How Much Space Between Insulation And Roof

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.

How much space between insulation and roof.

Typically fiberglass or cellulose are the material choices. Panels of polystyrene come to mind because their r value is better per inch of thickness than roxul pink stuff. Insulation is technically a solid with a lot of air in it therefore it is not an air gap. If the current gap is 3 4 the most you could do is insert 1 5 max of insulation.

Typically we suggest you have an air gap between 1 2 and 3 4 for the radiant barrier to work. You will however have to follow up with great stuff foam to ensure filled gaps if you go that direction. This is one of the two most common types of insulation. Apply a 2 inch layer of spray foam insulation r 10 to r 12 directly to the interior surface of the roof sheathing.

Here are four approaches i recommend you investigate for insulating your attic. 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. 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. R value for loose fill per inch is between r2 and r4 higher value with.

With a warm roof the usual process is to split the insulation into two layers. Often installed into wall cavities as a way to retro fit walls lacking insulation it can also be blown into unfinished attic spaces.