Rotten roof timbers.

[trialscot]

Hi,
I'm renovating a 1920's 1½ storey end terrace and the ½ storey part has the roof timbers shown in the pic, obviously from water ingress over some time.
The two on the right are probably saveable when dried out, the two on the left are rotten for about four feet up but not actually falling to bits.
I'm thinking of stripping the roof tiles and sarking, about 6mx5m, sistering the timbers then cutting out the rotten bits.
Is this sensible or a complete non starter?.
I'm not a complete novice in this sort of practical thing and I can't really see the roof collapsing when repairing like this but,as usual, advice will be very welcome.
The white on the timbers is old plaster and not rot.

http://s251.photobucket.com/albums/gg292/trialscot/?action=view&current=DSCF0295.jpg

 

[noseall]

why bother sistering, just remove and replace.

if you are going to the trouble of removing the tiles and sarking boards, you will have a clear run at the rafters.

remove the rotten rafters wholesale and use them as a pattern against the new timbers.

check the wall plate too.

 

[trialscot]

Many thanks for that, it makes it sound straighforward. I did wonder if there would be a danger of some sag in the ridge if I just removed and replaced them one by one, but after reading your post and thinking logically, if the tiles are off there's no weight on the trusses.
Yep, the wall plate is gone too (and some of the cupboard floor and most of the plaster on the ceiling below!) so quite a jolly day or two in store!.
I really have to strip the roof anyway as it's pretty nail sick, the old single romans are single nailed onto only ½" x ½" battens. At least if I break any tiles they're easily available,as they're being imported to Scotland from Spain and the south of France. These houses were obviously either built on a shoestring or the contractors were cutting outlay to the very minimum they could get away with, coz some things have been thrown up rough as a bears bum.
Having said that, there are double glazed windows and doors fitted by a very "high up in the world" company about five years ago and you wouldn't believe the shoddy work that's just covered up by plastic trim stuck to the wallpaper with silicone and now flapping in the breeze!.

 

[Deluks]

I assume those containers of water were put there to catch ingress? In any case, empty them out, or your roof will never be dry.

 

[Nige F]

I would believe the window fitters.. ....I am Tensing my butt cheeks with Hilary-ity...must go, I`ve got to take my Sherpa van in for MOT PS you`ve got Sarking Hell, there

 

[trialscot]

Deluks,
I never realised just how much condensation these tubs of water were causing until I read your post and started poking about.
Thanks.