# Metal Roof and Bathroom Ventilation fan



## CompetitiveEdgeMetal (Nov 9, 2014)

Ok first of all I am a Metal Roofing Contractor and I have a customer who is wanting a new metal roof installed in his doublewide. I'm going to strip it down fix any problems install underlayment (Shinglelayment synthetic underlayment) and put the metal on. He wants the bathroom ventilation fans removed and just have the 1 1/2 inch pipes coming up through the metal. My question is it safe to remove the bathroom ventilation pipes coming through the roof and just cut holes in the underlayment for it to vent, I just don't want to do that and then have problems because of it later, all opinions are appreciated. If that's not the best way what is? I would think it would be ok to do it that way and it can vent through the Ridge and the ribs in it. By the way will be installing Master Rib Metal. Thanks!


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## roofermann (Jul 7, 2012)

Not OK in my area, check you local code. :thumbup:


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## CompetitiveEdgeMetal (Nov 9, 2014)

Not concerned on code is it going to cause issues?


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## CompetitiveEdgeMetal (Nov 9, 2014)

I just don't want it to cause issues later on


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## roofermann (Jul 7, 2012)

CompetitiveEdgeMetal said:


> Not concerned on code is it going to cause issues?


Great business strategy!


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## CompetitiveEdgeMetal (Nov 9, 2014)

Well it's just a doublewide and its at the customers request and another contractor is the one that recommended doing it that way, if I told him not to do it that way he would most likely go with the other guy which has promised him the world, it'll never get looked at by an inspector no permit is even required, I just want to make sure it's not going to cause problems down the road. But in the case that it is I'm definitely going to tell him that they need to come through the metal and stay. The customer isn't always right but they are in most cases lol


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## 1985gt (Dec 21, 2010)

So the sew vent pipes will still go through the roof but they don't want the bath fan vents to penetrate the roof? If that's the case you will have all kinds of condensation issues. So yes it will cause issues like rotten decking and rusting steel.


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## CompetitiveEdgeMetal (Nov 9, 2014)

Ya they want it to come through the hole in the roof and vent through the ribs in the metal not penetrate the metal though I don't see why it would cause a problem


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## CompetitiveEdgeMetal (Nov 9, 2014)

By the way it will have a synthetic underlayment under the metal and a hole will be cut in the underlayment for it to vent through the ribs


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## shazapple (Dec 3, 2010)

I agree with 1985gt, its going to ruin the decking and steel eventually. 

Why not just extend the pipe and vent it out the gable end? Don't try to reinvent the wheel...


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## Randy Bush (Oct 23, 2014)

Agree with above thoughts, don't do it that way. It is asking for nothing but trouble.


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## 1985gt (Dec 21, 2010)

CompetitiveEdgeMetal said:


> Ya they want it to come through the hole in the roof and vent through the ribs in the metal not penetrate the metal though I don't see why it would cause a problem


How is it going to vent? On ribbed panels we use the foam closures on the eve and ridge ends of the panels. How will it vent? 



CompetitiveEdgeMetal said:


> By the way it will have a synthetic underlayment under the metal and a hole will be cut in the underlayment for it to vent through the ribs


you underlayment won't matter, there will be a hole there. Do you think the air will magically know not to go between the underlayment and decking?

Even if you extend the pipe up and seal it to the underlayment the bottom of the panels will still be getting that warm moist air from the bathroom. 

Think of it this way, what happens to the decking of a normal shingle house when the bath vent is to run to the outside or becomes disconnected? it rots out the decking damages the insulation ect. Even though the house has good soffit and a ridge vent.

It's a foolish idea, let the other guy do it and deal with the call back. Mobil homes are not known for the superior build qualities.


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## CompetitiveEdgeMetal (Nov 9, 2014)

I didn't want to do it that way, I finally talked him into leaving them in after he signed the contract, he originally got the idea from another contractor which he "trusted" the opinion of I told him in the beginning it would most likely cause problems but figured I'd check into it anyways, he actually wanted to remove them because he thought it would be less chance of any leaks, I finally explained to him that there would be no more chance of them leaking that it would be for the 1 1/2 pipes if anything it'd be less of a chance considering they have the mushroom cap on top and I've NEVER had any pipe leak, doesn't really require a rocket scientist to put on a rubber boot screw it down and caulk it. Thanks for all the input guys


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## JBL (Dec 14, 2014)

CompetitiveEdgeMetal said:


> Ok first of all I am a Metal Roofing Contractor and I have a customer who is wanting a new metal roof installed in his doublewide. I'm going to strip it down fix any problems install underlayment (Shinglelayment synthetic underlayment) and put the metal on. He wants the bathroom ventilation fans removed and just have the 1 1/2 inch pipes coming up through the metal. My question is it safe to remove the bathroom ventilation pipes coming through the roof and just cut holes in the underlayment for it to vent, I just don't want to do that and then have problems because of it later, all opinions are appreciated. If that's not the best way what is? I would think it would be ok to do it that way and it can vent through the Ridge and the ribs in it. By the way will be installing Master Rib Metal. Thanks!


In california you can moved the fans ventilation any where you want it. They are just flexible pipes , can you cancel them.No!.


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