DIY Concrete screws

[Grimly Curmudgeon]

In my local supplier, they have concrete screws...

At three quid a pop. No wucking fay, am I paying that for a fecking bolt, especially if I want 12 or more. I recall a couple of years ago, the same supplier didn't have concrete bolts, but had these... And I'd used a couple of them to see if they bolted into concrete well enough. They did, so I repeated the experiment today and drove one of the 3quid screws into its 12mm hole (quite easy) and drove one of the coach screws into its 10mm hole (a lot tougher) and it held ok. A pneumatic impact hammer was needed for both, though.

The difference in price? The coach screws are less than a quid each.

[Jim K]

mmm try fixing something worth fixing to the concrete with both types and share the results?

I;d expect the proper (massively overpriced) concrete screws to cut a better sharper thread in the concrete and so grip better than a forced in coach bolt - that, I;d expect, got worn out & mangled during the "pneumatic impact hammering" stage...

Jim K

[Grimly Curmudgeon]

Possibly, but the function of the bigger bolts is to take some of the shear load on their shoulders (it's a wall plate with a dozen joist hangers). Each larger bolt is neighboured by two smaller ones, which are cheap as chips and a piece of piss to drive in. So, there's no shortage of load-sharing and plenty of strength in the assembly as a whole. I just object to paying through the nose to a supplier who thinks they can charge what they like for stuff like this.

[Phil L]

I've been using these for years:

About 8p each. You can get thicker ones, but I've used the 7.5mm ones for wallplates on numerous occasions

[The Medway Handyman]

Big range of Thunderbolts at Toolsatan.

I use these all the time for decking wall plates & awnings. Brilliant.

[Nightjar]

screws...

these...

The concrete screw also has an integral anti-vibration head and is probably made from a stronger steel.

Colin Bignell

[Andrew Mawson]

I've taken to using chemical anchor gunge with normal 10mm studding with nuts & washers. (though admittedly I did buy a box of 25 12mm x 160mm Multi-monti from Screwfix the other day)

AWEM

[Grimly Curmudgeon]

That's what I'm using for the neighbouring smaller screws - 7.5x150mm There's an average of one of those per foot, with the larger screws one every two feet.

[meow2222]

I once idly wondered if it might be possible to make screws from glass fibre & cement. Its just about possible to use wood in some cases.

NT

[Grimly Curmudgeon]

Unfortunately, not. I can get them to drop stuff to a virtual address in Antrim which then forwards to me for a very modest fee, but it's a faff and really only worthwhile for a reasonable value item.

Interesting, ta.

[Grimly Curmudgeon]

Out of curiosity, I had a look at the shear and load specs for some of these. Not exactly the same as the ones I'm using, but close enough.

Bloody hell, they won't pull out and I've got 26 of the feckers in place.

[Jim K]

Exactly 8p - plus delivery & VAT on top...,

I was a bit pissed off to find toolsatan had upped the price by 100% of their small packs of concrete screws a couple of wks ago. The pack size went from 25 to 10 & the price went up a bit!

Jim K

[alan]

That's what the builder thought as he installed the UK guest house balcony that was featured in this group a few months back.

[Grimly Curmudgeon]

Balcony is all about pull though. The wall plate's in shear.