Timber Roof Truss Span Tables

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.

Timber roof truss span tables.

Span tables span tables can be used to determine the size of a timber member of a particular strength class required for a given span. View joist rafter tables. Stairwells rooflights and dormers attic trusses will provide living accommodation in the roof space. Therefore care has to be.

Finally the truss calculator will compute the best dimensional method to connect the pieces of the truss with steel joints and a bridge. These steel joints are needed to support the overall truss. Support might be needed for very large spans. View allowable load tables.

Roof truss span tables alpine engineered products 15 top chord 2x4 2x6 2x6 2x4 2x6 2x6 2x4 2x6 2x6 2x4 2x6 2x6 bottom chord 2x4 2x4 2x6 2x4 2x4 2x6 2x4 2x4 2x6 2x4 2x4 2x6 2 12 24 24 33 27 27 37 31 31 43 33 33 46 2 5 12 29 29 39 33 33 45 37 38 52 39 40 55 3 12 34 34 46 37 39 53 40 44 60 43 46 64 3 5 12 39 39 53 41 44 61 44 50 65 47 52 70. Span tables for flat roof joists to bs 5268 7 2 imposed loads of 0 75 kn m for maintenance and snow load are applicable where there is no permanent access no fixed ladder or staircase and most areas where the altitude does not exceed 100 metres refer to bs 6399 3. Simplified span tables for southern pine lumber and glued laminated timber glulam headers beams and girders. Floor joist span use this table to determine the maximum lengths of floor joists based on species of lumber joist spacing and joist size.

Consequently timber sizes are larger and spacings may be reduced to 450mm centres. An added benefit are the strong lines that purlins create by running parallel to the ridge beam s. The more complex the truss framework is the greater quantity of these joints will be required. Table assumes a maximum flooring mass of 40kg m2.

Surveyors span tables for designing roof rafters. Spacing loadings to attic trusses are usually greater than normal trusses see page 4. Timber frame truss and purlins. Member tables for seasoned timber stress grade f17.

View size selection tables. Rafter or uss spacing w lintel span. Listed are 46 tables based on common loading conditions for floor joists ceiling joists and rafters. For pitched roofs flat roofs and ceiling joists.

The same thing is true for the bridge of the truss. Adding purlins between heavy timber trusses is an elegant way to reduce the cost of a timber frame roof because purlins permit an increased on center distance between trusses so you purchase fewer trusses. Joists crippled over supports shall be considered as single span joists.