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littlespark

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Sometimes you need to work in an old house, and there’s a number of threads on here about how to, say, fit downlights in a lathe ceiling.....

Here’s a start... on lathe and plaster walls without making a huge mess....

Mark where you want the socket to go. Height wise, measure an existing one from either the floor or the top of the skirting.
Tips from a pro..... 244132B3-C0A2-43F2-B6D0-41E6299F78A8 - EletriciansForums.net

Next, use a pad saw to find a gap between the lathes. Hit and miss jabbing with the saw until it breaks through.
Tips from a pro..... 000F67B4-FD5B-4D99-A618-53BD3FCFC593 - EletriciansForums.net

I will be using a regular dry lining box, so you don’t want to be too close to a vertical joist. Use the pad saw to feel to the left and right. If you can feel a joist, just adjust your planned position.

Tips from a pro..... 810E0380-C348-480C-BE14-18684CF45E5F - EletriciansForums.net

Once you have the final position, you can draw around a regular metal back box to give your cutout size.

Tips from a pro..... 30041AE4-3623-4FC5-9C6A-BD90F6C544B0 - EletriciansForums.net

Using a multi tool on a fairly slow speed, you can chip away at the plaster, but not the lathe quite yet.
yet.

Tips from a pro..... 6F575B83-56CC-45A5-B3C4-450DA7A3BA0C - EletriciansForums.net

Now, with the multi tool on a high speed and a fine toothed wood blade, you can cut neatly through the lathe without much problem. A small wood screw screwed into the middle of the lathe and held tight in pliers will help as the lathe will want to push into the hollow wall.
Tips from a pro..... 0767A9C8-44E8-4BA4-B331-0BDF05A98A03 - EletriciansForums.net

Now for the biggest tip I can give. Very very important whenever you are doing anything like this;



Always remember to charge your phone fully, or it will die when you’re in the middle of trying to make a hints and tips thread???
 
Sometimes you need to work in an old house, and there’s a number of threads on here about how to, say, fit downlights in a lathe ceiling.....

Here’s a start... on lathe and plaster walls without making a huge mess....

Mark where you want the socket to go. Height wise, measure an existing one from either the floor or the top of the skirting.
View attachment 86407

Next, use a pad saw to find a gap between the lathes. Hit and miss jabbing with the saw until it breaks through.
View attachment 86408

I will be using a regular dry lining box, so you don’t want to be too close to a vertical joist. Use the pad saw to feel to the left and right. If you can feel a joist, just adjust your planned position.

View attachment 86409

Once you have the final position, you can draw around a regular metal back box to give your cutout size.

View attachment 86410

Using a multi tool on a fairly slow speed, you can chip away at the plaster, but not the lathe quite yet.
yet.

View attachment 86411

Now, with the multi tool on a high speed and a fine toothed wood blade, you can cut neatly through the lathe without much problem. A small wood screw screwed into the middle of the lathe and held tight in pliers will help as the lathe will want to push into the hollow wall.
View attachment 86412

Now for the biggest tip I can give. Very very important whenever you are doing anything like this;



Always remember to charge your phone fully, or it will die when you’re in the middle of trying to make a hints and tips thread???
M12 CMT? If it is a 12v, do you rate it? I know 18v will have more punch but I've got a bucket load of M12 batteries, thinking just basic jobs like drywall, breaking the tongue between floorboards etc
 
M12 CMT? If it is a 12v, do you rate it? I know 18v will have more punch but I've got a bucket load of M12 batteries, thinking just basic jobs like drywall, breaking the tongue between floorboards etc
The multi tool? M12 Free gift from Howdens for opening an account.

Good enough for what I need it for
 
Sometimes you come across very thick old plaster and can fit a metal box flush directly on the laths, can be a little bit bouncy though and you need to be careful not to split the laths.
 
I try to position them actually on the vertical joists in a metal box. Even if the 25mm sits a little proud you can take a small bit out of the joist.
You lose a little in the choice of area you can have it, but it's a much easier and stronger fit.
 
Yes I've done that as well HHD, although the majority these days seem to just whack a surface box straight above the skirting. ?
 
another tip. totally unrelated but...... when you remove a redundant accessory, before binning it, save the terminal screws ( aslong as undamaged). the number of times i've taken ,say, a new cooker switch out of the van stock to find that 1 or 2 screws have worked loose in transit and disappeared for ever is ridiculous.
 
i'm referring to terminal screws, not 3.5mm pins.
And yet can you buy a pack of say 100 (brand specific) from a wholesaler? Can you hell, you think they would knowing this sort of thing happens.... Maybe they ship them out backed off and held in by a to test bit of thread, look at it wrong and poof there goes the screw
 
For what its worth: Vertical support members in a wall are studs, joists are horizontal support members normally in a floor or ceiling.
 
Fitted many hundreds of sockets into lath and plaster walls over the years, have tried the methods detailed in this thread, but have found that any that leaves a cut end of laths unsupported will eventually cause problems.
The method I eventually settled on was to cut a rectangle of lath and plaster away, making the vertical cuts in the centre of the adjacent studs, down to the skirting board (especially pre part M) and horizontally just above the top of the proposed socket, and also removing the plaster from the next lath up.
At this stage, you could get a drill inside the wall, and drill a nice central hole down to the space below the floorboards to bring the cables through, then fit a good solid noggin between the studs to screw a metal socket box to. Finally comes two layers of plasterboard, either 9.5mm, 12.5mm, or one of each, depending on the surrounding plaster thickness, with the outer one overlapping the lath left at the top, to reinforce the join when it's skimmed over.
 
but have found that any that leaves a cut end of laths unsupported will eventually cause problems.
Exactly this. The plaster to the sides of the cut out is not supported, so very weak. It can be reinforced though, using timber battens, without too much trouble:

  • Cut the hole out of the lath and plaster for the backbox with multitool (we're gonna use a steel BB).
  • Cut a couple of timber battens, something about 2" X 1" should do. They're going to go inside the wall, vertically, to either side of the hole, and need to be long enough to extend beyond a couple of un-cut laths, both top and bottom. About 150 - 200mm long is about right.
  • Reach inside the hole, and carefully pull away the plaster 'keys' from either side of the hole where the battens are to go. We want the battens to press right up against the back of the laths without being fouled by any bits of plaster.
  • Now the fiddly bit.
  • Liberally coat the face of one batten with PVA, water based gripfill, or similar. Maneuver the batten through the hole and into position vertically to the side of the hole, glue side pressed up against the back of the laths. Hold in place, and drive a screw through the plaster, through an un-cut lath, and into the top of the batten. Repeat for the bottom of the batten. You can put screws through the cut laths into the batten too if you like.
  • That side is now reinforced, and will be about as strong as you can hope for in a lath and plaster wall. Do the same for the other side of the hole with the other batten. You can now fix the backbox in place by screwing through the sides into the battens.
  • Filler over the screw holes and you're done.
 
Exactly this. The plaster to the sides of the cut out is not supported, so very weak. It can be reinforced though, using timber battens, without too much trouble:

  • Cut the hole out of the lath and plaster for the backbox with multitool (we're gonna use a steel BB).
  • Cut a couple of timber battens, something about 2" X 1" should do. They're going to go inside the wall, vertically, to either side of the hole, and need to be long enough to extend beyond a couple of un-cut laths, both top and bottom. About 150 - 200mm long is about right.
  • Reach inside the hole, and carefully pull away the plaster 'keys' from either side of the hole where the battens are to go. We want the battens to press right up against the back of the laths without being fouled by any bits of plaster.
  • Now the fiddly bit.
  • Liberally coat the face of one batten with PVA, water based gripfill, or similar. Maneuver the batten through the hole and into position vertically to the side of the hole, glue side pressed up against the back of the laths. Hold in place, and drive a screw through the plaster, through an un-cut lath, and into the top of the batten. Repeat for the bottom of the batten. You can put screws through the cut laths into the batten too if you like.
  • That side is now reinforced, and will be about as strong as you can hope for in a lath and plaster wall. Do the same for the other side of the hole with the other batten. You can now fix the backbox in place by screwing through the sides into the battens.
  • Filler over the screw holes and you're done.
I find this the best method also. ^^^^^^^
If possible though I build a "saddle" out of ply wood that you can fit through the cut out and twist into position.
The saddle is made of 2 stirps of ply as the vertical battens then one strip screwed to the back as the horizontal batten. I pre drill the fixing holes so not to split the lath's and then pull the saddle tight up against the inner wall whilst inserting the fixing screws. The back box can then be fixed in place, packed out if required to the depth needed. This method works best on double socket outlets as the saddle slides through the wider gap then twisted into position.
 
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