Hip Roof: How Many Tiles, Battens, Membrane Rolls and Gutters
Short answer: a hip roof on a 12 × 9 m house with a 30° pitch and a 0.5 m overhang has 150.1 m² of roof surface (the footprint with overhangs is 130 m²). With a tile needing 13.2 pieces per m² that is 1981 tiles, or 2081 with a 5 % allowance. You also need 89 ridge tiles for the 3 m ridge and four hips of 7.64 m each, 183 battens of 4 m, 3 rolls of membrane and 17 gutter lengths of 3 m for 46 m of eaves. The roof calculator works all this out from the wall dimensions, pitch and overhang.
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How a hip roof differs from a gable roof
A hip roof has no gables: all four sides end in eaves, so the gutters run around the whole roof. Instead of two gable edges it has four hips running from the corners to the ridge, and the ridge is shorter than the house. Tiles along the hips are cut at an angle, so there is more waste than on a gable roof of the same area.
That is why the quantities cannot be taken from the footprint alone: you need the true area of the sloping planes, the length of the ridge and hips for ridge tiles, and the eaves perimeter for gutters.
What data to prepare
- External wall dimensions (length and width) and the roof pitch in degrees.
- Eaves overhang – on a hip roof it is the same on all four sides.
- Tiles per m² and batten gauge from the technical sheet of the chosen tile.
- Rafter spacing and section, and the timber lengths you can buy.
- Membrane roll width and length and the laps the manufacturer specifies.
How to use the roof calculator – step by step
- 1. Choose the “hip” shape and enter the wall length and width (12 and 9 m).
- 2. Enter the pitch (30°) and the eaves overhang (0.5 m).
- 3. Choose “tiles” as the covering and enter the tiles per m² (13.2) and batten gauge (0.35 m).
- 4. Check the rafter spacing (0.8 m by default), sections and available timber lengths.
- 5. Switch on membrane and gutters and check the allowances: tiles 5 %, membrane and timber 10 %.
- 6. Review the plan and section, save the calculation and export a PDF material list.
Example: a 12 × 9 m house, 30° pitch
With a 0.5 m overhang the roof footprint is 13 × 10 m = 130 m². The true area is 130 ÷ cos 30° = 150.1 m². The ridge is 13 − 10 = 3 m and each of the four hips is 7.64 m (30.6 m in total). The eaves perimeter is 46 m.
| Item | Quantity | How it is obtained |
|---|---|---|
| Roof tiles | 2081 pcs | 150.1 m² × 13.2 = 1981, plus 5 % allowance |
| Ridge tiles | 89 pcs | (3 + 30.6) m × 2.5 pcs/m, plus 5 % |
| Battens and counter-battens | 183 pcs of 4 m | battens at 0.35 m and counter-battens on the rafters, plus 10 % |
| Breathable membrane | 3 rolls 1.5 × 50 m | 69.8 m² usable per roll after laps, plus 10 % |
| Gutter | 17 pcs of 3 m | 46 m of eaves, plus 5 % |
| Downpipes | 5 | one per 10 m of gutter at most |
| Rafters | 63 | 0.8 m spacing, each on the shortest available length |
Why the allowance is not the same for everything
Tiles are bought by the piece, but they are cut along the hips and some break in transport and laying. Membrane has laps at side joints and roll ends, so a 75 m² roll covers only 69.8 m². Timber is lost in cuts and joints. That is why the calculator has a separate allowance for each group that you can change.
Most common mistakes
- Roof area taken from the house footprint, without the pitch and without overhangs.
- Ridge tiles counted only for the ridge, without the four hips.
- Tiles per m² and batten gauge guessed instead of taken from the tile's technical sheet.
- A pitch below the minimum allowed for the chosen tile (about 22° for the tile in the example, or 17° with an extra underlay).
- Gutters counted only for the two long sides – a hip roof has eaves on all four.
Sources and assumptions
13.2 pieces per m², a batten gauge of about 350 mm and the minimum pitch are taken from the technical sheet of the tile in the example; for another tile enter its own values. The 1.5 × 50 m membrane roll matches the membrane's technical sheet, while laps of 10 and 15 cm, 2.5 ridge tiles per metre, 3 m gutter lengths and one downpipe per 10 m are default assumptions of the calculator. The calculator does not check the structural design of the roof. These are typical values – the data on the pack or technical data sheet of the product you buy applies.
Frequently asked questions
How many tiles does a 12 × 9 m hip roof need?
With a 30° pitch and 0.5 m overhang the roof has 150.1 m²; at 13.2 pieces per m² that is 1981 tiles, or 2081 with a 5 % allowance.
How long is the hip of a hip roof?
For a footprint with overhangs of 13 × 10 m and a 30° pitch each hip is 7.64 m, 30.6 m in total, and the ridge is 3 m.
How many rolls of membrane for a 150 m² roof?
With a 1.5 × 50 m roll and laps of 10 and 15 cm one roll covers 69.8 m²; with a 10 % allowance you need 3 rolls.
How many gutters does a hip roof need?
The gutter runs along the whole eaves perimeter: for 46 m that is 17 lengths of 3 m with a 5 % allowance and 5 downpipes.
Calculate yours: Roof calculator