What kind of fixings would I use for fixing shelving tracks (i.e., heavy duty) in to plasterboard walls, where there is only a gap of about 1/2in behind the board before the breezblock?
The smaller hollow fittings from B&Q are about 2" in length, so is it necessary to drill the appropriate hole into the block? Therefore it can't be done with a hand drill, so presumably I'd need to acquire a power drill with a masonry bit.
The battens are in the wrong places and too far apart (min 60cm) for the tracks anyway.
how heavy is heavy duty? how wide & deep will the shelves be?, how many of em?, how much proposed weight in total (incl stuff on shelves) ? how many screws/ fixings holding it all on the pboard wall? how thick is the pboard?
plasterboard screw anchors are pretty good (radiators etc) but there will be a limit to the plasterboard's strength.
"Heavy duty" and "plasterboard" don't make very comfortable bedfellows!
You need to fix to the blocks, not to the plasterboard, and you need spacers to stop the fixings from sqeezing the plasterboard into the gap.
This is what I would do in your situation:
Deternine the screw positions, and drill holes for suitably sized rawlplugs through the plasterboard, and 2" into the blocks
Drill 1" diameter[1] holes in the plasterboard, concentric with the screw holes
Make spacers by cutting discs out of a piece of 1" broomstick, whose thickness is the same as the distance from the face of the block to the outer face of the plasterboard, and with holes drilled in the middle for the screws to pass through
Insert rawlplugs into the holes in the block, followed by the spacers
Using screws which are long enough to go through your shelf tracks and through the spacers, and at least 1.5" into the rawlplugs, bolt it all up tight
If your "breeze-blocks" are light-weight thermal blocks (when was it built?) these are quite soft, and can easily be drilled using a normal HSS bit in a hand-drill. But, assuming that you'll be using 3"x10 screws, or thereabouts, you'll need to use heavy duty rawlplugs - so you'll need a fairly long 7mm drill bit. You *could* also drill the 1" holes in the plasterboard by hand - preferably using a cylindrical hole saw. However, life would be much easier with a power tool - even of the rechargeable battery-powered variety.
[1] the actual diameter needs to suit the size of broomstick from which you are making the spacers, but it should be approx 1"
Absolutely. Those who fix things like rads etc direct to it have never had anyone put their weight on it...
The other rather more expensive way would be to use expanding bolt fixings. (Rawlbolts is one brand) They are V expensive at B&Q etc but can be bought more cheaply in bulk at Screwfix, etc. You could then use steel washers to achieve the correct spacing. Maybe only one needed per bracket
- use ordinary wall plugs for the others - but can take a very heavy load.
Time machine, go back and put studs behind the plasterboard. They only need to be flimsy, just enough to resist compression.
Obviously you can't fix to the plasterboard. Less obviously, fixing to the block wall behind with a Uno plug is going to leave nearly an inch of screw poking out as an unsupported cantilever through the gap and the plasterboard. Having a stud underlying it would be far better.
So what I wouldn't do is to just use a long screw into a Uno. Not for shelf uprights anyway. Personally I'd probably drill oversize and drop tube spacers into the hole (cheap 20mm steel conduit, or scrapbin) Otherwise use some sort of oversized frame anchor with maybe an 8mm screw, rather than the 5 or 6mm you'd use through a stud.
As others have said, the way to do this is to fix into the blocks using a long frame type fixing but this could result in the plasterboard deforming when the fixings are tightened up.
My suggestion to overcome this is to:
Mark out and drill your fixing holes but go only just through the plasterboard.
Use these holes to squirt in a little fill & fix foam and allow it to fully set (48hrs). Only use a little, it expands a lot and you only need a 10cm dia blob behind when fully expanded.
Drill though the existing holes and foam into the block just deep enough to allow the plug of the fixing to fit flush to the plasterboard.
Fit the plugs and screw the shelf uprights to the wall tightening just enough to pinch it all up and no more.
The foam will make sure that the PB isn't deformed.
For a fixing I would suggest a narrow frame type fixing, narrow as the shelf uprights probably wont accommodate large screw heads. eg:
Screw a sheet of 18 mm chipboard/ply to the wall (straight through to the blocks) and fix to that. Then you can fix what you want where you want and it makes it more furniture like.
mmmm I did ask the OP how "heavy duty" we are talking about - so far no response....
for e.g. Yesterday I put up some shelves in an alcove - pboard on one side masonry on other - *yes* I used two screw anchors in the pboard side .... I can sit on the shelves without any problem and I am a non- trivially hefty 100kgs....
It sounds like you have the shelves supported at each end, left and right? That would put those fixing in shear only which is the only way they have any real strength. The o/p is using shelving track which is a cantilevered load that will tend to pull the fixings out of the wall. If they are overloaded in that mode they will just pull out of the wall without warning. Not fit for this purpose (or radiators) IMO.
all depends on size and potential weight of whatever is being hung....and the probability? of stupid people climbing up/on it... Amongst other things I have a towel rad mounted with pboard screw fixings - no problems so far.
OK, thanks for all the replies - lots to think about!
These are standard shelving track, will be 60cm apart or less. There are 8 screws in 1.4m track, and I propose to put four 80 cm melamine shelves on a pair.
Nothing too heavy on the shelves, some pb books, papers, etc, odds and sods in my study, just to get them off the floor and tidy. But the shelves themselves are fairly heavy. I understand by now that I must fix into the breezeblock and am still investigating methods. I don't have a power drill, but a small diy electric screwdriver. I'm sure that if the hollow wall fittings would "fit", it would work ok, since there are 8 of them a side. Obviously I shouldn't use anything smaller.
I may just opt to get someone in to do it in the end! It's getting complicated.
As you say, the load is well spread on 4 fixings per side so if the shelves are shallow (say 200mm deep or less) and lightly loaded then I think you may get away with using good quality shallow wall plug holding just in the plasterboard
If you take this course my suggestion would be Rawlplug Uno wall plugs in 10x36mm size (grey). IME they are the shortest good quality plug and hold well in plasterboard. For greatest strength they need an accurately and cleanly drilled hole of 10mm dia, I drill at 7-8mm hole then open up the hole with a 10mm bit. As it's just PB you can (and should) just use a standard drill bit and could use a hand drill.
I've suggested the 10mm Uno to give the largest gripping area on the plasterboard, the next size down 7x30mm (brown) I think would be a bit small. If it really is just soft breeze block behind and the plugs are still going to foul then you may be able to drill a bit out of them using your hand drill and 10mm bit but the bit will be scrap when you are finished.
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screw size 1 1/4" x 10 or 30mm x 5mm. Regular blunt threaded screws such as these:
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sharp threaded goldscrews:
B&Q stock Unos too.
Btw, the original advice was good for shelves of unknown size and loading, the more info in the o/p the better.
Books are heavy, they are effectively lumps of wood and soon add up. maybe you should think about shelving units that are self supporting and just use PB fixings to stabilise it?
If you dont want the visible ply backing, I'd be tempted to use blobs of plaster to form the spacers between PB and blocks. Slap it in where you're going to ahve holes, then drill the holes later. The strongest screw to block fixing is resin, I've not much idea what load you're looking at, but resin can be quite cost effective if you'll have uses for the other 390ml, or if its just a few holes and you use =A31 tubes.
Uno are the best plasterboard plugs I've ever used - very strong fix. I use the brown ones for heavier duty jobs. As long as you drill the hole deep enough to get the plug flush e.g. into the block a bit.
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