The length of each nail must be a minimum of 1 inches long and for roof overs atlas recommends a nail length of at least 2 inches.
Roofing nail length code.
We have to use 30 mm long nails if we are installing thicker shingles like the laminated shingles cambridge xpress or cambridge xtreme 9 5.
Your contractor is correct in his interpretation of the national roofing contractors association standards as well as the ohio building code which state that nails must be long enough to penetrate through all roofing materials and extend through the underside of the deck or penetrate a wood plank by of an inch even if that surface is less than inch thick.
Check the local building codes and regulations.
Roofing nails minimum 12 gage 0 105 inch 3 mm shank with a minimum 3 8 inch diameter 9 5 mm head complying with astm f1667 of a length to penetrate through the roofing materials and not less than 3 4 inch 19 1 mm into the roof sheathing.
These 2 pictures show inadequate penetration of the wooden deck.
Wood shakes nail type minimum length 18 straight split 5d box 1 3 4.
Fasteners for asphalt shingles shall be galvanized stainless steel aluminum or copper roofing nails minimum 12 gage 0 105 inch 2 67 mm shank with a minimum 0 375 inch diameter 9 5 mm head of a length to penetrate through the roofing materials and a minimum of 0 75 inch 19 1 mm thick the nails shall penetrate through the sheathing.
When nailing shingles proper penetration into the roof deck is essential to ensure the nail and shingle remain secure.
So if i assume 1 2 osb sheathing i should be able to cut the nails off with 1 4 still sticking through the sheathing into the attic.
The correct penetration of the wooden roof deck looks like this.
The cap nail shank shall be not less than 0 083 inch for ring shank cap nails and 0 091 inch for smooth shank cap nails.
Looking at a 2005 tile roof installation manual it looks like the minimum penetration of a roofing nail into roof sheathing was 3 4.
Roof pitch visual examples.
For all owens corning shingles roofing nails should penetrate into the wood deck by a minimum of inch or completely through the roof deck by a minimum of 1 8 inch.
However where the roof deck is less than three fourths of an inch thick the nail should be long enough to penetrate fully and extend at least one eighth of an inch through the roof deck.
Using the correct size of roofing nail will ensure that your roof stays intact for many years to come and can help you avoid the common problem of roofing nails that extract themselves over time and cause you to lose shingles.
Where the roof sheathing is less than 3 4 inch 19 1 mm thick the fasteners shall.
Cap nail shank shall have a length sufficient to penetrate through the roof sheathing or not less than 3 4 inch into the roof sheathing.
Planning and executing a good roofing job requires knowledge of every aspect of the job.
