expanding bolts in brick

I need to make a very strong fixing to a brick wall using expanding bolts 90mm long. I drilled 14mm dia holes in the brick.
After going into the brick about 30 t0 40mm, the drill broke through into a cavity in the brick and then started to 'bite' about 30 to 40 mm further in.
I suspect the bricks are the type with 3 large vertical holes.
Help!
( I have wondered about the following solution;
get a mastic gun and empty cartridge
fill it with wet cement and inject the cement into the brick via the 14mm hole hammer a 12mm wooden plug into the hole to consolidate the cement in the void
drill out the wooden plug after the cement has set
Any comments on this idea? -or alternatives? The fixing will need to take a large load. Thanks
--
Chris Holford

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wrote:

Is the load in sheer or straight pull? I build a mezzanine in the roof of a garage using Mulitmonti bolts. Theres a ton of stuff on it now. Cross posted to uk.diy as thats probably a good place to get an answer from
Dave
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Rather than the uncertain repair that the OP proposes, I would suggest simply filling the original drillings and starting again *with a much longer fixing*.
Is this a single leaf of masonry, or is there an inner leaf? Is the outer leaf possibly not intended to take extra structural loads?
I'd also recommend multimonti - I think some very long ones are available now.
IIRC the data sheet with multimonti covers all common load configurations. I used multimonti (10*140mm), 4 to a joist hanger to support an upper floor in a chapel conversion (all inspected and passed by building control). In that configuration the safety margin from calculations was generous - however, like most building work, quality of workmanship makes a huge difference. I made up a jig to ensure that all pre-drillings were set as accurately as possible, and every single bolt was totally secure (and I set a couple of test multimonti, then tried (unsuccessfully) to lever them out with a very long crowbar).
The OP doesn't say what his application is. Is it safety critical - a roof, floor or structural component? If so, professional or very experienced advice may be necessary, and/or building control oversight.
Are there dynamic factors, wind or snow loading?
Where you're using fixings as critical structural component, I really wouldn't do anything that isn't *certain*, and the repair method proposed sounds far from certain.
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RubberBiker wrote:

Me too. Easier to pull a sailor off your sister than pull one out.
--
Dave - The Medway Handyman
www.medwayhandyman.co.uk
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On 1 May, 16:16, "The Medway Handyman"

The only thing I wondered about multi-monti (I've not used them). SInce they cut their own thread, the hole size must be quite critical to the strength. With a slightly wobbly SDS, or slightly crumbly brick, the hole could be a millimeter larger, which could make all the difference ? Simon.
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sm snipped-for-privacy@hotmail.com wrote:

I guess it is, but in practise I've not really had any problems. I use the 6mm with a 5mm pilot & the 7.5mm with a 6mm pilot. You get the odd failure, just like you would with any fixing, but overall they are brill.
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Are the multi-monti better than the bolt things which expand?
Do you just drill a pilot hole with a sds drill then drive them in with an impact driver?
Do they unscrew, or is that that once they're in they're in?
[g]
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On Fri, 01 May 2009 17:39:53 +0100, george (dicegeorge) wrote:

=======================================Screwfix give a good description of their usage including drill size(s) required:
http://www.screwfix.com/prods/45200/Fixings/Multi-Monti/Multi-Monti-Hex-Head-7-5-x-60mm-Drill-Size-6-Pack-of-50www.screwfix
http://tinyurl.com/chc8h5
Cic.
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==========================================
Using Ubuntu Linux
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Much better in my opinion. They don't expand so they they don't damage the bricks. They also need a much smaller hole.

Yes.
No, you just screw them in with a normal screw driver, nut driver or spanner. They're very easy to drive home. They come with a choice of a normal bolt head or a Torx head.
In general I would use a longer Multi-Monti than an expanding bolt to ensure a good fix.
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george (dicegeorge) wrote:

Much less chance of a brick splitting & you can use them pretty close to edges - although not 'right' up to an edge.

Yup. Decent drill driver will put them in, impact driver is obviously faster.

No, you can take them out & put them back no problem, or take them out & resuse them.
Brilliant things. Somebody here put me on to them, can't recall who, but thanks :-)
--
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Dave S coughed up some electrons that declared:

Or switch to resin anchors? No doubt that they're strong enough and they won't damage the brick near a cavity.
Cheers
Tim
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Tim S wrote:

Lovely stuff - can't recommend it enough
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I notice they are carbon steel.
I assume sufficiently oversized w.r.t. corrosion over 40yrs, or is it Build-Like-Barratt these days?
Then again get enough damp to eat a big screw away and even a tough brick can be drilled with a screwdriver.
Anchor bolts are available in stainless, as are resin fastenings, the problem with anchor bolts is they can be very fussy about hole size and stainless needs oversizing being a relatively low grade. Still most roofs are still standing held together with little more than a big nail at an angle with more attention to the finger & cigarette position than wood, nail & hammer.
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We were somewhere around Barstow, on the edge of the desert, when the
something like:

That's a good point and it's just as well for most of us that during construction things tend to stay where they're put. The standard of workmanship I've seen in the construction industry would boggle your mind.
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wrote:

Another vote for resin - also keeps water from entering the hole
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Unlikely it's the 3 hole type.... more likely is it's a std brick with a 'frog'. Can't you drill elsewhere? 50mm in from the edge of the brick will be solid all the way through . You can't be sure which way up the frog is without drilling,......
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Pretty sure its not the frog...
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On Fri, 1 May 2009 09:12:39 +0100, Chris Holford

    It would have been useful to know more about the nature of the load and it's direction - up, down, sideways, outwards, inwards? We also don't know if you can remove the brick concerned.
    My own approach would be to chop out the offending brick and replace with something better, a relatively simple task.
    Alternatively, fill the cavity with cement, as you suggest, via the 14mm hole. The easiest way to do this is to use a 'skeleton gun' and a standard 300cc cartridge of something cheap, which you waste, and refill with your cement. Experiment - keep the cement as stiff as reasonably possible, consistent with the need to inject with your gun.
    If you want to get more technical, there are options involving readily-available high strength epoxy resins which can also be injected from a cartridge. Let me know if you need more on that. --
Chris Edwards (in deepest Dorset) "There *must* be an easier way!"
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On Fri, 1 May 2009 09:12:39 +0100, Chris Holford

Slightly enlarge your holes, fit resin sleeves, inject resin and insert some studs. In 24 hours they are stronger than the wall :)
Screwfix carry a wide range but Toolstation in my experience will be much cheaper for the studs but I don't think they do the sleeves which are **essential** in your situation, a decent local builders merchant should carry them though.
No connection etc with Screwfix and Toolstation except as a happy customer!
http://www.screwfix.com/cats/100071/Fixings/Injection-Fixing http://www.screwfix.com/prods/36745/Fixings/Injection-Fixing/Fischer-Resin-Sleeves-12-x-85mm-Pack-of-50 http://www.screwfix.com/prods/15789/Fixings/Injection-Fixing/Studs-M12-x-160mm-Drill-Size-14-Max-Fixture-100-Pack-of-5 http://www.screwfix.com/prods/23386/Fixings/Injection-Fixing/Fischer-Polyester-Styrene-Free-Resin-300ml
http://www.toolstation.com/shop/Screws+Fixings/Chemical+Fixings/d90/sd1960 http://www.toolstation.com/shop/Screws+Fixings/Chemical+Fixings/Chemical+Stud+A2+Passivated+12x160mm/d90/sd1960/p93878
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How about drilling right through the wall and fixing with long bolts, nuts and washers. I did this for some security grilles outside the workshop windows. To prevent the pikeys unscrewing them I got the outer heads welded to the grilles.
Cliff Coggin.

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