Strapping or No Strapping | Todd Miller

Strapping or No Strapping

June 12, 2009 | Filed under: Battens or No Battens, Misc, Roofing Answers, Roofing Installation

Question from June in New Hampshire:
Q: Greetings: – We are in the process of contacting contractors regarding the installation of a metal roof on our home and with each contractor that comes to the house we are getting more and more confused:

1. Should it be installed over the existing asphalt or strapping
2. Standing double locking seam- Does this tend to sweat on top of asphalt shingles?- one contractor states yes – the other recommends using it?

My response:
A: Thanks for investigating metal.

1) Some products CAN be installed on strapping. Very few MUST be installed on strapping. Most products CAN or MUST be installed on solid deck. If you currently lack attic ventilation and have difficulty achieving it then there is good reason to consider strapping but you must choose an appropriate product and you may wish to install vertical strapping followed by horizontal and then actively venting the resulting chamber.

2) A double lock panel should not pose any special issues in comparison to other styles.

I hope this helps some. If you have special circumstances that need to be considered please let me know.

todd Miller

has spent his entire career in the metal building products manufacturing industry. He is president of Isaiah Industries, an organization recognized as one of the world’s leading metal roofing manufacturers. Todd is currently Vice President of the MRA (Metal Roofing Association) and a Past Chair of MCA (Metal Construction Association). Through his website, he strives to raise the bar on standards and practices to provide property owners with the best possible products for successful roofing projects.

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4 responses to “Strapping or No Strapping”

  1. Wilson says:

    I was told to use Foam type strapping instead of wood, what do you think
    I’m going over the shingles with the steel panels over the strapping
    Thanks in advance for your expertise

  2. J says:

    Hi..

    I’m planning on putting metal roof on top of an old roof that currently has shingles.. It’s just on a woodshed so there’s plenty of air flow.. the sheathing on top is roughcut pine under the old shingles.. Do I need to put up strapping or can I just put up metal?.. I like old rustic look so I’m not worried if it looks perfect but I was wondering if it would rot quicker without strapping.. Thanks!

    • Thanks. Good question. May I ask, is the woodshed “open air” … or is there some sort of heat or moisture source inside of it? I generally am in favor of not battens but I want to make sure we’re not creating a situation where you might end up with condensation inside the woodshed?

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