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Discuss Downlights lath and plaster ceiling advice please in the Electrical Forum area at ElectriciansForums.net

PJH2903

Regular EF Member
Been asked to put a load of downlights into a lath and plaster ceiling. Done plasterboard but not lath and plaster. Is it easy enough to do or will it be a right pain?
 

Gavin John Hyde

Electrician's Arms
Its not too bad, often find though that when drilling the holes for the lights the lathe can flex a bit so you have to put a bit of effort in, also if you have that horrid grey plaster full of flint and stuff it can ruin a holesaw. I had a job last year where the lathe started smouldering from being cut as the saw got so hot going through it. if you are worried about the ceiling loosing its strength afterwards then a good dollop of fast drying glue or grab adhesive up in the ceiling on top the edges around the hole helps to strengthen it.
 

Andy78

Respected Member
As above, factor in a new holesaw into the cost.
Brief the customer that the outcome depends on the age and dryness of the plaster. I have seen this job go fine and end in complete disaster when the plaster is so dried out it has come off in large swathes when disturbed.
 

Charlie_

Electrician's Arms
Choose a fitting with a small cutout but with much larger outer diameter.
Also can you get above the ceiling?
If so cut up some thin pieces of ply with holes in. Then your fitting can push up through the board.
Good quality springs that nearly break your fingers are handy too
 

Taylortwocities

Electrician's Arms
I’m with Midwest. The L&P downlight installs that I have down have been a right pain. Even with a new,sharp hole cutter, the laths are so dry they shear off in very inconvenient places.

Only take this sort of job on a time and materials basis.
 

telectrix

Scouser and Proud of It
Respected Member
cut from above.
 

ruston

Respected Member
If the ceiling already has signs of , or repaired cracks in it ; as @Andy78 be prepared - and warn your customer of possible disaster.
It is difficult to give a price for this sort of job , so take care.
 

Vortigern

Regular EF Member
It is a very tenuous thing to do. The outcome is very unpredictable. What is certain is that if you do manage to drill a clean hole, you can't keep putting the light in and out of the ceiling as the hole will deteriorate very rapidly. I hope the lights you propose have a large halo as this does help in concealing the first plaster of paris layer you hit that crumbles really easily. I think I remember seeing recessed lights that have a separate collar you can insert that obviates crumbling edges as they are contained within the separate collars inserted into the hole prior to fitting the light.
 

Dustydazzler

Regular EF Member
It is a very tenuous thing to do. The outcome is very unpredictable. What is certain is that if you do manage to drill a clean hole, you can't keep putting the light in and out of the ceiling as the hole will deteriorate very rapidly. I hope the lights you propose have a large halo as this does help in concealing the first plaster of paris layer you hit that crumbles really easily. I think I remember seeing recessed lights that have a separate collar you can insert that obviates crumbling edges as they are contained within the separate collars inserted into the hole prior to fitting the light.
Many years ago there were several manufacturers who made a specific collar for their DLs to use for lathe and plaster ceilings.

I have even seen one electrician use no nails glue to hold DLs in a lathe ceiling , all well and good until the next poor sucker has to pull down....
 

Marcus Vaughan

Regular EF Member
Been asked to put a load of downlights into a lath and plaster ceiling. Done plasterboard but not lath and plaster. Is it easy enough to do or will it be a right pain?
You have good advice there already. Would definitely agree the outcome is unpredictable. I have put plenty in where no filler or patching is required, and its always a sigh of relief, but only this week had a bit of disaster where plenty of plaster came away and left me with a mess to patch up - and that's no easy task once the plaster starts to separate from the lathes.

Go slow with the drill (on the plaster bit)

Agree to look for clues as to the state of the existing plaster, look for cracks and sagging, get on the stepladder and press the plaster to try and get a feel for its condition.

I'd also be interested in recommendations for the best down lighter to use to tackle lathe and plaster.
 

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