheets should be lapped a minimum of 150 mm, preferably taped, and butted up to foundation walls and piles. Weigh down the sheets with bricks or concrete to avoid them being displaced by air movement

  • improve subfloor ventilation

  • remove any roofspace insulation that is wet or where there is mould present. Wear protective clothing and a disposable mask

  • allow the ceiling space and framing timber to dry out

  • install new insulation into the dry space, covering the whole ceiling area (but not the top plate)

  • where the roof space is fully accessible, fit bulk insulation between and over ceiling joists, with no gaps or folds

  • where the roof space is only partly accessible and segment or blanket-type insulation cannot be fitted by hand, consult an experienced specialist contractor to install blown-in, loose-fill insulation

Cause

Moist subfloor air moving through an uninsulated framing space where holes were drilled in top and bottom plates to allow framing to dry when wet timber framing was used for construction

Repair

  • identify the cause of the subfloor moisture and address it. If it is caused by a leaking pipe, make a repair, or call a licensed or certifying plumber to repair it

  • if surface water is flowing under the house, lower the ground levels around the building and slope the ground away from the house. Install channels or sub-surface drains and discharge into a stormwater drain or soak pit 

  • lay polythene sheeting at least 0.25 mm thick to cover the ground under the house. Ensure that the ground is shaped so no water accumulates on the polythene. Polythene sheets should be lapped a minimum of 150 mm, preferably taped, and butted up to foundation walls and piles. Weigh down the sheets with bricks or concrete to avoid them being displaced by air movement

  • improve subfloor ventilation

  • remove any roofspace insulation that is wet or where there is mould present. Wear protective clothing and a disposable mask

  • allow the ceiling space and framing timber to dry out

  • install new insulation into the dry space, covering the whole ceiling area (but not the top plate)

  • where the roof space is fully accessible, fit bulk insulation between and over ceiling joists, with no gaps or folds

  • where the roof space is only partly accessible and segment or blanket-type insulation cannot be fitted by hand, consult an experienced specialist contractor to install blown-in, loose-fill insulation

Cause

Moist air flow from kitchens and bathrooms into the roof space through wrongly installed ceiling vents or open recessed downlights

Repair

  • install ducting for kitchen and/or bathroom extract vents so steam and moist air is carried to the outside

  • close off unnecessary airflow routes from inside the house. If recessed downlights are open to the roof space, replace with IC or IC-F labelled downlights that can be covered with insulation. Alternatively, remove the lights, close off the holes and mount new light fittings on the ceiling

  • remove any insulation that is wet or where there is mould present. Wear protective clothing and a disposable mask

  • allow the ceiling space and framing timber to dry out

  • install new insulation into the dry space, covering the whole ceiling area (but not the top plate)

  • where the roof space is fully accessible, fit bulk insulation between and over ceiling joists, with no gaps or folds

  • where the roof space is only partly accessible and segment or blanket-type insulation cannot be fitted by hand, consult an experienced specialist contractor to install blown-in, loose-fill insulation

Cause

Kitchen and bathroom extractor fans discharging into the roof space

Repair

  • install ducting for kitchen and/or bathroom extract vents so steam and moist air is carried to the outside

  • remove any insulation that is wet or where there is mould present. Wear protective clothing and a disposable mask

  • allow the ceiling space and framing timber to dry out

  • install new insulation into the dry space, covering the whole ceiling area (but not the top plate)

  • where the roof space is fully accessible, fit bulk insulation between and over ceiling joists, with no gaps or folds

  • where the roof space is only partly accessible and segment or blanket-type insulation cannot be fitted by hand, consult an experienced specialist contractor to install blown-in, loose-fill insulation

Cause

Aluminium foil used instead of a roof underlay, resulting in moisture condensing on the foil rather than being absorbed by the underlay

Repair

  • remove the foil and install the appropriate roof underlay to the underside of the rafters or purlins

  • remove any insulation that is wet or where there is mould present. Wear protective clothing and a disposable mask

  • allow the ceiling space and framing timber to dry out

  • install new insulation into the dry space, covering the whole ceiling area (but not the top plate)

  • where the roof space is fully accessible, fit bulk insulation between and over ceiling joists, with no gaps or folds

  • where the roof space is only partly accessible and segment or blanket-type insulation cannot be fitted by hand, consult an experienced specialist contractor to install blown-in, loose-fill insulation

Cause

Moisture from the cavity of brick veneer-clad walls where the cavity is open to the roof space  

Repair

  • if it is suspected that roofspace moisture may be carried up from the subfloor space, identify the cause of the subfloor moisture and address it. If it is caused by a leaking pipe, make a repair, or call a licensed or certifying plumber to repair it

  • if surface water is flowing under the house, lower the ground levels around the building and slope the ground away from the house. Install channels or sub-surface drains and discharge into a stormwater drain or soak pit 

  • lay polythene sheeting at least 0.25 mm thick to cover the ground under the house. Ensure that the ground is shaped so no water accumulates on the polythene. Polythene sheets should be lapped a minimum of 150 mm, preferably taped, and butted up to foundation walls and piles. Weigh down the sheets with bricks or concrete to avoid them being displaced by air movement

  • improve subfloor ventilation

  • remove any roofspace insulation that is wet or where there is mould present. Wear protective clothing and a disposable mask

  • allow the ceiling space and framing timber to dry out

  • install new insulation into the dry space, covering the whole ceiling area (but not the top plate)

  • where the roof space is fully accessible, fit bulk insulation between and over ceiling joists, with no gaps or folds

  • where the roof space is only partly accessible and segment or blanket-type insulation cannot be fitted by hand, consult an experienced specialist contractor to install blown-in, loose-fill insulation