Roof material calculator

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Roof material calculator

The sloped area of a roof from its footprint and its pitch.

It runs entirely in this browser tab: nothing you type is uploaded, and it makes no request of any kind.

Settings

The shape
A column is round, so it takes a diameter rather than two sides. Choices: A gable roof, A lean-to, A hipped roof.
The pitch is given as
A rise over a run is how a pitch is written in half the world. Choices: {amount}°, A rise over a run.
Overhang
The eaves, in centimetres, added on every side of the footprint. A number from 0 to 150.
Batten spacing
Set by the covering, and it is written on the pack. A number from 10 to 60.
Reserve
A trade convention rather than a measurement: the quantity without it is shown too. A number from 0 to 40.

How to use it

  1. Paste your text into the box above, or open a file.
  2. Adjust the settings beside it until the result is what you wanted.
  3. Copy the result, or save it as a file. The result updates as you type.

Questions

Where do the coverage rates and densities come from?
They are the published typical figures — what a tin of emulsion claims, what a cubic metre of dry sand weighs, what a bag of screed covers. They are printed on the result so you can compare them with the bag in front of you, and the bag wins.
Is the ten per cent reserve part of the calculation?
No, and that is why it is a setting. It is a trade convention for breakage and offcuts, and the quantity without it is shown on the same result, so you can order either.
Can I use this instead of a heating engineer or a structural check?
No. A heat loss from six fields is an order of magnitude, not a design: a standard calculation takes every room, orientation and junction separately. The snow tool weighs snow; whether your roof carries it is on its drawings.
Does anything I type here leave the page?
No. There is no account, no server and no network request. What you type stays in this tab, and in the link if you choose to share one.

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