Bed shakes in new loft conversion when windy

[james75]

I e-mailed the owner of the loft conversion co. a couple of months ago to tell him what was happening, on the off-chance he might have a light-bulb moment. Here's what he said:

"It's not completely abnormal for movement in a building (specifically the roof, as it's a timber structure), when there are particularly strong winds.Your house , of course , is much more likely to be affected because of the open position.Additionally, the concrete tiles on your roof are very heavy and this probably has a bearing on the movement, too.

The whole roof will be moving when there are really windy conditions but you'll feel it in the floor because the weight of the roof is bearing down onto the vertical dwarf walls, which in turn, are bearing onto the two steels which support the floor joists.

Unfortunately, I don't think there is anything that could be done , other than some very serious structural alterations."

 

[joe-90]

It all looks too flimsy to me. You can't go taking the middles out of trusses without giving serious thought to what might happen. If you've got those heavy concrete roof tiles you'll have several tons up there. A house shouldn't shake in the wind. It didn't shake when the trusses were complete - and it shouldn't shake now.

 

[amwc]

Shouldn't there be a steel ridge beam on a trussed loft con. The collar ties are only holding the rafters down and not doing the job of a raised tie truss. The rafters should be a min of 150 deep i think? But the ridge looks unsupported to me.

 

[joe-90]

Shouldn't there be a steel ridge beam on a trussed loft con.

I think you are right. It would certainly handle the buffeting by the wind far better.

 

[freddiemercurystwin]

This thread's doing my nut in. You can forget about getting a certificate from the cowboys who took your money, there's probably more chance of my grandad winning the lottery and he's dead!

Two things:

You have a load of photos so if you want to find out if the structure is adequate you're gonna have to part with a little more cash and pay for a bona fide structural engineer to do some assessment/calcs on the new structure. This may involve opening up areas for inspection if the photos are inadequate. You will not glean this from a forum.

If you want to sell the house anytime soon you're gonna need a certificate. For that Building Control will require evidence the works have been carried out in accordance with the Regs and that an adequate structural solution has been designed and built. Whilst photos will help, this too may involve opening up areas for inspection if the photos are inadequate. You will also need structural calcs for this as just mentioned, you will not glean this from a Forum either.

You may have to face up to the fact that additional works may be required to legalise the works and not just for inadequate structural works.

So you can keep on coming back to this thread but at the end of the day you will not receive the responses you would like to hear.

 

[geraint]

Shouldn't there be a steel ridge beam on a trussed loft con. The collar ties are only holding the rafters down and not doing the job of a raised tie truss. The rafters should be a min of 150 deep i think? But the ridge looks unsupported to me.

Why sould there be a ridge beam.....

 

[amwc]

Geraint,
I don't know I'm asking the question, To take the place of the trussed elements and support the ridge? I've just seen either a ridge beam or purlins used as the size of the rafters wont span

 

[geraint]

Geraint,
I don't know I'm asking the question, To take the place of the trussed elements and support the ridge? I've just seen either a ridge beam or purlins used as the size of the rafters wont span

A ridge beam will not take the place of a trussed roof.... let alone make undersized rafters comply....

If there is no dormer, there is no reason to fit a ridge beam....

 

[joe-90]

It need a ridge beam plus heavier rafters. The ridge beam transmits the force to the end walls and down to the foundations. Without it you will get sway as there is nothing to stop it from swaying.

 

[geraint]

It need a ridge beam plus heavier rafters. The ridge beam transmits the force to the end walls and down to the foundations. Without it you will get sway as there is nothing to stop it from swaying.

So how does a ridge beam stop it from " swaying"

 

[noseall]

i think the point Grrr is making is that if you have lousy rafters, stiffening the ridge is not going to stop the diaphragm effect.

I personally think that the triangular stiffness has been compromised therefore the joists and rafters, as well as the way they are connected, needs looking at.

Also, diagonal and lateral restraint needs reinstating. The wind load needs sharing and displacing.

Probably.

 

[geraint]

i think the point Grrr is making is that if you have lousy rafters, stiffening the ridge is not going to stop the diaphragm effect.

I personally think that the triangular stiffness has been compromised therefore the joists and rafters, as well as the way they are connected, needs looking at.

Also, diagonal and lateral restraint needs reinstating. The wind load needs sharing and displacing.

Probably.

Difficult to say looking at the pics, but i would have thought that the new rafters should be bigger... Sistering the same size is not right in my mind...
And I would always birdsmouth the stuwork... Far more stable. and the ridge ties should be bolted, but that would not sove the problem....

 

[nrwilliams]

Sorry for bringing up an old thread, but did you get any resolution to your issues?

I am having a loft converted currently and have some concerns over the build.

Thanks

Neil

 

[freddiemercurystwin]

Sorry for bringing up an old thread, but did you get any resolution to your issues?

I am having a loft converted currently and have some concerns over the build.

Thanks

Neil

Its completely bonkers tagging stuff onto this thread, please start a new one.

 

[james75]

Sorry - me again!

Bedroom is still shaking in the wind.

I want to get it sorted out. What I want to know is, if I get a structural engineer round to check it out and it is discovered that the conversion is dangerous, do I have any rights against either the building control company who passed it or the original builders? Can I claim from either to cover the cost of rectifying it?