That could be the way to go. I assume you have scaffolding in place. If the cladding is removed could you build an internal temporary support whilst standing on the scaffolding. Building it from the inside would be difficult, depending on your age and mobility. Presumably it is just a case of internal temporary supports to replacing the vertical timber members at the front.
Timber cladding in that location is always going to be a maintenance liability. Personally I would either replace it with something else which does not rot or if that is not acceptable for aesthetic reasons, then have a weatherproof facade made of non rotting material with the timber cladding as an easily removable/replace decoration, with ventilation as you intend.
On my recent new build, I have dormers and went for lead cladding. It suited the property, accommodates any movement and is low maintenance. Expensive to buy but cheap to install. Tile alternative would have required very expensive external corner tiles. Timber cladding was ruled out, looking to the future I need low maintenance.
I don't know for sure, but it's possible the the mock tudor cladding was put on when the house was re-roofed with concrete tiles. The original woodwork would probably have been ok as would the pebble dashed lath and plaster infills.
Lead would look nice. Accoya would be the ultimate choice for new cladding. As I'm removing the old lath and plaster, I won't need to worry so much about ventilation as the cladding will be fully exposed front and back.
I'm working may way along the main cross beam, machining off the rot. I think the corners are going to be the most difficult parts as the rot likes to travel in from the ends of the beams and the corners is where the beams all meet. I have't fully exposed the corners yet either.
I have plenty of time to work my way through it though and I think I have just caught it in time. Just...
It's interesting that the front didn't look too bad a year or two ago, but I guess the rot has been there a while, eating the cladding from the inside out. This year was when it finally made it through the cladding and became noticable from the outside.
On the plus side, my new Trend 25mm router bit is cutting sooo much better than the unknown brand 15mm cutter I had before. I am clearing 30mm wide channels now, an inch deep in 3-4 passes, then taking off the 5mm remaining strip with the multitool. Still a little limited in length of cut, but actually there is a limit to how far you can go without having to stop, get up and move anyway.
The indexing on my jig means I only need to have 3 fixing holes for each section of beam. I can cut the whole width off in 5 runs. Less as I get to the end of the beam as it's got a slope on the top running down from the mid point.
Today I will going into the worst part of the rot, cutting out 50mm or so. As the cuts go through the mortises for the upright sections, I can take them out and put completely new upright sections back in.
The more I work on it, the less daunting it looks!
