Downlights lath and plaster ceiling advice please

[PJH2903]

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]

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.

 

[snowhead]

Take a small bag of patching plaster with you, just in case.
And warn the customer there could be some issues.

 

[Andy78]

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_]

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

 

[Midwest]

Cut a very large hole where each down light is going, install cable, then have client put up some new plasterboard and skim. Install down lights in new plastered ceiling.

 

[Taylortwocities]

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]

cut from above.

 

[Taylortwocities]

cut from above.

If you can, yes.

The issue, from below, I found is that the old plaster very quickly will blunt the holesaw. So I used an old one to cut through the plaster, then a new, sharp one to cut through the lathes. It is a real PITA of a job, IMO.

 

[Dustydazzler]

Do a few and see how it goes...

But forewarn the customer they might need to overboard the ceilings worst case

 

[Charlie_]

Don’t throw blunt hole saws away..
They come in handy for old plaster

 

[ruston]

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.

 

[The Ghost]

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]

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]

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.