Replacing Floor Joist Cavity Return Duct

Our contractor is considering putting a return vent without any metal ductwork inbetween 2 studs.

Replacing floor joist cavity return duct. If your interested i could get some digital pic s and send them off for your viewing pleasure. Still commonly used is the panned floor joist. Return air duct is connected together using s slips and drive cleats. Did that cause problems.

I live in a cir. In the double cavity return it looks like the joists used to rest on wood. Using floor joists as return ducts by panning can cause leakage because negative pressure in the cavity will draw air from the outside into the cavity through the construction joints of the rim area at the end of the joist cavity. The closest return is a 20 x14 is on the main floor near the bottom of the stairs which is relatively central to the house.

No emails in forum posts. It is impossible to create an airtight seal with this method and together with the negative pressure that is created inside the cavity air leakage occurs through joints of the rim at the end of. Install the square return air duct perpendicular to the joists. Panned floor joist are a commonly utilized as return ducts by nailing gypsum board foil insulation osb flooring panels or sheet metal to the joists.

Well i think i need to replace the rim joist here. Using floor joists as return ducts by panning can cause leakage because negative pressure in the cavity will draw air from the outside into the cavity through the construction joints of the rim area at the end of the joist cavity. This allows the air to get into the return air duct. The photo below shows some of the joists in the vented crawl space that the basement was completely connected to.

Figure 1 shows a floor joist cavity used as a return air duct by nailing a sheet good such as gypsum board sheet. Cut holes in the top of the return air duct to match the holes in the panning. Saw a guy using tji joists for panning cap the end of the joist cavity about 2 feet from the rim board with panning caulk sides and fill 2 area in with insulation. New ducts are probably a non starter so i m looking into the tamarack in door or transfer grilles in the walls to maintain pressure balance if the bedroom doors are closed.

In the single cavity return there are what appear to be bricks below the joists. As a result this panned joist return duct sucked in a lot of air from this basement when the furnace or air conditioner were running. In the single cavity an ant crawled over the brick while i was setting up the photo and there were some dead ants in the dirt. 1895 row house toronto and the return air path is located withing two adjacent joist cavaties and one of the supply duct path s is located within a stud cavity up to the second floor.

Sheetrock will complete the closed cavity. Is this safe to do or is it building hvac code to use ductwork in this situation.