Metal Roof Leaking at an Overlap: What to Check
A metal roof leaking at an overlap needs the water entry point traced before a repair is chosen. We investigate roof leaks and consider the joint, surrounding sheets and nearby details together.
End laps and side laps: which joint is involved?
Metal roof sheets can meet along their sides or overlap end to end. The type of joint and the surrounding detail matter when investigating how water is getting in.
Side lap
The joint along the side of adjacent sheets. Describe which part of the roof it is on and any visible gap or earlier work shown in existing photographs.
End lap
The overlap where one sheet meets the end of another along the roof slope. Joint detailing and the condition of the overlap are part of the inspection.
You do not need to climb onto the roof to identify the joint. Existing roof photographs, a previous report or a description of the indoor leak can give us a starting point.
The ceiling stain may be away from the entry point
Water can travel before it appears inside. A leak below a sheet overlap is a clue, but it is not enough on its own to establish that the overlap is the source. Nearby flashings, penetrations, fixings and the condition of the roof need consideration.
| Observation | Useful detail to add |
|---|---|
| Leak during particular rain | The approximate time, duration and wind direction if known. |
| A stain that appears later | How long after rain it becomes visible and whether it grows. |
| Leak after earlier work | What work was done, where and when. |
| Water near a known roof joint | The joint's location in existing photographs or roof records. |
Keep notes from separate rain events. A short record of a repeating pattern can be more useful than a single photograph with no date or location.
What the investigation needs to consider
- The type of overlap and its condition.
- The condition of the surrounding sheet material and any corrosion.
- Nearby fasteners and previous repair work.
- Flashings, penetrations or other details that could admit water.
- The route between the roof area and the visible indoor damage.
Poorly detailed or sealed end laps can allow moisture problems within the joint. The appropriate response depends on the actual detail and condition, not simply the amount of sealant visible on the surface.
Why another surface patch may not answer the problem
Adding sealant over a suspected spot does not prove where water entered or establish the condition within the overlap. Earlier patches may also make it harder to understand what is happening without a closer investigation.
The repair scope should explain the identified cause and the area being addressed. If the surrounding roof has broader condition problems, our repair-or-replace guide sets out the questions for a wider assessment. If the roof is membrane rather than overlapping metal sheets, see membrane roof repairs.
Prepare a leak enquiry without going onto the roof
Send the property address, the room or elevation affected and photographs taken safely indoors or from the ground. Include previous repairs and any existing roof images. Keep clear of damaged ceiling areas and tell us if water is continuing to enter.
Roof access and checking the joint belong in the work assessment. There is no need to walk the roof, lift a sheet or test a fixing before contacting us.
Your questions
Should I seal the overlap myself?
The entry point and joint condition need to be established first. Contact us with the leak pattern and any earlier repair records so we can discuss investigation.
Can a leak at a joint mean the whole roof needs replacing?
A local defect and a wider roof condition problem are different possibilities. An assessment of the affected detail and surrounding material helps determine the scope.
What if the leak only happens in heavy rain?
Record the timing, weather and location each time it happens. That pattern is useful information, even if the roof looks dry between events.
Tell us when and where the leak appears
Send the leak location, rain pattern and any earlier repair details. We can discuss tracing the cause and the work needed at the affected roof area.