Build­ing codes dic­tate need and lo­ca­tion of kitchen vent

Winnipeg Free Press - Section F - - HOMES - ARI MARANTZ

QUES­TION: I came across an ar­ti­cle you had writ­ten about kitchen ven­ti­la­tion and was hop­ing you might not mind giv­ing me your opinion on a range-hood ques­tion. We are build­ing a new home and are try­ing de­cide be­tween a ducted range hood, or no range hood, over a propane stove.

The house will have an open wrap­around porch on the side the vent would have to exit. The vent would blow into the at­tic space of the porch. This space is es­sen­tially out­door space, as the porch roof would be metal, and the ceil­ing would be ven­ti­lated vinyl sof­fit. This is en­closed space, and maybe that mat­ters. Do you think we would have is­sues if we do this?

I don’t think we could take it up through the porch roof be­cause snow slid­ing from the main roof would take it out. I don’t think we would want to blow it down onto the porch area from the porch ceil­ing, al­though maybe that would be an op­tion. Any thoughts you might be will­ing to share would be ap­pre­ci­ated. Thanks, Stephen Fox An­swer: Your ques­tion nicely out­lines an is­sue that may fall into a bit of a grey area, which can be fairly com­mon in new-home con­struc­tion. While your porch de­sign is the main rea­son for this dilemma, build­ing codes may also have to be taken into con­sid­er­a­tion when mak­ing your de­ci­sion. That will re­quire you to con­sult with the li­censed gas fit­ter that will be in­stalling your LP ap­pli­ance to help guide your de­ci­sion.

When build­ing or de­sign­ing a new home, or do­ing ma­jor ren­o­va­tions on an older home, lo­gis­ti­cal prob­lems arise that may re­quire some cre­ative think­ing. Your con­cern with the vent hood ter­mi­na­tion lo­ca­tion for the pro­posed kitchen range hood is a per­fect ex­am­ple of such an is­sue. In a typ­i­cal home, the vent hood for this ap­pli­ance would be sur­face-mounted on an ex­te­rior kitchen wall, not far from the ex­haust fan unit it­self. That would limit the amount of duct­ing to be in­stalled and in­su­lated and pro­vide ad­e­quate and safe ven­ti­la­tion for your LP range or cook­top. You are ab­so­lutely cor­rect in wor­ry­ing about a proper ter­mi­na­tion point for this de­vice in­side or un­der­neath an en­closed area, even if it is an un­heated sof­fit area. That lo­ca­tion would not be proper for a cou­ple of rea­sons.

The first con­cern with ter­mi­nat­ing any ex­haust fan within a par­tially en­closed roof, at­tic or sof­fit area is lack of proper air­flow. Re­strict­ing com­pletely open air­flow di­rectly out­side the vent hood can re­sult in poor fan op­er­a­tion, but more im­por­tantly, con­den­sa­tion and ice buildup in the sof­fit area. If the warm, moist air ex­hausted from your cook­ing hits the cold sur­face of the roof or sof­fits in your porch dur­ing the win­ter, con­den­sa­tion is al­most a cer­tainty. This will lead to frost or ma­jor ice buildup when this con­densed air freezes, lead­ing to ici­cles and pos­si­ble mois­ture dam­age. The only way to pre­vent this is to en­sure the area out­side the vent hood is com­pletely un­ob­structed so vented air is blown away or evap­o­rated with­out con­tact­ing cold sur­faces nearby.

The next con­cern with im­prop­erly lo­cat­ing the vent hood in the porch area may be lim­ited to kitchen range hoods only. Not only will range hoods vent out wet air from cook­ing, they will also vent out odours, com­bus­tion prod­ucts and other dis­solved prod­ucts from food prepa­ra­tion. Among those pol­lu­tants may be grease from fry­ing foods on the range. While some of this may be col­lected or trapped by a fil­ter in the range hood, it is quite com­mon for some of this greasy air to make it to the vent hood. If this is vented above the sof­fits act­ing as the ceil­ing of the porch, grease will be col­lected in this en­closed area. That can cre­ate messy stains on the sof­fits but also an­other lo­gis­ti­cal prob­lem. Ac­cess to the vent hood and duct will not be pos­si­ble if it is hid­den above the sof­fits. The vent hood must be ac­ces­si­ble so it can be re­paired if da­m­aged, cleaned, or ac­cess to the duct­ing is re­quired due to block­age. That may be par­tially rec­ti­fied by in­stalling the vent hood on the un­der­side of the sof­fits, but that is also a poor choice due to the po­ten­tial for back-draft­ing into the sof­fit area on a windy day.

While the pre­vi­ous prac­ti­cal is­sues are a def­i­nite con­sid­er­a­tion in choos­ing your range hood, there may also be more reg­u­la­tory items to ad­dress. Be­cause you are in­stalling an LP (propane) range, there may be re­quire­ments for ven­ti­la­tion of that ap­pli­ance. Build­ing codes typ­i­cally will re­quire ad­e­quate ven­ti­la­tion for any gas-fired ap­pli­ance, so leav­ing the range hood out of your plans may not be an op­tion. If this is manda­tory un­der your lo­cal build­ing codes, there will also be spec­i­fi­ca­tions on the lo­ca­tion of the range hood rel­a­tive to the ap­pli­ance, clear­ance to com­bustibles from the range and pos­si­bly specs on the type of duct­ing and vent hoods, as well. Th­ese may pre­scribe where a vent hood is al­lowed to ter­mi­nate and clear­ances from win­dows, doors and other items on the ex­te­rior of your home. Con­sult­ing with a lo­cal li­censed gas fit­ter or a mu­nic­i­pal build­ing of­fi­cial should an­swer those ques­tions.

Think­ing about lo­gis­ti­cal con­sid­er­a­tions for items such as your range hood prior to con­struc­tion of your new home is wise, but don’t for­get about reg­u­la­tory re­quire­ments as well. While it may be pos­si­ble to ter­mi­nate the vent hood for your range hood through the roof of your porch, ex­it­ing an ex­te­rior wall, or down­ward through the foun­da­tion wall, check­ing to see what the lo­cal build­ing codes al­low will help de­ter­mine the an­swer to your ques­tions more ac­cu­rately. Ari Marantz is the owner of Trained Eye Home In­spec­tion Ltd. and the past pres­i­dent of the Cana­dian As­so­ci­a­tion of Home & Prop­erty In­spec­tors — Man­i­toba ( Ques­tions can be emailed to the ad­dress be­low. Ari can be reached at 204-291-5358 or check out his web­site at trained­


Range hoods are evolv­ing and com­pet­ing to be a fo­cal point in kitchens.

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