Wall plug drill size and screw size question

[john2k]

I’ve got the following wall plugs it the red 6mm one https://www.toolstation.com/rawlplug-uno-universal-contract-wall-plug/p49379

Does this mean I need to use a 6mm drill bit to make the hole? Also what sort of size diameter and length screw works with this size wall plug? How does one determine size of screw?

Thanks

 

[pete01]

5.5mm drill bit

2 inch 10 screws

Thats what I use anyway for most things.

 

[blackworx]

A 6mm wall plug will usually require the use of a 6mm masonry drill bit, with your drill on the hammer setting.

You can use 3 to 5mm diameter screws, although 4mm will be best. 3mm can be too loose, and 5mm can be so tight that it will start to spin the plug, which will prevent you from fully tightening the screw.

If the masonry is quite loose/powdery (and very easy to drill into) you might be better off with a 5.5mm drill. You can always drill a 5.5mm hole to begin with, then expand it to 6mm if the plug wont fit. It's ok to use a hammer to tap the plug home but be careful not to damage the wall. The tighter the fit of the plug in the hole, the better.

The depth of the hole you drill should be at least equal to the length of the plug, but should generally be a little longer.

The length of the screw should usually be at least equal to the length of the plug plus the thickness of whatever is being screwed to the wall, but can be a little shorter. You are aiming to fill as much of the plug with screw as possible. If it is longer (which is fine) be aware that you'll need to drill a deep enough hole to accommodate the screw sticking out the end of the plug inside the hole.

 

[johnny2007]

The length of the screw should usually be at least equal to the length of the plug

Don't know about cheap plugs, but Fischer recommends length of screw to protrude 10mm out of the plug on final installation.
So with a 40mm plug and screw going flush to the wall, you'd need a 50mm screw.

 

[noseall]

I’ve got the following wall plugs it the red 6mm one https://www.toolstation.com/rawlplug-uno-universal-contract-wall-plug/p49379

Does this mean I need to use a 6mm drill bit to make the hole? Also what sort of size diameter and length screw works with this size wall plug? How does one determine size of screw?

Thanks

Red plugs (5-6mm bit) are for small stuff. I'd say up to 75mm 4's etc.

We only ever use brown plugs and 7mm bit. Or 6.5mm bit in soft aerated blocks (no hammer action).

 

[Harry Bloomfield]

A 6mm wall plug will usually require the use of a 6mm masonry drill bit, with your drill on the hammer setting.

Could be slow, and hard work, depending on the masonry you intend drilling. Most people recommend an SDS drill, plus bit.

 

[stevie888]

I rarely use my SDS as I can get into most materials with just the combi and a decent bit. Had to drag it out last week as it happens as 1 hole in 6 found a very hard brick.

 

[^woody^]

How does one determine size of screw?

By whatever you are intending to fix, not by the size of the plug or hole size.

Depth of hole would normally be 1.5x the length of the plug. And for all but the lightest things, the plug should sit flush with the masonry, not the plaster - use bigger plugs if need be.

 

[blackworx]

Don't know about cheap plugs, but Fischer recommends length of screw to protrude 10mm out of the plug on final installation.
So with a 40mm plug and screw going flush to the wall, you'd need a 50mm screw.

Yeah I use Fischer myself however never had any issue in masonry as long as the plug gets expanded properly, which it does if the screw is the correct size.

I think Fischer also has a design element where the plug is intended to be pulled further into compression by the screw exiting the far end causing it to "bunch up" to provide an anchor especially when used in drywall, but in masonry I don't think this effect is particularly important. Totally agree longer would still do no harm tho, so on reflection you're right probably better to just recommend that anyway.

 

[opps]

By whatever you are intending to fix, not by the size of the plug or hole size.

Depth of hole would normally be 1.5x the length of the plug. And for all but the lightest things, the plug should sit flush with the masonry, not the plaster - use bigger plugs if need be.

In the past, when working in Victorian houses with 20-35mm plaster and soft red rubber bricks, I have (occasionally) found that when tightening the screw, after burying the plugs, the plugs can pull forwards. In such cases, I bury the first plug and then push in a second plug. With harder bricks, there is seldom a need to use a second plug.

 

[^woody^]

It may be OK to just seat the plug in plaster for a lightweight picture or suchlike, but perhaps not for a shelf holding up a ming vase or the 100" flatscreen.

I do find that I have got into a routine of adding a bit of polyurethane glue to almost every plug nowadays.