sagging roof

[KMBoro]

Been looking at a property that is pretty cheap to be fair - the vendor has been honest (up to a point) about some structural problems. He said that the slate roof was taken off in the 1980s and replaced with a concrete tile but obviously the woodwork in the roof was not suitably strengthened and the roof has sagged.
I have had one or two roofers have a look from the outside and had some varied ball park figures quoted - one said he would replace the roof for £8000, another told me there was no need to replace the roof, rather he would take off the tiles, strengthen the roof, re-felt it and put on the existing tiles, job done for £3500.
My worry is that there is something worse lurking beneath the roof in terms of the structural integrity of the house. I did notice that one of the bedroom walls seemed to be bowing at the top. The house has been on the market for a long time, originally priced at £170k, but now is offers around £100k. Obviously I would get a building survey, but anyone got any thoughts as to whether I should just walk away....I would have thought that if it was as simple as getting the roof strengthened for £3.5k then either the vendor would have got that done or a builder would have snapped up what would surely be a bargain

 

[terrypin]

A common mistake amongst so-called roofers was their practice of replacing slate with tiles, usually to sell the slate which would boost profit. Unfortunately the extra weight would compromise the structures integrity.

Just taking the tiles off and strengthening the timbers may not cure the sagging and possible spreading.

 

[KMBoro]

Thanks Terry, that was my worry...It could be a lot more expense than I had originally hoped....could be time to look elsewhere...

 

[foxhole]

A strenthened sagging roof is still a sagging roof.