Flat roof replacement in Perth
Flat roof replacement covers skillions, low-pitch roofs, extensions, patios and parts of commercial buildings where the roof has only a slight fall. Roofing Perth arranges flat and low-pitch roof replacement across the Perth metro area through independent local roofing contractors. They measure the actual pitch, check how water leaves the roof, and quote a replacement that deals with the cause of any leaks, not just the sheets.
Where flat roofs are found in Perth
- Modern homes with skillion roofs and parapet walls, common in newer estates and infill builds.
- 1960s and 1970s homes with low-pitch steel roofs and box gutters.
- Extensions and enclosed patios added onto older houses.
- Garages, carports and granny flats.
- Shops, offices and warehouses, covered in more detail under commercial roofing.
Why they fail
Water moves slowly on a shallow roof, so small problems become leaks:
- Pitch below the profile minimum. Every sheet profile has a minimum pitch. Below it, water backs up at laps and under flashings.
- Sagging. Purlins or battens that have moved create low spots where water sits.
- Undersized box gutters. Many older box gutters cannot handle a heavy downpour, and overflow inside the building.
- Failed flashings. Parapet cappings and wall flashings crack, lift or lose their sealant.
- Debris. Leaves and dust build up quickly on low pitches and dam the water.
What a proper replacement includes
The new roof should start from the drainage plan:
- Measure the existing fall and confirm the new profile's minimum pitch. If the fall is too low, the structure can sometimes be packed to increase it.
- Use long single sheets where possible, avoiding end laps.
- Size box gutters and sumps for the roof area, and add overflows.
- Turn up sheet ends at the high side and turn down at the gutter so water cannot blow back.
- Detail parapet and wall flashings properly, with a capping that sheds water away from the wall.
- Add a blanket under the sheets for heat and condensation.
Where part of a roof is genuinely flat, such as a balcony over a room, a membrane waterproofing system may be the right answer. That is a specialist job and should be priced separately.
Before you get quotes
Note where leaks show inside, when they happen, and whether water sits on the roof after rain. Photos from a safe vantage point help. Check whether the roof is shared with a neighbour or covered by strata rules, because that affects who decides and who pays.
Read roof leaks and water damage for more on tracing leaks, and see metal roof replacement for older steel roofs. Planning prices are on the cost guide.
Keeping a low-pitch roof working
Once the new roof is on, the biggest risk is blocked drainage. Clear leaves from box gutters, sumps and rain heads before winter, and again after strong winds. Keep trees trimmed back from the roof where you can. Check overflows are not blocked or covered. If water marks appear on ceilings near parapets or box gutters, have them looked at promptly, because on a low pitch a small leak can saturate insulation and ceilings quickly.