PEB (Pre-Engineered Building) Construction · Question

Why does a PEB roof sometimes leak at sheet joints and fasteners?

Short answer

Leaks at sheet joints and fasteners usually come from small workmanship or movement issues rather than the steel frame: sealant that has aged or was applied poorly, fasteners over or under tightened, washers that have perished, overlaps too short for the slope, or blocked gutters. Diagnosis needs a careful look at the actual leak points, ideally by the supplier or a competent roofing contractor.

In more detail

A metal roof is a large surface that expands and contracts with heat. Over seasons, this movement works at laps and fastener holes. Where the original sealing was thin, or the sealant was not suited to the exposure, tiny gaps open and water finds them, especially in driving rain.

Fasteners are another frequent point. A fastener that is not driven straight, or is tightened unevenly, may crush its washer or leave it loose. Roof foot traffic and later additions such as solar mounts, vents and pipes can also create new openings that were never sealed properly.

Roof slope or lap length too modest for the rainfall in the area
Gutters, valleys or downpipes that overflow and push water back under sheets
Damaged sheets from handling, scratches or corrosion at cut edges
Skylight sheets and ridge accessories not fitted tightly

Roof work is a safety risk

Do not climb or walk on the roof to search for leaks yourself. Fragile sheets and height make it dangerous. Engage trained people with proper access and fall protection.

Note where water appears inside and when, take photographs, and report the problem in writing to the supplier or erector while the warranty period applies. Ask for the cause to be identified, not just a patch of sealant over the symptom. Keep handover records handy, since they show what was installed.

Key points

Most leaks trace to sealant, fasteners, laps, accessories or drainage, not the main frame.
Thermal movement slowly loosens details that were marginal at installation.
Later additions like vents and mounts are common new leak sources.
Report leaks in writing within the warranty period, with photographs and dates.
Never inspect the roof yourself; use trained and protected personnel.

Who this applies to

Owners of existing sheds seeing water ingress during the monsoon.
Facility managers deciding whether to repair, reseal or replace roof details.
Buyers planning a new building who want to specify fewer leak risks.

Last reviewed 3 October 2026

This answer is general information, not advice on your particular case. Terms, eligibility, and requirements change, so check the current position with the relevant institution or authority.