ᐅ Affordable insulation for a wooden roof to achieve 0.24 W/(m²·K)?
Created on: 12 May 2015 17:37
1
1080pHello,
I recently bought a small house from the 1920s and now need to insulate a flat roof of about 45 m² (480 ft²) to achieve a U-value of less than 0.24 W/(m²·K) according to the 2014 Energy Saving Ordinance. Since the ceiling height is limited, a inverted roof seems suitable—meaning insulation made of XPS (extruded polystyrene) or PUR (polyurethane) placed directly on the existing bitumen membrane, which will then be sealed again with bitumen membranes. I would like to do much of the work myself but need advice on the type and thickness of the insulation material.
The roof construction is simple: interior plaster – vapor barrier – wooden boards (about 5 cm (2 inches)) – bitumen … and with some luck, there is still a layer of polystyrene under the plaster inside. The roof has a slope of about 5° and is intended to be used for a photovoltaic system.
My first question is how exactly compliance with the Energy Saving Ordinance is verified. Does an energy inspector come after two years to measure the U-value? Or is it sufficient to provide plausible information about the installed insulation upon request, or…?
My second question is how to determine the insulation requirements—that is, which material and thickness I need to install. Do I have to carry out a (quite complex) U-value measurement beforehand, or is there a calculation method for the different materials?
What would be the most cost-effective way to achieve legally compliant insulation?
Thank you and best regards,
Benny
I recently bought a small house from the 1920s and now need to insulate a flat roof of about 45 m² (480 ft²) to achieve a U-value of less than 0.24 W/(m²·K) according to the 2014 Energy Saving Ordinance. Since the ceiling height is limited, a inverted roof seems suitable—meaning insulation made of XPS (extruded polystyrene) or PUR (polyurethane) placed directly on the existing bitumen membrane, which will then be sealed again with bitumen membranes. I would like to do much of the work myself but need advice on the type and thickness of the insulation material.
The roof construction is simple: interior plaster – vapor barrier – wooden boards (about 5 cm (2 inches)) – bitumen … and with some luck, there is still a layer of polystyrene under the plaster inside. The roof has a slope of about 5° and is intended to be used for a photovoltaic system.
My first question is how exactly compliance with the Energy Saving Ordinance is verified. Does an energy inspector come after two years to measure the U-value? Or is it sufficient to provide plausible information about the installed insulation upon request, or…?
My second question is how to determine the insulation requirements—that is, which material and thickness I need to install. Do I have to carry out a (quite complex) U-value measurement beforehand, or is there a calculation method for the different materials?
What would be the most cost-effective way to achieve legally compliant insulation?
Thank you and best regards,
Benny