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Roofing code questions (before I get embarrassed asking the building inspector)

strobit

Registered User
Joined
Aug 27, 2021
Messages
13
Location
MN
1. Is the 3/8" minimum nail head size for asphalt shingles just a suggestion? I ask because all of the roofs around here seem to be being nailed with heads that measure a bit small. I have a box of coil roofing nails from a few years back with actual .375" heads and boxes for hand nailing are .375", but the coils I've seen lately have roughly .325" heads.

2. What is a solidly sheathed deck? If I step on a previously rotted area and it squishes down a 1/2", is that solid? 3/4"? 1"?

3. Does code specify a minimum width for the last shingle of a course used at the rake?

4. Is there a min or max specification for the overhang of starters and shingles over the rake's drip edge? Should the shingles completely cover the rake edge starters?

5. Besides cosmetics, is it a problem to have inaccurate exposures, crooked shingles, and overlapping edges?

6. How much of a stagger from one course to another is required?

7. Will a significant number of crooked or overdriven nails pass inspection?

If it matters, location is Minneapolis, MN
 
This has a couple of answers.

Do you know how many times it has been re shingled?

# 2 sounds like some decking needs to be replaced.

Might read thru this

 
All your questions

First start with the manufactures requirements/// guidelines !!!!


Will code require that the installation meets or exceeds the manufacturer's guidelines?


This has a couple of answers.

Do you know how many times it has been re shingled?

# 2 sounds like some decking needs to be replaced.

Might read thru this


Thanks, that was an interesting read, but unfortunately still seems to be a bit of a gray area and may just depend on the inspector.

This re-roof is at least the 3rd shingling that the deck has seen. Judging from the empty nail holes, I don't think that it's been much more than that, maybe 4.
 
Sometimes yes code requires follow manufacture

Plus if you don’t and try to file a warranty claim,,, May not work

Sounds like you need new decking,,, mine is on 2nd maybe more,,, so next will bite the bullet and redeck
 
1. Is the 3/8" minimum nail head size for asphalt shingles just a suggestion? I ask because all of the roofs around here seem to be being nailed with heads that measure a bit small. I have a box of coil roofing nails from a few years back with actual .375" heads and boxes for hand nailing are .375", but the coils I've seen lately have roughly .325" heads.

Having done a few roofs and being a cod geek, I don't know on this except follow mfg instructions.
2. What is a solidly sheathed deck? If I step on a previously rotted area and it squishes down a 1/2", is that solid? 3/4"? 1"?
I believe solid sheathed means continous, edge to edge. With wood shingles, perhaps other materials before asphalt shingles, it was not uncommon to have spaced sheathing - like 1 x 5 every 7 inches so there are 2" gaps. That was my 1904 house and when I did a tear off I had to put ply over it. On the other hand, the original wood shingles where never exposed looked and smelled like new - 90 years after they were installed.
3. Does code specify a minimum width for the last shingle of a course used at the rake?
mfg instructions, but I like at least 1full tab
4. Is there a min or max specification for the overhang of starters and shingles over the rake's drip edge? Should the shingles completely cover the rake edge starters?
I don't think so
5. Besides cosmetics, is it a problem to have inaccurate exposures, crooked shingles, and overlapping edges
I'd say it was a problem but don't know if it's a code issue.
6. How much of a stagger from one course to another is required?
most would say a tab but I think it says on shingle wrapper
7. Will a significant number of crooked or overdriven nails pass inspection?
probably because unseen. get a nail gun and spare your arm.
If it matters, location is Minneapolis, MN
hope that helps. do see if you're building dept has handouts for diy roofing. and I really was only answering the solid sheathing question. lots of stuff goes into codes but hard to take out old stuff.
 
2018 IRC R905.2.5 Fasteners
Fasteners for asphalt shingles shall be galvanized steel, stainless steel, aluminum or copper roofing nails, minimum 12-gage [0.105 inch] shank with a minimum 3/8-inch-diameter head, complying with ASTM F1667, of a length to penetrate through the roofing materials and not less than 3/4 inch into the roof sheathing. Where the roof sheathing is less than 3/4 inch thick, the fasteners shall penetrate through the sheathing.
 
Thanks Bill1952. It seems as though a lot of it hinges on the manufacturer instructions.

Mark, the code says 3/8" minimum head size, but the coil roofing nail heads I've seen being used around here (hail storm, a lot of new roofs going on) are smaller. Do these smaller heads pass for 3/8" - sort of like how 1/2" plywood isn't quite 1/2" anymore?

nail.head_-700x542.jpg
 
I have to ask if you measured that .325 or read it on package or data sheet? I went looking on line and could not find any except in copper, which I'd guess is for copper flashing and/or slating. I wondered if it could be a misprint or were they for other than asphalt roofing.
 
The residential code is pretty clear on it's requirement. I've never pulled out my tape to measure nail-head size, certainly not a pair of calipers. I know what a roofing nail meant for asphalt shingles looks like. Are you asking as an inspector, contractor, DIY, or what?
 
I'm a home owner and that's a nail from the asphalt shingle roofing job just "professionally" done on my house.

Sorry PCinspector, I haven't seen the box, just what's been left on site.

Bill, that's the actual measurement with my calipers, not sure what the boxes said. They range from .315 to .350 (because the heads are often a bit oval) but most seem to be in the .320 to .330 range.

Joe, yeah, when I was cleaning up after they left I saw some of the good old original nails along with some new ones that must have been misshoots and immediately noticed the difference. That's why I looked up the code and pulled out the calipers. The old original nail is a full .375" and all the new ones are noticeably smaller. I initially thought the small nails must've only been used on the metals, but nope, they're in the shingles too. I suppose that's one reason why there are so many that are overdriven.

My roof likely needs to be redone for a myriad of other reasons (some hinted at above), but if these nails are not acceptable per code that means that several of my neighbors' roofs may also have problems. One neighbor gave me the remnants of a coil left in his yard that measure about .340" to .350" across the heads.

Pic below shows an original .375" head nail on the left and a new nail on the right:
wHLIL7H.jpeg
 

strobit,​

Thanks for posting your question! In my jurisdiction, we do not look at residential roof nails. But because of your post, I went out and looked at the new nails left on the ground by the roofers. And I also looked at the coil nails used in the nail guns. They are all only 5/16" diameter. It looks like they have 0.105 inch (12 gauge) shanks.​

 

strobit,​

Thanks for posting your question! In my jurisdiction, we do not look at residential roof nails. But because of your post, I went out and looked at the new nails left on the ground by the roofers. And I also looked at the coil nails used in the nail guns. They are all only 5/16" diameter. It looks like they have 0.105 inch (12 gauge) shanks.​


From a literal sense ("minimum 3/8-inch-diameter head") these nail heads are clearly too small. But is code supposed to be taken literally or is there some gray area in interpretation for things like this? A roofer I showed the smaller head nail to said that's what their supplier sells and they "all" use those nails in their guns, but the nails he uses for hand nailing are the larger .375" heads.

So I guess I'm wondering if they need to do my roof over since the nails they used don't meet code or is using undersized nail heads just accepted standard practice?
 
From a literal sense ("minimum 3/8-inch-diameter head") these nail heads are clearly too small. But is code supposed to be taken literally or is there some gray area in interpretation for things like this? A roofer I showed the smaller head nail to said that's what their supplier sells and they "all" use those nails in their guns, but the nails he uses for hand nailing are the larger .375" heads.

So I guess I'm wondering if they need to do my roof over since the nails they used don't meet code or is using undersized nail heads just accepted standard practice?

What size does the shingle manufacture say to use???
 
There it is.
Thanks. My concern is that the contractors are going to blow it off (pun intended) by saying that these new nails are what are being sold as 3/8" head roofing nails and that the building inspector might say they are close enough. I would hate to make a big stink about it if these nails are now accepted standard practice.

BTW, I did the math. The surface area of a nail head, minus the shank, is 25% smaller on a .325" head compared to a .375" head.
 
I have been searching online for anything about roofing nails with heads less than 3/8" diameter and find nothing. Going to a big box store later and will take a tape measure.
 
Thanks. My concern is that the contractors are going to blow it off (pun intended) by saying that these new nails are what are being sold as 3/8" head roofing nails and that the building inspector might say they are close enough. I would hate to make a big stink about it if these nails are now accepted standard practice.

BTW, I did the math. The surface area of a nail head, minus the shank, is 25% smaller on a .325" head compared to a .375" head.

Next step

1. call the manufacture and ask the question

2. Also ask if it remains with the nails used,,, will you honor the warranty???????
 
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