We inherited this AC closet setup from the previous owner of the house we bought. The HVAC unit is framed in so that it's pulling the return air from the vent below. Combustible air for the furnace is supplied from a duct coming from the attic - which means (I guess) that the slats venting this door are no longer necessary.

On the inside, they tried to seal off the door by installing a thin sheet of plywood across all these vents (didn't have room for a picture). The closing mechanism is just a magnetic catch by the knob, like a cabinet.

The inside of the door frame measures ~30x66.5. I can't seem to find any doors this size on the websites of home improvement stores, which leads me to believe this is not a standard size and would have to be a custom job.

So - how do I replace this with a door that doesn't have these ugly, dust-collecting slats?

Has anyone done this before?

Pictured: AC closet door

  • BTW when you perform this - you might want to seal the door area with a foam.
    – Ken
    Apr 7, 2018 at 16:02
  • 1
    For sure. There's a bead of weather stripping foam around the jamb on the inside.
    – Bill
    Apr 7, 2018 at 18:21

3 Answers 3


I have done this before 28 x 54. Your door width is a standard size your 'custom' issue will be the height of the door. Return air duct at the floor with no baseboard .. odd .

Anyway you purchase a prefab indoor door unit and you cut it down to size where there is no paneling design inlays.

Mine just happened to work out nicely - these doors are typically hollow and have a 4 board outer frame - the thickness of the door - foam might be in certain parts but not all parts.

So After cutting mine in the correct spot - simply separate the base frame of the bottom of the door (it is like 1 x 1 x door width) put glue in the hollow area of the door and on the 1 x 1 x door width piece - you slide that into the space and clamp it down between some 1 x 3's - let it sit overnight to seal.

Now you have your door and you will need to make the frame or modify the frame you bought with your new door (that is what I did) and the return vent sizing on your wall to fit everything nicely.

So I made my return air vent and the mounting and layout and then installed my door frame - I knew the door size I had and measured everything and drew it all out on paper before I did anything. There is a 2 x 4 at the base of my door frame that goes across and the frame sits on it.

Below is the finished project - I did this about a year ago so I don't have the before pictures. I purchased my interior door and frame from Surplus Warehouse it cost me about $60.00 all inclusive.

Door for AC Ac Door with knob

Where to cut

  • Nice! Thanks for the quick response. Baseboards are a work in progress. I figured we would have to do something like this, I was just hoping not :^) So looks like for me, there might be some extra room beneath that 2nd hinge - would it be alright to leave the hinges "unbalanced" like that? How difficult is it get a regular slab door and put hinges on it, instead of getting a pre-hung door?
    – Bill
    Apr 7, 2018 at 18:17
  • 1
    @Bill the slab door has no hinge cut out, [prefab/frame cheaper than the tools needed] to cut out the hinges and knob latch. Yes the difference in hinges 7" top, 8" on bottom, I could have matched that, but the inside of ac unit sealed up right there, plus I thought on removal of AC, I might like/need that inch. These doors are hollow so they are really light, I have no issues. This was very easy and took me less time to do than the searches I made.
    – Ken
    Apr 7, 2018 at 22:02
  • 1
    @Bill My biggest fear was how the door was internally... if after cutting it would I be able to use the door as I had intended or if it fell apart after spending the $50 on it. I had divine fortune a business trip to fix a machine at a door factory and I was able to see exactly how they were made and saw the complete guts. So I said piece of cake as long as I do it where there is no raised area or recessed area you will find stiff foam inserts there on some doors.
    – Ken
    Apr 7, 2018 at 22:20

Cutting a standard solid door to size can look odd if it has any panels or other decoration that will no longer be in a place that looks like they were intended to be there. A few alternatives:

  • You could just cut a solid sheet of thick, furniture-grade plywood to size and stain or paint it. Furniture grade has a veneer of good wood on one side that will finish well. If you plan to paint it, you won't even need furniture grade. You could even add a simple frame to the outside to give it more of a door appearance.

  • Another approach that will look dressier is to use window shutters of a non-louvered design. A common design incorporates raised panels like a door. You may find a single shutter the right size, or you could use two shutters that each open, or a bi-fold (sink the hinges so the two panels are tight when closed). There are hinges that allow the panels to swing completely outside the opening rather than accordion-folding inside the opening. If you can't find off-the-shelf shutters the right size, there are places that will make you a custom sized one if you want a single piece that looks like a door.


Cover the inside of the louvered part of the door with thin plywood and seal the edges with caulk.

  • 2
    Ah, that's what the previous owner did. I'm not a fan of the look of it, plus all the doors / trim are painted this awful off-white (or worse, they're old and stained :O). I imagine this thing would be a pain to sand and re-paint, so I just wanted to replace it with a new door that didn't have the slats.
    – Bill
    Apr 7, 2018 at 19:08

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