Chasing/Tracking of walls??

awnow

What is the general consensus as regards the preferred method to chase or track masonary walls in a new dwelling, for electrical cables (in conduit)?

From my experience, I have seen contractors use two methods:

(1) the use of large compressors with small air-driven chisels which 'rip' up through walls to create a track - no diamond disc / twin-cutting blade required.
(2) the track in the walls being cut with a twin-blade grinder/cutting machine and then chipped out a with a kango.

I have been told in the past that option (2) increases the liklihood of hairline cracks appearing in the smooth wall finish while this is less likely with option (1). I cannot verify this but as I'm due to hire in someone to chase my dwelling in the coming 1-2weeks, feedback from other posters in terms of their experiences/views would be greatly appreciated.

Also on tracking, I have read on another (much older) thread regarding if there's still a necessity to chase external walls which are to be fitted with composite board (insulated pasterboard). I was planning to track the external walls as I hate the thoughts of a sub-contractor coming in and hacking out the back of the insulation to create channels for the many conduit drops and flush boxes. It means the flush boxes will sit a wee bit deeper in the wall but this can be rectified by using extension attachments which project the box out 25mm from the internal surface of the masonary wall. When composite board is used, I have seen some people run their conduits & boxes on the surface but it seems an incorrect & even a lazy solution as the composite boarding is compromised for the sake of a bit of chasing. Any views on this?

From a structural perspective is there any great detriment to masonary walls as a result of tracking/chasing them? It's not something you like to have to do but without battening/studding-out walls has anybody used another alternative?

Carlow52

The hairline cracks appear because the cut is clean and the extra material in the chase gives rise to differential drying along a precise line.

It can be minimized by letting the first fix material, usually bonding, dry out first but not practical in most cases as the trade wants to get on with job.

It can also be minimised by taping across the chase.

The clean cut chasing causes less 'damage'.

On the issue of composite boards, the proper way, IMO, to do this is not to perforate the insulation at all and use a services duct outside the insulation.

d o'c

i did my own, and did it as follows
before chasing........
2 std heights around the gnd floor , 1 for most sockets, other for lightswitches (utility/kitchen sockets). i set these as my box 'tops', marked on template lath. Get the vertical placement marked for all the boxes. Use template to mark wall, I use lintel as benchmark. run laser level, mark all horizontal 'tops'.
A simple mark on the wall is hard to seen when cutting starts, so I use a small 4" grinder with diamond blade to make a shallow cut in the wall. You can use the grinder to lightly track 4 sides of each box once you have the tops .

chasing..
I used a concrete saw with water, ( be careful with power cables) keep cutting depth fairly even, keep fairly plumb, the boxes are lightly tracked already, cut them out also. Verify track depth with a piece of conduit, fine tune with hammer and chisel
use kango at an upward or downward angle, avoid using perpendicular to the wall.
fine tune wall so boxes sit fairly plumb and level. Fit boxes with plastic rawl plugs and screws, fit conduit. I used heat gun to help conduit 'behave'.
Damp tracks with water go around all tracks and boxes with sand cement and glove, leave a keyed finish



Std metal elec boxes have a small adjustment on one of the retainer screw holes (it's slides in a short slot) which can help to level at 2nd fix, alignment for plumb will be the finished wall
Longer screws are available for walls with insulation fitted, avoid cutting the insulation, you loose heat and it can make a flimsey board for fitting

I have seem some rough chasing done where a 100m block had been broke through to the opposite side in places, hence I prefer the saw/kango and dress method..

awnow

Carlow52 wrote: »

The clean cut chasing causes less 'damage'.

On the issue of composite boards, the proper way, IMO, to do this is not to perforate the insulation at all and use a services duct outside the insulation.

This stands to sense, from both structural & energy efficiency perspectives, and good practice. Any other views?

greened

Anyone use the twin cut grinder for chasing?
Looking to buy/hire one and cant find one yet

Carlow52

greened wrote: »

Anyone use the twin cut grinder for chasing?
Looking to buy/hire one and cant find one yet

http://www.hilti.ie/holie/page/module/product/prca_rangedetail.jsf?lang=en&nodeId=-95980

but u will need to contact the IMF if u are thinking of buying.:D
The other idea is auctions such as those run by Wilsons in Kingswood