# Mechanical Ventilation of Multi-family Low Rise



## Josh Koci (Dec 12, 2017)

FBC 403.3 states "Private dwellings, single and multiple garages, common for multiple units and separate for each dwelling" require mechanical exhaust.

We are designing a multi-family low rise residential condominium on beach front. This building contains a 2500+ SF above ground parking garage with a single point of entrance and egress. The garage door is a ventilated rolling steel door with an area of 128 SF. We think that this would be classified as an enclosed garage and require mechanical ventilation but the door is ~5% of the total SF and meets natural ventilation. 

There is also a 525 SF private garage bay with the same door as the above parking garage. Under the FBC it appears that this space is required to be mechanically ventilated, but I cannot think of a private garage that has any sort of mechanical ventilation. 

Can anyone provide code references for whether or not we need mechanical ventilation for these situations.


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## cda (Dec 12, 2017)

Welcome


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## JBI (Dec 12, 2017)

The corresponding provisions in the unaltered (2015) IBC require a mechanical ventilation system in accordance with the IMC. 
The Code clearly requires mechanical ventilation. 
Possible solution could be to make it an 'open' parking garage as defined in the IBC. For Florida that may be a reasonable alternative...


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## Josh Koci (Dec 12, 2017)

Thank you for the response on the main garage. Those will need mechanical ventilation. Does this also apply for the private 525 SF garages? and if so how is this different from a typical residential garage that does not have ventilation?


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## cda (Dec 12, 2017)

Not into a lot of hot air,

But does 402 natural ventilation sub for the mechanical???


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## cda (Dec 12, 2017)

This is from 2003

http://www.floridabuilding.org/fbc/committees/mechanical/TAC-Memin1003.pdf


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## cda (Dec 12, 2017)

Maybe ahj are ignoring it or do not know about it??


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## Josh Koci (Dec 12, 2017)

cda said:


> Not into a lot of hot air,
> 
> But does 402 natural ventilation sub for the mechanical???



I am unsure. I would assume yes, until you get to the footnote under mechanical ventilation that "requires" mechanical ventilation for the garage.



cda said:


> This is from 2003
> 
> http://www.floridabuilding.org/fbc/committees/mechanical/TAC-Memin1003.pdf



Thank you for this. Very applicable and useful.



cda said:


> Maybe ahj are ignoring it or do not know about it??



That is a good possibility. I'm still researching.


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## cda (Dec 12, 2017)

Maybe ahj are ignoring it or does not know it is there??

There are a couple FLA’s on the site, give it a day or two


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## JBI (Dec 12, 2017)

Enclosed garage provisions specifically require mechanical ventilation per IMC, so natural option not applicable for enclosed garage. If IBC 406 (or FBC 403) simply stated 'ventilation per IMC' then natural might be an option. 
As far as the single bay, if it is part of the same building it will require mechanical if enclosed. Again the easy way around this is to make the garage 'open'.


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## JBI (Dec 12, 2017)

(can't edit my prior post...) 
The difference between this and a private residential garage is that a private residential garage can only impact one or 2 families.


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## tmurray (Dec 12, 2017)

Personally, I would let the small garages go because there are no ventilation for garages serving single dwelling units most of the time. If it was a problem, then ventilation would be required for all of them.


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## cda (Dec 12, 2017)

JBI said:


> (can't edit my prior post...)
> The difference between this and a private residential garage is that a private residential garage can only impact one or 2 families.




So have not seen mechincal ventilation on attached apartment  garages ???

Seems like when you open the door, you really ventilate the area ??


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## JBI (Dec 12, 2017)

cda said:


> So have not seen mechincal ventilation on attached apartment  garages ???
> 
> Seems like when you open the door, you really ventilate the area ??



The concern would typically be running the engines without opening the door... less likely in Florida than say New York State, but probably the underlying concern.


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## Josh Koci (Dec 12, 2017)

Thank you all for the responses. 

We have decided not to ventilate the private garages as tmurray said if it was a problem then you would see them on all residential single dwellings. 

As for the main area the structural engineer says he cannot provide us with the required openings to consider the garage as "open" because he has to have a minimum of 80% frangible walls. So we are going to end up ventilating the parking garage with a mechanical exhaust fan interlocked with a CO & NO2 sensor per FMC 404.1.


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## cda (Dec 12, 2017)

Josh Koci said:


> Thank you all for the responses.
> 
> We have decided not to ventilate the private garages as tmurray said if it was a problem then you would see them on all residential single dwellings.
> 
> As for the main area the structural engineer says he cannot provide us with the required openings to consider the garage as "open" because he has to have a minimum of 80% frangible walls. So we are going to end up ventilating the parking garage with a mechanical exhaust fan interlocked with a CO & NO2 sensor per FMC 404.1.







Is the answer of the day

401.2 ventilation required


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## cda (Dec 13, 2017)

Either or??


401.2 ventilation required


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## Josh Koci (Dec 13, 2017)

cda said:


> Either or??
> 
> 
> 401.2 ventilation required



Mechanical ventilation is required based on the garage being an "enclosed garage" and considered to be an occupied space. 403.3 requires mechanical ventilation for Private dwellings, single and multiple garages require mechanical ventilation.

401.2 applies to the smaller single garages, but definitely does not apply to the larger garage as there are many other codes IBC, FMC and FBC that call out that a "enclosed" garage requires mechanical ventilation. The larger 2000+ SF garage does not have enough exterior wall openings to be considered open by code.


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## ADAguy (Jul 16, 2018)

Also note that unless garages are completely open the partial walls may become wind collectors during hurricanes, just a thought.


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