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My house was built in 1979 and is located in Quebec, Canada. I was trying to find stud behind my wall (it is an exterior wall) but my stud detector was returning nothing. I decided to cut the drywall to see how it was made. I stumbled on what seems to be fiberboard. There is 1/2 inch between the drywall and the fiberboard.

wide shot of the wall showing cut drywall with particle board behind it

detail shot showing the particle board & drywall

  • Why is there fiberboard there?
  • What is this construction technique?
  • How can I found my stud without poking around with a nail and ruining the vapor barrier ? (Not sure if it will?)
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  • Was your home built after the Great War? I have remodeled homes that had fiber board covered by coats or layers of wall paper+ Drywall. Some We’re glued to the fiber board, in those cases it was an asbestos based glue (the ones that I had to have tested only the black had asbestos) the cream color did not. I remember these houses were under 1100 sf closer to 7-800 single bath. additions did not have the brown compressed fiber board material some call beaver board but not the same as todays beaver board, get a stud detector that can handle stucco it found them 4 me cost a bit more but worked.
    – Ed Beal
    Commented Feb 10, 2022 at 0:57
  • Would expect the fiberboard on the outside(under siding). A 1/2 inch space should mean there are 1x? furring between drywall and fiberboard.
    – crip659
    Commented Feb 10, 2022 at 0:58
  • @crip659 , after the Great War ~1920 and until the early 40’s fiber board was a common interior finish that was skim coated or wall papered in trac homes of the day (or less expensive smaller homes). It was the bridge between plaster/lath add sheet rock, drywall or gypsum board, became the standard after the housing boom after ww2 fiber board was not legal in many locations. But it was a common low end interior “board” that was covered much like drywall/Sheetrock is today but wall paper was much more common in those days.
    – Ed Beal
    Commented Feb 10, 2022 at 1:11
  • We use fiberboard for sound control. Maybe the house is near a street, shops, etc. and the fiberboard was used to help the STC rating of the wall. I’m sure the fiberboard is attached to the studs. If you find one nail you might be able to measure over 16” or 24” to find other studs.
    – Lee Sam
    Commented Feb 10, 2022 at 6:32
  • It's likely that the drywall is installed over lath strips as @crip659 noted. It's likely those strips are nailed directly over the studs behind them. Keep cutting the drywall left or right until you find the strips then run a thin drill bit in. You will most likely find that it's solid as far back as you can go. DO NOT go too deep, there could be wiring in this exterior wall and you don't want to drill through that.
    – FreeMan
    Commented Feb 10, 2022 at 14:58

1 Answer 1

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This technique is used for sound management. The extra mass and space created reduces sound transmission between rooms (or residences, in the case of condominiums, etc.) and from the exterior.

You should be able to locate fasteners in the fiberboard or furring strips to find studs. A deep-scan studfinder may see them.

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