I'm planning to do a loft conversion - do I need to treat the roof timbers/ treat for dry-wet rot (although there are no visible signs of rot as the house hasn't been worked on for about 100years)?

Hi, no you do not have to treat for something that doesn't exist. Breathable felt and correct installation of the roof insulation will allow the timbers to stay dry and free from future rot. Julian

put some roof vents tile vents in they will sort the problem if any arise

it could work for you as piece of mind but breathable felt is all you would need in the roof joist ,

I would always treat timbers as a precaution,using breathable felt,helps the air to flow around roof space. I would also put air vents in the flat roof. Regards TRM.Builder.

only needs treating if there are signs of rot or woodworm, if its ventilated you should be ok,if insure used a qualified pca member or techincian ,if no signs it does not need treating so don't get ripped off,but if it puts ur mind at rest do it