Method of fixing joists on a flat roof

[CaptainSkutter]

Hi, I'm building a 4m x 3m single skin 4" block shed in my garden. My question is what is the best and most secure method of fastening down the joists?

I'll be installing a wall plate and strapping down but, I've seen a multitude of opinions on how to fasten down the joists to prevent uplift.

I've seen:
1. Skew nails/screws through the joist into the wall plate
2. Truss clips to attach the joist and plate, like this: https://www.ironmongerydirect.co.uk/product/simpson-strong-tie-truss-clip-47mm-width-882010
3. Upside down long-leg joist hangers into the joist, plate and blockwork
4. Twisted restraint straps into the joist and blockwork

Would appreciate any experienced opinion here - it could be that they're all fine and just offer differing levels of belt and braces.

Thanks in advance

 

[^woody^]

Twisted strap, min 1500mm long, on every 4th joist.

 

[DAZB]

For the small extra outlay i would also use truss clips on every rafter and you could always fix the wallplate down with resin fixed fixings which have a very good grip in most substrates.

 

[noseall]

For the small extra outlay i would also use truss clips on every rafter and you could always fix the wallplate down with resin fixed fixings which have a very good grip in most substrates.

Woody is referring to a method without a wall plate, i.e. built-in joists.

 

[DAZB]

@noseall , you sure about Woody ? the OP said he has a wall plate and using straps ..."I'll be installing a wall plate and strapping down" and not sure why you let me know that but cheers.

 

[noseall]

@noseall , you sure about Woody

Yes. Twisted straps are used in the absence of wall plates.

 

[noseall]

i would also use truss clips on every rafter

We use them often on rafters too - top (lean-to roof) and bottom.

 

[DAZB]

@noseall I know twisted straps are used but the OP actually IS using a wallplate in which case standard "L" shaped straps will work as will the truss clips to secure the joists/rafters.

 

[CaptainSkutter]

Ok, thanks all for your comments. I think the consensus is that truss clips alone will be fine provided the wall is strapped down, which it is.
Thanks again all.

 

[b123b]

Question . If I worry about my L shaped straps on my wall plate can I add twisted straps to be on safe side ? Or is it pointless ?

 

[noseall]

Question . If I worry about my L shaped straps on my wall plate can I add twisted straps to be on safe side ? Or is it pointless ?

You would normally add more L shaped straps....

 

[catlad]

Question . If I worry about my L shaped straps on my wall plate can I add twisted straps to be on safe side ? Or is it pointless ?

If its what you want then yes. Before brackets, clips and joist hangars 5-6" skew nailing was the only way of fixing down rafters & joists.