AIR TIGHTNESS
for warmer homes & saving money
It´s a common misbelief that air tightness is "a complete new thing", which has been developed within the last few years and just for the sake of making construction more complicated and expensive.
In reality, this strategy is almost as old as the mankind, settled in accommodations. Vikings used moss and grass for closing gaps at their log homes for better protection against arctic breeze. Buildings in many African and Asian regions have been covered with clay to be protected against (sand) storms. Igloos were always covered with an additional layer of snow, to have the inside secured against wind and cold.
Fortunately we´re not affected by such extremes here in Ireland, but we still have to take attention to air tightness for our buildings.
What effect does inappropriate air tightness create in your home?
First and foremost you´ll notice it every winter by having losses of living comfort,
caused by draughts and heat loss.
Also, the unwanted loss of heating energy will lead to higher efforts for keeping the house warm.
A totally underestimated aspect is the potential risk of damages to the building structure due to lack of air tightness, mostly caused to timber structures like roofs or stud walls.
And a health risk can be created by Radon, accessing the building through gaps and cracks in the building envelope.
Loss of comfort
Draughts, caused by by a leakages in your building envelope, will create discomfort and lower the room temperature in your home.
Waste of energy
Uncontrolled heat loss, caused by poor air tightness performance, will lead to a higher heat demand, to keep the house warm in the cold season.
Structural damages
Lack of air tightness can create structural damages in the cold season. Warm air is escaping through the building envelope and could lead to condensation.
What you should know about air tightness
- What is an air tightness layer?
- Where to place the air tightness layer?
- Do I need air tightness at all?
- Can I make my building too air tight?
- What is currently required by Irish regulations?
- Can I measure the air tightness grade of a building?
- What means air permeability?
- What means air change rate?
- 50Pa differential pressure is equivalent to... ?
- Can I save money by having an air tight home?
- What would it cost, to make my home air tight?
How to achieve good air tightness ?
What details need to be considered
Standard Air Tightness
A standard air tightness performance to comply with most building regulations can be achieved by taping all doors and windows internally and installing air tightness membranes. Please note that Irish standards for air tightness are lower in comparison to other European countries.
Air Tightness above Average
For an air tightness result above the average, you´ll need to take additional attention to details like floor-to-all junctions, chases for conduits on cavity walls and services through
the air tightness layer. Better attention to details will lead to better air tightness results.
Air Tightness for Passive House
To achieve Passive House standard (0.6 ACH) for air tightness, you should take an adequate planning, installation and monitoring into consideration. Also, it´s essential to have other trades like electricians or plumbers on board, to ensure that your effort for perfect air tightness is not counteracted by others.
prodomo Ireland is there to help you on your way to an successful air tightness performance for your project, no matter what kind of building you have
and what type of client you are.
Air Tightness for new build
Air Tightness for nZEB
Air Tightness for Passive House
Air Tightness for Architects/ Engineers/ Contractors/ Developers/ Self-Builders
Air Tight Window Taping
Select the right strategy for your windows & doors
The best window is worthless without having the surrounding joints completely insulated & sealed. The sealing works as an air tightness and vapour control layer. Expanding foam is good for insulation purposes but doesn´t create a permanent air tight & vapour check barrier. That´s why a comprehensive window sealing is so important. An appropriate sealed window eliminates the risk of draughts, heat loss and condensation/ mould.
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Standard window tape
This method requires an additional sealant, because the tape has just a slim self-adhesive sealing strip, for boning to the window frame.
After taping to the frame, beads of air tightness sealant should be applied to the block to allow a permanent bonding between the tape and the wall.
Attention is needed for details like corners and extending window straps.
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Self-adhesive window tape
Currently the most common taping strategy for windows.
To achieve a good bonding performance, please take note of the follwing details:- the substrate has to be smooth and clean
- application to dry substrate only
- some substrate requires additional primer
- best bonding performance is dependent to temperature
- full bonding performance is achieved after approx. 24hrs
- perforated tape needs a plaster coat to cover the perforation
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External sealing of windows and doors
Some structural details require additional window sealing on the outside.
External sealing for windows and doors is required for some insulation strategies/ structural details like external wall insulation, stone cladding or timber frame structure.
The external sealing layer is mainly there, to protect the building structure against driving rain.
Beside window tapes there are other options like sealants, coatings or foam tapes for creating a functional protection of the window joint on the outside.
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Window sealing with air tight paint
A serious alternative for certain construction details.
Taping to concrete and screed floors is always tricky and requires additional attention.
Air tight paint can make this detail easier and more resistant against potential damages.
It saves the requirement for additional primer and perfect cleaning.
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Window sealing with approved sealant
The window sealing strategy with 30 years guarantee!
Whenever you need to seal slim joints again, you can select a complete and certified system for the air tight sealing.
PICHLER Elastocell® air tight foam and PICHLER FD300® create a fully certified and approved sealing system - the only one with a 30 year performance guarantee.
The joint around the window should be filled with PICHLER Elastocell® air tight foam and sealed later with PICHLER FD300® sealant.
A special application nozzle ensures the sealing of joints up to 30mm width.
The perfect sealing system for retrofit!
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Taping of roof windows
Just required in buildings without an air tight membrane.
Please ignore the detail for buildings where an air tight membrane will be installed, because the membrane has to be joint with the roof window frame.
The roof window on the photo had to be taped separately because the house was insulated with spray foam without any additional air tight & vapour control membrane.
Air Tight Membranes
To protect your building structure
Air Tightness Membranes prevent unwanted air infiltration (draughts) and heat loss. But their main task is, to protect the timber structure of your building (e.g. roof structure) against condensation, mainly caused by warm & humid room air in the winter. That´s why the most building professionals call and specify air tightness membranes as vapour control layers.
Air tightness & vapour control layers have to be installed always at the warm side of the building shell.
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Highest Ceiling
Mostly found in bungalows & multi storey houses, where the highest storey has been designed as full storey.
In the most cases the membrane has to brought down to all the walls, to seal every room separately.
Attention is needed to all perforations and penetrations through the air tightness membrane.
We always recommend the use of air tight sealant, to bond the membrane to the surrounding walls.
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Pitched Roof
Typicall samples can be found in dormers and storey and a halfs.
The air tightness membrane can either brought down to the knee walls or all the way down at the pitched roof towards the wall plate.
Attention is needed around existing stud partitions.
The most insulation materials (except Cellulose) have to be installed to the pitched roof area pior the installation of membrane.
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Vaulted Ceiling
Pretty similar to the installation in pitched roofs.
The air tightness membrane has to brought down over the wall plates to the side walls and roof windows must be joint to the membrane.
Please measure and adjust the single layers of membrane to prevent an overlap close to the ridge.
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Timber Frame
The entire timber frame structure has to be covered with an air tightness membrane on the inside of the building envelope.
Alternatively a sheeting can be used, with attention to the air tightness performance of the selected board.
Every overlap and penetration through the air tightness layer should be sealed to perfection.
Professional installers and self-builders with attention to detail can achieve air change rates even lower than the recommended Passive House Standard of 0.6 ACH (air changes per hour @ 50Pa differential pressure).
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Flat Roof
Preparation and planning is the key for flat roofs.
When designed as warm roof, the vapour control layer has to be positioned right underneath the insulation (on top of the sheeting).
Cold roofs with insulation in between the joists should be filled completely with insulation material, to prevent voids and pockets and their high risk of condensation.
The membrane has to be installed underneath the joists and needs to be taped and sealed to perfection.
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Through floor joists
One of the supreme details for the installation of air tightness layers.
The challenging task is, to bring the air tightness layer from down below through the joist layer without discontinuity.
Leaving the joist level exposed is not an option because the air will infiltrate in between the joists.
Be prepared when planning an attic conversion at a later stage.
What else needs to be considered for a complete airtightness strategy ?
Keep the overall picture in mind
In recent years we all noticed how important it is, to create a full air tightness strategy, which includes every part of the building.
The more air tight we want to have our building, the more attention we need to put into small details, to prevent the enhanced risk of uncontrolled air infiltration through these areas.
Spots like chasings for conduits on perimeter walls or junctions between floor and walls are becoming more important when it comes to a functional air tightness with values of 1.5 ACH (air changes per hour @ 50Pa differential pressure) or less.
But how can you make your complete house steadily air tight?
By just using air tight membranes, tapes and plaster coating for certain building areas only?
All three solutions above do create an air tight layer, but you need to pay a particular attention to have a complete airtightness strategy for the whole building envelope in place.
Air Tightness Testing & Training
to improve and verify the performance of your home
We perform air tightness tests according to the current standard I.S. ISO 9972:2015, but have cancelled our membership of the NSAI air tightness testing scheme in October 2020.
We believe our clients deserve genuine air tightness testing with permanent continuous professional development rather than a "certified" tester from a scheme, where the payment of an annual fee is the only criteria to become (and stay) a member.
To be clear - there are many knowledgeable air tightness testers on the NSAI air tightness tester scheme but the scheme itself doesn't provide any benefit for the involved parties.
To achieve a good final air tightness test result, we recommend a preleminary test of the building during the construction stage. Because of the fact that the final test (official test according to Part L, for inclusion in BER) has to be made at the very end of the construction phase, the option to eliminate potential leakages is very limited.
Please note that an official air tightness test is depended to some technical requirements. To achieve a clear and genuine test result, the test should be done in calm weather with almost equal outdoor and indoor temperature.
Survey and consultation for (existing) homes
prodomo Ireland is specialised in surveying new and existing buildings regarding issues with draught, heat loss, dampness/mould, odour pollution or lack of sound proofing.
Such a test can be can be done all year round and the included report will state and explain existing difficulties and also provide suggestion how to get them sorted.
Depending on the size of the building, the survey will take approx. 2-4 hours on site and the report will be delivered within 5 working days after the testing.
Usually you wouldn´t need to leave the building during the survey, as there´s no harm involved in such a survey. But during the current pandemic, we prefer to perform the survey alone for the occupier´s safety.
As per 01.01.2024 - this service has been stopped for an indefinite period.
Training Courses (for air tightness)
If you want to gain knowledge and practical experience about air tightness, you should participate in one of prodomo Ireland´s training courses.
You can select between different training courses for your individual needs.
All courses will be provided in our training facility in Tralee, Co. Kerry.
Kerry was an important centre of knowledge and education over a thousand years ago and we at prodomo Ireland are committed to this. We would like to play our part in ensuring that building standards and finishes enhance our living comfort.
prodomo Ireland does training courses for self-builders, educational training boards & CPD.
If you´re in need of a tailored course, please do not hesitate to get in contact with us.
As per 01.09.2023 - airtightness training courses for the public have been discontinued.
Is there a difference in air tightness products
The more expensive, the better ???
You´ll always find self-proclaimed experts, advising that good air tightness performance is depending to a certain brand or product. Also, you can find plenty of marketing promises about the grandiosity of certain products.
But is there a such noticeable difference in air tightness products in reality, which would justify the enormous price differences?
Well, it´s like almost everything in life - when you ask two people about, you´d probably receive 3 opinions. But in the most cases the personal preferences stand over reliable facts from science and reality in construction business.
An interesting fact about air tightness products can be found in one of the Passive House Institute publications, where their first Passive House development in Darmstadt, Germany has been surveyed and re-tested 25 years after the houses have been built. No noticeable deterioration in air tightness performance was observed, even though at the time the houses were built there were no special products for air tightness available and therefore existing products such as builders film and acrylic sealants had to be used instead of the "intelligent membranes" available today, which are ultimately only made of relatively simple hydrocarbon compounds (plastic) and were actually originally manufactured for other purposes.
prodomo Ireland
Your specialist for air tightness, thermal brackets & energy saving.
We deliver products and solutions to Irish clients for more than seven years when it comes to air tightness and thermal brackets for doors & windows. To allow clients all over Ireland to benefit of our knowledge, experience and "Teutonic thoroughness", we´re focused on consultation & supply . If you´re looking for installation as well, we might can recommend a qualified tradesman.
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prodomo Ireland
Unit 9 - Ridgeview
Monavalley Business Park
Tralee
Co. Kerry
V92 W2TH