Hi all Any advice on how to effectively attach ectrical boxes to brick & Block walls that have been very badly chased i.e. A very uneven back with up to 3cm to fill in some parts to get them to finish slightly proud of the wall ready for plastering?
You will need to flatten the brick or block using a comb chisel,chisel or and bolster,whichever is your choice. When you have the bricks/blocks flat fit deeper boxes or fit extension collars to the boxes to bring out to plaster finish.
This cowboy has used foam on quite a few occassions over the years, to secure back boxes. Want to move with the times Deleted member 11267. See this thread: https://community.screwfix.com/threads/expanding-foam-guns-recommendations.197306/
Certain foams used to damage the pvc on cables,read regulation 522.5.3. Kiab I have, unlike you, worked in the building and construction industry on sites,both industrial, commercial and domestic over the years. Every thing I know is through actual experience and not browsing diy forums. From what I gather you once maybe worked in a builders merchants. I will not be the only one on here who laughs at the porkies you come out with,maybe some of the stories are true you heard when behind the counter.
I've worked both side of the counter, mainly domestic nearly 40 years, make it 35 years, if I allow for accidents,etc.
I have used foam when I have encountered hollow brick walls were you can't get a fixing or fast dry cement, in this case tho just level off brick fit a deeper box
My favourite ..... gotta be bonding plaster; Almost no depth limitation Cheap Sets even quicker if outta date Dampen brick or PVA 5-1 water Chuck in bonding Tap in back box to required level Drill and plug through bonding into brick Semi tighten screws, fully tighten once bonding set I’m only diy me but I’ve used this method few times and it’s a lovely job
Bonding plaster all the way. Fill the hole and set the back box in. Push in a couple of red plugs and screw when dry. Jobs a good un. Tea and biscuits time.
Thing is with me as diy, whenever I’ve bought a can of foam, I only need a squirt of it, never the full can Have a can of the Everbuild foam cleaner and it’s really excellent stuff. Cleans the spray tube in seconds and cleans the nozzle on the can Can goes back into garage for some months, next time you need to use it, can never works, even though I’ve cleaned it out so waste 80% of the can Not worth me buying gun and gun grade foam, just don’t use enough So for me, I decant a sack of bonding into two 10ltr paint buckets and it lasts me for an age As mentioned, when out of date, it sets quicker which can be handy and if using for a small repair, is fine as you may only have 5-10 mins workable time So no, nothing like foam really chips
Thanks for your response. Do I need to make the bonding mix thicker than normal & will the box need to by held in place while it goes off?