best small wall plugs

[WillyWarbux]

I'm going to be putting up some shelves into a brick wall (covered with 1/2 inch plaster)

Heavy solid oak shelves. Each shelf is 7.1Kg

Bought some metal brackets that say they can hold 100Kg+ and the holes in them accommodate a 5mm screw max.

There are 3 holes in each bracket so I'm hoping to hit solid brick most of the time. But likely to hit some mortar here and there. Putting up 5 shelves, so the brackets need to stay aligned, which might mean putting up with mortar on a few holes :-/

Will a classic Fischer red wall plug (6mm drill hole, 4-5mm screws, 40mm length) be enough for this kind of job?

What's the best plug for a solid wall using 5mm screws?

And do you think it'll be an issue if I hit mortar? Can mortar bear any weight?

Cheers.

 

[sircerebus666]

7kg is not heavy , and reds will be fine , however it all depends how much weight the shelf will be carrying , you might need to go to browns

 

[WillyWarbux]

Recently watched a YT video testing reds V browns using 5mm screws and the reds interesting bore more when pulling straight away from the wall (so, not like real life as a shelf is pulling away at more of a 90° angle), but still interesting.

But the larger browns visually look far more attractive. The reds only have 15mm of expanding plastic that'll go into brick. Browns have 22mm.

I have a spare piece of crappy wall of the same material hidden within a cupboard. I think I'll test on that prior to hanging my shelves.

 

[sircerebus666]

Visually look more attractive? Don't understand

The plugs will be hidden in the wall you would never see them?

 

[foxhole]

Always found reds too small and browns too big, I use 6 mm which are usually grey.

 

[sircerebus666]

If you're talking about drill size aren't reds 6mm and browns 7mm? With yellow 5mm , blue 8mm and Grey's 10mm

You can get grey Fischer's which are 6mm but they are the same as reds

This was certainly the case last time I used plugs anyway

 

[Deleted member 174758]

Reds are 5.5, browns are 7mm. Despite what is being said reds won't take quite a few of the screws used to fix framing (6.0mm and to a lesser extent #12, 5.0.mm and #10 sizes). And the hole you need drill often needs to be smaller than the nominal plug size in softer blockwork and even some soft stonework (this to avoid getting a sloppy fit in the hole). It can sometimes be hit and miss to initially find the right size of hole that works. Going to a 6mm hole us one way, but i find it easier to carry a few extra sizes of drill than extra sizes of (sometimes difficult to source) bulky plugs. Fixing into the mortar joint makes for a less strong fix, but it can be done with 7mm or larger plugs. It normally doesn't work well with reds because the plug isn't in contact with the brick, block or stone. Don't see many yellows, or blues for that matter

 

[Harry Bloomfield]

not like real life as a shelf is pulling away at more of a 90° angle), but still interesting.

That test is a bit of a nonsense. Wallplugs have certain sizes of screws they are designed to work best with. From memory - Red work with #8 and #10, brown work with #10 and #12, plus maybe #14. Yellow #6.

If too small a screw diameter is used, the the screw will not force the plug expandto grip the wall adequately. More important than a directly pull out of a wall, is the ability to withstand a pull at 90 to the axis of the screw, that is the load most screws need to take.

 

[sircerebus666]

I've always used 6mm with reds and never had any problems whatsoever , I suppose it depends on the drill you're using any wobble would enlarge the hole slightly

 

[johnny2007]

Drill the holes in the brackets to a reasonable size.

 

[SamKB]

More important than a directly pull out of a wall, is the ability to withstand a pull at 90 to the axis of the screw, that is the load most screws need to take.

Actually, if you think of a loaded shelf on a right angled bracket, the biggest problem is the rotational force on the bracket which is pulling the top screws directly out of the wall rotating around the bottom screw.
The lateral force on the screws is only relevant if the hole is to big, wall too soft, or plug is oversized for the screw, allowing the screws to angle down and the vertical force of the shelf to drag the screws out. If the holes, plugs and screws are correctly sized to not allow sideways movement, then true lateral force on the screws is only relevant if the screw shears.

 

[sircerebus666]

Actually, if you think of a loaded shelf on a right angled bracket, the biggest problem is the rotational force on the bracket which is pulling the top screws directly out of the wall rotating around the bottom screw.
The lateral force on the screws is only relevant if the hole is to big, wall too soft, or plug is oversized for the screw, allowing the screws to angle down and the vertical force of the shelf to drag the screws out. If the holes, plugs and screws are correctly sized to not allow sideways movement, then true lateral force on the screws is only relevant if the screw shears.

Not quite

Plugs use friction , overcome that friction with enough weight and the plugs will pop out

Ask any parent whose kids have used their curtains as a swing!

 

[SamKB]

It's a bit late to comment on this, but for future reference, given the 1/2" of plaster and solid brick behind and the 5mm screw limit, I would either use the strips of cut to length wall plug, or 1.5/2 plugs to get the extra depth right into the brick. Drill your 6mm hole 65mm deep (for a 60mm screw), clean it out with the drill bit and blowing, tap your first plug in as far as it will go using the screw, then cut the tip off your second plug so it fits flush to the wall: nice solid bond deep enough into the brick, or mortar that the expanding plug wont crack anything, and the outer plug stopping lateral movement in the plaster. If the outer end of the hole has got a bit big after fitting the first plug then use a 7mm plug for the cut off second one.

 

[SamKB]

Yes, enough weight at any angle other than lateral to the screw.
If you look at the holes after the curtain rails come down, the top ones have been pulled out as the bracket rotates, and the bottom one then re-angles expanding it's hole and drags out diagonally.
Direct lateral force on a plugged screw will increase the friction as the screw bites into the plug and forces it into the wall of the hole. Only if the hole then collapses does the pull start to overcome friction as it becomes angled downwards so the screw is being pulled out. This is the reason for making sure the hole and plug are not to big for the screw; if it were purely lateral force i.e. flat against the wall (a heavy mirror perhaps) and a solid wall, you could actually use nails pushed into accurately drilled holes.