Advice on leaking polycarbonate conservatory roof

[blueade7]

Hi, I recently moved into a new house with an old conservatory that's past its best shall we say (see photos). We'd ideally like to prolong it's life for a few years until we're able to knock it down and replace it with an extension.

I've already replaced some timber that had rotted due to a previous gutter leak, and applied a tonne of wood filler and sealant here and there. It's watertight now, except in heavy rain, there's a leak or two from the polycarbonate sheet roof which is only going to get worse. Water must be getting in under the knackered old flash band between the polycarbonate sheets.

I've already replaced the portions of the flash bands I could reach (you can see the contrast in the photos between the old and new band), which has resolved the issue there, but I can't easily reach the rest. I've considered replacing the flash bands by:
(a) Climbing on top of the conservatory by balancing on wooden boards placed across the rafters - the easy option but would it support my weight?!
(b) Removing and replacing every sheet using a ladder from inside the conservatory - but a fair bit of extra work when all I need is to replace the bands, and I can see this potentially requiring me to replace sheets if they're damaged on removal.

I'd appreciate any thought and recommendations on what to do and roughly how to do it. Cheers!

 

[Deluks]

Looks like water is within the sheets?
When these age, the outside of the sheet can crack and split, not always obvious. This lets water into the chambers of the sheets, which runs down and usually drips into the room, or may have been the cause of your leaking gutter problem.

Spread your weight with boards is a good idea. Make sure the floor beneath you has a soft covering, just in case!

 

[blueade7]

There is a bit of water visible in the sheets but I think this is basically just condensation - I don't *think* this is the cause of the leak. It's getting in near the top where the sheets meet the house. The flash band is pretty worn up there.
The rafters are quite long (max 3.3 m) so I'd be a bit concerned about whether they'd hold up underneath me. I could perhaps make some wooden struts to provide vertical support for the rafters from inside the conservatory.

 

[Deluks]

They look to be in the region of 4x2, hardwood. Spreading weight over two or more of them should hold you ok, (watch out for the board sliding down, a few strips of gaffer tape will help secure it.)
Just make sure the rafters are securely fixed at each end.

If it were me, I'd be tying a rope round the waist, and through the velux and around something solid, if anything it gives you more confidence to use both hands when applying the flashband.

I have used struts before, a length of 4x2 back to the house wall at the base, and held in place at the rafter end with a few blocks of wood screwed in place.
We don't know if you are built like John Goodman or a Somali pirate so use your judgement, it's at your own risk!

 

[blueade7]

Thanks for your help. Closer to Somali pirate, but think I'll go with the struts (+ mattress) anyway as whilst the rafters seem sturdy, I don't know for sure there's no rot in them.