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Living above a motorcycle shop, ventilation help

yZ8Lxq3Dgy | Posted in General Questions on


I own and operate a motorcycle shop. We sell and service motorcycles. Above the shop is my apartment. The only thing that divides my apartment from my showroom and mechanic shop is 5/8 fire rated drywall. My showroom and mechanic shop are split by a floor to ceiling wall with 5/8 fire rated drywall on both sides. During the summer I only cool my showroom and apartment. Leave shop door open during work hours. When winter is here I pull cold air from mechanic shop and heat it (during summer I tape off return and supply vent).

I am afraid all the harmful gas, and other fumes are getting sucked in and forced into my apartment. In general I am afraid living and sleeping above all these motorcycles is causing damage to me.I would say on average 10-12 bikes. When a bike leaks gas onto the ground, I can smell it within 15 minutes upstairs. We always have projects with customers leaky bikes.

Do I need to keep supplying fresh air into mechanic area? Have fresh air pulled into cold air return?
I must use the same furnace for both areas, because we recently bought one big enough to work efficiency

Please help me get some fresh healthy air into my apartment. All summer I left windows open upstairs as much as I could allow.

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  1. GBA Editor
    Martin Holladay | | #1

    The best solution to this problem is to hire a home-performance contractor to perform blower-door directed air sealing. The idea would be to seal the leaks in the ceiling of your shop. There may also be some leaks through the partition wall that you describe.

    If I understand correctly, you are using the same forced-air furnace and duct system to heat both spaces. That's probably not a good idea. It would be better to have separate heating systems. If the supply and return systems of your HVAC system aren't balanced, and if your duct system is leaky -- situations that are very common -- the HVAC system could be contributing to your problem.

    The least expensive way to solve the problem is to install two ventilation fans: one supply fan to pressurize your apartment, and one exhaust fan to depressurize your motorcycle shop. This should prevent smells from entering your apartment. Although the solution doesn't cost too much to implement, it could waste a lot of energy over the years to operate those fans continuously.

  2. davidmeiland | | #2

    The combined heating system is a huge problem. The two systems need to be separate, and the shop needs an exhaust fan pulling air out. You have little choice but to waste heating energy in the shop, if you want to have clean incoming air.

  3. yZ8Lxq3Dgy | | #3

    Thank you guys for your replies. I woke up this morning to the worst gas smell in a while, customers bike leaked all over the ground. The whole showroom and apartment smelled so o bad, moved everything outside and let fresh air blow through. I hope to get this done before winter, because this will not be an option. I attached a quick write up of the way my building is laid out 60X40 FT with 16FT ceilings(7 in apartment). I am willing to attach photos of the building, if needed.

    The HVAC system is used to heat the whole building in the winter, and is located in the back of apartment. During the summer, I use HVAC metal tape to block off the clod air return used in back shop, also turn damper off to the supply for the shop. I recently upgraded our furnace and would like to keep it supply both, if possible. If not, I may need to find a cheaper alternative to supply heat to back shop only.

    What would you recommend for exhaust and supply ventilation fans? I can only supply air into apartment on one specific wall. Is there a way to have the shop flushed of the stale gas smell, and supply fresh air every hour or so after we close?

    Also, My bedroom is directly above showroom, and the bikes for sale. They have gas in them, but do not leak, is that ok and safe?

    Sorry for all the questions, just trying to make this right, and you guys have been my only help on this weird topic. I can install something as simple as fans, just would like to begin before cold weather gets here.

    Thanks in advance.

  4. BobHr | | #4


    Martin is right a blower door test and air sealing would be a good starting point.

    Your mechanic shop is going to have exhaust fumes and numerous chemicals, cleaners etc. It should be sealed off from the showroom and apt. Do a little research on air barriers. The mechanic shop should also have its own heat source.

    Where is the furnace and how do the ducts run. Are they accessable.

  5. yZ8Lxq3Dgy | | #5

    Yes Everything is accessible. If you refer to my picture, furnace is located in back of apartment(above shop), then the return and supply trunk line run piggy back down the dividing wall on the showroom side. The 6IN supplies to the apartment is the only ones I can not reach once they leave the trunk, they are dry walled in the ceiling.

  6. davidmeiland | | #6

    Nick, where are you located, city/state or climate zone?

  7. yZ8Lxq3Dgy | | #7

    To be honest, I do not know my climate zone. I am in Coal City, IL 60416. I have been looking into other heating options. Just because I would like to go above a beyond to ensure a fresh clean air in apartment. Maybe a gas ceiling mounted heater, and start with a caulked trim base board, and spray foam any gaps, or cavities in the major dividing wall.

    Thanks in advance everyone, can't wait to start this jump into a better air quality.

  8. davidmeiland | | #8

    Looks like you're at about 6500 HDD. I think you're going to have to separate the heating systems, as well as doing very good air-sealing. I would talk to HVAC contractors about the best options for accomplishing this. In this climate the first choice would probably be a mini-split heat pump for the apartment, and let the existing furnace and ductwork serve the shop and sales areas. If you have natural gas service, it may be a wall furnace in the apartment is the most cost effective. Some mechanical contractors are good at air leakage and sealing work, others not so much.

  9. yZ8Lxq3Dgy | | #9


    Thanks for your reply. I think that would be a great idea, but the only wall available is full of windows.
    Front and rear of building has awnings. I think I may go with first recommendation. Use existing HVAC to supply to sales showroom and apartment, and purchase a gas heater for shop. Do my best to
    seal the the dividing wall and ceiling of the shop to apartment. Do you think that would be efficent?

    Then also install ventilation for shop also, if you guys can point me in the right direction.

    As for today, i moved leaky bikes into my enclosed trailer, for a good nights sleep.

  10. gusfhb | | #10


    Don't take this the wrong way, for many of my friends[ and my former single self] you are living the dream. however, I dunno about Illinois, but here in the People's Republic of Mass, if a building inspector walked in to your place, they would just order in the bulldozers. There is no way that any commercial space dirtier than a bookstore can share HVAC with a dwelling unit. I would be very careful of even applying for permits until you are really really sure of the exact legal status of your situation. You may end up in a world o' poop.

    Even if this has been like this 'forever' it aint right

    My blind guess is that you ought to have 2 sheets of 5/8 sheetrock between the dwelling and the shop, firestopped, hermetically sealed, blessed by the Cardinal. IIRC that is what is required here between to adjacent unsprinklered commercial units.

    The Code Authority couldn't care less if you clean Amals on your kitchen table and gargle with the remains, what he pictures when he sees 'dwelling unit' is a family with 3 kids living in it, and crowd with torches and pitchforks outside his house if he allowed it and things went badly.

    First step commercial space, one heating system, residential another. If it is an older building with an existing use, the firestopping is probably not required, but would be a really really good idea.

    the flames will move much faster than the fumes.

  11. yZ8Lxq3Dgy | | #11


    I appreciate the response! Took a ton of work to get where I am at, and to say we have been open 4 years at the age of 27 I am happy. The one and only reason I bought this place was to be able to live here because I couldn't afford both. This building is grandfathered the way it is. When we bought the place we remodeled the entire place with out touching existing apartment. walls. We have met every code and the inspector opened us for occupancy. All exterior walls to the apartment are 5/8 fire rated. The dividing wall is also fire rated on both sides 16FT tall to the roof.

    I would love to supply the apartment with its own heat and air, but there is no room on the one wall available. I have all the duct work running off the main trunk line, and do not think I can afford to buy a new furnace and AC unit for my dinky 400sq ft apartment.

  12. user-651098 | | #12

    Martin and others,
    Nick's living space is only 400 SF.
    Would an on-demand Hot Water heater coupled to one or two wall mounted radiators fix his heating problem at an affordable cost?
    Would installing a small HRV for the apartment plus sealing the living space from the shop solve the ventilation and cross-contamination problem?
    Nick, You mentioned a wall of windows. Can you utilize passive solar energy and thermal mass to reduce your heating issues? Are your windows a major source of heat loss at night?

  13. yZ8Lxq3Dgy | | #13


    The front and rear of the building have awnings. The only wall available is one. That wall has a bathroom and a bedroom/living area. I installed two large, brand new energy efficient windows in that take up whole wall. I used foam and batted insulation, along with window spray from to ensure a good seal. The building is a metal Morton style tin.

  14. GBA Editor
    Martin Holladay | | #14

    It's possible to use an on-demand water heater for hydronic space heat, but there are many ways to screw up the design and installation of such a system. Horror stories abound, especially when such systems are installed by HVAC contractors without much hydronic experience.

  15. gusfhb | | #15

    It sounds like the heating unit is in the apartment already, probably oversized for just that purpose but it is there. Adding a [flammable location] heater to the shop would be fairly easy.

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