Rawl Plugs in Masonry

[mickeymouse]

OK this is shockingly basic to most of you I'd think, but it really ran rings around me, not having any way of knowing this stuff. Every guide I've seen says to drill the hole the size of the rawl plug, which I obediently did. So then I put my screws in, my cordless driver jams so I flex the muscles, put in a manual, lean against the screw and twist... it snaps.

I do this 5 times in different spots until having used all the good spots up I end up hacking out the screws, refilling with concrete and putting easi fill over the top of it.

So, in despair I phone a builder friend. We have a long conversation. He too is telling me to drill the hole the size of the rawl plug. I say "can't I just drill it the length of the screw so they don't snap?". "What?" he says, "The screw isn't the same length as the rawl plug?". Nope, I says, and the screws came with the rawl plugs too, from rawl plug the company as in John Rawlings. "Well drill the hole the bloody length of the screw then."

So I does. It works great. If any of you happen to read this who have a guide saying to make it the length of the rawl plug shouldn't it say make it the longer of the rawl plug or the screw? Or was I just lucky? They've got quite a load on them, probably 20 kilos a hole and they are all holding fine.

 

[Richard C]

Great story I bet not many would admit to ; nothing so obvious as the bleedin obvious, wisdom is everything

 

[dave.m]

MM,
The screws may have been longer to allow for the thickness of whatever they were going through to attach to the wall. But usually you only use screws that do not go beyond the end of the plug.

I usually put a bit of tape around the drill bit about 5mm longer than the plugs and drill the holes to the depth where the tape touches the surface.
Then use the appropriate screws for the job that will go through the item to be screwed and into the plugs but not bottom out in the hole.

 

[big-all]

excellent lesson there for both sides
i do hope i wasnt one off the "confused ones lol
although i usualy say the drill size plug size and screw size including length based on material thickness plus plug size

 

[Bahco]

Use a 7 mm drill bit for brown plugs and 5 mm for red plugs.

 

[joinerjohn]

Common enough mistake by DIY'ers. Overtightening screws. Why once it has tightened do you feel the need to apply even more pressure until it snaps???

 

[foxhole]

Use a 7 mm drill bit for brown plugs and 5 mm for red plugs.

What about grey plugs?

 

[dave.m]

Drill sizes for different coloured Rawlplugs:

http://www.toolfastdirect.co.uk/acatalog/Plastic_Rawlplugs.html

 

[mickeymouse]

Common enough mistake by DIY'ers. Overtightening screws. Why once it has tightened do you feel the need to apply even more pressure until it snaps???

Because the screw wasn't flush with what it was holding, so it needed tightening more.

To the others, I did drill the correct diameter hole with the drill bit size from rawls catalog, the mistake I made was:

I treated the rawl plug like a magic black box you should put into wall holes instead of thinking what it was doing . So when every single internet guide I read said make the hole the depth of the rawl plug, I thought "these people know more than me, I will do what they say", even though it occurred to me drilling the hole deeper would stop the screw snapping, instead of thinking about the how and why of the wall plug, I just sheep-like followed what was laid out in front of me.

The mistake for people writing these guides is:

Assuming people will use their "common sense" (in this case assuming they will think about why it is you put wall plugs in the wall), but if they are like me they will think you know more than they do and do exactly what you say, even when they think it's wrong, or alternately, not thinking about the scenario where the screws might be longer than the thickness of the item being held plus the length of the plug.

 

[joinerjohn]

Sorry Mickey, thought you were just overtightening them. When fixing anything to a wall, you should measure the thickness of whatever your fixing to the wall and the depth of the rawlplug. These measurements will give you an approximate length of screw. I usually drill about 10mm deeper than this, just to be on the safe side.
Worst one I have seen recently were a couple of 4" screws used to hold a mirror up on the wall and 1 1/4" screws to fix some timber 3/4" thick.

 

[ban-all-sheds]

Once the screw has gone through the end of the plug the extra length will be doing SFA.

 

[Hass]

seems like a minor type mistake that we all make in our early days whilst learning.

I always use a drill bit that is .5mm smaller than the plug otherwise the plug does not always fit sungly in the drilled hole.

Always use the plug size suitable for the item your planning on mounting ie. for a large tv wall bracket, don't use 5mm wall plugs or your nice shiny tv might hit the floor and crumble. Same applies to mounting very heavy items on plasterboard. Unless it is supported through the framework then the plasterboard won't hold it for long.
regards

 

[ladylola]

When fixing anything to a wall, you should measure the thickness of whatever your fixing to the wall and the depth of the rawlplug. These measurements will give you an approximate length of screw.

Only one thing to add to this is the depth of plasterwork as this has no structural strength and you need to fix into the brickwork.Plaster thickness is fairly standard on new buildings around 1/2" or so but it can and does vary quite a bit on older buildings. I've encountered plaster 2 1/2" thick at times where the plasterer has attempted to plumb up a particularly bad wall. As a simple test when you drill into your wall the drill will go easily through the plaster and only encounter resistance when it hits the brickwork.

 

[Nige F]

Who is this John Rawlins ...I spend the winter whittling willow withies and cutting into specific lengths to plug my walls You using Chineses screws? . I only use Nettlefold`s finest

 

[ladylola]

I'm always amazed how many people don't know how to make proper wooden plugs for between brick joints and rely just on plastic plugs!
Oh the days of plugging chisel and axe