# Does 2 x 7 = 14?

I want to hang a mirror that weighs 10kgs. I've got some picture
hooks from Homebase which will hold up to 7kg each.
Simple logic says to me that 2 of these should be OK to hang the
mirror. (It's going into lime plaster on a chimney breast). Before I
pile ahead - I just want to check that my simple logic is sound.
Thanks,
Michael
It is only true if the load distribution is known. I would use bigger fixings myself.
2 x 7 = 14 - for one value of 2 :-)
Mary
First question is does 1 * 7 = 7? Always be very sceptical about safe loading data for fixings. In many cases, and certainly this one, it will be far more dependant on the substrate than on the fixing itself. Be doubly suspicious when the information comes from Homebase.
10 kg is not light. The 7 kg 'rating' will almost certainly not apply in old lime plaster. I'd go for at least one screw going a good inch into the brickwork behind. You want something like a 2 or 2.5 inch no. 8 round-head screw for this, and a decent plug.
Traditional civil engineering usually has a safety factor of about five. Bulding materials, especially old ones, are unreliable. Minor faults seriously reduce strength. So plan to hold a much higher load. Maybe not 50 kg though!
Peter Scott
I think what most of your correspondents have in mind is your trying to fix to the plaster. That has never been a serviceable method. You need to find the grounds upon which the plaster rests.
If it is brick/block or stonework, you can use the plug and screw method advised. If it is a stud wall then you will have either plasterboard most likely fixed to uprights at 400mm centres or if on laths the studs will be 16 or 24 inches apart at the centres.
You could put a strip of baton between the uprights if your stud-work doesn't work out to a suitable fixing otherwise. You'd have a job making it look tidy though.
You should have seen the '5 ton breaking strain' pulley we used to lift and engine(well we *wanted* to lift the engine, but it was the front of the car as it happened). Broken it wasn't, but it was never the same afterwards. ;-)
Depends how much you like picking bits of broken mirror out of your carpet. B-) I tend to over engineer but I don't have things falling off the wall...
Did have fun with a kitchen wall cupboard that was on a rough stone wall covered with 2"+ thick, very old and very soft, plaster. Ended up using 6" frame fixings into the stone work. A kitchen cupboard full of dishes weighs quite a bit though.
I had a large mirror (probably in excess of 10kg) over the fire place in the last house. There was picture wire on the back of the mirror. Fixings were two heavy duty picture hooks, each with three pins. Like this (largest one, bottom right):
plasterwork over the fire was in good condition and I certainly wasn't worried about the mirror falling down - the big problem was getting it perfectly aligned - took two blokes (one each side of the mirror) and a woman (to say left a bit, right a bit, etc). What we realised was important was to get the mirror perfectly aligned and drop it directly onto the hooks, rather than trying to hang-then-adjust.
Pity you can't rely on a man to get it right :-)
Mary
On Tue, 4 Dec 2007 18:10:44 UTC, "Dave Liquorice" wrote:
I had a similar situation...lots of crockery and dodgy wall. I used Rawlbolts!
In message , Dave Liquorice writes
I did an emergency fix of cupboard with those - was still up when we moved house.
Emergency, as in one night, fairly late-ish (9-10 pm), heard a crash, one of the wall mounted kitchen cupboards, had come detached from the wall - swung forward from the top, and was luckily resting against the end of a fluorescent tube fitting.
Me and the lodger shoved it back up against the wall, and I used a couple of frame fixings from stock to hold it up. worked a treat
Pity you had to rely on a woman to use her 'intuition': Every time I get something spot on with a spirit level my wife swears its crooked. Showing her the bubble makes no difference.

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