PUF roof leakage: why panel roofs leak and how to fix them

Where do PUF panel roofs leak?

A roof panel’s top skin is a continuous coated steel sheet, so water rarely gets through the face. It gets in where panels meet each other, where something passes through them, and where the roof meets a wall, a ridge or a gutter.

How do you find where the water gets in?

Water travels along ribs, purlins and the underside of panels before it drips, so the wet patch inside is often a few metres from the real entry point. Work from the outside, from the low end upwards.

• Mark every wet spot inside and note whether it drips in all rain or only in wind-driven rain.
• On a dry day, inspect the roof above and uphill of each spot: screws, laps, flashing, openings.
• Run a hose gently over one detail at a time, starting low and working up, while someone watches inside.
• Work safely: use a harness, walk on the purlin lines, and never step on skylight sheets.

How do you fix a leaking PUF roof?

1. 01

   Make it safe and clean

   Fix lifelines, plan where to walk, and clean dirt, moss and old failed sealant from the area so new sealant can bond.

2. 02

   Replace failed screws and washers

   Replace screws whose washers are cracked, missing or crushed, using the same size with a new sealing washer. Tighten until the washer just compresses; over-tightening dents the rib and opens a path for water.

3. 03

   Re-seal side and end laps

   Lift or open failed laps where possible, apply sealant tape or a compatible non-hardening sealant, and add stitching screws along side laps at the spacing the maker gives. Make sure end laps are long enough for the slope.

4. 04

   Refit the ridge and wall flashing

   Fit profile fillers under ridge and wall flashing, seal them, and make sure flashing overlaps in the direction water flows. Flashing is made as per your requirement, to the profile and lengths of your roof.

5. 05

   Seal penetrations properly

   Pipes, vents and skylights need a collar or flashing that sheds water around the rib, not a bead of sealant alone. Replace improvised patches.

6. 06

   Clear and size the gutters

   Clear blocked gutters and outlets. If water still backs up in heavy rain, the gutter or outlet is too small and needs resizing.

7. 07

   Water-test and inspect again

   Hose-test each repaired detail, then check again after the next heavy rain. Note the repairs for the yearly inspection.

Avoid covering the roof with paint-on coatings or tar as a first fix. They hide the actual fault, trap moisture and often fail again at the same joint. Fix the detail; coat only if the panel face itself has corroded.

How do you stop a new PUF roof from leaking?

• Keep the slope at or above the minimum in the maker’s data sheet for your panel and lap type.
• Lay panels with the side lap away from the prevailing wind and in the right order, from the low end upwards.
• Avoid end laps where possible by ordering panels in one length; continuous panels are cut to order. See continuous vs cam-lock.
• Fix screws square to the sheet, on the crown or as the maker specifies, with new sealing washers.
• Order matched flashing for the ridge, walls, gable ends and gutters with the panels.
• Plan openings before the roof goes on, so collars and flashings are ready.

Installation details also appear in our installation guide. Roof panel rates for each thickness are on the price board, from the 30 mm roof panel upwards; transport is extra.