What is causing these screw pops?

[pulck]

I had a loft conversion done a few years ago. About a year later, I started getting screw pops along one edge of a bathroom wall. (The bathroom is at the rear of the dormer and this is the rear wall.)

Someone told me to scrape out the plaster over the affected areas, tighten the screws behind, and then fill and repaint. However, the screws wouldn’t tighten further, so I just filled over them.

About a year later, the screw pops have returned in the same area. I’ve now scraped them out again, but before repairing I’d like to understand the underlying cause.

What I've noticed is that the screws are very long - about 12cm - and have been driven in at an angle rather than straight. They've also been driven in quite deep, sometimes 1cm into the plaster. When I tried to drive in an 8cm drywall screw just below one of the existing ones, it did not connect with a stud.

Does this suggest the stud is somehow positioned oddly and that the boards weren't fitted properly?

Since the screws won't tighten, what should I do before refilling to stop the screw pops coming back?

Sorry for the dumb questions - I have little to no knowledge of plastering.

 

[foxhole]

If screws don’t tighten they allow movement which causes the plaster to pop .Cant see any plasterboard in pics ?

 

[pulck]

If screws don’t tighten they allow movement which causes the plaster to pop .Cant see any plasterboard in pics ?

I just assumed there was plasterboard but maybe not. If that's the case, what are these screws for?

 

[foxhole]

I just assumed there was plasterboard but maybe not. If that's the case, what are these screws for?

Remove a screw and replace with one 10-20mm long to see if it bites .

 

[robinbanks]

when you say the screws won’t tighten, what kind of driver are you using to determine this

 

[pulck]

when you say the screws won’t tighten, what kind of driver are you using to determine this

I've been hand tightening. I have an impact driver but didn't think it a good idea to over tighten, right?

 

[pulck]

Remove a screw and replace with one 10-20mm long to see if it bites .

The existing screws are drywall screws. So when I remove one, the hole is too wide for any very short screws I have to bite at all, so I'm not sure what this would prove.

I can tell you that the existing screws any bite right at the end of driving them in. Doesn't that suggest there's timber far behind the plaster. But if this isn't plasterboard, what purpose are these screws serving?

Again, sorry if these are dumb questions!

 

[Harry Bloomfield]

I can tell you that the existing screws any bite right at the end of driving them in. Doesn't that suggest there's timber far behind the plaster. But if this isn't plasterboard, what purpose are these screws serving?

If they are only biting right at the end of screwing them in, then stopping solidly, they must be hitting something hard at the bottom of the hole - preventing them screwing in further. in which case - If you saw the tip of the screws off, that should allow them to screw in a little further.

 

[pulck]

If they are only biting right at the end of screwing them in, then stopping solidly, they must be hitting something hard at the bottom of the hole - preventing them screwing in further. in which case - If you saw the tip of the screws off, that should allow them to screw in a little further.

Would you mind explaining why this will help? The existing screws are already pretty deep in the plaster. Will making them deeper stop the screw pops happening? Also, I would love to understand what these screws are actually doing.

 

[Harry Bloomfield]

Also, I would love to understand what these screws are actually doing.

The screws are there, to fix the plasterboard, to the sub-surface. If the plaster is popping off the tops of the screw heads, then obviously the plasterboard is moving in relation to the screw heads, which suggests the screw heads are not holding the PB tight enough. You are suggesting the screws will not tighten, which suggests that the screw sharp-end, is hitting something very hard. Shorten the screw, and it should screw a little further, tightening the head against the PB.

 

[opps]

120mm screws? That is freakishly long.

It sounds like someone has driven the screws too far into the plasterboard.

Plasterboard screws normally have a bugle profile and are designed to sit just under the plasterboard skin.

 

[pulck]

120mm screws? That is freakishly long.

It sounds like someone has driven the screws too far into the plasterboard.

Plasterboard screws normally have a bugle profile and are designed to sit just under the plasterboard skin.

Exactly! That's why I'm asking what the purpose of these screws is - so that I can get to the bottom of what's causing the screw pops.

They are drywall screws and, as I said before, they are driven in at an angle, quite deep into the plaster. And when I try removing and reinserting them, they don't bite until they hit something way behind the plaster. Is it possible the stud was placed oddly and the plasterer essentially bodged the job? I'm really confused!

 

[opps]

Exactly! That's why I'm asking what the purpose of these screws is - so that I can get to the bottom of what's causing the screw pops.

They are drywall screws and, as I said before, they are driven in at an angle, quite deep into the plaster. And when I try removing and reinserting them, they don't bite until they hit something way behind the plaster. Is it possible the stud was placed oddly and the plasterer essentially bodged the job? I'm really confused!

From the photos, it kinda looks like you have plasterboard over a moisture resistant backing (maybe).

I would expect that there is a timber stud running along the wall. I have no idea why the screws are at an angle.

I suspect that the problems are the result of the screws being buried to too deep.

Try drilling above or below the screws holes and see if you can get a decent fitting.

Standard plasterboard is 9.5+mm the backing might 18(?)mm. If so, a 50mm plasterboard screw might suffice.