How To Install Flex Ductwork In Attic

Give your ducts the proper support.

How to install flex ductwork in attic. Pull both sides of your ductwork so that the insulation is free of the ends and then wrap duct tape around both pieces. Another biggie that i see all the time is sagging ducts. How to properly install ductwork in an attic tip 1. Add a support joint and then place another piece of the ductwork onto this.

The supports need to be at the manufacturer s recommended spacing but no longer than 4 maximum. Mastic comes in a bucket air duct sealant comes in a tube they re basically the same thing. Slide connectors inside the duct on each end. Use metal connectors to join duct sections.

Pull the webbing back toward the joist to form a loop. Secure all connections and seams air tight with heat resistant tape recommended by the duct manufacturer. The straps that hold up the flex duct need to be no less than 1 5. Cut a piece of foil tape to length.

Your support joints must be at least 4 inches long and be beaded both sides. The first thing you want to do is take either air duct sealant or mastic and spread it around the take off. Spread it around with either your fingers or a disposable chip brush or disposable paint brush. Slide the webbing under the flex duct.

Add extra insulation to ducts in areas such as attics where cold wind might blow in. But without proper support ducts can develops sags or kinks that reduce airflow 4a 4b. The official recommendation from the adc is that flex ducts should sag no more than 1 2 per foot of length between supports. This is an especially relevant tip for flex ducts more on that in a.

Slide the backing up and over the pipe. Sometimes the best route for a flexible duct run is up and over an obstruction. Attach the joint into the middle and secure with more duct work. Choose properly sized ducts.

Raise the webbing until the bottom of the flex duct sits 1 2 to 1 inch off the bottom of the attic. If the ducts are going to be concealed all seams need to be taped or caulked. Peel off part of the backing. Leave backing on the tape on metal ductwork.