In addition to having the loft converted into a bedroom, for use by our daughter, we are also upgrading the insulation in the bedroom she currently shares with her brother. This room is on the first floor, and already is insulated externally on one external wall (the side wall of our semi-detached house). However, unlike on our ground floor, there is no solid wall insulation on the other external wall in this room. This cold wall is still prone to condensation and mould in winter. Which is obviously not what anyone would want in a child's bedroom.
So, we are going to have internal solid wall insulation fitted to the uninsulated cold wall. For this we are going to use 'breathable' materials, as we did for solid wall insulation in the rest of the house (but not the new loft conversion work). This involves us specifying and ordering Pavatex woodfibre boards (Pavadry), plus the fixing and taping materials, so our builders can install them.
This isn't as simple as you would hope, in that the product suppliers (NBT) don't deal directly with individuals, so we have to go through another builders' merchant. There has been some back and forth about which organisation can provide price quotations etc. Hopefully, somebody will take our money at some point, and we will get the products on site, on time.
The product range seems to have moved on since we used earlier versions of this product in 2009/10. For example, it is no longer required that the finishing layer of plaster be lime plaster. Instead it can be finished with standard plasterboard. This makes it easier for conventional builders to install - as most will have no experience with lime plaster. It seems a little odd, since we were persuaded on the lime plaster arguments with the previous product. However, I haven't got a moisture movement model, or the knowledge to use one, so I am going to assume the manufacturers have done the calculations and that using gypsum plaster / plasterboard will not be detrimental.
In the main loft conversion, all is going well - with work on pause for a few days, until the staircase is installed and the loft room connected to the rest of the house.