Roof Tie-Down / Single Block External Wall

EngCarol · Sep 02, 2024 3:28 pm

Hi!
I am an engineer who doesn't have much experience in Perth market and currently preparing a roof tie down detail sketch for fixing to a single block external garage wall top. I had a quick google research and have found out that Mi-Tek blockfast is a good solution if it is a common practice to use concrete filled U blocks on top block course in Perth. The blockfast is going to be wrapped around the reo bar placed in U block before the pouring of concrete.

Can anyone please advise me? I do not want to look unprofessional with my blockfast and u block sketch.

Many Thanks in advance!

Eng. B A · Sep 02, 2024 3:48 pm

Just make sure the top coarse is adequately connected/bonded to the remaining of the wall to avoid splitting at top. You could cast in vertical hawked bars with enough anchorage length in the concrete core filled wall and threaded at top and connect with upper trusses/rafters with steel angle brackets.

EngCarol · Sep 02, 2024 4:37 pm

Thank you for your reply. I didn't think about the vertical hawked bars previously.

What I understand from the architectural drawings is, the block wall is non-reinforced. There are engaged piers 1200 mm centres. My idea was concrete fill the piers with tie-down bars and place a U block on top course with lateral reo bar/wrap the tie down and pour concrete. I also find the steel angle bracket better, but I am in a position that everyone around me complains about the economy of construction at the moment.

As a conclusion, I hope you don't find U blocks, etc are odd, right?

Eng. B A · Sep 02, 2024 6:03 pm

For engaged piers, you normally reinforce it with central L bars that is casted into footings and threaded at top with angle bracket connection to roof beam if the walls are non structural and aren’t concrete core filled. Generally the block walls would have at least N12 at 1800mm c/c vertical bars (more reinforcements may be required depending on wind rating, wall height, site class, supported roof area and openings etc..) and threaded at top for tie downs. (Only tie down blocks are concrete core filled).

EngCarol · Sep 02, 2024 6:05 pm

Thanks for the detailed replies mate!

This makes sense.

chippy · Sep 02, 2024 7:30 pm

EngCarol

Hi!
I am an engineer who doesn't have much experience in Perth market and currently preparing a roof tie down detail sketch for fixing to a single block external garage wall top. I had a quick google research and have found out that Mi-Tek blockfast is a good solution if it is a common practice to use concrete filled U blocks on top block course in Perth. The blockfast is going to be wrapped around the reo bar placed in U block before the pouring of concrete.

Can anyone please advise me? I do not want to look unprofessional with my blockfast and u block sketch.

Many Thanks in advance!

In Perth even with a single brick wall you often run a shelf lintel through 4 courses below plate height and they run between the piers and are site welded to the rod that runs up the piers. You effectively end up with a double brick wall with no cavity on the top 4 courses.
The shelf lintel is punched so straps can be installed and then tied into the roof. Everything is then tied back to the footings.

EngCarol · Sep 02, 2024 7:53 pm

Thanks Chippy

That's a great info. I remember my previous site inspections for a few other jobs and reasons, but now remembering that top 4 course, everything make sense now. Thaks again.

I will call the architect to discuss if we really need a block wall tomorrow.

chippy · Sep 02, 2024 8:07 pm

EngCarol

Thanks Chippy

That's a great info. I remember my previous site inspections for a few other jobs and reasons, but now remembering that top 4 course, everything make sense now. Thaks again.

I will call the architect to discuss if we really need a block wall tomorrow.

Beautiful thing with the shelf/recess lintel is you just use maxi's so standard brickwork. All the brickies and roofers in Perth are used to this style so there is nothing out of the ordinary.