Surveyors’ span tables for designing roof rafters

for pitched roofs,  flat roofs  and  ceiling joists

 

Surveyors and structural engineers utilise data from tables below to help calculate the correct size, strength and centres of roof timbers for the required spans and loadings.

 

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PITCHED ROOF RAFTERS

 

 

Rafter spans  C24 strength class timber

Table1

 

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Purlins – span tables

Table2

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Ceiling joists – span tables

Table3

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Ceiling binders – span tables

Table4

 

 

FLAT ROOF JOISTS

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Flat roof joists – Strength Grade C24 timber

Table5

 

Flat roof joists for walking on  – Strength Grade C24 timber

Table6

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