Expert: Keith Fuller - 9/10/2011

Question
We removed the metal, folding, louvered doors in front of our gas water heater & electric furnace.  We want to replace them with wooden, folding doors that are only louvered on the upper half of the door & not the full length of the door.  I thought they should be louvered from top to bottom like the metal ones.  Will having only the top part of the door louvered be OK or not?  The enclosed space will be 4 1/2 ft x 4 1/2 ft.

Answer
The louvered doors are there probably to provide combustion air for the flame producing appliances in the closet. When required, the air needs to be provided from locations 12" from the top and bottom of the space, whether it's via the door or a louver elsewhere. The size of the required vents can be obtained from the appliance's listing/manufacturer's installation instructions. If they're not available, they may be online if you search your manufacturer and model number.

You should check with your municipal building official for the code requirements where you're located, as the code does differ depending on where you are located and what type of appliances are being vented.

Sometimes the metal doors are used because the closed doors come close to the front of the appliance, so be sure if you use wood doors that you maintain the manufacturer's required clearance between the combustible wood and the unit(s).

If in doubt, use a full louvered door and err on the side of having too much ventilation rather than not enough.