Timber Frame Houses

Insulation Airtightness & Passive Home Design


Insulating the various components of the timberframe building’s fabric (walls, windows, floors, ceilings and roof) is the single most important step to reducing heat loss from the house, which ultimately drags down its overall Building Energy Rating (BER).
At Kilbroney Timberframe we use various types of environmentally friendly insulation called mineral fibre to reduce the heat flow through walls and roofs, as well as using doors and windows carefully selected for their insulating performance.
Insulating sloped roofs in order to achieve our A3 BER ratings, we use differing insulation methods for various parts of the building. In order to achieve values of less than 0.20 W/m²K we insulate the timber studs in the timberframe walls with an internal insulated mineral fibre lining in the traditional cavity.
For sloped roofs we employ “Warm Roof” construction techniques which involve insulating above and between the timbers in the roof, reducing the risk of condensation and thermal stress. To meet the desired U-levels at ceiling level we place a layer of insulation below the ceiling joists to insulate the spacing between them, already insulated with mineral fibre. This doesn’t reduce the storage space above the joists, which is often reduced by adding an additional insulation layer above the joists.


While efficient thermal insulation is undoubtedly one of the key elements in preventing heat loss within a home, problem areas often exist at the junctions where surfaces such as walls, roofs, windows and doors join. In order to achieve the Airtightness and A3 BER ratings for our timberframe houses, our team must ensure that all such joints are airtight to prevent even the slightest draughts. Airtightness is accomplished by ensuring that all joints and critical joints are adequately sealed to prevent air and vapour permeating between the insulated layers, which as well as energy loss can lead to problems such as condensation and damp or mould.
We use industry-leading airproofing adhesives from Siga and Solitex to seal even the tiniest leaks and defects in the building. Siga airtightness in Kilbroney Timberframe home’s structure, which facilitate heat loss and can compromise your energy rating. Although with the joints taped the building is effectively airtight, these specially constructed materials still allow the building to “breathe” in a controlled manner.

The airtightness of the building is measured by creating a partial vacuum within the house, and then measuring any intake of air through joints or potential gaps, commonly felt as a cool draught. While the overall building energy rating is determined by a BER-approved assessor when the house is complete, our team will test for airtight junctions throughout the timberframe construction phase to ensure that any problems are addressed as early as possible.

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