Which heavy duty dixing for a block wall?

[Triggaaar]

I need to fix some brackets to a block wall (I'd probably incorrectly call them breeze block) and they need to take a fair amount of weight - two brackets, with two top fixings each (taking most of the strain), two middle fixings (taking a chunk of the strain) and two bottom fixings (probably not taking a lot, due to the leverage). The weight should be about 40kg, a few inches from the wall.

I was planning on using those expanding bolts. Job done I thought, but the fixings shop pointed out they're no good for block walls (they'd just expand and break up the wall). He said block walls weren't really suitable for heavy loads - which is annoying, as most new builds have block walls on the inside.

So what can I use instead? I know resin is ridiculously strong (ie, resin threaded studs into the wall, add the bracket and add nuts), but will the block wall just allow the whole lot to pull out?


Thanks for any advice, much appreciated.

 

[Chrispy]

When you say "block" wall do you mean concrete or thermolite? plastic plugs and screws would be OK in concrete but thermolite is so soft and dry/crumbly very difficult.

 

[Triggaaar]

When you say "block" wall do you mean concrete or thermolite? plastic plugs and screws would be OK in concrete but thermolite is so soft and dry/crumbly very difficult.

Thermolite. Standard building blocks, not the heavy concrete ones.

 

[jasonB]

I would go with resin anchors as they don't split the blocks, its quite easy to split a thermalite in half with a Rawl bolt.

Make sure you blow the dust out of the hole before glueing.

J

 

[CraigyCraigo]

go for deep frame fixing and skew them in....... like a dovetail...... against the way they would want to pull out ie point the drill upwards for the ipper holes....... then you trying to shear alot more block away if they were to pull out.... not conventional but would work imho

 

[Triggaaar]

In my search I've also found Rigifix:
http://www.amazon.co.uk/Rigifix-M6-Line ... B004WDG2TO

They're designed for dry lined walls, where they take the load to the brick/black behind the plasterboard, but they also seem to be recommended for Thermalite blocks - though I'm not sure why (I'm not sure what clever technique they use to stop the thing sliding out of what is a soft wall).

Any thoughts on those?

I would go with resin anchors as they don't split the blocks, its quite easy to split a thermalite in half with a Rawl bolt.

Make sure you blow the dust out of the hole before glueing.

Thanks. I was going to hoover the holes, but I see screwfix sell little brushes designed to clean out the holes (£6 for 2).

go for deep frame fixing and skew them in....... like a dovetail...... against the way they would want to pull out ie point the drill upwards for the ipper holes....... then you trying to shear alot more block away if they were to pull out.... not conventional but would work imho

Oo, clever idea.

What do you mean by deep frame fixing?

Many thanks

 

[Phil Pascoe]

A friend of mine swears by just using good quality screws and screwing straight to the block, but I've not tried it. I've mounted things in powdery walls before by glueing the plugs in and leaving them for a day or two before screwing into them - use water based cartridge adhesive. Don't forget that very little of the weight on a shelf pulls outwards - it's virtually all downwards.

 

[Newbie_Neil]

I would go with resin anchors as they don't split the blocks, its quite easy to split a thermalite in half with a Rawl bolt.

Make sure you blow the dust out of the hole before glueing.

J

+1

Neil

 

[John Brown]

A friend of mine swears by just using good quality screws and screwing straight to the block, but I've not tried it. I've mounted things in powdery walls before by glueing the plugs in and leaving them for a day or two before screwing into them - use water based cartridge adhesive. Don't forget that very little of the weight on a shelf pulls outwards - it's virtually all downwards.

Is that true? I would have imagined that with a conventional (under)shelf bracket the bottom screw takes the downward force, but the top screw has a significant outward force to contend with.

 

[Triggaaar]

One of the resin fixings has failed. I was struggling to get the resin out of the tube (I expect there was a small blockage in it) so it was taking longer than I'd hope, and one of the filled holes started going off before I could get the stud it (I had to use force). I've just put the nuts on, and it's pulling the stud out. What should I do? Presumably I need to remove the stud and replace with something else, but what? I could put a smaller stud in (M6 instead of M8) with some new resin around it, but I don't know what the condition of the old resin left behind will be like.

Any advice much appreciated.

PS - I used Rigifix for a couple of the fittings, and they're excellent.

 

[G S Haydon]

Any Chance you can bring the loads down to the floor rather than relying on brackets? http://tmcwoodworks.blogspot.co.uk/2013 ... racks.html and http://tmcwoodworks.blogspot.co.uk/2013 ... pdate.html illustrate my point.

 

[Triggaaar]

Any Chance you can bring the loads down to the floor rather than relying on brackets? http://tmcwoodworks.blogspot.co.uk/2013 ... racks.html and http://tmcwoodworks.blogspot.co.uk/2013 ... pdate.html illustrate my point.

Thanks for those links, it's interesting to see what can happen. How much do you guess all that wood weighed - a lot I'd imagine.

I can't bring the loads to the floor, but it does give me an idea that I could fashion an angled brace underneath the bracket (forming a triangle) to allow some of the load to push into the wall below the bracket. I'd still need to fix/replace the dodgy stud I have though.

These are the brackets:
http://www.studiodecor.co.uk/index.php/ ... dard-chain

 

[G S Haydon]

Hi Trigaaar,

Heavy duty brackets! I think it's always going to be a bit of a gamble on lightweight blocks. Regarding the stud, if you can pull it out do so than run the drill through the hole again, clean and give it a shot. Resin anchor flow takes getting used to when things like silicone flow really easy. To help flow make sure the tube is warm. I've broken a mastic gun using resin anchors so I feel your pain! Brace would help.

 

[Triggaaar]

Heavy duty brackets! I think it's always going to be a bit of a gamble on lightweight blocks.

I've read Fischer's technical data on resin studs in Themalite blocks (mine aren't Thermalite, but hopefully aren't a lot weaker) and one M10 stud can take 400kg (although the recommended loading is a lot less). The brackets have 3 rows of 2 fixings. The weight on the pair of brackets will be between 45kg and and 80kg, but as some of it will be away from the wall I have no idea how much that adds due to leverage.

Regarding the stud, if you can pull it out do so than run the drill through the hole again, clean and give it a shot.

I'll definitely be able to get the stud out, but I don't think I can drill the hole again - I've tried before (years ago) and it was impossible to drill into hard resin. Is it possible, and do you have any tips, as this would be a brilliant solution for me.

Resin anchor flow takes getting used to when things like silicone flow really easy. To help flow make sure the tube is warm.

I thought you should make it cold so that it doesn't set as quickly (I didn't do that, but that's what I thought the top tip was)?

 

[G S Haydon]

Regarding warm, depends how warm is warm and how cold is cold and how briskly you can work

In theory fisher have got it right i'm sure. Just don't like fixing into light weight, like fixing into a bag of digestives.

I think my makita sds HR2450 and a masonry bit bored out the resin OK, perhaps you resin is super hard.

 

[Triggaaar]

In theory fisher have got it right i'm sure. Just don't like fixing into light weight, like fixing into a bag of digestives.

They hollow out the block, so there is a small entrance hole, with a big hole behind it - so for the stud to come out a whole chuck of wall needs to come out.

I think my makita sds HR2450 and a masonry bit bored out the resin OK, perhaps you resin is super hard.

I have decent SDS drills - I take it you had it on hammer? I'll try - will probably make a complete mess of the block.

Thank you for the help, much appreciated.

EDIT - Ok, old stud out, new hole drilled - it may have gone off at a different angle to the last one, I don't know or care, I'll be able to get a new fixing it. My new problem is that I broke out the back of the block, so if I simply put resin and a stud in, the resin will fall out of the back. I need to make some sort of plug to put in, that will push up against the insulation (rockwool) and stop the resin falling out the back.

 

[G S Haydon]

Sounds like you're having fun

 

[Phil Pascoe]

I didn't realise you were talking of a cavity wall - why can't you use toggle type fixings?

 

[Triggaaar]

Sounds like you're having fun

Just wish the working time with this stuff was a little longer. Got to go and buy some more nozzles tomorrow.

I didn't realise you were talking of a cavity wall - why can't you use toggle type fixings?

What are they? I think the fixings I've chosen are good, it was just too difficult to get out of the cartridge, and went off too quick.

 

[Phil Pascoe]

Sorry, my knowledge of computers is seriously limited but I'm sure some kind soul will post a picture for you. Thinking more about it though, I wonder if you can get them long enough. I see no reason why not.