Cavity Wall
From Swikipedia
Introduction
Cavity walls consist of two 'skins' separated by a hollow space (cavity). The skins are commonly masonry such as brick or concrete block. Masonry is an absorbent material, and therefore will slowly draw rainwater or even humidity into the wall. The cavity serves as a way to drain this water back out through weep holes in the base of the wall system. A cavity wall with masonry as both inner and outer skins more commonly referred to as a double wythe masonry wall.
Brief Description
Benefits of Cavity Walls
1. Resistant to moisture penetration – they prevent the moisture to penetrate within the walls.
2. High thermal energy efficiency – Cavity walls aid in minimizing heat loss and heat gain. It can reduce the heat loss up to 60% in a building.
3. Excellent fire resistance.
4. Cavity walling can be used as both non-load-bearing infill for framed buildings and for bearing-wall construction.
Cavity Wall Insulation Materials:
1. Blown Mineral Fibre
Blown mineral fibre consists of strands of fibreglass or mineral wool that are forced into the cavity using compressed air.
2. Polystyrene beads or granules
Polystyrene beads may be supplied loose or in a light sticky resin to hold them together. Polystyrene granules will stick together of their own accord due to their rough shape. Both types of material are blown into the cavity using compressed air.
3. Urea Formaldehyde Foam
Urea formaldehyde foam is created within the wall cavity by injecting and simultaneously mixing two chemical components to form the foam which then expands to fill the cavity.
References:
http://en.wikipedia.org/wiki/Cavity_wall
http://www.maconline.org/tech/design/cavitywalls/cavitywalls.html
http://www.carbonfootprint.com/insulation.html
http://www.answers.com/topic/cavity-wall-arch-in-encyclopedia
