Tile Delivery Shortfall on a Hip Roof With a Tight Handover
You are tiling a hip roof with a plan area of 180 m2 at a 25 degree pitch. The tile manufacturer's coverage is 10.5 tiles per m2 of roof surface, and the supplier has delivered 2,100 tiles. The roof has four hips and a valley-free design. You have allowed for hip and ridge capping separately. The handover is in five working days and the supplier says the next delivery is in four days. Your leading hand estimates wastage at 5 percent for cuts and breakages. The client has already paid a progress claim for 'roof tiling complete'.
1. Calculate whether the delivered tiles are sufficient, showing your working.
Read the worked answer
First convert plan area to roof surface area. The slope factor for a 25 degree pitch is 1 / cos(25 degrees) = 1 / 0.9063 = 1.103.
Roof surface area = 180 m2 x 1.103 = 198.5 m2 (round to 199 m2).
Tiles required before wastage = 199 m2 x 10.5 tiles/m2 = 2,089.5, round up to 2,090 tiles.
Allow 5 percent wastage = 2,090 x 1.05 = 2,194.5, round up to 2,195 tiles.
Delivered: 2,100 tiles. Shortfall = 2,195 - 2,100 = 95 tiles.
So the delivery is about 95 tiles short of a realistic allowance. Without wastage the delivery would be marginally sufficient, but cuts at hips and breakages will consume the margin quickly. Do not start laying until either the shortfall is confirmed with the supplier or you have a plan to source the balance, because running out mid-roof risks an incomplete, non-waterproof plane at handover.
2. What are your priorities for the next five days, given the shortfall and the progress claim already paid?
Read the worked answer
Priorities:
- Communicate immediately. Tell the supervisor and client in writing that the delivered quantity is short by roughly 95 tiles and that the four-day delivery will not allow completion by handover unless stock is sourced sooner.
- Source locally. Ask the supplier whether the same tile and colour is available from another branch or a competing stockist, and whether a partial load can be delivered sooner. Confirm the tile profile and colour match before accepting substitutes.
- Sequence the work to protect the building. Lay the tiles you have in a way that keeps the roof watertight - complete full planes and hips rather than scattering tiles - and tarp or otherwise weatherproof any unfinished area.
- Protect the client's position. The progress claim for 'roof tiling complete' is now inaccurate; flag this to the supervisor so the claim can be corrected or the client informed, rather than letting a false claim stand.
- Re-plan handover. Give a realistic revised date once stock is confirmed, and record the reason for the delay.
Do not rush the lay to stretch stock, as skipped or cut-short courses create leaks and callbacks.