Pandaren Strikes

At present Sustainable Energy Ireland (SEI) offers two home energy saving programs that qualify the participating house owners to claim reimbursement of the total cost incurred by them for carrying out certain home energy improvements. One such classified improvement is the cavity wall insulation. This system of insulation offers a convenient structural design that supports wall insulation materials.

Cavity Walls

Cavity walls are external walls of a building. These have an air gap that might be housed within the structure of the wall itself (example- Hollow block walls) or between two solid walls (or between two partitions having a narrow air gap separating them).The houses that were constructed from1932 to 1982 widely used this technique.

For most of the houses constructed after 1982, it would be reasonable to conclude that its construction followed the technique of wall cavity, though it may or may not have incorporated an insulation in between.
Almost all houses constructed after 1982 adopted the cavity wall technique with or without the use of insulation.

Why do you need insulation in cavity wall?

An air gap is maintained by wall cavity that provides good means of insulation. Come to think of it, all the means adopted for using insulating materials necessarily involve the creation of air bubbles or air gaps to get the desired results. You should understand that heat flows from the warmer end to the colder end. If the cavity width between two walls goes beyond a specified critical limit, the air within the cavity gets forced to move around because of convection currents that are set up. As a consequence it starts assisting the transfer of heat from the warmer end to the colder end instead of jamming it.

A filling with porous insulating materials helps restrict t air movement within the cavity, thus providing an optimum level of insulation.

But how do you get to know that your house has cavity walls?

It’s almost certain that houses built over the last twenty-five yeas would have cavity walls. In all probability those have provided with insulation also. Likewise, houses constructed fifty years prior to that have a very good likelihood of being with cavity walls, though insulation might be missing.
The pattern of bricks on external walls is a sure tell-tale sign. The following three patterns are followed for lying of bricks.

* Stretcher bond
* Flemish bond
* And, English bond
Amongst these three, only the stretcher bond patterned brick walls will have a wall cavity. In a brick wall with stretcher bond pattern, the bricks are laid flat on their side and in a linear manner known as end to end lying.

Width of the total wall is another sure way of assessing the needful. Because of the built-in cavity, the width is more than the normal 300mm as you might have expected.

One shouldn’t hesitate to get professional advice on the subject as it is a skilled job and only an expert with proper tools and equipments can confirm and advice on the status of air gap and confirm if some insulating material has been used and thus the present state of the wall.

Types of insulation for cavity walls:

Here are the materials that are most often used for the purpose.

* Fiberglass or mineral wool in short strands
* Cellulose loose fill or stabilized cellulose
* Phenolic and other Synthetic foam cavity board – (Used in new constructions only).

The time taken for having cavity wall insulation for an existing house would take around four hours but calls for the services of an expert who has all the necessary special tools needed for the purpose. It requires drilling of holes in the existing external wall at predefined and determined distance. This is followed by the insertion of a special nozzle and then the blowing of small strands of insulating material in the wall cavity. For a new house under construction, one may use phenolic foam rigid board or expanded polystyrene foam boards.