NEW BUILD

Building your new home is the biggest investment that you will make in your lifetime so it is vitally important that every aspect of the build is to the highest standard that your budget will allow.  With ever rising energy costs the insulation and airtightness of a new home is a vital cog in getting it right.

When selecting materials for construction, builders will choose good insulators to reduce heat energy losses

U-Values

What are U values?

U–values measure how effective a material is as an insulator.  The lower the U–value, the less heat is lost and the more insulation the material provides.

Minimum standards for u-values:

The cavity wall insulation you choose is vital in restricting as much as possible of the 35% of heatloss that a home loses through its walls.

While the building regulation for cavity walls now requires a U value of 0.21w/m2k many energy conscious home builders will try to get below this mark as it provides the best return on investment.

AIRTIGHTNESS

Only when the construction is airtight can warm air be retained within and cold air kept outside. Preventing unpleasant draughts means greater living comfort and increase energy efficiency, which in turn leads to lower heating cost. Airtightness also protects the building fabric against damage, helping to maintain its appearance and extending the buildings life.

How to achieve Air Tightness and Why?

Air tightness simply means eradicating all drafts. Drafts can be so small e.g. under window boards, around windows and doors but an accumulation can have a drastic impact on the energy loss in the dwelling and lead to significant discomfort and high running costs.

The only way to achieve Air tightness is a consistent air-resistant layer all around the inside of the building. This includes the area where the wall/floor meet, around the door and window openings.

A layer of breathable membrane behind the plaster slab on the upper ceiling, regardless of the structure type, timber frame or masonry construction the air tightness layer must be continuous from floor to ceiling.

C&W Insulations are certified contractors of the SIGA Air & Wind tightness System. This is comprised of a range of tapes and adhesives, and SIGA Majpell, a vapour control layer. This system has been certified by the The Irish Agrément Board.

The wind tightness tapes can be used with all suitable breathable roofing and facade membranes. The tapes and adhesives are free from residential toxins such as solvents (VOC), high boilers, formaldehyde, chlorine, plasticizers.

Air Tightness Terminology

• Building envelope – external elements of the building, walls, windows, front and rear doors,  floors and ceilings
• Air tightness  – defined as the resistance of the building  envelope to  inward  or  outward air leakage. Excessive air leakage results in increased energy consumption and a draught cold building.
• Air leakage – defined as the amount of air gaps or cracks in the building envelope, driven by pressure differences between inside and outside. Areas of air leakage, cold bridges, i.e. around doors, windows and between floor levels
• Air permeability – expressed as the amount of air leakage in cubic meters per hour per square  meter of the building envelope at a pressure differential of 50Pascals between inside and outside the building envelope, maximum permitted level  is 10  m2/m3hr@50Pascals, This is measured by the instillation of the blower-door fan into the main entrance of the dwelling.
• Air changes  per hour-  measures the ventilation in the building. This can be controlled by mechanical ventilation heat recovery or opening windows and doors