to pre-drill or not pre-drill -- that is the question...

jt kirkpatrick
5/1/2012
On through-fastened metal panels for roof installation, should you pre-drill holes for fasteners or not? std. fasteners with vulcanized EPDM to seal. opponents of pre-drilling say 1) is easier to not pre-drill; 2) screw is designed to pierce the metal; 3) when the screw pulls tight, it pulls the metal around the threads up slightly into the epdm gasket, ensuring not only a good seal but also a barrier should water seep through the outside edge of the gasket. proponents of predrilling say 1) is easier to pre-drill; 2) eliminates the "shards" of metal that can be produced by the screw piercing the metal (which cuts / damages the EPDM seal; 3) if hole size drilled is slightly larger than the screw (but of course less diameter than the gasket) then the metal is allowed to expand/contract slightly with temperature -- not pre-drilling will eventually break the screws as the metal *will* expand and contract whether the screws want to allow it or not. what say you?? thanks. jt
Todd Miller
Isaiah Industries, Inc.
5/1/2012
Opening up for comments
Guest User
5/2/2012
i like to pre drill all my metal with a bit half the size of a #10 screw that way you well get a nice looking screw pattern all the way up your roof if you dont your screws will be all over the place and out of line not very nice looking
Eric Novotny
An informed customer is the Best Customer!
5/2/2012
Despite the fact that the screw will potentially have a tighter fit around the panel with not-predrilled, I think that most over torque on gaskets are a result of trying to drive the screw through the metal at the same time. I prefer that the panel be pre-drilled or even better, go to a hidden fastener system if possible.
Guest User
8/11/2017
Can I put metal siding up flush with the metal roofing? This is just a protector building and won't be heated and we don't want to put in soffits or insulation...my question is do I need a certain gap for winter loads....thank you for your time in this matter...and hopefully for an answer
Todd Miller
Isaiah Industries, Inc.
8/11/2017
Kathy, if I am understanding things correctly, there will be some sort of trim at this joint and, depending upon exactly what types of metal panels are being installed, that trim may need to allow for expansion and contraction of the metal. Do you have any photos or drawings of this situation?
Guest User
10/31/2017
Can I screw into freshly cut pine batter boards without the batter board cracking this causing the screw to become lose. My project is a shed roof
Todd Miller
Isaiah Industries, Inc.
11/1/2017
You can try some test fasteners before installing the panels to verify the battens are not splitting.

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