Creating Clearance for a Wood Return Air Filter Grille

When ordering a wood return air filter grille, it is essential to pay attention the clearance you have around all 4 sides of the rough opening.  Given the structural properties of wood compared to metal, the wood grille will almost always requires more clearance.  Typically 2 ¼” around all four sides of the rough opening will accommodate a wood return grille.   So, what do you do if you do not have enough clearance?

The simplest solution is to contact WoodAirGrille and ask to have the filter housing offset.  This can reduce the clearance needed to as little as 1 ½” on as many as two adjacent sides.  There is no charge for this type of modification just as there is no charge for a 2” deep filter housing.  Though this modification can be done in the field, it is difficult and the amount of movement is more limited.  The factory can easily produce a modified housing that is cleaner and accommodates a closer offset.

The reason this is possible is because the frames of the grille itself and the mounting frame utilize traditional 1 ½” wide cabinet stock.  It is ideal to place the filter within the 1 ½” grille frame, but it does leave room, in a pinch, to move it over to one side or another.  It is still easy to get the filter in and out because it is not behind the frame.  The functionality is only marginally affected.   Notice the housing in figure 1 has been moved all the way to the bottom allowing this wood return air filter grille to clear the baseboard.

Sometimes you can increase your clearance by modifying the rough opening.  This method usually works the best if the clearance is only slightly off.  Typically you only have to adjust one side of the rough opening and if you need ¼” or so, you can typically trim the sheetrock to make it work.  A word of caution though – you do not want to remove material that creates a gap allowing air to bypass the filter.  (fig. 2)

The most common obstruction is the trim itself, specifically the baseboard.  The most common method for dealing with this, particularly in a new construction application is to simply modify the trim.  This can be as simple as using the grille as a template to cut the offending trim out of the way.  However, with a little planning an a few leftovers, it is common for the clearance issue to be turned into an attractive design feature incorporating the grille into a seemingly seamless part of the homes design.  (Fig. 3 & 4)

Rod Gunter is Operations Manager at Gunter Building Solutions and has over 20 years of experience in the homebuilding and cabinetry industries.  Rod has been responsible for building over 200 homes above the $500,000 price point.  Rod has trained large groups including all the major home centers on selling skills, construction techniques and sustainable natural wood products.  Rod resides with his family in Holly Springs, North Carolina.  Gunter Building Solutions owns WoodAirGrille.com which produces wood return air filter grilles and wood return air vents.