2 sided transparent materials / wall not transparent on inside

Hi all, I have my first forum question.

I have been learning how to model 2 sided walls in buildings. I have created a really nice Geodesic dome out of a single model/mesh. It looks great for my first go. I think I have flipped the normals correctly on the inside and outside as I can not walk through the model when Mesh Collider is added which was my problem at first.

Now I have another issue which I think is material related and maybe caused by the complex geometry on the dome. Essentially I've made a transparent glass material for the dome. When I'm viewing the dome from the outside the panels are indeed transparent but when view the model from inside the transparency stops and the walls become solid. Also note that surfaces become solid when viewed through the transparent surface on the outside. I have 1 material applied to the entire model.

My Shader is Standard > Transparent Rendering Mode

Hopefully someone might know what the deal is here. I'm going to try applying another material to the inside only whilst I wait for a oracle to answer. :)

Cheers, so close to my Bio Dome dream model.