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Community and Q&A

Narrowing Stud Cavities to Install a Wall-Mounted Heater

anonymoususer | Posted in Mechanicals on

We are near Vermont/New Hampshire border. We want to install a Cadet Energy Plus wall-mount heater in bathroom of our 1949 Cape, which is currently gutted (ie, all cavities visible). There is only one cavity in the entire bathroom where we can install the unit while meeting all manufacturer-required clearances. Problem: said cavity is not wide enough to accommodate the can. What do building codes say about reducing the *width* of a stud? IRC R602.6 says studs in an exterior wall (which the one in question is) may be notched max 25% of their depth. But I cannot find what percent of the *width* may be removed…? The cavity where we want to place the heater measures 6.1875 inches wide. The can measures 7.875 inches wide, tapering to 7 inches at the back; in other words, 1.6875 inches too narrow. Can I cut 0.84375 inches from the width of the two flanking studs (left and right)? This way, the can (which measures 9.75 inches tall) will fit. Each stud has actual width 2.0625 inches by actual depth 3.75. So I would be reducing width of each stud by 40.9% (Actually, a smaller percentage—probably in the high thirties—after accounting for future drywall). Pls note that the licensed electrician (Master) we were planning to hire did not know if the Code allows this. A licensed general contractor we have used in the past did not know either. Our local building inspector is unreachable by email and never returns voicemails. The structural engineer we have consulted with in the past charges $300 per consult. If we had a long list of other questions, we would contact him. But we don’t. Nor do we foresee having questions for him in the near future. We know there are other brands of electric wall-mount heater (probably same clearance requirements / can width). Our neighbors have the Cadet Energy Plus; we played with theirs and like it very much, so we are wondering if we can legally install it in a “too narrow” cavity by making the cuts described above.  Thanks in advance for any input.

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  1. plumb_bob | | #1

    Do as you plan then add an additional stud on the outside of the modified studs?

  2. anonymoususer | | #2

    Thank you, plumb_bob. I wish we could: unfortunately, there is a window just to the left of the left stud and an hvac duct just to the right of the right stud. Therefore we cannot sister either stud. I should have mentioned that in my post but forgot. :-(

  3. Trevor_Lambert | | #3

    You could notch it an extra 1/8" and insert an angle iron to reinforce the area. Or even better, if you have just a bit of wiggle room on the opposite side of the studs, slip the iron reinforcement in there.

    This might be overkill. If you consider that the studs would be 1.5" wide by modern building standards, then what you're left with after notching 0.844" is only 20% less. 1.2x3.75 is likely way stronger than a 1.5x2.8 (what you'd have if you notched 25% out of the depth of a 2x4).

    1. anonymoususer | | #5

      Thank you, Trevor--a helpful tip regarding the angle irons! Unfortunately, there is no wiggle room on the opposite side of the studs. But maybe I could insert an angle iron (ht 9.75 inches to match height of heater's wall can) into the cut area...? Thanks also for highlighting dimensional difference between today's tubafors compared to those of yesteryear.

  4. Expert Member
    BILL WICHERS | | #4

    Can you reframe the cavity a bit and move one of the studs over? That's usually not too difficult to do when the wall is open as long as those studs aren't holding up a header or something like that. Moving a stud an inch or so shouldn't be a problem.

    It would help a lot to have a pic, or at least a drawing, of the framing of the wall in question.


  5. anonymoususer | | #6

    Thank you, Bill. I did think about moving one of the studs over but cannot because the right-hand stud has an hvac duct just beyond it that occupies the entire cavity. The left stud has a window just to its left. We cannot move this window stud any further to the left because we already purchased triple pane window (to replace the one you see in foto) in the size needed to fill rough opening with "outie box" and minimal, manufacturer-recommended "wiggle room". In the attached foto, the cavity where we want to install the space heater has a pump soap bottle in it.

  6. user-5946022 | | #7

    So what is really the issue here is what the top of that window jamb stud looks like. Is that thing transferring load from above, or is it just acting as a jamb for the window?
    Are you placing this heater above the level of the soap bottle? If you are placing it below and it penetrates that horizontal sill, you need to install another support under the sill.

    1. anonymoususer | | #11

      Thank you, CL. We were hoping to place the wall heater above the level of the soap bottle. I am attaching a pic showing top of window jamb. I think we will go with Bill's and Malcolm's suggestion of installing a ceiling- or surface-mount heater instead of the Cadet Energy Plus wall heater that our neighbors have been pleased with. It may not be ideal, but the bathroom is so small that options for heater placement are very limited. We are not willing to enlarge bathroom. THanks again for your help.

      1. user-5946022 | | #13

        Your plan to install a ceiling heater sounds like a good one as the main drawback of the wall heater in an exterior wall is insulation is displaces.
        That jamb is clearly carrying some load from the header over the window. What is a bit troubling is that it looks like the header is either 2 pieces butted just to the left of the jamb, or that the header was inadvertently cut with other work. Hopefully those cuts in the header are superficial - ie no more than 1/8" deep.
        IF that is the case (cuts superficial) AND the right side of that header is bearing on the stud to the LEFT of the duct, you might have some leeway here to make that jamb narrower and fit in your heater.
        Your photo did not show enough of the area to be sure, but because it shows the header continuing past the jamb, I'm going to guess it is either toenailed to the stud to the right outside the photo, or bearing on that stud.
        Take a photo of the entire area and post it, and then also draw your heater configuration into a copy of that photo and post that. If you provide the entire context, people here can probably guide you - at least you will know you tried, if that heater is really the one you prefer.
        ETA: I just pulled the heater spec from the Home Depot site. With your situation, if really have your heart set on this heater, I would either
        a. get some rated hardware to ensure the header is secured to the stud that is to the left of the duct/right of the stud bay in which you want to install the heater
        b. Review the entire assembly to ensure that stud is carrying load and ensure those header cuts are superficial
        c. Carefully shave off only as much as needed from the jamb stud
        d. Install the thing.
        a. Build a soffit out either over the top of your window (which I presume is more than 6'8" above finish floor) or in the stud bay in question and install the heater in the soffit. This has the added benefit of allowing you to fully insulate the wall.

        1. anonymoususer | | #18

          Thank you, CL, for your long and thoughtful response. I will revisit the idea of narrowing the studs to install a wall heater once I exhaust my options for ceiling heater. I am so, so, sooo limited on this project because the bathroom is only 5 ft wide x 5 ft wide (not counting shower stall). It has toilet and vanity side-by-side, one window (directly on opposite wall from vanity), and a cabinet mounted on the wall behind toilet (not recessed) that measures approx 24" x 33", projecting out 8". There are only a few inches of space between the vanity mirror and the wall-mount storage cabinet. Perpendicular to this wall is the wall which has the door opening: nothing can be mounted on this wall because the door is sliding "barn style"; in the "open" position, the slab conceals the entire wall space. (We used to have a swinging door but changed to sliding because an elderly family member had difficulty entering the bathroom with her walker--no longer a problem with the sliding "barn" door). One the wall where the window is, all space under the window is taken up by towel bars. We tried cutting back on towel bars and installing hooks elsewhere but it made life complicated for the elderly family member who uses this bathroom, so installing a heater on the wall below window is not an option. A couple inches to the left of the window is the shower stall; roughly 18 inches to the right of the window is the perpendicular wall that has the sliding "barn" door. It is within this span (2 stud cavities) that I was hoping to install a wall heater but, as stated in my earlier posts, it would be necessary to narrow studs. I am really hoping to find a ceiling heater that will fit, since there's no space for baseboard heaters nor surface-mount wall heater anywhere.

          1. Expert Member
            BILL WICHERS | | #20

            You might try a pocket door instead of barn door. Pocket doors slide too, but they slide INTO the wall so they don't require any clearance on the wall in the room itself. The downside is that if you're building a pocket door into a 2x4 wall, the drywall won't be as solid feeling after putting in the pocket door frame since you essentially take out so much of the studs to make it fit.


  7. Expert Member


    Are you sure you want to inset an wall mounted heater in an exterior wall? That makes insulation difficult and hampers efficiency. Is there no room for a surface mounted unit, or baseboard? Maybe something like this?

    I you do go with the Cadet, be careful as to where you situate towel bars or coat hooks. My one experience installing them in a unit at a resort ended badly. A guest hung his coat over a chair back, touching the face of the heater, and burned the place down.

    1. anonymoususer | | #9

      Thank you, Malcolm. Unfortunately, we truly have no space in that bathroom for baseboard nor surface-mount unit. Not counting the shower stall, theres less than 30 sq ft of floor space. The one cavity where we can meet all manufacturer clearances with no towel bar/hook is the cavity shown in foto. I wish we could use the product you link but unfortunately, there just is not the space. I am editing to thank you for encouraging us to think outside the box (or cavity, in this case): we just might find a decent ceiling heater that we can either install flush with surface or recessed into joist bay. A while back I read one or more GBA articles on choosing the right space heater. Will have to reread and go from there. I think ceiling mount will be our only option given space limitations / clearance requirements. Thanks!

      1. Expert Member
        BILL WICHERS | | #10

        Have you considered a ceiling mounted heater? That might eliminate the issue with the wall, and the insulating issue that Malcolm mentioned.

        Regarding the wall though, are those “honest” 2x4s that are actually 2” wide? If they are, you can probably replace one or both with “modern” 2x4s that are only 1.5” thick, to gain some space in the wall cavity. A ripped strip of plywood can be used to keep the stud depth the same for the finished wall to attach to.


        1. anonymoususer | | #12

          Thank you, Bill. We will follow your suggestion of looking into ceiling heaters, reading GBA articles on electric space heaters to guide us in choosing the appropriate ceiling-mounted model for our needs.

  8. user-2310254 | | #14

    Do you have a vanity in the bathroom? If so, you might have room for a toe-kick heater.

    1. anonymoususer | | #19

      We do, but it stands on four 6-inch decorative wooden table legs. Furthermore, there are fewer than 2 inches space between the shower stall and the right edge of the vanity. I could be wrong but fear the building inspector would have a fit over that. :-(

  9. Robert Opaluch | | #15

    I've used a heat lamp installed over the toilet in a small bathroom, controlled by a light switch. It quickly heated up the (otherwise unheated) bathroom. Just installed the lamp in a overhead fixture. Cheap and effective. However, the home was well insulated and airtight, so the heating load would be fairly low.

    I installed radiant heat panels in the ceilings of other rooms.

    There are radiant "cove" style heaters that could be mounted over the doorway or window to heat the small bathroom, and not take up space except on the walls adjoining the ceiling, above the head of occupants.

    Personally I would try to avoid messing with the framing, especially if you are unsure of the reaction of the inspector. Stay on their good side.

    1. Expert Member
      MALCOLM TAYLOR | | #16


      Robert's suggestion of a radiant cove heater is worth thinking about.

    2. anonymoususer | | #21

      Thank you, Bob, for these helpful suggestions. We already have an overhead lamp, but I suppose there is nothing wrong with installing a one- or two-bulb infrared heat lamp as well: the local Big Box store carries units requiring only 6 inches clearance on each side, and we should have no problem meeting that. Radiant heat panels in 2 ft x 2 ft (eg, Ductoterra Solaray) should work as well, since they apparently have no clearance requirement. The radiant cove style heaters unfortuntately will not work because if we were to install them such that the bottom of the heater was flush with the top of the door or window frame, we would not meet the 2.5 inch clearance needed between top of unit and ceiling. I like very much the heat lamp or ceiling panel suggestion. Which have your customers preferred? This bathroom is mainly used by an elderly family member who is always complaining of cold.

  10. andy_ | | #17

    You could also do a heated floor. It's quite nice to have warm tile underfoot in the winter and it compensates for any shortcomings in heat for the rest of the bathroom. I have it in our small bath and it's been the only source of heat (other than running the shower!).

    1. anonymoususer | | #22

      Thank you, Andy. I love your suggestion! Our local Big Box store carries a heated floor product called Warmly Yours. I am reading the product lit to find out if it's compatible with vinyl and/or linoleum floor covering. It is so hard for me to imagine that heated cables could be sandwiched between a plywood underlayment and vinyl or linoleum floor covering...? (Isnt that asking for fire?!) From what I have read so far, it appears a layer of thinset cement is required but I am not sure...still seems so risky (?) Need to confirm with manufacturer. What brand is in your bath?

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