When should a wallplate strap be fitted?

[epsilonGreedy]

I thought the purpose of wall plate straps was to reduce the risk of the whole roof lifting off during strong winds. This risk is particularly high in my case with a hipped 30 degree roof profile likely to generate a low pressure vacuum on the lee side of the ridge like an aircraft wing. Coupled with that, my natural slate cover is lighter than manufactured tiles hence I need to ensure I get this part of the build right.

 

Another YouTube video suggested the wallplate straps stop the trusses tugging the wall plate off during erection of the roof structure. This confuses me as I thought the wall plate's mortar bond would keep things stable as the trusses are fitted.

 

Yet another online resource mentioned the trusses should not seat directly on a strap.

 

There are also internal stud frame positions and maybe chasing channels to wall lights or switches that might clash with a strap.

 

Considering all these factors how does this wall plate fitting workflow look?

• Bed in the wall plate 2 to 3 days ahead of the truss erection date.
• Finalise exact positions of internal stud walls and mark on blockwork.
• Same for bedroom wall lights positions.
• Mark up all truss seat centres on the wall plate.

 

The either:

• Fit the straps carefully with rawplugs and screws into the Fibolite blocks.
• Erect the trusses.

 

Or more likely because the roof carpenter will not have the patience to spectate on the rawplugging with his gas nail gun ready to fire.

• Fit the trusses minus wall plate straps.
• Carry on with the box eave carpentry.
• Once the pro carpentry team has finished but before the felting goes on and creates a wind lift risk, fit the straps solo.

 

[nod]

Bed the wall plate down Fix tge straps the following day 

I wouldn’t worry about clashing with studs 

[nod]

To be fare most sites I go on the hangers are fixed by the plastered with on clout nail prior to plastering 

For some reason the joiners who put the roof on tack the onto the wall plate But seem to think fixing them to the wall should be done by others 

[PeterW]

What’s the SE design ..? Could use twisted straps onto the trusses, and also worth looking at using concrete screws to hold the wall plate onto its bed too. 

[joe90]

I second using twisted ties from roof trusses onto walls with either rawlplugs/screws or concrete screws. I too have high winds in my area, I also used long straps to spread the load down the wall (may be a bit belt and braces but I feel safer).

[Mr Punter]

You would need the roof membrane or sarking on before there is any wind uplift risk.  Mortar will not prevent uplift, you need mechanical fixing, like straps down the wall.  The SE should spec this.

[epsilonGreedy]

13 hours ago, PeterW said:

What’s the SE design ..?

 

I don't have one yet. The truss company measurer is visiting next week. I will sound him out and also go back and review the notes on the original building control drawing.

 

13 hours ago, PeterW said:

Could use twisted straps onto the trusses, and also worth looking at using concrete screws to hold the wall plate onto its bed too.

 

 

12 hours ago, joe90 said:

I second using twisted ties from roof trusses onto walls with either rawlplugs/screws or concrete screws. I too have high winds in my area, I also used long straps to spread the load down the wall (may be a bit belt and braces but I feel safer).

 

Ah ha. These twisted straps tie the truss directly to the wall rather than introduce the intermediate truss to wall plate fixing to the overall solution. On first sight this direct fixing seems better now I am wondering if a twisted tie every 2m is superior to the truss to wall plate connection every 600mm.

 

I like the idea of long straps. I noted these on another build last year, they came 1m or maybe more down the block wall.

[joe90]

6 minutes ago, epsilonGreedy said:

don't have one yet.

I did not have an SE but the ties were specified in the architects drawing so already passed by building control.

[PeterW]

11 minutes ago, epsilonGreedy said:

 

 

I like the idea of long straps. I noted these on another build last year, they came 1m or maybe more down the block wall.

They should be standard 1200 straps which have 100mm leg with 1100m drop.