rotten soffits

Hi I own a 1970s concrete tile roof bungalow with shallow slope roof. The soffits are made of plywood and are rotten rain runs down the walls as well as into the gutters. I have just shone a torch through a hole in the soffit I can see the bottom of the concrete tile and a bit of sodden 1/2 inch chip board-sarking?.There is no felt to be seen.The only good news is the truss end looks ok. It appears the roof ends on the inner wall and the facia- soffit box chipboard sarking is extended to the truss end. I take it repair will involve at least two rows of concrete tiles being removed. How do you replace them?. What should I use as sarking? Should I use aluminium or damp course to replace the felt? I have found a source for cedar planks for facia and barge boards can I use this instead of plastic my cedar lining is 30 years old-it looks great. What should I use for soffits. Many thanks Tom

I can't imagine where or why chipboard would be used. You want to get any holes in your roof sorted now before starlings get in and start nesting. Apparently swifts swallows and martins are making it early this year too.

I have no doubt someone on here has a list of sites with tiling repairs illustrated. In the meantime you can get a ladder organised and have a look to see which rows of tiles are naied down. If you are careful you can lift a column of them up enough to see what is going on.

Roof tiles generally are nailed every so many rows usually every third or fourth. The others are held in place by the weight and because the tiles hook over the battons. With a slate rip -which you can hire, you can jerk out the nails and remove a section of the tiles. If they are at the corner you may as well just take them off in a triangle to the problem area. Have half a dozen or so replacements handy as they are quite cheap. If you have to use them, space the new ones out so a different coloured patch will not stand out too long.