Anchor straps

[Thedreamer]

Our structural engineer's plan show that we are to have anchor straps @ 1200 cts, at the internal loadbearing wall or racking wall. 

 

Might sound a bit daft but is a racking wall the same as the perimeter wall?

 

 

 

 

 

 

[ProDave]

An internal wall can also be a racking wall. The clue is if it is specified to be clad in something like OSB.

 

Our 2 internal load bearing walls are also racking walls.

[ToughButterCup]

10 hours ago, Thedreamer said:

[...]

Might sound a bit daft but is a racking wall the same as the perimeter wall?

[...]

 

OK, I'll bite.

What on earth is a racking wall?  And don't just tell me it's a perimeter wall.....  

[Ian]

They are there to provide resistance against horizontal loads (eg wind loads). Without them the building would collapse like a pack of cards.

[ToughButterCup]

17 minutes ago, Ian said:

[...]  provide resistance against horizontal loads (eg wind loads). [...]

 

So does that mean that a racking wall provides that resistance - and by extension  other non-racking walls don't ?

[dpmiller]

A "normal" internal stud wall has no diagonal bracing (plasterboard doesn't count) but adding a layer of OSB braces all the studs together.

[ProDave]

Yes as above. most of out external walls were specified with 2 layers of OSB to give the required racking strength and the 2 internal load bearing walls were also specified to have OSB cladding so they are racking walls as well as supporting walls.

 

It's to stop the wind blowing the building over.

[Russell griffiths]

You will also find all the components in a racking wall have to work together

for example it is no good having a very strong wall that is not secured to the floor correctly, if laterally pushed or pulled it would lift from its base so not performing as it should, hence the floor strapping. 

I found in our last timberframe place that even the nail spacing was specific to the design of the wall. 

 

The 1200mm spacing is usually in line with a standard plywood bracing sheet, so sheeting is normally placed vertically so 1200 along and 2400 high. 

[Thedreamer]

Thanks for the comments guys, that's very useful.

 

We have two load bearing walls in the middle of our timber frame. These straps are shown as being under the block work which will then be attached to the studs.

 

I also see from reviewing the plans again that we have the same anchor straps on the external layer of block work.

 

So when the initial block work is completed I should be left with a load of anchor straps in the air waiting to be nailed to the studs?

 

 

[Russell griffiths]

Sort of like this. 

[Thedreamer]

23 hours ago, Russell griffiths said:

Sort of like this. 

 Yes that is what I was expecting! I had a look on a few blogs and couldn't see the straps to the number I was expecting per my SE plans. Perhaps sometimes these are attached by heavy duty masonry screws rather than being under the blocks like the diagram above?

Edited April 1, 2018 by Thedreamer

[StructuralEngineer]

I'm racking my brain trying to think what the SE wants straps for. The sole plate should be fixed down to concrete anyway, and the top plate should be connected to the joists.

[Jeremy Harris]

Our frame is held down with steel hammer fixings through the inner sole plate to holes drilled in the slab ring beam.  Pretty quick and easy to do, with no requirement for awkward straps.  Using fixings through the sole plate seemed normal to our building inspector, but he hadn't seen the steel expanding sleeve hammer fixings that our guys used, so asked to see a sample.