Fixing bowing roof from inside.

[jocollett]

Hello!
I have a bowing roof on a mid terrace. The 4 purlins at some point in the past have had supports removed along the length and have rotated slightly and bowed. Ive had an engineer round who has provided the spec for steels to replace them with, although it's suggested leaving the purlin in situ and the rafters, fitting the steel to its face and new rafters alongside the old.

As the rafters are also bowed, the depth of the bowed section off the horizontal would need to be considered when fitting the new steels below. Either cutting a triangle out the old rafters at the bow or placing the steel under the lowest part of the bow and building up to the new rafters with a chock of timber.

Anyway I'm wondering, (as the roof tiles look in OK condition) would it be possible to cut the nails holding the battens to rafters from inside and then gradually wedge sections of batten up away from the bowing rafters until I could fit a new straight rafter under it and then carefully reattach the battern to the new rafter, working along the roof from the inside.

Does that sound like it could work if done gradually and with care or does it sound like a disaster waiting to happen?

Thanks!

 

[datarebal]

Sounds easy but doubt it'll work.
New purlin with folding wedges

 

[oldbutnotdead]

How are you going to cut the nails? Is there felt under the battens- if yes you're probably stuffed. If no then careful prising the battens up with a long wrecking bar might work but it'll take ages. Then threading new rafter between purlins and battens- how are you going to do that? Assuming rafters are 4 or 5 metres long, how will you actualy get them from outside into the loft and then into position?

 

[jocollett]

Thanks for the reply and helping me visualise those issues. Yes the battens are on the outside of the felf so any wedging would most likely destroy it at that point and getting rafters in sounds impossible without cutting them.
Sounds like it needs doing properly from the outside!

 

[oldbutnotdead]

Depends on what you want to achieve. If you can get the steels specified in place without destroying the inside of the house (again consider their length, weight etc., steels can be bolted together if appropriately specified so 3m lengths might be doable) and you can live with a bowed but stable roof then as @datarebal , wedge existing rafters.

 

[jocollett]

I suppose I might be able to lift the batton from underneath and then get a grinder, hacksaw under it to cut the nail. If that's possible and there feels to be enough flexibility to lift the batton, rafters could be pushed in from outside if I removed the soffit board and climbed up on a ladder or fed/pulled them in on the end of a rope.

 

[oldbutnotdead]

I'll come and laugh from a safe distance while you do that.

 

[jocollett]

The steels are a little over 3m and bolted centrally. The existing purlin seem to sit on the internal leaf of a cavity wall so would do the same with the steels and add a padstones. I think I could get the steels in via the house. I would test the route up the stairs with a piece of lighter timber of the same dimensions. The house needs refurbishment so if I need to dismantle banisters or doors that's now an issue really

 

[jocollett]

I'll practice on the back of the house first where no one can see!

 

[datarebal]

I was tempted to say no more . But I can see trouble is brewing . It's a stupid idea

 

[jocollett]

Thanks for the honesty I will scrap the idea.

 

[catlad]

I'm thinking you need to escorted back to the loony bin! but if nobody is available under the current situation then make sure you are filming it because I would like to watch!

 

[noseall]

Jeezus! Is this an early April fool?

 

[datarebal]

nearly