CAVITY WALL INSULATION WITH u.f. FOAM

Cavity Wall Insulation involves the mechanical injection of a suitable insulant into the cavity using specified systems designed to ensure complete fill. Urea Formaldehyde Foam is one of these recognised systems. It is injected into the cavity in a wet foam state 90-95% pre expanded through 19mm holes, it completes its expansion by moulding itself to the unusual shapes within a cavity and sets to form a rigid insulant.

The Cavity Insulation Guarantee Agency provides independent 25 year guarantees for Cavity Wall Insulation fitted by registered installers.  The Cavity Insulation Guarantee Agency was established in consultation with the Government to provide householders with an independent, uniform and dependable guarantee covering defects in materials and workmanship.  Independent research has confirmed that cavity wall insulation is a very reliable process.  Problems are therefore extremely rare, but if they do occur, CIGA has the expertise to ensure that they are swiftly rectified.

Composition & Durability
The raw materials for u.f. foam are manufactured under strict quality control to BS 5617 (1978) and installed in accordance with BS 5618 (1978). The foam is produced on site using u.f. resin and a foaming hardener. The foam sets immediately after injection and dries through the outer fabric of the building and into the atmosphere, as its water content evaporates.
It has sufficient strength and stability to be self supporting in the cavity and does not collapse due to ageing or building vibrations. It will last for the life of the building, is chemically inert to normal building materials, and is resistant to attack by rot, fungi and vermin. If necessary, e.g. to correct a building defect, or when making structural changes, the insulation can be removed.


Properties
1 Thermal Conductivity: the k value of u.f. foam should be taken as 0.040W/mºC for design purposes.

2 Density: A typical installed density is 10 kg/m³ (expressed as dry weight per dry unit volume).

3 Fire: The foam does not burn, but tends to shrivel and char when exposed to fire. It complies with Class P (not easily ignitable) of BS 476: 1968 Part 5, and the burning characteristics, when tested according to BS 4735: 1974, are:-

Mean extinction time - 23.5 seconds
Mean extent of burn - 25.1 mm
Mean burning rate - 1.0 mm/second

4 Water: The cured foam is resistant to water penetration and will not transmit water across the cavity by capillary action, or from below dpc level. However, the foam still breathes and is not a water vapour barrier.

Application
1 Survey: A pre-installation survey is carried out to ascertain the suitability of the property for insulation, and to determine the position of all openings, flues and vents which need to be kept clear.

2 Preparation: : Small holes, approximately 19 mm in diameter, are drilled at not more than 1 m centres, both horizontally and vertically in a pre-determined pattern: by drilling a series of sight holes, the flow of foam may be stopped to set in a vertical line at any party wall.

3 Installation: The foam is injected through the holes in a specified sequence, in order to ensure a complete fill of the cavity.

4 Making good: Following the installation, the injection holes are made good, the mortar colour matched to blend with the existing surface of the wall.

5 Post survey: This includes an inspection of the flues and airbricks, also the interior of the building to check for the presence of surplus material. If this has occurred in inhabited parts of the building, it must be removed.