We are preparing to plaster up the hole in the wall left by the metal box that contained the previous thermostat console. I was thinking of doing this by first building up a layer or two of undercoat bonding and then applying plaster. However, there is a weak looking wooden batten directly behind the hole that needs to be filled: The original thermostat box was screwed onto this wooden batten. It feels like it is not attached to anything on its right hand side situated behind the wall. What on earth should I do about this before commencing with the undercoat bonding? Cut away the batten? Or insert chicken wire in front of it?
Screw through plasterboard both sides with 38mm drywall screws, two each side, cut a small piece of plasterboard to fit the hole, screw to batten, cover joins with scrim tape, skim or tape and joint. No need for bonding.
Should I be screwing through the existing wall face either side of the hole so that the screws go through both the plasterboard wall and the batten beneath? Thank you for the great advice Wish there was a donation system!
I first used a cordless drill on low torque but once the screw caught the batten and pulled it forward towards the plasterboard the whole screw then went through the plaster: So I tried again screwing slowly by hand, but while the screw is now as far in as I dare without the plasterboard cracking any further, the screw head is not flush. Surely I cannot joint and plaster over this? What should I do?
I have gone in as slowly as possible by hand with these drywall screws and it has happened again, now even worse: It would seem that the tension of the springy batten is pulling the screw further in with a pressure which is too much for the plasterboard to bear? Surely now it would just make more sense to cut out the batten with a multitool?
Ultimately you're doing this to 'firm up' the timber, so that it doesn't have much movement in it like in your original post. As long as at least one screw either side has caught it, and pulled in to the plaster/plasterboard, it will be fine. You can then fix a small amount of plasterboard to the timber and then fill level with surface around (as well as the countersunk screws at the same time. You could place a bit of filler in amongst the 'damaged' section of plasterboard before fitting additional section of plasterboard for a bit of added security.
Remove the screws that you've tried. Squirt a load of stixall (or similar) into the area between the batten and the broken board and also into the broken plasterboard as well. Using another batten across the hole, screw through that into the springy batten and pull it up tight effectively clamping the broken plasterboard. It would be best if the second batten was predrilled. Once the adhesive has cured remove the external batten and fill the hole.
You should have used a spacer (e.g. a timber offcut or some other pieces of plasterboard offcuts) to fill the gap between the timber and the back of the plasterboard. That would have firmed things up without pulling the screws right through the outside plasterboard.
Thanks for explaining. I guess with both screws fully sunk now, at least the batten no longer moves when I poke it: Should I use any type of filler in particular?
Easi-fill is brilliant stuff, homebase sell if i remember correctly, a box that contains 5x1kg bags (lasts longer as opposed to opening one big bag which will go off) So back to original plan of trimming a piece of plasterboard to fit, bit of scrim tape around the side and perhaps cover screw holes too, then fill and sand smooth when dry. Might take a couple of goes
Where you went wrong was by firstly using the wrong screw, possibly using the wrong bit for the screw ie using a pozi2 when it should have been a Phillips2, but your largest faux pas was you didn’t pull the batten tight to the plasterboard with your finger whilst trying to drive the screw, all it does is muller the plasterboard trying to push the screw through as plasterboard is a soft material. If you have to do this again and you can’t get your fingers in to pull the timber tight to the plasterboard, drive a screw into the timber about halfway through and use the screw as something to grip to pull it.
Funnily enough, I had my hand fully inside the hole and the batten pulled flush up to the back of the plasterboard the whole time. I also used the exact screw that you recommended and the pozi bit specified on its packaging But so as not to seem ungrateful I will of course defer to your greater experience.