expanding bolts in brick

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

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,......

In article , TTman writes

Pretty sure its not the frog...

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.

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!"

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

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!

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.

Me too. Easier to pull a sailor off your sister than pull one out.

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.

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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Screwfix give a good description of their usage including drill size(s) required:

Cic.

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.

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 :-)

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.

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.

Lovely stuff - can't recommend it enough

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "js.b1" saying 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.

Another vote for resin - also keeps water from entering the hole