WHY IS AIR TIGHTNESS SO IMPORTANT?

Air tightness is essential to a comfortable, energy efficient and healthy home. On average, we spend 90% of our time indoors so it only makes sense to ensure our homes are as free from draught and cold spots as possible – especially when investing heavily in insulation! Air leakage can account for up to 50% of all heat loss in a well-insulated home. It is important to remember though that the building's envelope is still breathable – air tightness measures simply reduce air leakage to a minimum, ensuring a highly energy efficient build.

1. Reduced Heating Bills

The mixing of indoor and outdoor air is significantly reduced which reduces energy bills associated with heating and cooling.

2. Healthier Living

Air tightness prevents substances which can provoke allergies from being carried into the home via air leakage gaps.

3. Added Comfort

Air tightness is key to reduced overheating in summer and providing superior insulation in winter.

4. Improved Acoustics

Higher levels of air tightness can reduce sound transfer which occurs through the passage of air.

5. Longer Lasting Build

Air tightness protects the building’s fabric against damage from moisture-laden air leaking into the building’s envelope and causing condensation.

 

Achieving an Airtight Build - Timber Frame Versus Block

There are many different options depending on the type of build. For example, the walls in a block built home are only airtight if an internal plaster is applied straight to the block work and spread evenly at full coverage. It is important to keep this in mind if you intend to internally insulation to increase your u-value. There is an option to externally insulate your block build, however this would mean using insulated boards as your external walls rather than block which negates it's purpose.

In a timber frame structure, all areas can be sealed using an air tightness membrane and tape. It is undeniably a much easier and therefore cheaper build process!

Another benefit of timber frame is that your wall cavity is left completely free to do its job and the thermal responsiveness of the timber allows the build to heat and cool quickly. With block, self-builders are having to full fill their cavity in order to achieve the minimum Part L regulations.  To achieve maximum levels of efficiency, internal or external insulation is required in a block build – both of which can cause significant problems. In comparison, timber frame benefits from a 100mm exterior leaf of block, open cavity (as it should be!) and a thermally responsive inner timber frame structure packed full with quality PIR insulation - all of which has absolutely no impact on the successful application of an air tightness membrane.

OUR AIR TIGHTNESS MEMBRANE & TAPES

We supply and fit an air leakage membrane as standard at all junctions to your floors, walls and roof. This ensures continuity of your air leakage barriers. We also supply and fit a quality air tightness membrane to the walls, roof, exterior doors and windows of your timber frame house. Our service cavity, self-sealing fixtures and air tightness tapes ensure high levels of air tightness.

In response to the anticipated changes in building regulations to place more focus on indoor air quality (alongside air quantity), we include a price for air tightness in all of our quotations.

At the moment, in order to meet current Building Regulations as outlined in Part L (ROI) and the Technical Booklet F1 (NI), no more than 7-10 cubic metres of air can escape per hour for every square metre of the surface area of the external envelope at an internal air pressure difference of 50 Pascals. These measures are set to change - and as air tightness standards increase, it is important that we also consider appropriate controlled/mechanical ventilation.

"Build Tight, Ventilate Right!"

Ventilating an Airtight Home

Ventilation is important in any home regardless of its air tightness. It is essential that adequate fresh air circulates throughout the home. Controlled ventilation through windows and doors was suffice in older homes with poor insulation and uncontrolled air exchange through cracks and gaps in the buildings envelope. In fact, the leaky windows provided enough ventilation without even opening the window vents! Today, with insulation and air tightness at the forefront to increased energy efficiency, systems such as Mechanical Heat Recover Ventilation (MHRV) are becoming extremely popular.

Can I Add More Insulation Instead?

Insulation requires high levels of air tightness in order to perform to its highest capability. This is typically explained using the “woolly jumper” analogy – imagine going on a windy winter walk wearing only a single layer woolly jumper. Wind would blow through the holes, right? Now apply a light wind breaker barrier over the single layer. This has a dramatic impact on the insulating capability of the woolly jumper as it reduces air circulation. So in order for your insulation to be most effective, it requires an air tightness barrier to protect the build against air movement on both sides.

Free, Detailed Quote

If you have any questions on building a timber frame house and making it airtight, feel free to get in touch with our team at info@timberframeireland.com.

Quick Quote?

Simply email your plans to info@timberframeireland.com for a free, detailed quotation of your timber frame house.

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