Rooftop nail pops


  #1  
Old 01-16-19, 02:36 PM
M
Forum Topic Moderator
Thread Starter
Join Date: Mar 2005
Location: USA - N.E.Tn
Posts: 45,765
Received 868 Upvotes on 759 Posts
Rooftop nail pops

For the last year of so my son's house has been having re occurring leaks. What is happening is the nails under certain shingles are popping up and pushing the shingle up with it. Then when a blowing rain comes it leaks. I've been lifting up the shingle, pounding the nail tight and caulking the head with silicone or tar. Except for the shingles that pop up the roof looks decent, it's probably a dozen yrs old, installed by the previous owner shortly before my son bought the place.

Any thoughts on why the nails pop? or on how I'm fixing them.
 
  #2  
Old 01-16-19, 02:42 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 65,638
Received 4,089 Upvotes on 3,672 Posts
Wow..... I thought it was just me. I got a roof leak. I go out to the roof and there is a roofing nail sticking up thru the shingle smack in the center of the roof. I hammered it back in and tarred over it. Several weeks later I had another one in a different place. The roofing nail pushed up and thru the shingle over it. I've had 5-6 of these nails coming up.

I was told the magnetic field from the sun draws the steel nails out. I could only assume that nails that didn't hit something solid were getting pulled out.
 
  #3  
Old 01-16-19, 03:04 PM
M
Forum Topic Moderator
Thread Starter
Join Date: Mar 2005
Location: USA - N.E.Tn
Posts: 45,765
Received 868 Upvotes on 759 Posts
So are you telling me misery loves company
When I knock the nails back down they feel like they are going into solid plywood but I never did order those Xray glasses offered in comic books back in the early 60s.
 
  #4  
Old 01-16-19, 03:34 PM
P
Group Moderator
Join Date: Mar 2003
Location: NC, USA
Posts: 28,131
Received 2,261 Upvotes on 2,014 Posts
If a nail has popped I remove them and put another in a different location. I figure if it's risen once it's a zombie and will rise again.
 
  #5  
Old 01-16-19, 04:17 PM
XSleeper's Avatar
Group Moderator
Join Date: Dec 2004
Posts: 27,237
Received 1,958 Upvotes on 1,755 Posts
A lot of it depends on the kind of nail used and the condition of the decking. Hot dipped galvanized nails aren't as likely to pop up. The thicker the sheathing the less likely they are to pop up. Some roof nails (I'm talking about hand nails, not coil [gun] nails) sold are supposedly electro galvanized but they are bright shiny and smooth... so they are much more likely to pop up. And moisture in the attic and length of nail can have something to do with it. Then you get those guys who have cans of old nails and use rusty nails to begin with...

Crummy roof sheathing often is the culprit however... the sheathing won't hold a nail for long if the sheathing is not rigid. Same goes for old plywood roofs with high moisture. The plys expand (and eventually separate) with freeze-thaw cycles and that works the nails upward.
 
  #6  
Old 01-16-19, 04:34 PM
A
Member
Join Date: Jan 2013
Location: U.S.A.
Posts: 1,902
Received 73 Upvotes on 66 Posts
I would go into the attic and look at two things. First off, is in the sheathing in good shape? If you see suspect sheathing in the affected area poke it with your pocket knife and see what kind of shape it's in. Can you see the ends of the nails? I don't like the thought of nails poking me in a shallow attic either, but the nails should penetrate the bottom of the sheathing by about 1/4" minimum.
 
  #7  
Old 01-17-19, 03:23 AM
M
Forum Topic Moderator
Thread Starter
Join Date: Mar 2005
Location: USA - N.E.Tn
Posts: 45,765
Received 868 Upvotes on 759 Posts
I haven't been in his attic in a long time and don't remember how far the roofing nails protrude thru the plywood. I also don't know how thick the plywood is but would assume it's 1/2" I believe the sheathing was replaced when the roof was. I suppose moisture could play a part. Most of the nail pops are on the backside of the house which never sees the sun. Because he's in a holler the sun doesn't shine directly on the house until late morning.

So far what I've been doing is working as I've not had to hammer any nails down a second time. Each time it's a new location. I've done over a dozen on the backside of the house and only one on the front [which wasn't leaking]
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: