Which fixing is best for the job – The force is straight out/pull (tension?). Shield anchor or poly resin?

Question

in a rendered brick (London) wall.it holds a 4mm steel rope with a span of 7m, which holds the tail edge of a 25m sq tarp canopy along its whole length, and is currently fixed with an M8 raw bolt eye shield anchor, doing the job fine, but the bolt has pulled out about 6mm over the last couple of days. The shield is static, just the bolt and presumably cone is pulling. Maybe I didn’t tighten it enough – but didn’t want to over tighten. It has been windy so there will be a constant on/off pull out force. Steel rope initially tightened with turnbuckles. Any ideas or tips appreciated. longer/deeper resin fixings to a staple plate appear to be the gold standard, but a quick fix or more efficient re fix (gripfill the hole?) would be better. Or just keep tightening?

Answer 1

Never easy to know what you have got going on behind render, which can cover a multitude of sins. The fixing is only going to be as good as the material you are attaching to no matter how fancy dan it is, in this case you could be into lightweight block or a rough mortar joint.

If it's stock brickwork and you are into a brick rather than a weak lime mortar joint you might be able to get away with re- tightening, although if youar near an edge there is a possibility of it crumbling. Worth trying first - slacken off, tap back and retighten.

If that doesnt do it , and  if you can get to the back of the wall my inclination would be to use a length of studding, an eyenut on outside and regular nut c/sk below internal plasterwork possibly with a spreader plate. This should be highly resistant to pulling stresses, and doesn't really depend on the condition of the wall. That's a fair size sail you have going on there so you are right to be cautious about the fixings.

Answer 2

OK. I can answer this for you.

You will need to release the pressure from the bolt. Once you have done that you can go about sorting it out. London brick is notorisly dificult to fix into. I think what you have used sounds fine. Once you have released the pressure then gently tap the bolt back in and then tighten as before. Do not be afraid of overtightening it, its almost impossible to do so. The more you tighten it the more secure it will be. I cant see why you was afraid of over-tightening it anyway, If you need to get it undone in the future it wont be that hard.

Just remember to let off the pressure before attempting to tighten it, overwise you wont get the result you are after.

My advice to you if the hole the bolt is in is too large for the fixing is not to try and patch it up with grip glue and wotnot but to make another fixing point. Its always better to re-drill than to botch up an existing hole.

Good luck

Answer 3

I'd give the 10 to Bilbo. Obviously if you have access to the opposite side of the suface in question, it would help, but in the situation, given that various stress factors will likely NOT go away, anything in the form of a substance won't be substantial for the long term. Beyond that, if you don't fear serious damage to the wall, or even to pull it over, Tightening would be the logical FIRST step at least.

Just my two "sense"

Answer 4

if it was not tightened properly will pull out. slacken it slightly , knock it back in and re tighten it. if it douse it again fit next size up (re drilling the hole to suite)

Answer 5

Just a note is the fixing a Hilti type or Rawlbolt type. Hilti type has sleeve over bolt and were designed for lateral pulling Rawlbolt type have 3 prong legs that expand when tightened  and were designed for all forces. If you want to be sure go for larger size say 10mm bolt that will be 14mm hole for a rawlbolt.

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