This is an even bigger concern when the screws expand and contract during extreme weather. Dangers of too many screws: The main downside of too many roofing screws per square meter when roofing is the high risk of roof damage.Unfortunately, it also puts you and your family/guests in danger. Dangers of Too Few Roofing Screws: The main danger of using fewer screws than needed when roofing is that you may have a weak roof.Many DIY roofing installers often wonder whether there are significant consequences of using too few or too many screws/nails on the roof. Once you’ve settled on screws for your metal roofing project, the next question is how many screws you need. What Happens if you Don’t Use Enough Metal Roofing Screws? This makes nails the better option for DIY roofing installation projects.

Whereas screws require technical know-how and special tools to install, anyone with a hammer can nail down nails. Therefore, if you’re looking to keep costs down, consider high-quality roofing nails.Īdditionally, nails are easier to install. First off, screws are expensive to purchase. That said, though, roofing screws can be an excellent choice under certain circumstances. By withstanding contraction/expansion better, roofing screws significantly reduce the risk of roof leaks. The expansion/contraction mentioned above often results in spaces around the roofing nails, causing leaks.

Preventing roof leaks: Finally, screws resist leaking better than nails.

The threads allow screws to resist such pull-out. Such contraction/expansion often causes nails to pull out slowly over time.

Resistance to expansion and contraction: Another reason screws are a better fit for metal roof nailing is that screws withstand metal roof expansion and contraction better.

On the other hand, nails have smooth shafts that are more likely to pull out. The threads on screw shafts allow screws to hold onto wood for much longer.

Holding strength: The first main reason screws work better for metal roofing projects is that screws hold for much longer.

Though nails are more common in metal roofing projects, screws offer plenty of advantages. Generally, many roof experts prefer screws to nails. The idea is to place the screws close enough to ensure a firm roof installation and far enough not to distort or tear the roofing material. Alternatively, make sure that every third corrugation has a screw, including both sides of the panel side lap. Generally, it’s best to place roofing screws one and a half to two feet apart. Above all, an appealing screwing/nailing pattern makes your roof more and the home, in general, more beautiful. Correct spacing is also critical to ensuring a level roof. The correct nail spacing holds the roofing sheets more firmly in position. In steel building construction, secondary members such as purlins (roof) and girts (wall) are frequently cold-formed steel C, Z or U sections, (or mill rolled) C sections.One of the most important factors in a proper roof installation is screw (or nail) spacing. Section designations can be regional and even specific to a manufacturer. It is the practice in the steel industry that structural shapes are assigned representative designations for convenient short-hand description on drawings and documentation: Channel sections, with or without flange stiffeners, are usually referenced as C shapes Channel sections without flange stiffeners are also referenced as U shapes Point symmetric sections that are shaped similar to the letter Z are referenced as Z shapes.

In traditional timber truss construction purlins rest on the principal rafters of the truss.

For example, an 8 x 4 under purlin would support the center of a row of 6 x 2 rafters that in turn would support 3 x 2 roof purlins to which the roof cladding was fixed. Under purlins were typically propped off internal walls. In lightweight timber roof construction under purlins were used to support rafters over longer spans than the rafters alone could span.

Typical rafter spacing for metal roof