# Forum Home Renovation Roofing  Best way to fix a sagging roof

## bludger

Hi all,
I have a late 60's BV house with concrete roof tiles. The underpurlins are supported with a combination of struts and scissors. 
My problem is that the roof has sagged wherever it is supported by the scissors (up to 40mm in some places) and it is visible from the ground. I think the sag has been caused by shrinkage of the scissor timbers allowing the apex bolts to loosen. 
I intend to replaced the roof tiles later this year and I want to fix the sagging before I do.
I have 2 questions...
1) Is it possible to straighten 40yr old hardwood rafters that have sagged by gradually jacking & packing or are they set like that for life? 
2) Is attaching new rafters directly to the old ones and securing new battens & roof to them a viable option? Or is there a better way to fix this?
Thanks
bludger

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## nww1969

Very unusual you get sagging in a hardwood timber roof .
Mine is late 60's and still like new.
I think you would need advice from an old roof builder if you can find one.
They knew how to build roofs in those days. 
Your house built in the 60's would have been built by a builder and the builder would 
have got a roof builder to do the roof.
Not like these days where everything is lifted into place from the factory to your roof. 
Have a house a few blocks away about 12 months old and roof sagging with pine rafters.

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## Bloss

In fact NOT unusual to have sagging in an old HW roof (especially in Sydney - the Central Coast house is likely to have used much better locally sourced timber and to have been over-specced) much roofing was done using green often mixed species hardwood and then 30-40 ton of tiles were placed on top which meant that the roof sagged as it dried. Some of shapes and bumps and curves as the timber dried are amazing. Not uncommon for HW gang nail trusses to have similar problems because they were not properly kiln dried and in the early days especially were often underspecced. 
Not possible to straighten or even trying. Depending on how bad out of straight  and alignment the rafters are you can often get away with new battens using various sizes and packing onto the rafters. Alternatively you can fix new rafters adjacent to the existing rafters after removing all the battens and measuring up. 
So the answer to your Q1  is 'no' and Q2 'Yes' - but it really has to be done all at one go - not really a DIY job.

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## bludger

Thanks Bloss,
I was hoping for a relatively easy solution but it doesn't seem there is one!
One further question... if this problem is indeed due to the timber drying under the weight of tiles, could I assume that the roof would have now stabilised and not continue to sag further?
thanks

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## Bloss

> Thanks Bloss,
> I was hoping for a relatively easy solution but it doesn't seem there is one!
> One further question... if this problem is indeed due to the timber drying under the weight of tiles, could I assume that the roof would have now stabilised and not continue to sag further?
> thanks

  yep - sagging would have occurred in first year or so - most in the first few weeks. When concrete tiles are new they too are wet and heavier than they are after cured and dried. Really only appearance not structural.

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## autogenous

Smith straps

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