How To Install Flex Ductwork In Attic

The first thing you want to do is take either air duct sealant or mastic and spread it around the take off.

How to install flex ductwork in attic.

Slide connectors inside the duct on each end. The supports need to be at the manufacturer s recommended spacing but no longer than 4 maximum. Secure all connections and seams air tight with heat resistant tape recommended by the duct manufacturer. Peel off part of the backing.

Pull the webbing back toward the joist to form a loop. But without proper support ducts can develops sags or kinks that reduce airflow 4a 4b. Sometimes the best route for a flexible duct run is up and over an obstruction. Use metal connectors to join duct sections.

Give your ducts the proper support. Attach the joint into the middle and secure with more duct work. Another biggie that i see all the time is sagging ducts. Here s bob s trick for taping a seam on a pipe that s installed close to the subfloor.

How to properly install ductwork in an attic tip 1. The straps that hold up the flex duct need to be no less than 1 5. Slide the backing up and over the pipe. Mastic comes in a bucket air duct sealant comes in a tube they re basically the same thing.

Leave backing on the tape on metal ductwork. Your support joints must be at least 4 inches long and be beaded both sides. Choose properly sized ducts. Cut a piece of foil tape to length.

Add extra insulation to ducts in areas such as attics where cold wind might blow in. Add a support joint and then place another piece of the ductwork onto this. Pull both sides of your ductwork so that the insulation is free of the ends and then wrap duct tape around both pieces. If the ducts are going to be concealed all seams need to be taped or caulked.

The official recommendation from the adc is that flex ducts should sag no more than 1 2 per foot of length between supports. One of the most common mistakes when installing attic ductwork is choosing. Raise the webbing until the bottom of the flex duct sits 1 2 to 1 inch off the bottom of the attic. Slide the webbing under the flex duct.