Moving Floor Vents During Renovations

Posted on: 30 January 2015

An unforeseen issue that may turn up when doing large-scale renovations in an older home is the placement of air return and heater vents. In many older homes, vents may be covered with very large grates that come out from the wall several inches, or they may be flat on the floor but take up several square feet of space, rendering large portions of the room unusable for furniture placement. If your vents are presenting a problem during renovations, in many cases the best choice is to create new vents and hook them into your existing system. Here are some steps for making that happen.

1. Identify where new vents will be

This step requires consideration of both the layout of the room you are renovating and the layout of your crawl space. Heating and air conditioning vents are optimally located along outside walls near the middle of the wall so that the air gets the best distribution. Frequently this will place the vent below a window, which is good because a lot of people don't like to block their windows with furniture, so the vent is less likely to get obstructed with chairs, beds, tables, and other furniture. 

The harder part of this step is figuring out to get air from an old vent to a new one. In some cases, you may be able to shorten the ducting and hook it up to the new vent. In other cases, you may have to add a duct to reach the desired location. If you are adding duct work, try to plan the path with as few turns and angles as possible. For example, if you need to create three right-angles to get around a jutting bit of plumbing, it may be better to put your vent in a slightly less desirable location. An excessive number of angles in your ducting will reduce the efficiency of your heating and cooling system.

2. Prepare the new vent space above

When you have a plan of action for where your new vent will be and how to get air to it, you can create the new vent by simply cutting a hole in your subfloor. Place the hole so that you don't cut through any floor joists or other critical structural elements.

3. Hook up the new vent

This is the step that will take the most time. You will have to dismantle the original duct work and then build it again in your predetermined shape. For most small projects, flexible ductwork will work fine. This looks like an enormous foil-wrapped Slinky toy. It can be expanded and bent to create your desired path. If you are working closer to the furnace or must create some ducting that will be suspended from the ceiling, it may be better to start with some pieces of rigid ductwork. At the new vent site, you will install a register box, and hook this to the ductwork with foil tape.

4. Fill in the old vent

Your last step is to fill in the hole where the old vent was. This repair depends on whether the vent was in the floor or the wall, and whether you are dealing with subfloor, drywall, or lath and plaster. However, it's not a step you want to skip to make sure your newly vented room is circulating air properly!