I live in an old cottage where upstairs accomodation is in the roof. I do not want to loose headroom by applying blanket foil insulation to the rafters followed by 2x1 batons and plasterboard.
Therefore I am going to us either Cellotex or Kingspan (as thick as the space will allow) wedged in between the rafters followed by either foil backed plasterboard or insulated plasterboard.
What should the gap be between the plasterboard and insulation to allow ventilation?
Can I place the Cellotex up against the sarking boards (the house is old so I don't have any felt).
Are there big thermal advantages using a 20 mm insulation backed plasterboard (like the Kingspan Kooltherm) compared to a foil backed 12.5mm plasterboard? The Kooltherm is quite pricey which is why I ask this. Are there any alternatives available?
Many thanks in advance for your advice
Therefore I am going to us either Cellotex or Kingspan (as thick as the space will allow) wedged in between the rafters followed by either foil backed plasterboard or insulated plasterboard.
What should the gap be between the plasterboard and insulation to allow ventilation?
Can I place the Cellotex up against the sarking boards (the house is old so I don't have any felt).
Are there big thermal advantages using a 20 mm insulation backed plasterboard (like the Kingspan Kooltherm) compared to a foil backed 12.5mm plasterboard? The Kooltherm is quite pricey which is why I ask this. Are there any alternatives available?
Many thanks in advance for your advice