Hi there, I've had a search and can't find anything on blue bricks specifically - it may not be relevant but just wanted to check! The ledger board will also be supported by some posts, but I want it attached to the wall for neatness and stability too. The wall is rendered from the top of the existing blue bricks upwards and the ledger board will attach to those bricks just low enough to leave space for the decking to come up to where the render starts. I was looking at M10 P-type wallbolts with washer spacing at 600mm spacing (along a 3.6m board) but a friend of mine said he thought that it might be difficult to drill into the brick AND it may damage the brick using those fixings. I have a monster SDS drill that will have no problem making the holes, but does he have a point on the fixings possible damaging the blue bricks? Do I need to use another type of fixing? Someone suggested a sort of drilled hole/resin/threaded rod approach where the resin fixes the rod/bolt instead of using expansion. Allegedly there are some incredibly strong types of resin that do this but I know nothing about it.
I'm sure the pros will correct me if I'm wrong, but I would have though that Thunderbolts, or Multi-monti, whatever you wish to call masonry bolts, would be ideal in this situation, as there are no expansion forces involved. I must admit that I've always found them very useful.
Interesting. Never heard of them before, but looks like I can do with a smaller hole (e.g. 8mm for a 10mm bolt) and then just screw it in without any anchors and it just bites into the brick? Sounds good to me - but I'm sure someone will be along in due course to tell me why not to do it that way!
If the bricks are hollow one's you going to struggle to get any form of fixing to bite, if there are the resin option is best. If the bricks are solid, then Thunder Bolts are your friend.
Hmm. Is there an easy way of finding out which they are? Or do I have to do a test drilling to see if I can find a cavity?
Just use small drill, 4mm dia, using a cordless or percussion (not SDS) somewhere along the line that will be covered by your board. If it suddenly goes easy then you have voids. It probably depends when the wall was built, as far as bricks are concerned, I have always understood that older bricks had "frogs" but later ones had voids to save clay, but I maybe wrong.
Even if they are cavity bricks, couldn't I use the thunderbolts/multimontis close to the mortar gap, thus ensuring I'm in solid brick?
In this type of brick, I wouldn't risk it, they are very brittle, the pressure on the brick from the fixing would all most certainty crack it.
They are better than an expanding fixing, but if you think about how they work, you'll see that they do excert a certain amount of pressure on the brick, this is due to cutting a thread into the brick, engineering bricks are not particularly good at taking any form of stress pressure.
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