How Much Space Between Insulation And Roof

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.

How much space between insulation and roof.

The code calls for a minimum of 1 in. Typically we suggest you have an air gap between 1 2 and 3 4 for the radiant barrier to work. 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. For example cathedral ceilings built with 2x12 rafters have space for standard 10 inch batts r 30 and ventilation.

Generally spray foams have to be applied by a professional. The table below shows what levels of insulation are cost effective for different climates and locations in the home. This will keep the surface warm and help minimize condensation. The higher the r value the better the thermal performance of the insulation.

Unvented hot roof design cathedral ceilings are also an option. 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. Insulation level are specified by r value. If you already have insulation but it was put in some time ago it is worth checking the.

R value is a measure of insulation s ability to resist heat traveling through it. The recommended depth of blanket style insulation glass or mineral wool for a loft is 250 to 270 mm. Insulation costs between 1 400 and 2 300 blown in insulation is a little cheaper than batting fiberglass and radiant barrier insulation which cost 1 600 on average. Apply a 2 inch layer of spray foam insulation r 10 to r 12 directly to the interior surface of the roof sheathing.

Spray foam insulation is the most expensive option with the highest roi. They come with or without a paper or foil facing that acts as a vapor barrier. This flexible insulation material is most often packaged in rolls that come in various thicknesses and standard widths usually 16 inches and 24 inches to fit between joists or studs in a house s framing. Of airspace between the top of the insulation and the back of the roof sheathing.

Doesn t insulation count as an air space.