Cavity wall insulation for new builds

Pumped cavity wall insulation is one of the most popular methods of wall insulation for new build constructions. The pump method offers great flexibility as any size cavity constructed can be filled ranging from 80mm to 300mm and more. All currently required U-values can easily be achieved.

Method of Installation:

When insulating the building, the operatives follow the NSAI and manufacturers drill pattern. This is to ensure that the cavities are fully filled. The holes are drilled into the cavity walls of the building from either inside or outside. These holes are approximately the size of a one euro coin (22mm). Silver Bead along with an adhesive is pumped under pressure into the cavity.

Benefits of pumped insulation versus Board insulation:

The Reality of Board Installation

On site imperfect conditions exist, leading to imperfect installation of the board, including:

• No two blocks are ever perfectly in line and truly plumb
• Mortar protruding between block joints
• Boards unevenly cut with trowel or hand saw
• Boards not properly jointed
• Boards not taped
• No trim or gaps at windows.

Performance of Bonded Bead

• The efficiency of bead never changes – it will retain its designed calculation
• Lifetime performance in excess of 50 years
• The bead is all searching and will fill the complete cavity within the wall with no jointing or gaps
• The bead will not pass water to the inside wall and is free draining

Performance - BOARD

Completely reliant on a perfect fit to achieve desk top calculation although site conditions may not be perfect

• Board thermal conductivity = 0.022
• Gaps can lead to thermal looping and seriously damage U Values

Thermal Looping and its Effect on U Value

Desk U Value of 150 Cavity Wall = 0.21
With 3mm gap: 0.54 FAIL
With 10mm gap: 0.65 FAIL
If cavity is not sealed to outside air, gap becomes ‘slightly ventilated’ and bypasses the insulation board entirely.