Two pallets short and the gang standing about
The re-roof is stripped, the membrane is on and the battens are going up when someone realises there are not enough tiles for the rear elevation. Or the ridge tiles are a different profile from the ones ordered. Or the lead for the abutment was never on the order. Someone drives to the merchant, the gang waits, and the afternoon is gone.
The next job goes the other way: three packs of tiles and a roll of membrane come back to the yard because the order was rounded up out of nerves.
Why take-offs keep going wrong
The numbers themselves are not hard. The problem is that every estimator does them slightly differently. One allows for tile gauge on the actual pitch, another uses a rule of thumb. Waste for hips and valleys is guessed. Lead lengths are worked out from memory of what the last similar job used.
- Coverage per square metre depends on tile, gauge and pitch, and is looked up by hand.
- Waste allowances are applied inconsistently between estimators.
- Sundries such as clips, fixings, vents and dry ridge kits get forgotten.
- The take-off lives on paper, so the order is retyped for the merchant.
- Nobody compares what was ordered with what was used.
The cost of getting it wrong in both directions
Shortages cost labour: a gang standing idle or leaving early, a second delivery charge, a job that runs into the next one. Over-ordering ties up money in stock that sits in the yard, and returns to the merchant are not always credited at full value. Both eat into the margin you priced.
The take-off calculator we build
- Survey measurements are recorded by elevation: rafter length, eaves width, ridge, hips, valleys, verges and abutments.
- For each covering you use, we set up your own coverage rules: tiles or slates per square metre at a given gauge, battens, membrane, fixings and clips.
- Waste allowances for cuts at hips and valleys follow rules you set, not the estimator's mood that day.
- Linear items such as ridge, hip, verge and lead flashings are calculated from the lengths entered, with the lead code and width you specify.
- Sundries are added automatically from a checklist for that roof type, so dry ridge kits, vents and eaves protection are not missed.
- The result is a draft merchant order, grouped the way your merchant lays out its price list, for a person to check and send.
- After the job, returns and extra purchases are recorded, so you can see where the rules need adjusting.
| Roof element | Worked out from | Output |
|---|---|---|
| Main slopes | Rafter length, width, gauge | Tiles or slates, battens, membrane |
| Ridge and hips | Measured lengths | Ridge or hip tiles, dry fix kits |
| Valleys | Measured lengths | Valley troughs or lead, cut waste |
| Abutments | Lengths and detail type | Lead by code and width |
| Eaves | Width and ventilation | Eaves trays, vents, fascia items |
Your estimators still decide what goes on the roof. The calculator makes the arithmetic consistent and keeps a record of it.
What the yard and the gangs notice
Deliveries arrive with what the job needs, including the small items. When something is short, you can see whether the rule was wrong or the survey was, and fix the right thing. The office stops retyping orders, and you have a clear view of the material cost of each job before it starts.
Signs your take-offs need fixing
- Gangs regularly go to the merchant mid-job.
- Returned stock piles up in the yard.
- Two estimators would order different amounts for the same roof.
- Lead and sundries are the usual things missing.
- You cannot say what a job actually used against what was ordered.