What's the best way to prevent leaks when nailing into the roof?
April 10, 2012 3:05 PM Subscribe
I want to attach a weathervane to a rooftop. To prevent roof leaks after screwing through the shingles, what should I do? Silicone? Washers? My dry attic thanks you in advance for the advice.
At the peak of your roof this isn't going to be that big of a deal since the only water that's going to be going over the screws holding your weather vane down is that which falls down on them (everything runs off away from the peak). Squirting some roof sealer under the shingles you're drilling/screwing through in the area where the screws go would probably be more than sufficient.
The problem you may run into, depending on how your roof was done, is that there isn't anything under your ridge line for you to screw into. A cupola would solve that problem, but doing a quick search for weather vane cupolas tells me that, if I had a steady stream of customers, making weather vane cupolas in another activity that would earn me more money than trying to find the cure for cancer.
posted by Kid Charlemagne at 4:09 PM on April 10, 2012
The problem you may run into, depending on how your roof was done, is that there isn't anything under your ridge line for you to screw into. A cupola would solve that problem, but doing a quick search for weather vane cupolas tells me that, if I had a steady stream of customers, making weather vane cupolas in another activity that would earn me more money than trying to find the cure for cancer.
posted by Kid Charlemagne at 4:09 PM on April 10, 2012
Satellite dish installers use a product called Bishop Tape when installing lag screws right through the shingles.
posted by Max Camber at 4:16 PM on April 10, 2012 [1 favorite]
posted by Max Camber at 4:16 PM on April 10, 2012 [1 favorite]
Just put a circle of silicon sealant around each screw hole before screwing the base down and you'll be fine. Ideally, drill all holes, then clean any shavings away so both surfaces are clean first.
posted by dg at 4:45 PM on April 10, 2012
posted by dg at 4:45 PM on April 10, 2012
dg: "Just put a circle of silicon sealant around each screw hole before screwing the base down and you'll be fine."
Neutral cure silicone sealant, please, as the usual acetic acid curing stuff will eat the zinc (or copper, or whatever) plating on screws, mounting brackets, etc. & lead to corrosion.
As Max Camber suggests, most antenna/satellite/etc installers would use butyl rubber mat or tape. In theory, silicone sealant should weather better. In practice, although butyl rubber will eventually dry out where exposed, it'll seal better in the long run.
posted by Pinback at 8:33 PM on April 10, 2012
Neutral cure silicone sealant, please, as the usual acetic acid curing stuff will eat the zinc (or copper, or whatever) plating on screws, mounting brackets, etc. & lead to corrosion.
As Max Camber suggests, most antenna/satellite/etc installers would use butyl rubber mat or tape. In theory, silicone sealant should weather better. In practice, although butyl rubber will eventually dry out where exposed, it'll seal better in the long run.
posted by Pinback at 8:33 PM on April 10, 2012
Here's what you want -- self-sealing screws. They're made precisely for this type of application.
posted by dhartung at 9:59 PM on April 10, 2012
posted by dhartung at 9:59 PM on April 10, 2012
No, they're not, really. If you google around, you'll see that when used for mounting a bracket or plate it's recommended that a sealant be used between the faces. That's because they only stop water getting under the head of the screw, and do nothing to seal the actual hole you've made in the roof.
I was surprised to see many US websites showing those TEK roofing screws in the valley of corrugated sheets. Around here, that'd get your roofing job knocked back by the building inspectors…
posted by Pinback at 11:05 PM on April 10, 2012
I was surprised to see many US websites showing those TEK roofing screws in the valley of corrugated sheets. Around here, that'd get your roofing job knocked back by the building inspectors…
posted by Pinback at 11:05 PM on April 10, 2012
Yeah, if you are screwing a mounting plate onto a roof, you also need to seal between the plate and the roof surface. Also, if you use the screw shown in that picture to screw into wood, you'll likely be left with a hole the same diameter as the screw body - those screws are for screwing into metal surfaces, not timber. The equivalent timber screws have a pointed tip, not a drill tip.
why would anyone put screws in the valleys? That's just asking for leaks and, as you say, building certifiers would never pass it.
posted by dg at 11:48 PM on April 10, 2012
why would anyone put screws in the valleys? That's just asking for leaks and, as you say, building certifiers would never pass it.
posted by dg at 11:48 PM on April 10, 2012
Sorry. I have to stop passing on bad advice I read somewhere.
posted by dhartung at 12:19 AM on April 11, 2012
posted by dhartung at 12:19 AM on April 11, 2012
Not bad, just incomplete. The description of the screws is right, just the photo is wrong.
posted by dg at 12:20 AM on April 11, 2012
posted by dg at 12:20 AM on April 11, 2012
Friends of mine who do construction favor Through the Roof! sealant.
posted by attercoppe at 8:55 AM on April 11, 2012
posted by attercoppe at 8:55 AM on April 11, 2012
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posted by Mercaptan at 3:07 PM on April 10, 2012