How Much Space Between Insulation And Roof

Panels of polystyrene come to mind because their r value is better per inch of thickness than roxul pink stuff.

How much space between insulation and roof.

If the current gap is 3 4 the most you could do is insert 1 5 max of insulation. From the sound of it the roof has already been framed and that limits options. The quest for greater energy efficiency in buildings has led to increasing interest and need for insulation improvements in hvac equipment more airtight construction new materials and assemblies. Air gaps larger than this work well too they promote ventilation on the foil and help keep the air dry and the air temps lower.

Often installed into wall cavities as a way to retro fit walls lacking insulation it can also be blown into unfinished attic spaces. Insulation is technically a solid with a lot of air in it therefore it is not an air gap. Apply a 2 inch layer of spray foam insulation r 10 to r 12 directly to the interior surface of the roof sheathing. With a warm roof the usual process is to split the insulation into two layers.

If 180mm is to be installed then 100mm board might be introduced between the rafters there has to be a minimum 25mm air gap between the insulation and the underside of the tiles or slates with an 80mm board running across the rafters. It is important that air is allowed to circulate between the roof covering and the insulation to avoid condensation a gap of at least 50mm 2 inch must be left between the insulation and the inside of the roof covering. Senior engineer manager at icynene john broniek makes the case for the unvented attic assembly and why insulating the underside of the roof makes sense. R value for loose fill per inch is between r2 and r4 higher value with.

You will however have to follow up with great stuff foam to ensure filled gaps if you go that direction. Here are four approaches i recommend you investigate for insulating your attic.