A small wood framed building, similar to a house is being converted to a commercial daycare. The basement is to be renovated. The forced air furnace trunk runs under the basement ceiling joists and the air return is in the joist cavity.
Question is: Does the air return need to be physically ducted in metal and does the 5/8" drywall fire separation need to be installed directly to the wood joists and between the HVAC or can the HVAC be totally concealed in the fire separation? We know a damper is required at the floor penetration.
If there is a return air grille in the ceiling which is required to have a fire resistance rating then the ductwork would be required to be sheet metal (steel). The furnace room may require a 1-hour fire separation. Normally HVAC is totally concealed in behind the fire separation (except anything requiring access for servicing).
Note that if the basement area is to be used as a day care there is also a requirement that windows in play areas be a minimum of 10% of the floor area.
A change in occupancy like this requires both development and building permits. Recommend consulting staff (plans examiners) at the counter for confirmation of these requirements.
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