Gas and Oil Home Heating Furnaces - Cold Air Returns

Hi-

I'm finishing my basement, and my village requires a cold air return in all rooms except the bathroom. Since I have a ranch style house, the existing cold air returns (I estimate they are 15" x 6" by the time they return to our gas fired furnace) are hanging below the joists overhead, so I made my own cold air returns out of rectangular ducting that I am going to screw into the existing main cold air returns on one end, and terminate in the appropriate rooms' walls in the other. I will then use the channel that exists in the wall between the 2 x 4's as the "ducting" that will lead to the grating on the lower part of the wall for that room.

One end of the cold air returns I constructed are going to be screwed then duct taped into the existing main cold air returns. But how should I attach the other end of the cold air return to my wall? Should I just cut a hole in the drywall and slide the other end of the cold air return into the channel created by the 2 x 4's and drywall? Should I make flaps at the end of my cold air returns and use drywall screws to attach them to the wall? Does it matter?

I hope I'm explaining myself well enough. If I'm not, I'll be happy to explain further.

Thanks for your time in advance,
Steve

screwed then duct taped

Remember that there is only one type of tape and one mastic approved for duct work. What is commonly sold as duct tape is not suitable for use on duct work.

Hope this helps.

Hello-

1) How do I know if I have the approved duct tape?
2) What is mastic?
3) How do I attach my self-made cold air returns to the channel in my drywall?

Thanks,
Steve

The duct tape that you need is metal in appearance, on a roll, with paper backing to protect the adhesive while rolled up. You will probably find it with the usual duct tape products. It will be relatively more expensive than the cloth duct tape. It should be marked UL 181.

Mastic is glue - sealant for ductwork. Generally, mixed with water or mixed prior to packaging. It should meet UL 181, also.

Hope this helps.