Metal roofing · Sydney
Flat and Low Pitch Metal Roof Replacement in Sydney
Skillions, extensions and roofs with barely any slope. These need the right profile and careful laps or they leak.
- Trade
- Certificate III roof plumber
- Work
- Re-roofs, new roofs, guttering
- Material
- Metal only. No tile.
- Area
- Sydney, west prioritised
What is included
What you are actually buying
Pitch assessed before anything else
Every profile has a minimum pitch. Below it, no amount of care keeps water out under wind.
Long single sheets
The best fix for a low pitch roof is usually to eliminate the end lap entirely by running one length.
Concealed fix where it suits
A seamed panel goes lower than a lapped and screwed sheet, and on some roofs it is the only correct answer.
Drainage that actually works
A flat roof is only as good as where the water goes. Box gutters and outlets get looked at as part of the job.
Not included, deliberately
We work in metal only. No tile restoration, repointing or roof painting, no internal ceiling repairs, and no small leak chasing as a service. Job size is not a limit either way: there is no lower cut-off, and the crew scales up to roofs of around a thousand square metres.
How it works
From the first phone call to the clean up
Measure the pitch
Not estimated from the ground. The actual fall decides what can legally and sensibly go on the roof.
Find out why it leaked
On a low pitch roof the answer is nearly always a lap, a penetration or a box gutter, rather than the middle of a sheet.
Choose the profile to the pitch
Deeper ribs, fewer laps, or a concealed fix panel. This is the decision that determines whether the new roof works.
Set out to avoid end laps
Where the run allows it, one sheet from top to bottom, which removes the most common failure point completely.
Detail the edges and outlets
Box gutters, sumps, overflows and penetrations, which on a flat roof are the entire ball game.
The detail
What you should know before you commit
A truly flat roof is not a metal roofing job, and anyone telling you otherwise is about to build you a problem. What most people call a flat roof is a low pitch roof, and those we do.
Skillion extensions, rear additions, verandah roofs and 1960s and 70s houses with a very shallow fall are the common ones in Sydney, and they are their own discipline.
Pitch is a specification, not a preference
Every roof sheet profile carries a minimum pitch it is rated to work at. That figure exists because at a shallow angle, wind drives water back up the laps faster than gravity takes it down.
This is why a low pitch roof can be perfectly installed, with every screw in the right place, and still leak. The sheeting was never rated for the fall it was put on.
So the first thing that happens on a low pitch job is that somebody measures the actual pitch, and the profile follows from that number rather than from what is cheapest.
Corrugated
The most common profile and the least tolerant of low pitch. On a shallow roof it is frequently the wrong answer.
Wide rib trapezoidal
Deeper ribs carry more water in the pan and go lower than corrugated, which covers a lot of Sydney skillions.
Concealed fix and standing seam
No penetrations and a raised seam. This is what goes on when the pitch is below what a lapped sheet can do.
Membrane
At genuinely flat, metal is not the material. We will tell you that rather than sheet it and hope.
End laps are where low pitch roofs fail
An end lap is where one sheet overlaps another partway down the roof. On a steep roof water crosses that joint and keeps going. On a shallow one it sits there.
Wherever the run allows it, the answer is a single sheet from the top of the roof to the gutter with no end lap at all. Sheets are rolled to length, so this is usually a question of access rather than of what is available.
Where a lap genuinely cannot be avoided, it gets sealed and stitched properly rather than simply overlapped, and that detail gets discussed rather than assumed.
Box gutters and where the water goes
Low pitch roofs frequently drain into a box gutter rather than over an edge, and a box gutter is an unforgiving piece of roof plumbing.
It has to be wide enough, have enough fall along its length, have a sump and outlet sized for the roof area feeding it, and have an overflow that discharges somewhere visible rather than into the building.
A surprising number of low pitch leaks are not roof leaks at all. They are a box gutter that backs up in heavy rain, and replacing the sheeting without touching it fixes nothing.
If it is genuinely flat, say so and we will tell you honestly
There is a point where the fall is low enough that no metal roof is the right answer and it wants a membrane instead. That is not our trade and we will send you elsewhere rather than sheet it and let you find out next winter.
Common questions
Flat and low pitch: common questions
Can you put a metal roof on a flat roof?
On a low pitch roof, yes, with a profile rated for that pitch. On a genuinely flat roof, no. That wants a membrane and we will say so.
Why does my low pitch roof leak when the sheets look fine?
Nearly always an end lap, a penetration or a box gutter. At a shallow fall, water sits at the joints instead of crossing them.
What is the minimum pitch for a metal roof?
It depends entirely on the profile, which is why the pitch gets measured before anything is quoted. Concealed fix and standing seam go considerably lower than lapped corrugated.
Do I need a box gutter replaced as well?
If the roof drains into one and it is the same age as the sheeting, usually yes. It is also where the leak often was in the first place.
Other services
The rest of what we do
Standing seam
A sharper look with no screws showing on the roof. The panels join along a raised seam instead.
Full re-roof
We take the old roof off and put a new metal one on. While it is open we check the timber underneath and replace anything that has rotted.
Guttering
New gutters, downpipes and fascia, either with a new roof or on their own.
Next step
Get your roof measured properly
On the roof where we can get to it, off satellite imagery where access is awkward. You get a figure for your roof, not a rate applied to a guess.