How to work out what your are drilling into.

[FEP]

I have recently started working as a handyman - based on 30 or so years of DIY experience. Most of what I do is going well but inevitably I am finding some holes in my knowledge.

One thing that still confuses me is wall construction and what I am drilling into. I understand the various types of wall - plasterboard on studs; dot and dab; lath and plaster; plastered masonry etc etc. However, quite often things happen that I don't understand.

For example, why, when drilling into an exterior masonry wall, does the drill go so far - I am talking perhaps 60mm from the surface finish, and then seemingly find a void, jumping another 30 or so mm forward? I understand that most exterior walls are double skinned, but surely the inner skin would be thicker than 5cm. I have had the same happen when drilling into a chimney breast.

On another occasion, my stud finder confirmed a stud in a plasterboard wall in what seemed like an entirely logical position, but when I drilled through the plaster board there was a void behind. Drill jumps 50mm deeper - and then hits wood. WTF?

More broadly, how does one deal with the vast variation in hard wall materials - from breeze-block to concrete, via bricks of various hardness, that the drill discovers? Resin; wall-anchors;masonry screws; frame fixings; plugs etc etc I find it very hard to know in advance what will hold and what will just break the wall and create a mess - often in a material that you can't even see and with the customer looking on.

I'd be very appreciative of your words of wisdom.

 

[rsgaz]

when drilling into an exterior masonry wall, does the drill go so far - I am talking perhaps 60mm from the surface finish, and then seemingly find a void, jumping another 30 or so mm forward?

OR

 

[FEP]

Yes - of course. So would you switch to a spring toggle fixing?

 

[Burnerman]

You only use spring toggles and the like on plasterboard walls or other hollow substrates .......one of the tricks is to use a much smaller drill to start with until you realise what you are going to hit.
Look at the debris that comes out with the drill - even smell it.
HSS drill bits go through timber and plasterboard no problem, even thermalite......masonry bits don't like timber, although a SDS drill will bash its way through.
John

 

[FEP]

My point about the spring toggle was that if you were going to use a big plug or a wall anchor and now you know that much of it will be sitting in air, you could treat a brick with a void in it like a hollow wall. Indeed - what else could you do? If you keep drilling how do you know what you are going to hit and where?

So it's not just me trying to figure out what the wall is made of and the best way to attach a TV or kitchen cabinet to it?

 

[Burnerman]

When you use spring toggles or hollow wall anchors, you need to know how thick the wall is......up to around 20mm is possible, but hollow anchors do have a recommended depth so you choose the correct one.
If you are drilling through plasterboard and there's a void behind, you can use a frame fixer or better still a upvc window fixing that has minimal expansion. So long as the screw you are using is locating into solid material, all will be well 99% of the time.
John

 

[foxhole]

Drilling into standard bricks can hit the empty frog if the brick has been laid upside down , you need to carry a selection of fixings as the wall structure can vary, I have a 30's built home and has brick, clinker [cinder] block, thermalite, dot and dab, and stud plasterboard walls, some of the ceiling have three layers of plasterboard.

 

[freddiemercurystwin]

This:

you need to carry a selection of fixings as the wall structure can vary

I fitted an item on a single wall the other day that required four fixings, I had to use three different fixing methods as every time I drilled I got a different result.