#Lean to rafter spacing for metal roof install
#Lean to rafter spacing for metal roof crack

This way your rafter span will be about 6' at the most. In general, the rafter for metal roofs is either spaced at 16 or 24 on-center. I also like to set the posts so that there would be approx a 2' cantilever (overhang) and also bring the end posts in about 1' from the perimeter as well. The rafter spacing used for metal roofs is commonly set by the metal panel manufacturer to ensure it’s suitable for the dimensions of the roof structure.

#Lean to rafter spacing for metal roof crack

Note that these are normally only required to trussed rafter roofs and not for traditional purlin and rafter roof construction. I would suggest using 3 - 6 x 6 posts as they won't crack and twist as easily as a 4 x 4. The rafter spacing for metal roofing often needs to be set to support the metal panels directly fastened to the rafters. This is the right way to fix truss clips connecting the rafter and wall plate. Vertical strapping at eaves pitched roofsĪt eaves level, vertical straps 1m long should be fixed as shown in the diagram opposite at a maximum of 2m centres. Effective strapping at gable wallĮach strap should be fixed as shown in the diagram opposite with noggins between the rafters to support the metal strap along its whole length. Gable walls need to be strapped to the roof at the maximum 2m centres using 30 x 5m galvanised mild steel straps. This diagram illustrates the typical arrangement of a rafter and purlin roof and shows the dimensions referred to in the tables above. Other metals and materials may be incompatible also so keep this in mind when choosing your battens.Īnd you can always call on the helpful experts at No.1 Roofing and Building Supplies when you need some reliable advice.Roof pitch between 30 and 45 degrees strength class C24 Size of purlins in mm It’s important that you avoid contact between metal roof battens and copper.Ĭopper may be present in hot water overflow piping or downpipes and even the water flowing from this copper could cause serious corrosion issues for your metal roof battens or roof cladding. Most steel battens have a convenient groove on the bottom flange to make inserting screws a simple non-slip process. The following are the recommended screw spacing patterns for standard metal roofing projects to help you determine how many screws you need. Porch Roof Rafter Spacing: The ideal rafter spacing for a porch roof is 16 or 24 inches on-center. When attaching metal roof battens to the supports pairs of screws should be in line with each other and the supporting rafter. For instance, you need 0.8 x 10 8 screws for 10 square feet of metal roofing and 0.8 x 300 240 screws for a 300 square-foot metal roof. Additional Spacing Tips for Roof Rafters Lean-To Rafter Spacing for Metal Roof: We recommend 16 or 24 inches on-center roof rafter spacing for lean-to-object.

M5.5 x 40mm batten zips are usually the minimum fixing size for attaching steel roofing battens to steel beams and supports.

This is extremely important because using the wrong fasteners may lead to roof failure.įor example it might appear that using 75mm nails to attach a 35mm batten to a rafter would be sufficient.īut according to the table in AS 1684.2-2010 this is insufficient for battens at 900mm centres in a N1 wind speed area.Īvoid any contact between CCA treated timber and steel roofing as this can lead to discolouration and may void the warranty.Ī 12 x 40mm timber fixing screw through each flange is the minimum fixing size for fixing steel battens to timber. It represents the rise in inches for every 12 inches of horizontal run. The run for a lean to shed rafter ending into a wall should account for the ridge board nailed into the wall where the tops of the rafters rest into. How do you calculate lean-to roof pitch: Lean-to roof pitch is typically expressed as a ratio (e.g., 1:4). Plan your batten layout so that joined battens are staggered across the roof. Rafters in a lean-to roof are typically spaced at 16 to 24 inches (40.64 to 60.96 cm) on center, depending on the design and local building codes. When joins are necessary in timber battens ensure that the join meets over a rafter or truss. Specific tie-downs may be required for attaching battens to support structures in high wind areas.įixing timber battens to timber supports: Both 16 inches and 24 inches are common measurements for rafter spacing.

#Lean to rafter spacing for metal roof install

Your choice here will depend on your roof design and choice of roofing materials as well as what you’re trying to achieve.įor example if you have a roof cavity where you can install thermal insulation then your main focus for using foil backed blanket type products will be to reduce condensation and create a vapour barrier under the roof. There is a wide range of insulation blankets and reflective type sarking available for metal roofing. If you’re laying tiles you’ll probably need to lay sarking or underlay on the roof with the reflective side facing down before you attach your battens.