You can just see a galvanised steel column between two of the windows, and outside on the deck. The windows themselves are Wester Red Cedar timber. The roof is supported on the steel columns, with steel beams connecting them to form portal frames. There is bulk insulation running across the roof between the beams and rafters.

this photo looks like a thermal nightmare. the r-value of steel is nearly 0. those steel posts will get very cold when it is cold outside and i would expect that there would be some condensation at the posts. as to the steel beam, it is always better to insulate the beam from the outside so that it doesn't get cold.

insulating a steel beam is a real challenge and it is better to insulate the beam from the outside to keep it from getting cold. i faced this very challenge and i had only about 1" for insulation. i ended up using aspen aerogel spaceloft insulation. to achieve an r-12 blanket covering, i ended up having to use three 10mm thick spaceloft blankets. spraying foam insulation on the steel beam is also a good idea, and while it helps, keep in mind that the main route for thermal bridging across the steel beam is going to be straight through the flanges where the foam is going to be thinnest.

Thanks for your question, see my response to the next bit.

We are a door manufacturer that builds these type of bi-folding doors. Please check us out at www.lanaidoors.com

We regularly use Centor (http://www.centor.com.au) and Brio (http://brio.com.au) hardware in our folding and sliding doors. They both make very robust, high quality products.

the centor system looks to be much more robust than does the brio system.