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External Walls Insulation

Thermal insulation for external walls

The insulation is usually installed after the plumber and electrician have finished their “rough-in”. Any Data cabling, Security wiring etc is all in place. The exterior skin of the building is complete and brick veneer ties are all nailed off to the frame. A physical frame inspection has occurred and the next stage of interior wall lining is imminent. Batts (either made from Glasswool or Polyester) are the most effective way of creating the insulation barrier and are fitted snugly between the wall studs.

With the ever increasing demands for greater Energy Efficiency, Thermal Ratings are getting higher, however care needs to be taken to match the performance of the Insulation with the cavity/space available within the wall. Framing tends to be restricted to 70 or 90 mm which means the Higher Performing materials are necessarily denser and more Expensive. Squashing thicker Insulation into a restricted space downgrades the performance and may compromise the integrity of the cavity.

Brick veneer structures

If it is a brick veneer structure and there has been no external sarking or sheet bracing, it is necessary to restrain the batts from slipping into the cavity. This is done by running a polypropylene twine from top to bottom and stapling it in position.

We stock bulk rolls of twine or have 20mm wide strapping available which is ideal for the average house. Care needs to be taken around power points. We recommend a small cut out so that the electrician doesn’t push the batt against the brickwork when he connects up. Other forms of sheet cladding don’t require the cavity system and the batts can simply be installed between the studs.


Bulkhead InsulationBulkhead walls

Bulkhead walls exist where there is a variation in ceiling height such as raked ceilings meeting conventional ceilings or in split level structures where part of a wall backs on to the attic of a lower level. These short walls can be subject to big heat losses and gains and must be insulated on the vertical to ensure proper efficiency.

Earth Walls

These exist on sloping blocks and split-level houses and must be insulated and strung in place to avoid heat loss and gain.

Foilboard Super 15

Foilboard Super 15

Cavity Brickwork and Pre-cast Concrete walls

Are best insulated using FoilBoard that offers high R ratings utilising dual reflective surfaces  with minimised wall thickness.


Preferred Materials

We prefer to use Fletcher Insulation’s Pink Wall Batts and rest easily knowing that their particular formulation produces an environmentally friendly and  more rigid batt that will stand up in a wall as well as having a special silicone impregnation that prevents the batt acting like a wick and drawing moisture through a wall. Other forms of reflective foil and various foam materials will work as well, however many of these products are more difficult to install and are in our experience less user-friendly for everyday construction work.

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