Wall shelves fell down!

Hello all - DIYnot newbie here!

We put up some shelves in our flat about two months ago - 230cm long, made of 18mm mdf and fixed with masonry wall plugs to blockwork walls with four wooden brackets (spaced at 10-80-150-210cm along the wall) - and this morning they fell down. I think I possibly overloaded the top shelf with books and it took the lower shelves with it on its way to the ground but I was out when they fell down so I didn't see how it happened. The neighbours with whom we share that wall were also doing some hammering and drilling on their side this morning so that might also have something to do with it?

Anyway I'd like to put the shelves back up and ideally keep the brackets in the same place as they were. However I'm not quite sure how to do this. I've seen these Wet'n'Fix discs recommended on another thread but don't know how much to trust them. Does anyone have any thoughts on these or do I need to refill the holes and then redrill for the brackets? I'm quite new to this as it's our first flat so any step-by-step thoughts would be very welcome!

Also am I using enough brackets in the first place? Should I be putting up extra brackets for support if the shelves are for books? Any tips very much appreciated!

clareapparent said:

wall were also doing some hammering and drilling on their side this morning so that might also have something to do with it?

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Quite likely, vibration in the wall will have created dynamic loading on the fixing screws, dynamic loads due to vibration in the wall can be much higher that the static load of the shelf on the screws.

I would use a chemical anchor ( resin ) to fill the holes and secure a stud of threaded rod into the wall. Then use a nut to fasten the bracket to the stud.

If you do it this way you will see the nut which is a minor disadvantage. You will need to make a jig to hold the studding rods in exactly the right places as the resin cures.

It's hard to see in your photo, but I think you might have used low-quality plugs. I'd try something like a Fischer UX.

chris1982 said:

It's hard to see in your photo, but I think you might have used low-quality plugs. I'd try something like a Fischer UX.

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Thanks for your reply Chris! I think we used these plugs - would the Fischer UX ones be far superior? And can I put them back in the same holes or do I need to refill/redrill?

I don't know the plugs you used (but they don't list blocks as suitable substrate).
It's important that the drilled holes are just large enough to hold the brick. If they broke out when everything came down, you might need to start with new ones.

chris1982 said:

I don't know the plugs you used (but they don't list blocks as suitable substrate).

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Ah okay - I had assumed that blocks would be similar enough (i.e. in terms of being solid, unlike something like plasterboard) to the masonry/brick/concrete/plaster listed for those plugs, so there's my mistake. I'll take a closer look at the remaining holes and see if they'll still hold the plugs tightly enough. Thanks for your thoughts!

bernardgreen said:

I would use a chemical anchor ( resin ) to fill the holes and secure a stud of threaded rod into the wall. Then use a nut to fasten the bracket to the stud.

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Thanks for this Bernard! I hadn't heard of threaded rods but I'll have a look and see if they look beyond my skill set or not. Presumably you buy them in long strips and have to cut them to size with something relatively heavy duty?

it would be interesting to know how long your screws were, and how far they penetrated the wall, disregarding that part lost in the battens and plaster. Yours appear to have pulled out.

It looks from the photos like you used individual short battens. Continuous long battens would be much better. If you picture a claw hammer used to pull out a nail, your shelves will have applied leverage to pull out the top screw in the same way.

on shelving like yours, the worst pull-out load will be on the top screws, and it will be worse if the batten is not extended upward and screwed well beyond the highest shelf. it's better to have your heavy loads near the bottom, and extra-long screws at the top. All the other screws will just have a downward shear load on them, and are very strong in that way, unless/until the top screw starts to pull out.

You can improve the grip of plugs using injected resin, or a budget version, no-more-mails or equivalent injected into the holes before you press in the plugs. This is especially important if the plugs are not a close fit after you have vacuumed out the dust.

JohnD said:

it would be interesting to know how long your screws were, and how far they penetrated the wall, disregarding that part lost in the battens and plaster. Yours appear to have pulled out.

It looks from the photos like you used individual short battens. Continuous long battens would be much better. If you picture a claw hammer used to pull out a nail, your shelves will have applied leverage to pull out the top screw in the same way.

on shelving like yours, the worst pull-out load will be on the top screws, and it will be worse if the batten is not extended upward and screwed well beyond the highest shelf. it's better to have your heavy loads near the bottom, and extra-long screws at the top. All the other screws will just have a downward shear load on them, and are very strong in that way, unless/until the top screw starts to pull out.

You can improve the grip of plugs using injected resin, or a budget version, no-more-mails or equivalent injected into the holes before you press in the plugs. This is especially important if the plugs are not a close fit after you have vacuumed out the dust.

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Thanks for this John - you've explained this really clearly for me!

The screws were 6cm long, with 4.5cm penetrating the wall (and 1.5cm lost in the brackets). They reached nearly the end of the wall plugs (which were 5cm in length) but might it have been the case that I needed longer wall plugs and screws? I had a look for longer ones when I was planning the project but 5cm plugs were the longest I could find in Wickes.

I was using individual brackets like these, rather than long battens, but I can totally understand your point about the leverage and screws being pulled out. I wonder if there's a way of reusing these brackets without that becoming a problem though. For example (and bear in mind I'm quite inexperienced so this might be a stupid idea!), could I run a horizontal batten along the row of brackets at the top and fix this to the wall for extra strength?

I think you could fix a pair of sturdy batten to the wall, vertically, where the brackets can then be screwed to them. A large screw into a wooden batten will not easily pull out. The pilot hole should be smaller than the shank of the screw, so the thread cuts into the wood all the way. Let the battens be higher than to top of a large book on the top shelf.

Others may think of a better idea.

You need to establish what type of blocks you have, if thermalite then they hold screws like cardboard. If you have plasterboard over blockwork then 20mm of the plug is only in plasterboard and fresh air leaving just 25mm in blockwork, less than useless.

foxhole said:

You need to establish what type of blocks you have, if thermalite then they hold screws like cardboard. If you have plasterboard over blockwork then 20mm of the plug is only in plasterboard and fresh air leaving just 25mm in blockwork, less than useless.

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Thanks for this Foxhole! Do you know how I can find out what types of block we have? I'm new to all this, so not sure of how to go about it

My current plan is to use these Fischer High Performance Universal Plugs combined with this Fischer resin and possibly a couple of upright support battens (as John suggested) but if you've got any other ideas or thoughts, I'd be very grateful to hear them!

If you can push a fine bladed screwdriver into the wall without too much effort then you have soft thermalite blocks . The fixings you have will cope with just about any background ,resin is not needed .

As others have suggested you really need to find out more about your wall construction before you try again. It is likely some kind of masonry with plastered plasterboard on top but what we can't tell (only you can) is whether there is any air gap between the plasterboard and the masonry, and what kind of masonry it is. An experienced trade would be able to tell by the way the drill went in, or by probing with a screwdriver:

Get a screwdriver with a long slim shaft, like one that looks as though it's meant for small electrical screws, but not one that has plastic insulation on the metal shaft. Push it into the wall and rotate it back and forth at the same time. Plaster and plasterboard are fairly soft and you'll make good progress. If there's then a moment where it jumps easily further into the wall, that's an air gap. If it becomes much harder to push but doesn't feel particularly scratchy, that could be a wooden batten, if it's harder but still possible to make progress, that could be an aerated concrete block, if it's really hard and scratchy feeling that's either a mortar bed between blocks or a dense concrete block/brick. (If you're keen to do some research on these things some time take a look in your local wickes; aerated blocks looks like grey chocolate mousse inside, have a scratched appearance on the outside and are light and crumble when you push a finger nail into them. Dense concrete blocks look like grey rice crispy cakes and are pretty heavy. Stick your screwdriver in each to get an idea of the comparison)
Make another hole diagonally an inch away and see if it changes , to determine if you hit a bed. Use the screwdriver as a depth probe to see how far you have to go before you hit something solid- this depth should be completely disregarded when fixing. The general rule of thumb when fixing is at most one third of the fixing shall be taken up by the thing being fixed, and at least 2/3 of the fixing shall be in the solid substrate. If your bracket is an inch deep, you need 2 inches of fixing in the solid part of the wall. If your plasterboard and air gap amounts to 1.5 inches, you're going to want fixings at least 4.5 inches long. And they're going to have to be sturdy too as you're effectively hanging a weight on the end of a fixing that is sticking out of a wall by 2.5 inches, and it's only buried in the wall by 2 inches- no "4mm thick screws and crappy plastic plugs that came with the shelves" here!

For my money I'd invest in some concrete screws of a suitable length considering the 1/3:2/3 rule before, possibly making it 25:75 or more. Drill a 6mm wide hole using a masonry drill bit and drill set to hammer mode, use a drinks straw inserted into the hole to blow out the dust (it will jam the screw otherwise, close your eyes when you blow down the straw) and be careful as the screw reaches the point where the bracket is against the wall as a modern cordless, with those screws will certainly have the power to drive the entire bracket completely through the face of the plasterboard if there's an air gap behind it. A drill will go through plasterboard and aerated concrete like a hot knife through butter. In brick or dense concrete it's much slower progress and the characteristic brrrrrrrrrr sound. Periodically stop applying pressure and pull the drill bit nearly all the way out of the hole, as this clears the hole of dust. Too much dust buildup can jam the drill and snap it

A good cordless is so handy (I even clamp a whisk in mine and use it as a mixer for gravy/cakes etc, use it to turn the winder handle for the awning on the caravan..) that the 90 quid or so that a quality Bosch/makita/hitachi/dewalt branded combo costs would be money well spent. Make sure it has a hammer drill function and make sure it comes with batteries as sometimes the cheaper looking kits are drill body only

clareapparent said:

Hello all - DIYnot newbie here!

We put up some shelves in our flat about two months ago - 230cm long, made of 18mm mdf and fixed with masonry wall plugs to blockwork walls with four wooden brackets (spaced at 10-80-150-210cm along the wall) - and this morning they fell down. I think I possibly overloaded the top shelf with books and it took the lower shelves with it on its way to the ground but I was out when they fell down so I didn't see how it happened. The neighbours with whom we share that wall were also doing some hammering and drilling on their side this morning so that might also have something to do with it?

Anyway I'd like to put the shelves back up and ideally keep the brackets in the same place as they were. However I'm not quite sure how to do this. I've seen these Wet'n'Fix discs recommended on another thread but don't know how much to trust them. Does anyone have any thoughts on these or do I need to refill the holes and then redrill for the brackets? I'm quite new to this as it's our first flat so any step-by-step thoughts would be very welcome!

Also am I using enough brackets in the first place? Should I be putting up extra brackets for support if the shelves are for books? Any tips very much appreciated!

Click to expand...

Looks like they took the door handle off too.