The Hipped Roof – Part 2 Pattern Rafters

M. MartinOriginal 2005

Reviewed 2006

Lets first look at the pattern we know, then add to it.

For the hip lets look at it in solid form, for there is marks we need

to place on the edge as well

Cut for eaves overhang

Cut for top end of rafter Centre line

Birdsmouth

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With a hipped roof, we need to add creeper cuts to this pattern

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We can do this with your square or by measurement

The two distances you need are either (1) rafter spacings at base of square, or (2) true length at the top.

Now this becomes the centre line of first creeper

Measurements and calculations• Before we go any further, lets note down some more

figures.• (1) Rafter spacings, for our exercise, lets say they are

at 450mm centres. This means your centre to centre measurement on base of square would be 450mm.

• (2) Now for the true measurement at top, if you choose to do it this way, we need to do a simple calculation. Remember our ‘True length per / m’?

• True length per / m x rafter centres gives you measurement (2) above.

• 1.133 x .450 = .509mm• Lets look at the rafter again

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Steel Square centre to centre measurement

450mm measured at base of square

True length centre to centre measurement

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True length of 509mm is measured at top of rafter.

1st Creeper adjustment

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Centre line of first creeper

From this centre line point we need to mark the ‘long point for the first creeper' and we can do this with two simple measurements.

1) half mitre thickness of the hip

2) Half the thickness of a rafter. First lets look at what this means

Adjustment measurements

Half the mitre thickness of a hip

Half the thickness of a rafter

Adjustments on the rafter

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Centre line of first creeper

Gives you long point of first creeper

Back half mitre thickness of hip

Forward half thickness of rafter

The Geometry as to Why

Now lets look at the rafter again

Pattern Rafter with first Creeper

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Centre line of first creeper

Long point of first creeper

The last step is to mark remaining creepers, which you do with centre to centre measurement, either by square or by measurement of true length.

Marking remaining creepersNote: this will be there long point

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Start from long point of first creeper

Simply mark remaining long points from here, the simplest way is with a steel square

Long point of next creeper, and continue down the length of the rafter for longer lengths

One more item – the Crown end cut

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Simply measure ½ the thickness of a rafter from original centre mark, this is your crown end cut.

Crown end cut

Your finished Pattern for a hipped roof

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Crown end cut

Common Rafter cut

Centre line of ridge

First creeper long point

Second creeper long point

Birdsmouth

Plumb cut for eave overhang

Remember: longer rafter, more creepers marked

Have another look at the Hipped Roof