Packing out studs to get them plumb.

[lc155]

Hey all,

Working on a wall where the studs are old and just a mess. Aside from being twisted (which I planed flat as best I could), they're also not plumb and lean back a fair bit.

The simplest way to fix this would be to sister a whole new bunch of studs all plumb and job's done. That's the quick fix, but as I'm insulating I want to maximise the insulation, so doing it the hard way.

I don't have the skillset to rip full length timber wedges from studs to make a perfectly cut furring strip all the way top to bottom, so ruling that one out too.

So, last option seems to be shimming. I've measured about 5cm from the doorframe (since I don't have bottom plates in this old house to measure from) and shot a laser line (which I also squared with the adjacent wall since that was off too). This makes it much simpler as I can just keep referring to a tape measure and aim to hit the same measurement that the laser hits on the tape everywhere. Sadly, we don't have the easy rolls of felt/cardboard shims like they sell over in the US, so I've had to cut strips of hardboard and tack it to the face of the studs in layers to pack it out to get close to the laser line measurement. From there, I mark roughly where screws will go in (so every 300mm) and pack it up with either cardboard or plastic packers to ensure solid contact.

So far so good, I hope. However, what do I do with the spaces between each final packer? Want to avoid any situation in the future where the plasterboard could bow in those areas and deform (such as something being fixed to the wall over a small gap). Would using an adhesive that sets solid like gripfill or pinkgrip work? I'd just gun it in the gaps before screwing the plasterboard on and hopefully it spreads out and fills it all.

I've included an attached diagram that hopefully makes more sense.

 

[RrogerD]

I think that you're making things hard for yourself and creating more of problem than you are trying to resolve.

If you aren't able to rip full-length wedges, remember that you'll need to the same on the other side also then, simply embrace the twists. It's an old house, it's going to have quirks.

Leaving gaps between packing shims is going to be a problem with bowing, especially along plasterboard joints.

 

[lc155]

I think that you're making things hard for yourself and creating more of problem than you are trying to resolve.

If you aren't able to rip full-length wedges, remember that you'll need to the same on the other side also then, simply embrace the twists. It's an old house, it's going to have quirks.

Leaving gaps between packing shims is going to be a problem with bowing, especially along plasterboard joints.

The other side is a finished wall (with laths) so can't be touched, so I'm just focusing on the current problem. I'm also a bit too OCD for the whole 'old house thing.' If I'm in a position where I can fix something up I may as well.

And yes, the question is about the gaps. Which is why I'm wondering what I can use to fill those gaps that sets hard when screwing the plasterboard on.

EDIT: I forgot to mention I will be putting up plasterboard horizontally, so the joins will be at noggins I screw in myself. No issues with joins cracking.

 

[RrogerD]

Much as it pains me to say it (I generally hate the stuff), possibly try expanding foam, to fill in the small gaps?
Affix boards into place and then drill holes at the uprights and squirt foam into each. Be sure as not to use too much as it expands to double it's size (?). I'd probably also screw facing-plates at each foam-injected position to avoid the boards being pushed outward as the foam expands. Obvs remove plates after foam has set hard.

 

[SFK]

simplest way to fix this would be to sister a whole new bunch of studs all plumb and job's done. That's the quick fix, but as I'm insulating I want to maximise the insulation, so doing it the hard way.

Put new studs, not touching old studs or back wall, in middle of old studs and slightly (a couple of cm) forwards.
That will improve sound and thermal insulation as free standing from old studs wall and easier to put in place.

 

[StephenStephen]

How about a thin piece of ply screwed either side of the stud then infill over the stud in between them with plaster or caulk or something?

 

[robinbanks]

If you're really bothered about it, fit the plasterboards to the side you've packed out then fill the interstitial gaps beweeen packers with expanding foam. It'll bind the PB to the stud and stop any bowing unless you really wang a fixing into it

For the future concern about fixing things to the wall, just remember that's the wall with the voids and screw in near existing screws (use a magnet to find) or don't screw the thing up so tight you crush the PB; line the back of the thing being fixed with adhesive, and screw it up so it's nipped firm but not crushing the PB. If you feel you do need to screw it really tight, drill a hole for the screw to go through, pump a load of grip fill through it and let it set solid, then screw through. You don't need to fill everything now, just fill wherever you put a fixing in future. If you don't think you'll remember which walls are which, pre drill every plasterboard before you fix; the drill bit will tell you whether there is a gap behind the PB or not, as if there is a gap it will slide with no resistance a short way, after it emerges the back of the PB and before it hits the stud

Put new studs, not touching old studs or back wall, in middle of old studs and slightly (a couple of cm) forwards.

Diminishes insulation though and OP has said they don't want that

Affix boards into place and then drill holes at the uprights and squirt foam into each

If you're fixing the first side of the wall you can foam them up after you fit the board and not need holes. If you're fixing the second side of the wall you can apply the foam to the stud, wait a short while for it to acquire some structure, then fit the plasterboard and not need holes there either

to avoid the boards being pushed outward as the foam expands

It's not that strong; foam will simply press out the sides of the gap rather than bending a 12.5mm plasterboard fixed at most 150mm away

 

[robinbanks]

.

 

[Notch7]

Ideally you should try sawing tapered pieces - it’s perfectly possible with a rip saw.

but as an alternative here is an option:

fix a taut string line to the position you want for the face of the studwork vertically

get some thin timber battens or thin plywood, put It on the stud packed out at top and bottom positions to line up with string line. Then put in sufficient packers so your strip ends up following line of string line. Then get use mastic gun and put in a bead of silicone both sides so the strip is fully supported.

job done.

 

[lc155]

If you're really bothered about it, fit the plasterboards to the side you've packed out then fill the interstitial gaps beweeen packers with expanding foam. It'll bind the PB to the stud and stop any bowing unless you really wang a fixing into it

For the future concern about fixing things to the wall, just remember that's the wall with the voids and screw in near existing screws (use a magnet to find) or don't screw the thing up so tight you crush the PB; line the back of the thing being fixed with adhesive, and screw it up so it's nipped firm but not crushing the PB. If you feel you do need to screw it really tight, drill a hole for the screw to go through, pump a load of grip fill through it and let it set solid, then screw through. You don't need to fill everything now, just fill wherever you put a fixing in future. If you don't think you'll remember which walls are which, pre drill every plasterboard before you fix; the drill bit will tell you whether there is a gap behind the PB or not, as if there is a gap it will slide with no resistance a short way, after it emerges the back of the PB and before it hits the stud


Diminishes insulation though and OP has said they don't want that


If you're fixing the first side of the wall you can foam them up after you fit the board and not need holes. If you're fixing the second side of the wall you can apply the foam to the stud, wait a short while for it to acquire some structure, then fit the plasterboard and not need holes there either


It's not that strong; foam will simply press out the sides of the gap rather than bending a 12.5mm plasterboard fixed at most 150mm away

If you're gunning gripfill in later on, why wouldn't I be able to just bead some down the voids before installing plasterboard? Is it too viscous and may not be pushed aside like the foam to fill the void when screwing on? Does it go off too quickly? If the latter, wouldn't the much longer working time solvent free stuff work there? Just trying to work it out as I've already tacked on hardboard and packers, so just gunning in gripfill (kind of like wet shimming?) and moving on would be the quickest way, but if there's a reason not to do that then fair enough.

How about a thin piece of ply screwed either side of the stud then infill over the stud in between them with plaster or caulk or something?

So you mean like wet shimming the whole length of the stud, with the screwed in ply acting as guides? I guess that'd be one way to do it.

Ideally you should try sawing tapered pieces - it’s perfectly possible with a rip saw.

but as an alternative here is an option:

fix a taut string line to the position you want for the face of the studwork vertically

get some thin timber battens or thin plywood, put It on the stud packed out at top and bottom positions to line up with string line. Then put in sufficient packers so your strip ends up following line of string line. Then get use mastic gun and put in a bead of silicone both sides so the strip is fully supported.

job done.

Oh, I know it's possible and see it done—I'm just not good enough to get straight cuts doing it that way. Not great cutting regular wood, never mind down the whole length and tapering to zero! Disaster for the humble DIYer like me (honestly dealing with the imperfections of timber makes me wish the UK had moved onto steel studding as standard like France does, then you never have to worry about your walls not being straight and true).

So you're suggesting lining plywood with the laser, then filling the voids with mastic? Basically what I was thinking of but in reverse?

 

[robinbanks]

If you're gunning gripfill in later on

Why use gripfill in 99% of places where it's not necessary when you only need a bit round the odd screw hole in the future?

However, if you want to put it in now it'll save having to remember to do it later. Maybe use plasterboard adhesive (or some other powder+water) instead of gripfill; could work out to be a lot of gripfill

Don't overthink it..

 

[lc155]

Why use gripfill in 99% of places where it's not necessary when you only need a bit round the odd screw hole in the future?

However, if you want to put it in now it'll save having to remember to do it later. Maybe use plasterboard adhesive (or some other powder+water) instead of gripfill; could work out to be a lot of gripfill

Don't overthink it..

Mostly because I'm a perfectionist, is all. The worst voids are only around 3mm deep, as the hardboard I've stacked up is 4mm thick per strip. I imagine filling those wouldn't have used too much gripfill.

 

[lc155]

Why use gripfill in 99% of places where it's not necessary when you only need a bit round the odd screw hole in the future?

However, if you want to put it in now it'll save having to remember to do it later. Maybe use plasterboard adhesive (or some other powder+water) instead of gripfill; could work out to be a lot of gripfill

Don't overthink it..

Actually, I do have some spare tubs of tile adhesive. The Americans seem to love 'wet shimming' with thinset. Maybe that'll work well to fill the gaps?

 

[robinbanks]

Go for it, should be a real quick op, just before you fit a board, to whip down the stud wiping a wedge of adhesive off as if you're trying to clean your trowel, and let the plasterboard press it into place

 

[lc155]

Just one more quick question. I've been trying to glue the packers with a spare tube of stixall I've had and while they do adhere, the stixall doesn't seem to glue to the plastic very well, so they're easy to dislodge. Could leave it that way but worried screwing the boards in may dislodge them if they're not stuck well.

If the stixall doesn't stick to plastic very well, any other adhesives do the job? Don't know if gripfill or the classic solvent stuff does a better job or not.