How do you check roof sheet fixing in Burao?

Loose roof coverings often start with the fixing, not the sheet. When a roofer has learned only by copying others, fasteners go in at wide spacing, at the wrong position on the corrugation, or into timber that has not been checked. A short inspection before the sheets are walked on catches most of it.

What does a roof sheet fixing skills gap look like on a roof?

It looks like a sheet that lifts at one corner, a fastener sitting in the wrong position for the profile, or a line of screws driven at an angle because the purlin below was not marked. A roofer who has only worked on one roof type may not know why the fixing position moves with the profile. On trapezoidal profiles, general practice is to fix through the valley where the sheet bears on the purlin, and on corrugated profiles through the crest, but the sheet manufacturer's fixing data governs. Confirm the position with the supplier's data before the crew starts.

The gap also shows in the tools. A roofer without a depth-setting screwdriver or a torque-controlled driver can overtighten and crush the washer, or leave the screw proud so the next sheet rocks on it. Walk a completed bay and look along the fixing line: any washer squeezed flat or sitting above the sheet tells you about the tool and the habit. Ask whoever holds the building records for the plot for the approved roof detail.

Why do loose roof coverings appear after strong winds?

Because wind does not pull evenly on a sheet, and the fasteners carry the load at the corners and edges where pressure is highest. A roof fixed with an even but wide grid can look tight on the day and still lift at the gable end when the wind changes direction. General practice is to tighten the fixing spacing at the edges and corners and keep the field spacing wider, but the project specification and the sheet supplier's span table set the numbers. Confirm both before the crew starts.

Lap direction matters too. If the side lap faces into the prevailing wind, rain is driven under the sheet. Ask the designer or the sheet supplier which way the laps should face for the roof's orientation. Take the lap direction from the roof's actual orientation on the drawing and the designer's advice rather than assuming.

How do you test whether the fixing is sound before you sign off?

Pick one bay, and check four things. First, the fastener type: self-drilling screws with a sealing washer for steel purlins, and the correct length so the thread passes through the purlin, not just into it. Second, the pattern: mark the spacing on the sheet and compare it with the specification. Third, the lap: side laps should close tight and end laps should sit over a purlin. Fourth, the pull-out: a gentle pull by hand on a fixed sheet should not move the fastener or open the washer.

A pull-out test done properly needs a load figure from the engineer, so ask the engineer for the acceptance value and how to test it. Ask the fastener supplier for the product data sheet and keep a copy with the delivery note. Where a roofer cannot explain why a fixing position was chosen, that is the skills gap to close before the next bay, not after handover. Photograph each completed bay from the same position so a later lift is obvious.

What to do next

Ask the roofer to fix one trial sheet on the real purlins, in front of you, using the fasteners and the pattern the specification calls for. Check the washer compression, the lap direction and the screw length, then measure the spacing. If the trial sheet passes, photograph it and keep it as the benchmark for every bay that follows.