Rafter Calculator to BS 5268-2:2002 and BS 5268-7.5:1990

1 Enter Rafter Details

Is there a purlin supporting the rafters?

Yes

This demo version is fixed at 1m clear span. The full version allows any size

Rafter slope (min 15, max 45)

degrees

Rafter spacing

This is the distance between rafter centres. Usually 400, 450 or 600mm, but any value can be used up to 610mm max

Are there any brittle finishes (e.g. plasterboard) on the underside of the rafter?

Yes

2 Loadings

Dead load on the slope

Typical tiled roof with plasterboard on underside of rafters: 1 kN/m²

Typical tiled roof: 0.75 kN/m²

Typical slate roof: 0.5 kN/m²

Other

Imposed loads (roof snow load and short-term point load)

Altitude not exceeding 100m: 0.75 kN/m² snow load & 0.9 kN point load

Most areas exceeding 100m but not exceeding 200m (refer to BS 6399-3): 1 kN/m² snow load & 0.9 kN point load

Other (e.g. parts of Scotland, Pennines, North East England and heights over 200m, refer to BS 6399-3)

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Rafter Calculator