On 09/10/2019 10:03, Robin wrote:
On 09/10/2019 02:07, Bill Wright wrote:
On 08/10/2019 12:50, Robin wrote:

Expanding bolts are a good way to crack bricks. Better to use resin
anchor or concrete screws - and a pair spaced across courses if the
wall is at all suspect.

Only if the bricks are very weak.

I defer to your vastly greater experience.Â* I'm probably be biased (or
is it scarred?) from living the past 45 years in London among
predominantly London stock.Â* [Cue "soft Southerner" digs.]


I really should have said that although expanding bolts are OK for 80
90% of the time in reasonable bricks, you do get an occasional failure
when the brick has a flaw. And you do have to keep your hole well away
from the edges of the brick. And they are hopeless in soft bricks,
unless you are prepared to not tighten them properly (which is often done).

I have always preferred sleeve anchors for that reason. They do seem to
stress the brick less. They aren't without their problems however. It's
best to use the ones with a nut at the visible end rather than a bolt
head. There are a few tricks.

Tap the thing into the wall by hitting the nut with it slightly off the
end of the bolt, so you don't damage the thread in case you need to take
the nut off. Why would you do that? If there's a small cavity in the
brick in the wrong place you might need to take the nut off and put some
washers under it.

If the whole bolt is turning when you try to tighten the nut it means
the anchor hasn't engaged. Put a blade under the nut and gently lever
the bolt forwards, and simultaneously turn the nut. The anchor should
bite and stop the bolt turning.

If the nut seems tight but the thing you're fixing doesn't seem to be
tightly held, undo the nut a few turns and hit the bolt with a hammer so
it relocates the sleeve. Then retighten.

Always drill deeper than the bolt length, and clean the hole out.

If the SDS drill bit is worn at the edges the hole will be a tiny bit
smaller that it should be. When you put the bolt in it will be very
tight. Don't hammer it in; that won't work. Get a new drill bit.

Try to look at an individual brick from above/below if you can find one
where that view is visible. Then you'll know where the cavities are.

Using long bolts and going right through the brick can/will cause the
brick to shell as the drill emerges. That can make a weak point and when
you tighten the bolt it can give way and collapse into a cavity.

I normally use 100mm or 125mm sleeve anchors with M8 thread. Drill is
10mm diameter. It's easier to get a good fix with a big diameter than
with a small one.

Bill