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I'd like to hang a gas central heating vertical radiator on a single timber stud behind a thin plasterboard wall. The stud is 38mm wide (actual size) and (presumably, difficult to measure) around 75mm deep. The radiator would weigh around 35kg in total, spread across a number of screws which can vary between four and ten (I have some freedom with that).

Would that be ok? If yes, what screw size would you recommend?

Thank you.

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You didn’t give us all the info we need, but I’ll make some assumptions and you tell me if I’m wrong.

Calculating the maximum load depends on 1) species and grade, 2) length of stud, 3) fastened to narrow side or wide side of stud.

  1. I’d use a common species (here in the U.S.) of SPF and a common grade of No. 2 and Better.

  2. I’d use 8’ unsupported length. (If the actual length is longer, then the value will be less…and shorter will be more.) If the “thin plasterboard” can hoLd the stud in line so it doesn’t bend, then it could hold significantly more.

  3. If load is fastened to narrow side it will be significantly more than narrow side due to buckling. I’ll use wider side.

Your stud is about 1.5” x 3”. (Our standard stud is 1.5” x 3.5”.) I’ll use your stud size.

Therefore, checking for bearing parallel to grain, the maximum allowable load is 1,200 psi x 1.5” x 3” = 5,400 lbs. However, if the stud is resting on another stud, the maximum bearing value is 385 psi x 1.5” x 3” = 1,732 psi before it starts crushing.

Columns tend to buckle when loaded. In fact, loads fastened to columns with a bracket that holds the load off the side by, say 12”, will cause the column to buckle much sooner than one fastened directly to the column. I’ll use one fastened directly to the column and it is 1,160 lbs. you’ll have to convert to kg.

Therefore, bending governs in the design.

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  • That's excellent, thank you! I'm fastening my hang load to the narrow side, btw, and the stud is about 230cm high. I'm afraid it's unsupported along its whole length (apart from the 9.5mm drywall in front of it, which I'm not sure can be considered support). Finally, the center of mass of the hung load is about 8cm off the face of the stud.
    – anon
    Jun 19, 2021 at 15:30

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