I am building a conservatory with a 75mm cavity and am really stuck on the type of insulation to use.
The cavity wall to be insulated is approx 13 M2 and so is quite a large part of my small conservatory. Its important to me that the conservatory is well insulated so I can use it all year round. Which type of insulation would you recommend?
Im I correct in thinking if I use insulation boards such as Celotex (for 75mm cavity) I will need 50mm thickness as to leave a 25mm clear gap? And if I use something like Rockwool cavity batts I can fill the whole 75mm?
If there is not much of a difference in U values then it will then come down to the difference in costs.