Right screw for the right plug?

[Matte_Nörden]

It has been said before. There is nothing in an ordinary home that can't be screwed with wood screws into an OSB. A 6mm screw can withstand several hundred kilos of vertical load.

That's true. However, it is very rare for a screw to be subjected to a purely vertical load. Imagine you are installing a shelf with brackets. The shelf will then want to pivot around the lower attachment point, and in the upper screws, there will be a tension load. This can quickly become dozens of times larger than the vertical load.

 

[MathiasS]

The exact figures were 266 kg in vertical load and 166 kg in tensile load. Per screw. We have had this discussion on the forum a hundred times. Luckily, SP has filled a cabinet with lead and tested when it falls down, so we don't have to guess.

 

[Eddi Thomason]

According to http://kampanj.byggelit.se/download...7615507DD64258&NAME=Handboken_v%E4gg_webb.pdf (last page) SP has conducted some strength tests on different panel materials.
The screws used were TFX SPAX-S wood screws 5x60.
11mm OSB3 withstood an average of 169kg tensile load and 12mm plywood withstood an average of 191kg tensile load.
In other words, if you have OSB behind and use screws with a 5-6mm diameter, it will usually hold.
End of story!?

 

[Matte_Nörden]

According to [link] (last page) SP has performed some strength tests on different board materials.
The screw used was a wood screw TFX SPAX-S 5x60.
11mm OSB3 withstood an average of 169kg tensile load and 12mm plywood withstood an average of 191kg tensile load.
In other words, if you have OSB behind and use screws with a 5-6mm diameter, it will usually hold.
End of story!?

Yes, it might seem so. What I want to highlight is just that depending on the construction and the distribution of the fastening, you can quite easily reach several hundred kg tensile load. However, kg is an incorrect unit to use in these contexts, but we should be lenient with that.

 

[MathiasS]

You are completely right. One can imagine 1m long shelves mounted with brackets that are 15cm high, even if it's not very common, or there are certainly considerably better ways to do it. Attaching to OSB is more than sufficient for all practical purposes.

 

[End]

Even on Fischer's boxes with plugs, it indicates which drill, length, and thickness of screw to use.

Thanks for the tip about not using cutter screws with plugs. I hadn't thought of that.

Where does it say not to use Cutter screws with plugs?
I favor using Cutter screws together with Fisher's SX plugs in concrete and masonry, and it holds significantly better than regular wood screws.

 

[MathiasS]

The problem is probably that the sharp "cutter* at the tip tears apart the plug. But I also use cutters in various versions, and it usually works well. But it might not be optimal.