Multiply the load per square foot by the total area of the roof.
Roof load width verandah.
The maximum overhang of house rafters or trusses shall not exceed 750 mm from outside of top plate to end of rafter truss.
When you refer to a beam s allowable span what you re really describing is the allowable spacing between posts.
For the pergola beams shown in illustration the roof load width is the dimension representing half the rafter span plus any rafter overhang.
The roof load width is half of the rafter span.
Multiplied by 40 pounds per square foot equals 8 000 pounds.
The size of the roofing material is needed to calculate how much load the roof members and substructure need to support and therefore what size the underlying timber parts need to be.
Size grade continuous span verandah beams span values in mm roof load width mm 900 1200 1500 2400 3000 4000 5000 6000 140x35 f7 3600 3400 3100 2400 2200 1900 1700 1600 190x35 f7 4800 4500 4000 3200 2900 2500 2300 2100 140x45 f7 3900 3500 2800 2500 2200 2000 1800 5300190x45 f7 4800 3800 3400 3000 2700 2500.
You would require three post to cover the 6 5 mtrs of beam length.
This number represents the total load that your roof must carry.
If you have single span rafters of 4 8 mtrs the roof load width is 2 4 mtrs.
If an example roof is 10 feet by 20 feet the total area is 200 square feet.
25 degree maximum pitch n3 single span no ceiling and roof load 25kg m2.
Roof beams 20 verandah beams 22 garage roof.
For any species the allowable span generally increases as the joist or beam increases in size.
Refer to as1684 2 and 3 clause 2 6 4 for other configurations.
Roof load width rlw and floor load width flw can be determined from as1684 or from the images below.
If you can source a beam of 6 5 mtrs long in one piece the size required would be 240 by 45 in f5 or f7 or mgp 10.
Verandah beams gl8 sheet roof 21 verandah beams gl8 tile roof 24 ridge beams f7 42mm sheet roof 25 ridge beams f7 42mm tile roof 28.
Rafters and verandah beams rafters f7 span guidesheet roof maximum allowable spans mm note.
Ns not suitable.
Sheet roof spacing mm rafter size 600 760 900 1000 1200 66 x 30 1250 1150 1050 1000 950 90 x 30 1650 1550 1550 1400 1300 138 x 30 2600 2300 2150 2000 1800 185 x 30 3000 2650 2450 2350.
For any particular load the allowable span of patio cover joists and beams depends on wood species and board size.
Use the drawing above to identify the relevant measurements for calculating rafter and verandah beam sizes.
