Screwing tinto a hard wood section behind the plasterboard?? (much wider than a stud)

[J_Me]

I have a house built in 2016 - with mostly plaster board hollow walls.

I’m a novice at DIY, but (with a lot of googling/Youtube) I’ve successfully used ‘GripIt’ fixings to put up heavy mirrors/art on the plasterboard. I was planning to use them for the floating shelves I wanted to put up.

BUT, I’ve discovered about 40cm of the wall near corner of the lounge (where I want to put shelf brackets) doesn’t sound hollow when knocking.

It’s the outside wall of a semi. The green dotted lines in the photo are the ‘normal’ studs. The yellow scribble (~40cm wide) is the harder bit. The ~10cm nearest the corner does feel very hard, brick maybe (but I don’t need to drill/screw quite that close to the corner.)

I wondered if this stretch could be a large plank of wood (I’ve tried googling stud walls and corners, & am just overwhelmed.) Might this be the case in a relatively modern house?

And if so, am I right in understanding I can just screw the screws [that came with the shelves] directly into the wall (i.e. no drilling a hole first, no rawl plugs??)

I want to put a heavy ornament on it, & checked the limit for the shelf which said “Maximum load: 20 kg” and I’d planned to use red GripIt fixings ('up to 74kg,) so am concerned I get it right!

Any tips are appreciated. Thank you in advance.

 

[Alec_t]

doesn’t sound hollow when knocking

That's not a reliable indication of what might be behind the plasterboard. If you're going to be fixing things to walls, a metal/pipe/wire/stud detector would be a worthwhile investment.

 

[foxhole]

You won’t know till you put a hole thru the plasterboard. No pipe/ stud detector is going to tell you.

 

[J_Me]

You won’t know till you put a hole thru the plasterboard. No pipe/ stud detector is going to tell you.

I thought that about putting a hole through, but when searching for what rawl plugs/fixings one uses for wood, I found you don't drill a hole first

 

[foxhole]

I thought that about putting a hole through, but when searching for what rawl plugs/fixings one uses for wood, I found you don't drill a hole first

No need to drill just push a screwdriver thru , small blade , if it sticks into what’s behind its wood and you can screw direct to it.

 

[J_Me]

No need to drill just push a screwdriver thru , small blade , if it sticks into what’s behind its wood and you can screw direct to it.

Ah, thank you for that idea (I have thin precision screwdrivers that wouldn't make much of a hole.)

 

[Alec_t]

You won’t know till you put a hole thru the plasterboard.

Agreed. But it's nice to be reasonably sure that you won't be poking that exploratory hole through a wire or pipe.

 

[J_Me]

Thank you both. Simple knocking's clearly not a reliable indication in itself. TBH I wasn't just going to assume, I came searching first.
I had a little poke (after turning the downstairs fuse box off - which I alway do before drilling into a wall. I'm inexperienced at DIY, so hesitant, but not cavalier.)
After the normal plaster board, there is a small gap. Even though my amateur knocking in a certain spot sounds different, the plasterboard doesn't go straight into wood. It's about 4cm deep before hitting (poke-able) wood not rock hard brick. I tried a long thin screw (thinner than I'd want to use for a shelf), which obviously wasn't firm through the plasterboard. So I guess I go back to my original plasterboard fixings!

 

[btjtaylor]

Is there a socket or switch nearby you can remove? Will give you a clue as to the wall construction

I can see in your photo there is a double socket, you might find the patress box is attached to a timber stud (all of mine are in my 2020 new build), will give you a good starting point. The studs should be evenly spaced, usually they're about 40cm

When i'm mounting stuff, if I find a stud, I just go straight into it with woodscrews

I'm quite fortunate in that I managed to go roudn the whole property when it was just stud walls and take photos, so I know where all the pipes/cables *should* be, but it's best to check as assumptions make an ass of U and me

 

[lostinthelight]

I may be wrong but thought within 150mm of a corner was classed as a zone for electrical wiring so extreme care needed