Roof Issues

Rusty Knight

Hi all,
My neighbour finished his self build last year, and all was well in the world until 3-4 months ago.
He started hearing loud 'thuds' in the night (ok ok stop sniggering, no ghosts here), coming from the roof section over the front door. Not surprisingly, this worried him no end and we suspect it may be the steel girder that runs across the front door area. The roof extends out over the footpath to form a covered area directly outside the front door. The rafters for this section of roof are attached to the wall plate which runs along the steel beam.

Together we have monitored this for a while and it only happens in good weather, i.e. I suspect the sun heats the girder which flexes a little when both heating and cooling. Because of the load on it the slightest movement sounds like a naval gun going off! He says you can feel the thud in other sections of the house.

I persuaded him to remove the soffit and have a look; it turns out the steel beam is just sitting on the block on flat which closes the wall.

My question; I saw on the Discovery channel last year a steel roof frame being placed on concrete pads, and they used something like shims or 'slip plates' to cope with any movement. Would these work? Can they be got somewhere? Is it a simple matter of jacking up the beam a little, and sliding these plates in?

The house was built by direct labour, and there was no engineer involved, in an effort to cut costs due to little cash flow. So in reality he has no one to blame but must obviously fix this. Any ideas? And the lower the cost the better.......

Thanks, Rusty.

Carpenter

Rusty Knight wrote:

Hi all,
My neighbour finished his self build last year, and all was well in the world until 3-4 months ago.
He started hearing loud 'thuds' in the night (ok ok stop sniggering, no ghosts here), coming from the roof section over the front door. Not surprisingly, this worried him no end and we suspect it may be the steel girder that runs across the front door area. The roof extends out over the footpath to form a covered area directly outside the front door. The rafters for this section of roof are attached to the wall plate which runs along the steel beam.

Together we have monitored this for a while and it only happens in good weather, i.e. I suspect the sun heats the girder which flexes a little when both heating and cooling. Because of the load on it the slightest movement sounds like a naval gun going off! He says you can feel the thud in other sections of the house.

I persuaded him to remove the soffit and have a look; it turns out the steel beam is just sitting on the block on flat which closes the wall.

My question; I saw on the Discovery channel last year a steel roof frame being placed on concrete pads, and they used something like shims or 'slip plates' to cope with any movement. Would these work? Can they be got somewhere? Is it a simple matter of jacking up the beam a little, and sliding these plates in?

The house was built by direct labour, and there was no engineer involved, in an effort to cut costs due to little cash flow. So in reality he has no one to blame but must obviously fix this. Any ideas? And the lower the cost the better.......

Thanks, Rusty.

Hi
For god sake get an engineer involved in it worth it in the end

muffler

Yeah, I think Carpenter is right. Your friend most certainly needs somebody with a bit of expertise in this area.

If its been happening recently I cant really see the heat as being the problem.

kadman

Unfortunately people leave out the most essential elements in a self build, namely professional input at the top level. Shim packs would be little use if the steel beam is only sitting on a block on the flat, and the collar ties of the overhang are far up the roof zone. The loud bangs could also be the steel beam moving outwards from the building , due to the downward settling of the roof weight, causing outward pressure on the steel.

Hope fully its not. He should a professional survey done now.

Maybe this will act as a heads up for would be self builders.



kadman

muffler

One possible simple explanation might be if the wallplate or rafters were native timber. If the wallplate was bolted to the RSJ it could be creaking.

The steel girder you referred to should have been supported on padstones initially but it would be impossible to conclude anything without a visual inspection.

A structural engineer is required but if your neighbour wanted an unofficial opinion then he could do worse than consult with a good reputable builder

rooferPete

Hi,

Your description sounds like your neighbour tried to cantilever the roof out too far, the way the RSJ is held in place would be a good starting point.

I am trying to recall the weather conditions lately and I reckon we haven't had enough heat to cause an RSJ to expand like you describe.

What we have had are a few gusts of wind, not severe and probably lucky for your neighbour because if the problem is what I'm thinking the noise is being caused by the wind load on the roof.

It's just a guess but if I am right it might be a good idea to erect a scaffold and open the facia / soffitt at the end and jack the steel up to remove just enough pressure and fit supports under the overhanging ends of the RSJ's.

That may save the main roof structure or wall from major damage in the event of a real wind that is not unusual at this time of the year.

Of course I agree with the others who recommend the services of a professional, in fact I'll be cheeky and recommend a professional team this time.

Regards,

Peter.