Foam Cavity Wall Insulation U Value

The u o factor for all frame walls is based on the r value of cavity insulation and the continuous insulation r value if used.

Foam cavity wall insulation u value.

Most cavity insulation installed since the 70 s is what known as foam board or styrofoam or air board insulation panels. If you do and it consists of blown mineral fibre or polystyrene beads and you re still receiving high energy bills we recommend switching to expanding foam insulation. These can be supported with a detailed report. Note from this.

When continuous foam insulation is specified 100 of the wall is assumed to be covered at the specified r value. Now on paper they have great insulation values but when placed in your cavity by block layers or bricklayers they have a huge weakness. In this instance to achieve a u value of less than 0 2 w m 2 k you need to apply either internal or external wall insulation too although you will only need to apply 50mm of celotex either internally or externally to achieve this. Polyurethane products are well known for their increased thermal efficiency which results in lower u values.

The lower the u value the greater a product s resistance to heat flow and the better it s insulating value. Foamular 250 retards the transmission of water vapor and moisture in masonry walls. The r value is the reciprocal of the conductivity of a material and is the measure of the capacity of a material to resist heat transfer. For more information see our articles and how to videos below.

The maximum u value you can achieve by retrofitting cavity wall insulation in any property older that 1975 is 0 5 w m 2 k since you are limited by the thickness of the cavity. U values are expressed in units of w m2 k. The entire wall is assumed to have structural sheathing. U value ratings generally fall between 0 16 and 1 20.

We provide u value calculations to show compliance with current building regulations standards and best practice. For example if you have a type of insulation that has an r value of r 5 per inch of thickness you will need a depth of 6 inches of this insulation installed in your attic to reach r 30 if you live in zones 2 or 3. If the user does not enter a continuous insulation sheathing r value or enters a value of 0 0 the software assumes a sheathing r value of 0 83. Installing our cavity wall insulation product technitherm and using our spray foam product duratherm which both have a low thermal conductivity value of 0 025 w mk means you can achieve lower u values.

Users need to make a selection from each of the drop down boxes. Foamular 250 extruded polystyrene xps provides continuous insulation in insulated concrete sandwich panel walls in masonry unit cavity walls or when used with non penetrating surface mounted furring systems over masonry or concrete walls. Usually white and very light. It is designed for all users but specifically those who want to make an assessment of the u value achieved with various combinations of block and thermal insulation prior to finalising a wall design.

We are able to provide contractors architects specifiers and homeowners u value calculations for their projects when using our products. U value calculator for cavity walls.