Holding conduit in chase prior to plastering

[Tim S]

Hi,

Anyone got a method that's faster than this:

pin in B&Q pin plug, pin bent over).

I tried cut off (cut the plastic end off to make an L-clip) 10mm2 cable clips bashed into the mortar line, but the mortar is too random. Bent the nail half the time. Otherwise worked well.

Tried No-more-Nails. Not strong/fast enough, especially on dusty brick.

Can't cut the chases to naturally hold the conduit - need an oversized cut to accomodate SDS chisel...

The problem arises from the back boxes, where the knock out is set back, so there's a bit of a bend on the last section which tends to pop the middle section proud of the surface.

My method at top works, but it's a bit painful with all the drilling and wibbling. Wondered if anyone had a faster trick?

Cheers

Tim

[js.b1]

1 - Use a chisel that is not much wider than the oval & wiggle it re edge-grip.

2 - Oval Conduit Hoop Clips into the mortar. TLC sell them in various sizes.

3 - Pieces of cut 1mm plastic snapped into the cutout to hold the oval in (or oversized nylon P-clips), remove as you plaster in. Bit of bonding plaster with PVA will hold the oval against the back wall via "suction" if the wall is reasonably flat and soon go off for another plaster coat on top.

[RobertL]

the elecricians who just rewired my house seemed to have simply banged flat head nails into the brick on each side of the conduit.

R

[Jim]

I guess an added bonus of this approach is that it'll be easier to pick up the conduit with a metal detector.

[Mike]

I use galvanised flat heads .... roofing felt nails.

Mike P

[Tim S]

js.b1 coughed up some electrons that declared:

Although I could by another SDS chisel to suit the chaser's 20mm setting, I also find that sometimes two close chases tend to end up becoming one.

Found them - that's an option...

Thinking about this, the old metal strap cable ties would be very good too as they are adjustable and have no real thickness. Pity you can't get them... Or can you?

Now that's a very interesting idea... It really only needs to be held in a couple of places. As a variation on your idea, my plastering technique could easily be adapted to plaster to full depth over 1/2 the length in sections to hold it, then come back and remove them when the plaster's gone off a bit and fill in for a guaranteed result. I'd do that when I'm on my second mix (seems to take two mixes for me to do this many chases so it's no real extra effort to plaster 1/2 of all chases rather than all of 1/2 the chases!).

I'll try these excellent ideas on the next room

Thanks!

Tim

[Tim S]

Mike coughed up some electrons that declared:

Do you find them hard enough to go into random mortar? Otherwise in reply to you and Robert, seems like another good idea.

As a variation, are there any screws that can be driven directly into mortar without pre drilling? Not having to wield a hammer would reduce risk to conduit... A countersunk head would probably match teh oval's side bend radius quite well.

[meow2222]

FWIW cable can be held in with strips of tape across the front. The inherent wobbliness of the cable means there are then many low points to which some sort of mortar/plaster/filler can be applied. When dry the tape is removed, the rest of the cable pressed back and plastered over. Can't really do that with conduit though.

[RobertL]

Another thing they advised me was that lime plaster would not bind to the conduit and that i'd be best off using conventional plaster. (I had wanted lime to be consistent with what was there already).

R

[John Rumm]

Ah, just don't cut such nice straight lines - a slight deviation in the chase (rather than the width of the chase) will allow the conduit to be held by the chase edges.

Failing that the occasional clout nail or floorboard brad into the mortar.

[js.b1]

You can get galvanised (or stainless) eyelet-strapping.

Choice very much depends on what your brick & mortar are like.

For me capping or clip nails shatter on the bricks, but the mortar disintegrates. With soft mortar it only takes seconds with a non-hammer cordless 6mm masonry drill to drill/plug/clip. Nails should be galvanised or alkyd paint if the wall is damp (rust stain). I prefer snap-in oval clips (1 hole, oval snaps into clip).

Clips sound a chore, but you only need 2 on a full height drop - wedge at ceiling, wedge at backbox via scrap of cable.

[Stuart Noble]

Car body filler for anything that's difficult to keep in place

[Lobster]

.... a plasterer I employed used a similar technique but apparently saved on nails by using just a single nail right through the middle, with the added 'advantage' of securing the cable within as well. Bless.

Didn't find out until fault-finding on the new wiring a few weeks later :-(

David

[js.b1]

I always PVA plaster over conduit if the covering of plaster will be thin.

Example of snap-in-clips with oval...

capping over two cables, but due to smashed capping during nailing & bowed wall it was impossible to replace cables. Further up there was a lovely crimp without heatshrink corroded to crunchy. Backboxes rusted such that face screws wouldn't bite and I dislike retapping to M4. Elsewhere tiles perfectly cut around the rear profile of the sockets, so if you changed the sockets you had to painstakingly grind the tiles to a "conventional outlet".

It is easier to get one cable down one oval, PVC cable tends to kink, double oval if you ever think you may need more.

Damp patch top left, must investigate that someday (lean-to w/ tiles bedded into mortar on I suspect rotted felt, rest is actually ok being closed boarded).

[nightjar]

I use blobs of Plaster of Paris. It sets quickly and leaves nothing under the plaster that can rust.

Colin Bignell

[auctions]

't know of any retailers that stock them though

A

[Andrew Gabriel]

Get a smaller chisel. A 1/2" chisel, matches the smallest oval conduit. Plaster chasers (usually) come with spacers to exactly match the oval conduit sizes. Cut free-hand (against a pencil line, but not against a straight edge), and the natural deviation of the channel will hold the trunking without needing any fixings at all.

I make the chaser cut deeper in the last couple of inches.

[Tim S]

js.b1 coughed up some electrons that declared:

Yep - Will do that. The bits that are showing are going to get 2-3mm of skim on the top.

Hell, the walls in that room are knackered. Had to use a spanner to sound out every part of every wall, mark up and scrape loads of loose old skim off.

Given it a double dose of diluted PVA to firm up the edges.

I think I can now accurately sound the differences between loose paint, loose skim, loose undercoat and the prescence of wood (ie wallplate or bits over the door). Bring back steam trains, I could get a job as a wheel tapper - seem to have the ear for it.

Loose undercoat was only in small bits so I just said ***** and soaked those in tons of PVA. Otherwise I'll end up with the whole room back to brick!

Front room's just as bad. Hope the kitchen is better (it's bigger)...

joints.

[marika]

Get movin'!

mk5000