# Advice on How to Penetrate Roof Curbs



## funkking (May 27, 2020)

I got a call to wire up an exhaust fan and a make-up air unit for a gas station. But I'm not quite sure how to properly penetrate the roof curbs. I certainly don't want to penetrate the roof if it can be avoided. I've attached a couple pics of the units themselves and the access from inside the station.

Thanks in advance for your help everyone.


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## Southeast Power (Jan 18, 2009)

I feel for the butcher that penetrated that rubber roof and just put bull around that curb.
I would have the owner call our a rubber roof contractor and install a proper pitch pan for you.
Would in no way touch that curb.
Some fans have a tube inside of them to fish power through.


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## BluejacketBob (Nov 26, 2020)

Roofer needs to install a "witches tit". I've never seen tar used on a white roof before, that's definitely not good.


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## Switched (Dec 23, 2012)

BluejacketBob said:


> Roofer needs to install a "witches tit". I've never seen tar used on a white roof before, that's definitely not good.


Second that... That looks like that PVC roof. They use those PVC welders and special sealants, not black jack.

If there is a pitch and it's asphalt I got no issue taking care of it. If it is anything else... Roofer needs to seal it and that is discussed and goes into the contract.


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## Cow (Jan 16, 2008)

I agree with the others.

They need to get a REAL roofer there to take a look at that exhaust fan, and then give you a roof penetration for your conduit at the same time.


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## wcord (Jan 23, 2011)

Assuming that the owner isn't going to spring for additional roof jacks.

You can drill thru the side of the curb for the exhaust fan. Seal the hole with a weatherproof caulk.
Here, I would drop a piece of Sealtite or Teck and jb it in the ceiling.
Without seeing the interior of the other unit, somehow I have the impression that it is a fresh air intake. Pop the top off and see if you have room to drill/fish a cable down the inside.
Take the money and go to the next job


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## splatz (May 23, 2015)

If your customer has a warranty on the roof, and that's often the case with a commercial flat roof, you usually just can't touch it. Most if not all the roofing manufacturers require that any work be done by one of their authorized installers / service companies or the roof warranty is void. Even if your customer tells you not to worry about it, don't do it, if anything happens, they'll forget all about telling you not to worry about it. You just can't do it. 

(BTW, if you ever put a commercial roof on, when you're shopping, you might want to make sure there's a few local authorized installers so you don't wind up hijacked by one that knows they have a monopoly and make their living gouging their customers on service work like this.) 

If the customer has no warranty at stake, you could give it a shot. If you correctly identify the material and if you choose and use a sealant that works properly with that material and the boot you choose, it should work. Unless you make a mistake. If it doesn't, or you do, does your insurance cover you? If the penetration is considered a routine part of the electrical work you're insured for, it should, I would think it would be covered. You could get a waiver / disclaimer signed by the customer so that if anything happens, and if you can lay your hands on it and present it to the arbitrator, and if they accept it, you'd be OK. But it's getting to be a lot of "if's" isn't it? 

So I think the best thing with commercial roofs is going to be to spell it out very clearly in writing in your contract that the customer is responsible for sealing the penetration. I will make the hole, but they have to seal it up. They can have the authorized service company, or their maintenance staff, or some wino off craigslist seal it up, or leave the hole and put a bucket under it if that's more their style, but whatever they do, it's on them.


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## wcord (Jan 23, 2011)

I never make a hole.
Many years ago, my PM, told to do so and seal it up with roof tar. A simple hole (precast concrete roof, membrane, asphalt, tar and gravel). If I remember correctly, 2 gals later, he called a roofing company to fix it properly.
I won't even fill a pitch pocket. 
If we have make a new penetration and the customer doesn't want to hire the roofer then I hire a roofing company.
Damn water leaks. I learned my lesson once already


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## oldsparky52 (Feb 25, 2020)

In the 1st picture, what is the purpose of that small tube looking stub on the left side of the unit (as we are looking at it) where we go from square to round?


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## CMP (Oct 30, 2019)

oldsparky52 said:


> In the 1st picture, what is the purpose of that small tube looking stub on the left side of the unit (as we are looking at it) where we go from square to round?


That tube is for a grease drain, the catch tray has not been installed. A complete hack job.

I wouldn't touch that job as is. Solid welded duct indicates it's over a fryer. Raw open holes in the ceiling below, without flashings is a another violation. Complete evidence of a mechanical contractor who has no clue of what their doing.

The mechanical contractor not lining up a roof contractor to properly flash the curbs and provide you some roof booties for your conduits, is a sure sign that there will be some liability later.

Likely a tenant in a leased space, going for the cheapest price he could find, landlord be dammed. But when the rain starts coming in or the fire going out, they will be looking for you.


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## 99cents (Aug 20, 2012)

It’s unanimous. It’s a roofer’s job. I have seen roofers do lousy work and had one Sawzall right through a live conduit but it doesn’t matter. It’s on him.

I have a GC who won’t hire a roofer. He’s the one who goes up there with a step bit. I refuse. Just because I have liability insurance, it doesn’t mean I like using it.


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## VELOCI3 (Aug 15, 2019)

I forget. Does the blue Sheetrock have mold inhibitors for when that fan curb leaks?


Sent from my iPad using Tapatalk


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## 99cents (Aug 20, 2012)

Make sure you leave lots of slack in your cable to allow for disassembly and service work. I got snagged on it once, not by the electrical inspector but the HVAC inspector. I had enough slack below to pull up and make him happy. Now I make a loop with a cable tie on it.


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## 99cents (Aug 20, 2012)

CMP said:


> That tube is for a grease drain, the catch tray has not been installed. A complete hack job.
> 
> I wouldn't touch that job as is. Solid welded duct indicates it's over a fryer. Raw open holes in the ceiling below, without flashings is a another violation. Complete evidence of a mechanical contractor who has no clue of what their doing.
> 
> ...


There are structural considerations as well, particularly with a heavy MUA unit. I don’t know the details but an HVAC guy I know talks about how picky engineers and inspectors can be (for good reason).


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## MechanicalDVR (Dec 29, 2007)

Holy hell, I agree with the general opinion. Get a real roofer for that mess.


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## kb1jb1 (Nov 11, 2017)

I have been on jobs where all trades did their respective roof penatrations and made them weather tight as best as we could. I like the PL polyurethane . After we were all done then the roofer came in for the permanent fix. That looks like a lap roof with the silver paint. Rubber does not have seams or laps. As mentioned by others, most fans that I wired had an internal sleeve for the electric cable and the disconnect switch was under the shroud.


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## kb1jb1 (Nov 11, 2017)

You might have to take the fan off the roof curb to see if there is a tube or chase for the cable. Leave slack in the cable because they have to clean the duct every 6 months if this is a commercial coo,ing kitchen.


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## Tonedeaf (Nov 26, 2012)

That looks like an exhaust and intake for a *commercial range hood*. I would remove the fan from the roof to look...sometimes there is a tube built into the curb for electric......alot of times the welded metal duck takes up all the space and there is no room for your wire. In this case your gonna need a roofer....to wire the exhaust fan. I would not side drill the curb any leak they are gonna blame you.

The intake fan you may be able to remove and wire through the duct .

I would use this Alumi Flash Systems | PortalsPlus
drill your hole through the roof with a hole saw big enough for your seal tight. and silicone your hole and the aluminum ring down to the roof for a temporary seal. Then tell the owner they need to get a roofer to finish. I installed 22 of these for new roof top units in a 4 story office building using this method......I did a service call 5 years later the flashing were still not roofed in.


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## funkking (May 27, 2020)

Tonedeaf said:


> That looks like an exhaust and intake for a *commercial range hood*. I would remove the fan from the roof to look...sometimes there is a tube built into the curb for electric......alot of times the welded metal duck takes up all the space and there is no room for your wire. In this case your gonna need a roofer....to wire the exhaust fan. I would not side drill the curb any leak they are gonna blame you.
> 
> The intake fan you may be able to remove and wire through the duct .
> 
> ...


Looks like a nice product. 

I did speak to a commercial roofer and he verified that the install is jacked up, as all of you mentioned. I'm a new contractor and am trying to get customers, so I decided to take this job. And as I feared, it's been a **** show. When I applied for the electrical permit, the building department said that drawings had already been submitted by an architect for the hood system, but that the contractor never paid for or picked them up. I said, "well that's funny, the owner of the business never mentioned anything to me about drawings and the hood system is already installed." They told me that they can't approve my permit until the hood contractor gets his **** together. They did give me the architect's number and I was able to get the submitted drawings from him. They also include the electrical detail (mostly), so that's nice. 

I told my customer to give me a call when they get things squared away. The hood wiring is just a portion of the overall project. I did mention to my customer that we will need to add money for proper roof penetrations. He agreed. I'm sure it'll come together in the end, but in the meantime, my anxiety during this project will be high.


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## funkking (May 27, 2020)

kb1jb1 said:


> I have been on jobs where all trades did their respective roof penatrations and made them weather tight as best as we could. I like the PL polyurethane . After we were all done then the roofer came in for the permanent fix. That looks like a lap roof with the silver paint. Rubber does not have seams or laps. As mentioned by others, most fans that I wired had an internal sleeve for the electric cable and the disconnect switch was under the shroud.


Here's a pic of the inside.


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## CMP (Oct 30, 2019)

If the contractor is unlicensed and not able to get a permit, another one may be called in to repair the mess and get it passed inspection. If that happens, do your best to try and hook up with the qualified one for future work. Same goes for the fire contractor that does the fire system. I worked with many contractors like this over the years, and had very good relations, they can sell your part of the job as they are selling theirs. It can make for a turn key installation and much happier customers. The follow on work from the happy customer, will benefit you as well, as long as you avoid teaming up with hacks.


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## funkking (May 27, 2020)

CMP said:


> If the contractor is unlicensed and not able to get a permit, another one may be called in to repair the mess and get it passed inspection. If that happens, do your best to try and hook up with the qualified one for future work. Same goes for the fire contractor that does the fire system. I worked with many contractors like this over the years, and had very good relations, they can sell your part of the job as they are selling theirs. It can make for a turn key installation and much happier customers. The follow on work from the happy customer, will benefit you as well, as long as you avoid teaming up with hacks.


Thanks for the good advice. My inexperience has gotten me in to a bit of a mess with this one, but I'm hoping it will work out in the end. The customer's family owns many businesses in the area, so if I can just get push through and get my portion done without issue, I believe there might be future work for me. Although, I'll be more investigative up front next time.


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## funkking (May 27, 2020)

They still haven't gotten their act together with this one. No progress has been made whatsoever. I refunded them the deposit they gave me and walked away. I will sleep better now actually.


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## Tonedeaf (Nov 26, 2012)

funkking said:


> They still haven't gotten their act together with this one. No progress has been made whatsoever. I refunded them the deposit they gave me and walked away. I will sleep better now actually.


They would have had to sue me to get the deposit back....your time is worth something. At minimum I would of deducted all cost to date....your time is not free.


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## funkking (May 27, 2020)

Tonedeaf said:


> They would have had to sue me to get the deposit back....your time is worth something. At minimum I would of deducted all cost to date....your time is not free.


I actually did hold back a bit. But honestly, I'm just glad to be done with this project. A big lesson learned for me on this one.


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## MikeFL (Apr 16, 2016)

Just read the first post in the thread and the most recent few posts. Sounds like the job is over or cancelled.

Anyhoo: Back in the day we used to "pitch pan" everything. Drill your hole right through the roof deck, insulation, roof covering, etc. and put a pitch pan down. Run your work and fill the pan with pitch, mammy, or whatever you call your favorite roofing tar. Mound it up good on the top. Water is never getting through there. It would just be a whip of liquid tight, right?





__





pitch pan - Google Search






www.google.com


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## Veteran Sparky (Apr 21, 2021)

I read most of the responses here but not all. I didn't see anyone mention however, that typically an electricians liability insurance does NOT cover roof penetrations/repair. I NEVER penetrate a roof. Just like I never spackle, do plumbing or many other things in this trade. Have a roofer make the penetration end of story.


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## Slay301 (Apr 23, 2018)

Take that lid off the top I bet there’s a hole for your conduit to pass through


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## SWDweller (Dec 9, 2020)

Conduit with water poof fittings for anything inside the exhaust duct. When they clean it you want to be golden. 

Never an easy situation. Some just do not get the importance of a flat roof. 
After several mistakes I do not penetrate roofing any more. I will run the conduit though their hole, heck I will even give them the tools to cut the hole. Patching/sealing is best left to those who do that for a living

Had a job, specs said to use a certain lead roof jack on all penetrations. Expensive. So we got all of our stubs done and then put the jacks on for the roofers use. Their project manager walked the roof throwing them all off the roof. Came down and said my roof my guarantee, We do not use these. First time I had worked on a rubber roof.


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## five.five-six (Apr 9, 2013)

I don’t do roofing repairs, it’s always up to the customer but if they want, I’ll hire a roofing contractor for them and mark the price up. I’m very upfront about that. 


Actually on residential PV installations, I have become proficient at repairing underlayment and sub roofing on tile roofs but other than that, I don’t repair or seal roofs.


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