Hi yes you can buy upvc capping fascias and soffits.
However you must make sure that the original woodwork is of sound condition. As you shouldn’t cap over any rotten wood.
All rotten wood should be cut out to the nearest roof truss end where the wood is good.
and replaced before any insulation.
Mainly box ends and gable ends
where the old wood fascias are open to the elements.
If the old fascias are rotten on the sides of the roof where the guttering sits
Its a good idea to check the under felt that should sit into the guttering to allow any water that gets under the tiles to reach the guttering.
As on most older roof’s it usually rots and drops down behind the old fascias a causes
The rotting proces.
If this is the case you will have to Usually remove 3 rows of tiles and re under felt and batten and fit the EPS felt support tray system
Or if you are really lucky you might just get away with the
EPS felt support tray system depending on how far the under felt has failed.
Make sure you have all the right fixings and fixtures
ie polly pins-correct corners and joints. Full box end boards
Finials.
And the right silicone sealer
And make sure that you use starter trim to fit the soffits.

As some don’t use starter trim to fit the soffits
And just silicone that isn’t the right way to fit.

Also upvc Circular disc vents are a good idea to allow ventilation.

Make sure you use good Quality screws usually 5 by 40 are good size.

I hope this helps you
👍🏼

Yes you can buy new plastic fascis which are designed to cover the old wooden ones

Yes clading over your original fascias or soffits is possible, however the original timber would have to be in a good state i.e not rotted, if it is rotted then the timber should be cut out and replaced, once the timber is covered with upvc cladding this will add a degree of protection to the original fascias. Cladding over is a cheaper option than full replacement however from dOwn below you cant tell the difference so it still looks nice.

Yes you can buy upvc fascias made to cover over old timbers as long as the timber is not rotten at all and if wood is covered soffits must be ventilated to stop tge old timbers sweatind and circulate the the air

You can buy all new plastics and cover over your old fascia. However, you will need good solid fixings behind it so it may depend on how good the timber is behind the old fascia. Hope that helps.

Yes over capping is possible is the original timber Fascias are in good condition.

Yes you can use UPVC capping fascia and soffits depending on the condition of the existing wooden fascia and soffits

When working in rooms such as bathrooms, where heat is generated, I would advise to use a water resistant filler such as Polycell Moisture Resistant Filler. This will help to achieve a crack-free fill between two surfaces where movement can occur.

Yes this is a option providing the wooden fascia’s underneath are in a good state. All Upvc suppliers stock capping and full replacement boards so it is pretty common.