Every rafter on the roof, with the sum that produced it

Put in the span, the plate length and the pitch. Get back every member you have to cut, every angle you have to set, and the arithmetic behind each one.

What it costs

The app is free to download. Gable and lean-to roofs are free, and stay free. The full schedule, the PDF, printing, saving, all of it. Nothing is held back and nothing expires.

Your first hipped roof is free too, and it is the whole thing. The complete jack ladder, the hip lengths and bevels, the shortened ridge, the cut schedule and the PDF. No watermark, no locked export, no trial stamp across the page. It stays saved and you can open it forever.

After that, £19.99 once unlocks every hipped roof you will ever cut. Once, not every year. There is no subscription, no renewal and nothing to cancel, and there never will be.

Anything you have already worked out stays yours. Saved jobs open whether you have paid or not. On a roof, in the rain, with no signal, is not a moment to be asked for money.

What it works out

Gable, hipped and lean-to roofs. For each one:

• Common rafters: run, rise, true length, the tail for the overhang, and the overall length to order.
• Hips: the shallower hip pitch, the plan run, the length to the apex, the shortening where the hip meets the crown rafter, and the cheek set-back so you have the long point and the short point.
• Jack rafters: the whole ladder, left hand and right hand, cut to the hip face rather than its centreline, with the common difference stated once above them.
• The ridge: board length, and a depth deep enough to take the rafters' plumb cuts, which is more than the rafter depth at every pitch.
• Every cut: plumb, seat, edge bevels and the hip's double cheek, stated against the edge of the timber, the way the reckoner states them.
• Birdsmouths: notch depth, plumb-cut length and seat-cut length, which are three different numbers, plus the height above plate that keeps the roof planes true.

It shows the working

Tap any figure and you get the derivation, step by step, with the values already substituted. Not a formula to fill in yourself, but the actual sum:

Deductions are always their own step. A length that quietly contains a ridge allowance is the thing this app is built against, so you see the undeducted figure, the deduction, and the result.

It asks rather than assumes

Where a carpenter makes a choice, the app makes you declare it instead of picking one behind your back. Where the run ends. Whether the hips are backed or dropped. How the birdsmouth is sized. Which reference the bevels are stated from. Where the first jack sits.

Every schedule prints the settings that produced it, in words, so two people reading the same sheet cannot disagree about what the numbers mean.

Checked against published tables

The geometry is written twice, by two independent methods: a three-dimensional model of the roof planes, and the per-metre-of-run system the trade texts teach. Ten thousand random roofs are put through both on every build, and the two have to agree.

On top of that, thirteen worked examples from published sources are asserted figure by figure, including four read straight from Goss's Roofing Ready Reckoner.

On the roof

• Works with no signal, because it never needs one.
• A4 cut schedule to print, share or keep.
• Saved jobs store what you typed, so a correction to the geometry fixes every job you have already saved.
• Site rounding to 5 mm when you want it, which rounds lengths down, because timber can be trimmed and not stretched.
• Full Dynamic Type and VoiceOver, with every figure spoken.

CutRoof calculates geometry from your dimensions. Structural design and timber sizing are the responsibility of a competent person.