Worked example: when the leak is the gutter, not the roof
A leak over a production area keeps coming back after sheet repairs. The firm that did the repairs now quotes a re-clad, a second firm quotes a gutter lining, and a third quotes more sheet repairs. This worked example shows how to compare three quotes that each assume a different cause. It is an illustration of the method, not an account of a real building, job or price.
The situation
The building is an industrial unit with a profiled-metal roof and box gutters along the valleys. Water appears on the floor near a valley after heavy rain. Two rounds of sheet repairs have not stopped it.
Three quotes, three assumed causes
- More sheet repairs assume the leak is in the sheets or fixings.
- A gutter lining assumes the leak is at the box-gutter joints, laps or outlets, and that water is tracking behind the cladding line.
- A re-clad assumes the roof as a whole is at the end of its life.
Each can be right on a different roof. The comparison starts with the evidence for the cause, not with the prices.
Questions that find the cause
- Where exactly is the water appearing, and does it follow heavy rain, prolonged rain or snowmelt?
- Has anyone inspected the gutters, joints and outlets from the roof, with photographs?
- Has a water test been run on the gutter with the outlets blocked?
- What condition are the sheets and fixings in away from the valley?
- Are the outlets and downpipes sized and clear for the area they drain?
If the gutter joints have failed, repeated sheet repairs will not stop the leak, and a re-clad may be more than the fault needs. If the sheets have failed across the roof, a gutter lining alone will not be enough.
Comparing the quotes once the cause is known
- Scope. A gutter lining quote should say the gutter length in linear metres, the lining system, how joints, outlets and stop ends are detailed, and whether outlets are renewed.
- Access. Work in valleys between fragile rooflights or fibre-cement sheets needs edge and fragile-roof protection under the HSE roof-work guidance.
- Asbestos. On a building from before 2000, ask whether the sheets or gutters contain asbestos and whether a refurbishment survey has been done.
- Guarantee. Ask who issues it, for how long, and what maintenance it requires, such as clearing gutters and outlets.
- Production. How the work is phased so the production area stays protected and running.
With the cause agreed and the scopes aligned, the price comparison becomes meaningful. The quote sense-check handles mixed area and linear-metre quotes if you enter the gutter work as its own quote, and the gutter refurbishment guide explains the lining options.
Worked example for illustration only. Not a real building, job or client. Last checked 25 October 2026.