Underlayment..Ventilation..Batten System...

Guest User
12/29/2009
I actually have a few questions I would like you to answer please... 1.We own a metal roofing business and have heard about problems with screws backing out over a short period of time..due to the expansion and contraction of the metal,what is the best way to PREVENT this from happening? These metal roofs have been installed directly to the roof decking or over the old shingles(over an underlayment of course), would using a WOODEN batten system do anything to help this problem,maybe due to the extra airflow, does this help some of the expansion and contraction? or is there another type of screw that should be used? and what is the best length of a screw to use???? 2.If we use a "WOODEN" batten system, the underlayment is supposed to go under the batten system, does this underlayment (which is a good 50 year synthetic underlaymet/vapor barrier) totally prevent condensation, so that the "wooden" batten system does not get wet? Our concern is about the wood rottening over time since it cannot be treated,because treated cannot come in contact with the metal roofing, what is the best type of wood to use for this? Also what is the suggested size for the wood to be..2 x 4? 3. We were wondering if there is "METAL" batten system? if you know where we can purchase something like this instead of using wood? We also thought that would solve the problem of the screws backing out. THANK YOU! and sorry for the list of questions!
Guest User
12/29/2009
I thought before you start a metal roofing co you should know what your doing
Guest User
12/30/2009
If you don't have anything productive to say.....why waste your time & mine? I didn't say "WE" were having these problems,but we know OTHER companies that have, and we would like to know what is causing it or how to prevent it,as far as the screws ever backing out...in case the problem ever happens to us,and as far as the battening goes,Its NOT "Required",but we are considering doing it and would like to know the proper way it should be done....So...only answer if you "know" something on these issues,otherwise,your comments are not wanted.
Guest User
12/30/2009
Its actually common sense. 1) A properly installed screw is on the flat between the minor ribs closest to the factory overlap(not on the high rib) 2)A underlayment is not required however is recomended 3) When a batten system is installed it does help create a flat surface and does get the steel off the shingles. The taller the battten 1x? or 2x? the more volume of air between the steel. 4)an underlayment does not stop condensation but may help it. A better performer would be a bubble wrap with foil that would go under the purlins/battens 5)There is a hat channel you can buy. This is not typical in residential. This will also change your screw type wich will be harder to find and more costly. They do make a steel binder screw with a anti back out system. P.S. sorry for all the answers
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