Why Is Metal Roofing Nail In Flats Instead Of Ribs

Screw the flats not the humps.

Why is metal roofing nail in flats instead of ribs.

Wood screws with combination metal and neoprene washers should be installed in the flat area of the panel adjacent to the ribs and tightened such that the washer is compressed as illustrated above. As the metal roof expands and contracts it is likely that over time the screw will snap off. Not on the hump. Nail can split the washer and dimple the metal causing leaks.

Work up from the initial row starting at. Not any of the humps. Place the first screw about 7 inches from the bottom and each subsequent screw about 18 to 24 inches apart along the vertical run. After doing it that way all that time it hasn t changed.

This is because a nail doesn t seal as well so should be kept out of the flat. Lay the starter row of metal shingles at the drip edge and affix to the roof with metal roofing nails. Narrowing things down a lively discussion occurred including some of his grad students on whether steel roofing and siding for post frame buildings should be attached with screws through the flats or on the tops of the high ribs. As a nail was driven and its head came in contact with the roofing the soft lead was supposed to conform to the surface of the roof to provide a seal.

Old time roofers still continued to pre drill on the ribs while the sheets were stacked flat on the ground but then used the new gasketed screws anyway. Which one is correct. Wood screws with combination metal and neoprene washers should be installed in the flat area of the panel adjacent to the ribs and tightened such that the washer is compressed as illustrated above. And never put a metal roof on treated lumber.

Do not put strips under the metal when going over an existing roof. The instructions for nails still say on the ribs and not in the flats on most mfg. Nail can split the washer and dimple the metal causing leaks. If for some reason you should decide to use nails put them through the top of the main ribs.

But these fasteners were notorious for leaking which is why they were always driven through the high points of the roofing profile.