Rooftop nail pops
#1
01-16-19, 02:36 PM
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.
Any thoughts on why the nails pop? or on how I'm fixing them.
#2
01-16-19, 02:42 PM
Group Moderator
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.
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
01-16-19, 03:04 PM
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.
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
01-16-19, 03:34 PM
Group Moderator
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
01-16-19, 04:17 PM
Group Moderator
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.
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
01-16-19, 04:34 PM
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
01-17-19, 03:23 AM
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]
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]
