Heavy Duty Drywall Anchors – Test Tuesday! [141]

Ever wondered how strong drywall anchors really are? Today I’m testing some heavy duty drywall anchors to see how much force they can really handle. These are my go-to fixings for attaching heavy items to plasterboard so let’s see how they do – welcome to Test Tuesday!

Watch the full video here:

Introduction

A little while ago I looked at what little red wall plugs could handle in brick and block. Today it’s the turn of metal cavity fixings in drywall. IMPORTANT: These tests are not scientific in any way and you should not rely on these results when using these fixings. Always go by the manufacturer’s own specifications and datasheets!

How do you use a setting tool?

To fit the expanding metal drywall fittings I use in this video you need to use a setting tool. They can be installed just using a screwdriver but I highly recommend against this! You’ll just chew up the plasterboard and have problems. Setting tools are essential in my view and range in price from around £10-£50. I use a professional Fischer setting tool – expensive but worth every penny! I’ve had cheaper ones before and they all broke and ended up in the bin.

What are the best heavy duty plasterboard fixings?

There are loads of fixings available that are supposedly ‘heavy duty’ for plasterboard. It can be quite daunting when you see the vast array of plugs and fittings available! A lot of them are utter rubbish – I’ve removed hundreds of poor quality plasterboard fittings over the years.

My personal favourite fixings for drywall are expanding metal drywall anchors. Screwfix own brand ones are called Easyfix Wall Anchors and the Fischer branded ones get called Metal Cavity Fixings. The main advantages of these are:

  • Versatile
  • Simple to use
  • Don’t require a MASSIVE hole
  • Re-usable
  • Can be used with dot & dab
  • Rated at 15-20kg of axial / tensile load per fixing

There are many other decent drywall anchors on the market but in my professional view none are as versatile as these. For example, spring toggles require a bigger hole and can only be used once (when you remove the screw the toggle drops in to the cavity). Grip It fixings require a MASSIVE hole. Self drilling ‘helter skelter’ fixings are useless and should go straight in the bin. Watch out – there’s a LOT of wrong or misleading information out there!

My test results for heavy duty drywall anchors

In the tests from the above video I saw the following peak figures. These are NOT safe loads, they’re failure loads, see notes below:

  • M5 x 43mm Test #1:  42.6kg (around 94lb)
  • M5 x 43mm Test #2: 48.8kg (around 107lb)
  • M5 x 52mm Test #1: 64kg (around 141lb)

The above were tested using 12.5mm plasterboard and the expanding metal fixings were fitted using a professional Fischer setting tool. In all cases it was the plasterboard that failed, not the fitting itself.

Fischer’s own datasheets show a highest recommended load for a single anchor of 0.15kN (15.3kgf) in 9.5mm drywall and 0.20kN (20.4kgf) in 12.5mm drywall. They say this includes a safety factor of 3 and are valid for tensile, shear and oblique loads under any angle.

With a safety factor of 3 I couldn’t get values quite as high as the datasheet but this could be down to the Easyfix fittings being slightly different or variations in the quality of the plasterboard. Either way, the fittings didn’t fail until they were well beyond the 20kg recommended limit. I’m still sticking to my own personal limit of 15kg per fitting!

A quick note on axial vs shear loads

All of my tests are based on an axial load – this also sometimes gets called tensile or tension loads and involve pulling the fixing straight out of the plasterboard (i.e. not at an angle). This is pretty much worst case scenario for any fixing. A lot of manufacturers will advertise ridiculously high load ratings of their products. Normally when you do a bit of digging they’re actually referring to shear loads as opposed to axial loads. Shear loads are where you pull the fixing at 90 degrees to plasterboard. It’s a fairly meaningless measurement of loads on fixings since so many other factors come in to play when you talk about shear forces. The easy way to think of it is:

Axial or tensile load

Imagine a washing line attached to the wall with a single screw. The forces on the screw will mostly be axial – i.e. the screw is trying to be pulled OUT from the wall.

Shear load

Imagine a picture hanging on a screw. The forces on the screw will mostly be shear, pulling DOWN the wall.

In my own tests I’ve found that regardless of the fixing type the plasterboard always gives way around 60kg of axial load. You should never exceed around 1/3 of the peak load. So 20kg is a fairly standard MAXIMUM loading in plasterboard for the very best fixings. If anyone is quoting figures higher than this they’re almost certainly talking about shear loads.

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