Here Comes the Inspector....Make Up Air....

beekeeperswifeJune 13, 2012

Almost at the finish line on our new construction.

Back in October when we met with our builder initially, and we talked about the kitchen we would be doing, I told him we will undoubtedly have a big vent fan and we need to think about makeup air. Never heard of it. (not building houses with GW ranges and ventilation...ever)

Fast Forward to the day they dug the foundation....met the job supervisor. Just wanted to mention this to him, he's out there in the trenches dealing with the inspectors daily.....nope, no worries. House this big, will never be a problem.

House is framed, electrician in kitchen doing rough wiring, see the job supervisor again. We are laying out the kitchen for him. Again, the discussion of the vent and makeup air comes up. The electrician agrees, yep, you need mua. He said nope, never need that. Inspector won't even notice.

This same conversation was had several times, especially when they were in the house doing the hvac work. I know if the mua is done at the time of installation of the heater,etc. it is a lot cheaper.

Fast forward to today. Final inspection is scheduled for Friday. Guess what my job super found out? If the range hood vent is over 400 cfm, there needs to be mua. Well, golly. Surprise. The vent hood has been sitting in my kitchen since April waiting to be installed. My dh has been telling them, this is more than something that you can put up with drywall screws and liquid nails. Don't wait, in case there any problems. It certainly has been a challenge for them. Can't say it's all the way in yet...but it's really close. I took him a spare 300 cfm motor in case it would be easier to mount that, rip out the 1200 and put it back in later. I love cracking the window even in the winter when I'm cooking.

I told my dh that we brought this up enough times that we really should not pay any fees that are above what it would have cost to have it done during rough in. Anyone else have an opinion?

Oh, and the hvac company came in last week to do the blower test to see how tight the house is. It was a 3, supposedly very tight for the size home we are building. I asked him about the makeup air. He said the inspectors are not enforcing it now but when the code is revised again they will start. We have a very strict township.

Just thought I'd share. But I'm not sure what else we could have done. I suppose insist on having the makeup air, but how can you push against people who are doing the building and saying it isn't necessary?

This ought to make for interesting financial discussions in the next few days.


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That's a real pain, sorry to hear this. I would say the builder should pay for the hole in the wall and the instal, and you buy the unit.

We installed a MUA system in the cooking school today as a demo unit on one of our hoods, because it is becoming more of an issue nationwide over the last 6 months, its really not that bigger deal to install. Your contractor was warned enough times IMO.

    Bookmark   June 13, 2012 at 4:57PM
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Tough call - in hindsight you should have researched the local code and shown it in writing to your builder and insisted on them installing it even if they thought it wasn't necessary.

At this point it sounds like you really need makeup air as a safety issue not just to pass inspection. I agree with trevor on how the costs should be split. Good luck.

    Bookmark   June 13, 2012 at 5:12PM
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trevor, thanks for the support

weissman--I DID!!! They told me that the inspector "wasn't smart enough to know about it" I'm not kidding you!!

It is soooo hard not being in control of everything. Really. As a DIYer, this has not been a picnic of a ride. It has totally killed us that the hood has just (almost) gone up....when the kitchen is complete, rangetop w/24" shelf installed, granite in.....oh.

I think I need another Moscow new adult beverage.

    Bookmark   June 13, 2012 at 6:46PM
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Bee - oh no, how awful! I feel pretty lucky my builder was on top of things...we talked about MUA as far back as the closing on the lot. We are in the same state as you but diff area. Our builder has built many $1-2 million homes and said he has not had to install a MUA system yet (ours is not even close to that $ range), but the codes have gotten a lot stricter. FWIW, ours is about $700 for a damper system connected to our furnace cold air exchange, but the damper is opened automatically when the hood turns on. Apparently, it is also an issue with some hoods having the correct electrical wiring to be able to open the damper automatically. He was worried the variable control on the Modernaire hood I wanted wouldn't work for that purpose, but I guess he and the electrician were able to get it figured out.

Trevor - what type of system did you install?

    Bookmark   June 13, 2012 at 7:24PM
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Annie Deighnaugh

We ran into a similar issue v. our wood stove. Fortunately we had installed a fresh air exchange unit and that seemed to satisfy the building inspector.

For the woodstove, it was also a function of how much cubic footage of air was available for the other words what is the cubic footage that the stove sits in with no possibility of shutting a door. Considering the family room is open to the foyer which is open to the whole lower level, we were ok.

Don't remember him raising the issue v. the fume hood though....

    Bookmark   June 13, 2012 at 8:10PM
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Cottonpenny......The one we installed to our ModernAire hood today is actually the unit ModernAire are now distributing nationally via their distribution chain, its manufactured by CCB Innovations a US company, this unit does not require any alterations to the hoods wiring at all, yet still opens when you turn the hood on.

    Bookmark   June 13, 2012 at 10:14PM
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" He said the inspectors are not enforcing it now but when the code is revised again they will start. We have a very strict township".

To me, this is key. IF the city inspector approves your hood without MUA AT TIME OF INSTALLATION then they can't go back months later, re-inspect and say you fail. Nor if you were for some unforeseen reason to sell your house can the new owner be forced to put in MUA as typical codes apply "at time of installation".

I'm with you though about their carelessness and would urge them to reach out to your HVAC person for an immediate fix to this contentious problem, especially since your house registered tighter than was expected.

Sorry for your recent spat of troubles Bee. HTH.

    Bookmark   June 13, 2012 at 10:58PM
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"how can you push against people who are doing the building and saying it isn't necessary?"

It may not be necessary to get sign off, but with a tight house, I'd want it for safety even if it weren't code. [I do agree there should be some serious discounting given your repeated warnings to the builder]

We seriously considered it (it was not required for us) even though we have a very leaky house, removed the one fireplace, have an electric clothes dryer, replaced the in-house gas water heater with an external on-demand gas water heater, and, of course, added CO detectors. In the end, we did not do it, but might have if we had an enclosed kitchen or a gas dryer. Of course, were we live, we don't need to condition the MUA so it's not as big a deal.

    Bookmark   June 14, 2012 at 1:08AM
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Trevor - cool! I'm not sure what brand of system we are getting but would have steered my builder towards that one if I knew about it since he was so worried about compatibility.

    Bookmark   June 14, 2012 at 7:31AM
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Bee - sorry this is happening to you. We had something similar happen when we were building our vacation home in upstate PA. I don't even remember what it was since it was 15 years ago but it was fairly minor and not a safety issue. Our builder said that the inspector never checks for whatever it was.

Well the township inspector suddenly quit and a replacement was hired who checked everything in the book. Our builder had to correct the problem and even absorbed the cost.

    Bookmark   June 14, 2012 at 8:13AM
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I don't get it, Bee. Why are you offering to help your GC sneak past a building inspection? If I were you I would pick up the phone and discuss the MUA situation in precise detail with the building inspector himself. Putting in a counterfeit blower to avoid a red-tag on that hood is abetting incompetence.

At this point in time I think the building inspector is your friend, hard as it may be to believe. If that kitchen doesn't pass inspection the contractor doesn't get paid. HE is the one on the hook to provide you with a code-compliant, safe, home. Having your family's safety rest upon your, or your kids' ability to remember to crack a window in the winter when you stir-fry is simply unsatisfactory. I think this is a situation where you should fully disclose everything you know to both the contractor and the building codes people and let the chips fall wherever. I would in no case pay one penny more to that knucklehead for ANY cost of retrofit over and above what it would have cost you if the system had been installed properly when the HVAC folks were out there.

    Bookmark   June 14, 2012 at 8:46AM
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If you have a gas furnace, gas HW and gas dryer, then this is a Safety issue more than an Inspection issue.

I push against contractors with the contract.

    Bookmark   June 14, 2012 at 3:10PM
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Was the MUA on the drawings or mentioned in the contract? If so, the contractor owns it. It is his problem if the MUA is missing.

What kind of HVAC is in your house. One option is to introduce MUA into the AC/heater air return. The motorized damper and the sail switch is less than $400. The sail switch mounts in the range hood's duct. When the range hood is turned on, MUA enters the air handler return duct. I like this arrangement because the incoming MUA is tempered by the air handler.

    Bookmark   June 14, 2012 at 3:30PM
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The contract is irrelevant. This is new build, and the builder is required to build to code. Bee raised the issue with him a thousand times and he brushed it off. The cost of retrofit is his issue, period.

    Bookmark   June 14, 2012 at 10:53PM
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Sorry, I thought this was a remodel.

    Bookmark   June 15, 2012 at 4:36PM
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Okay, Bee, you are killing us here! What happened?

    Bookmark   June 16, 2012 at 2:55AM
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Bee....Have been thinking about you and your latest saga...Do you now have make-up air? Did you get your CO?....Are you in your new home???? As mojavean said...You are killing us with the suspense!

    Bookmark   June 18, 2012 at 6:39PM
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I think Bee might have ridden those Moscow Mules all the way to Moscow!

    Bookmark   June 18, 2012 at 7:42PM
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I'm back. Quite an intense week we've had.

First, the builder did understand that they owned the problem. Well, the part that would be above the cost of doing the mua when the house was under construction.

Today was the inspection. Foreman was expecting to be failed on the make up air issue. But lo and behold. Not a word. We passed, all they wanted was another heater vent installed in the unfinished basement. Nobody understands where that came from.

As far as the safety issue, I think we will be fine. I always always always, open the kitchen window when I run the fan. It's an old habit. I do it in the dead of winter. I'm usually so hot when cooking that I actually like the breeze!

The house does have Carbon Monoxide detectors.

They are reinspecting tomorrow for the extra vent tomorrow. We have a partial C.O., meaning we can move stuff into the tonight we put my '94 Saab convertible in there.

Thanks for thinking of me. Sorry I didn't get back sooner. I'm without internet for the most part.


    Bookmark   June 18, 2012 at 8:23PM
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I'm glad you (nearly) passed final inspection, but I think you're way to quick to dismiss the real dangers and inconvenience of inadequate MUA. Especially when the builder agrees to own the problem of not installing it at the proper time of the construction.

You say you always, always open a window when you cook. Does it ever rain when you cook? Are you the only person that will ever cook in your home? I don't know if you have kids that will eventually do some cooking of their own.

Do you have a wood burning fireplace? The smell of soot and ashes sucked into your house isn't pleasant or easy to get rid of, and that assumes the fireplace isn't burning at the time.

Have you ever operated a 1200 CFM hood? 1200 CF is the entire contents of a 10x12 room with a 10 foot ceiling being sucked/blown outside every minute. Of course, you won't push a full 1200 CFM out every minute because of inefficiencies of the ductwork and hood, but you still get a sense of how much air is moving.

What if you ever sold your home? I'd expect the lack of proper MUA to be seller disclosed in the real estate papers since it was code when the house was built and you knew it didn't meet.

I don't mean to go overboard, but you planned for the need for MUA. The builder is willing to do it for your original planned cost. I don't understand why you wouldn't take advantage of that now and live in a house that was completed properly.

    Bookmark   June 18, 2012 at 8:46PM
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knot--to answer your questions:

* cracking the window has never been a problem before, even when it rained.

* it's an adult only home, so only my dh and I will be cooking, children are all adults and they know to always crack a window to cook if they are there.

* no wood burning fireplace (regrettably)

* Yes, we had a 1200 cfm fan in last house. No makeup air, just a kitchen window nearby.

* Not sure if it has to be disclosed, it passed the inspection. Of course this is something that won't be an issue for a very long time. And if it was needed to be disclosed we would do so.

* We didn't actually plan for the MUA, we just mentioned it a lot of times. You know "Are you sure we don't need it?"

We don't really put that fan on high, and run it for a long time. It's not like I'm cooking something on high for extended periods of time. How long does it take to wok a meal? A few minutes. If I'm searing something in a pan, that usually is only for a couple of minutes.

Thank you for your concerns, I do understand your questions, but we never had a problem in the last house, and it was 1/2 the size of this house, so I think it will be fine.

    Bookmark   June 18, 2012 at 9:16PM
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Hi Bee...I have been following this post and would like to chime on on the need for a MUA system inside a high efficiency home.

I think what knot2fast was alluding to was that if you have the opportunity for the builder to pick up the cost then it would be beneficial to go ahead and add it.

You only have to evacuate 1% of your internal air supply before a vacuum is created. That doesn't mean your house is eventually going to implode from pressure, but it does mean that it will immediately start drawing replenishment air from the most convenient location (path of least resistance). If you forget to crack a window then you no longer control where the air is being pulled from. And if your house isn't able to find a location for clean air to enter that is equal to the rate of exhaust, then your internal air supply will be depleted and could become hazardous.

Not trying to scare you, just making a point for your safety. Tightly sealed homes that reduce energy costs will put a greater responsibility on the builder to maintain a safe environment for the occupants. Essentially, your HVAC system and its exchange rate for fresh air become sort of like a life support system. And the HVAC contractors do an outstanding job of calibrating for the proper balance inside your home. But, the use of high CFM range hoods is a variable that is consumer controlled and randomly unique to each household. So the HVAC system cannot account for the sudden loss of air volume when you operate your hood.

So, in comes the IRC provision for a make-up air system that is synchronized with the operation of a range hood. And it is a completely necessary and reasonable code to put in place, because it is written to protect the homeowners.

I would still recommend adding a make-up air system because your blower test rating definitely warrants one. And letting the range hood "crack the window" for you is safer option for you in the long term.


    Bookmark   June 18, 2012 at 11:23PM
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I hope you'll take this in the spirit of good humor that it's posted in, but your desire to stick with the open window even though you've still got a shot at putting in the code required MUA reminds me of the joke about the misguided financial advisor who back in the '60's was quoted as saying:
"Who'd want to buy something called a Xerox copying machine when we have this wonderful carbon paper?"

Since I'm building a house now, I can appreciate the fact that you're probably worn down and ready to get it all over with... although your build has gone so fast that I am in awe!

I think that you've accepted all sorts of new technologies and codes over the years and most have made your life just a tad better. You've gone the extra mile to have a high CFM fan, and seems like you're stopping short by not putting in the required MUA for such a tightly built house.

If for no other reason, do it for the people who might buy your house next.

    Bookmark   June 19, 2012 at 2:58PM
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+1 to Nate.

You have to do your own due diligence and you have to insist. High-BTU appliances are still relatively new, and lots of people "in the industry" don't understand their needs. For example it hadn't occurred to the person I worked with that you might need a wider-diameter gas pipe than normal.

    Bookmark   June 30, 2013 at 3:19AM
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Another thing to consider is that whether or not you have to DISCLOSE this problem when you sell, it will probably be DISCOVERED by the buyer's home inspector. You will then have to pay for it (either do it or discount the sale price so they can do it). Why would you not have the builder eat the cost now, instead of having to eat it yourself later?

Are you really willing to bet that however many years from now, when codes are even tougher about MUA and there's a new generation of inspectors who are savvier about recent technology, that you're somehow going to fly under the radar again? Why even bother to make that bet, since you have a builder willing to eat the cost now? I'm just not seeing what you gain.

    Bookmark   July 4, 2013 at 5:17PM
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Uh, "now" was last year. I don't recall what ultimately happened though, I'm guessing no MUA based on this thread.

    Bookmark   July 4, 2013 at 8:30PM
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Like Bee, I'd probably just crack a window. I will say, however, for others who might someday dig this thread out of archives, that MUA is aggressively enforced where I live.
We had final two weeks ago. Even though my hood paperwork clearly showed it was under the threshold, the inspectors made me remove all the panels and open it up to every extent possible. They went over it with a fine toothed comb and measured a bunch of stuff before passing us. I'd never heard of MUA.

When I asked my KC about it, he said yes, it is enforced but he knew my hood was under. He was a little surprised they made me open it up, but said his staff had learned the hard way that MUA was being aggressively enforced now.

    Bookmark   July 5, 2013 at 11:42AM
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