Expanding airtight tape and sealant for retrofitting new glazed units?

[low_and_there]

Hello again, looking for any recommendations for expanding airtight tapes or finishing caulks/sealants to use as part of my retrofit of the front door area (mentioned in another post recently).

 

Two scenarios to solve for:

 

1) Replacement of the fanlight (the single pane of glass above the door) with a triple glazed unit; the unit will be 32mm (4mm | 10mm | 4mm | 10mm |4mm with Krypton gas). The door frame is set back from the elements as we've got a little storm porch outside, so there's little risk of driving rain hitting it, but nonetheless it needs sealing. I am thinking of the following approach:

 

a) Using an expanding airtight tape - options I'e come across on this forum and from mentions elsewhere: 

 

- Isobloco

- Contega Fiden Exo

 

Does this approach make sense and any suggestions on particular products?

 

b) Seal on both inside and out with some airtightness product..  Options I've come across:

 

Mastic/sealants:

 

- Siga Primur

- Soudal seal system

 

Tapes:

 

- Tescon vana or similar, wrapped around the edges and under the wood finish.

 

2) Adding double glazed units behind the stained glass in the door itself. DG unit will be 14mm thick. Again, thinking that the expanding tape would be useful here, but not sure if it's overkill? Then layer over that the timber beading, sealed in with an airtightness sealant (as above).

 

 

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Given I'm only doing this on a very small area, I can't buy hundreds of metres of stuff, and the Soudal system, while it looks attractive, is pretty pricey overall, so that is a consideration too.

 

Thanks for any advice!