How are roof trusses fixed to walls?

[Gareth]

I'm in the process of buying a house and the surveyor has said that there is a problem with the roof: "the end trusses are not properly secured to the walls"

How should roof trusses be fixed to walls? Is it just a matter of nailing/screwing in a few bits of wood?

It's a fairly ordinary house, about 18 years old with timber trusses and cavity walls.

Thanks for any information.

Gareth.

[Phil L]

It needs some restraining bars going in - steel bars about 2ft long and an inch wide, full of holes - you nail one end to the truss and the long part is affixed to the wall - it's so that a strong wind can't lift the roof off. They take about 5 minutes to affix and cost about £3 each

[John Rumm]

Often known as "Bat straps" (after a common brand). One difficulty in retro fitting is that they often dip below the loft floor level ang get plastered over.

[Gareth]

Phil,

Thanks for your quick and helpful reply.

Gareth

[Gareth]

Thanks for that information.

[Kipper at sea]

The roof trusses are fixed to the gable wall by L shaped straps, these are fixed to the under side of the roof truss and the short leg is place over the inner wall. They should be fixed to the inside of the outer wall with fixings but I=92ve only seen this done once. They are not to stop the roof from lifting off in high wind. The one referred to in the other posting are fixed on to the wall plate at the eave and down the internal walls and plastered over, theses are the ones that hold the wall plate that the trusses are fixed to at the eave. Roll Edge Restraint Strap Bend 500 x 100mm Pack of 5 from Screw fix

[Charles Fearnley]

Fixing gable walls to the end two or three trusses with galvanised straps is now a requirement - and our new extension has just had these fitted and signed off by the BCO. However, when our house (bungalow) was built in 1970 this was not a requirement, and so the other end original gable does not have these straps, which like yours was picked up two years ago by our pre purchase survey. I asked our (friendly and helpful) BCO about this, and he said that the straps are to add extra support to the gable wall, and to prevent said wall from being blown or sucked out in extreme conditions. He also said that this only really happens to houses in very exposed conditions, and that there was generally no problem otherwise. Building regs are not retrospective, so while your surveyors was correct in saying that the lack of straps is not up to current spec, it's likely that you don't have a problem, unless you are by the sea or on a mountain. If you do want to add them they can be screwed to the underside of the trusses, and to the inside of the wall. This will give most of the support intended, if not quite as much as in their proper position above the trusses with the 90 degree ends over the gable walls.

Charles F

[Kipper at sea]

[e-mail]...

You are 100% correct about the straps being fitted above the truss / rafter but they nearly always come directly under a lath, which means they have to be taken off and re positioned. General practice today is to fit them underneath the truss or rafter. And yes that=92s the function of the straps, to support the gable walls, not to stop the roof from lifting.

[Andrew Gabriel]

Yes - it came about after a number of gable-end walls have blown out (or in) in high winds. With the advent of roof trusses and the demise of purlins, the gable-end walls had no weight on them and no lateral support, and were considerably more vulnerable as a result.

This is also something anyone thinking of fitting anything like a boiler (or other off-set weight) to a gable-end wall must consider; it doesn't take much to pull one over.