Airtight Construction

Elrond Burrell

The Passivhaus Standard requires airtight construction and a clear airtightness strategy is needed to achieve it. Elrond Burrell, architect and author of the popular blog 'Passivhaus in Plain English & More' looks at what we need to prepare.

The Passivhaus Standard requires airtight construction. What does this mean?

Essentially it means a draught-free building envelope.

A clear airtightness strategy is required to achieve this. The airtight line needs to be continuous even when formed of different materials. And it needs to be joined up, even where there are penetrations.

Sometimes airtight construction gets confused with how a building is ventilated or with ‘breathing construction.’ This post clears up these particular confusions.

And why does the Passivhaus Standard require airtight construction?

Airtight construction is draught-free construction. It is an essential part of the Passivhaus Standard to protect the building envelope, to ensure radical energy efficiency and to provide exceptional comfort.


Airtight Construction is a Draught-Free Building Envelope


Unintended gaps can be a result of poor design and detailing that doesn’t allow junctions to be constructed well and fully sealed. It can also be the result of poor quality work on site or mistakes during the construction.



Airtight construction can be formed from many different materials and components. These materials and components should be clearly identified on drawings as forming the airtight line. Some typical materials used for airtight construction include; wet plaster on masonry construction, reinforced concrete, Oriented Strand Board (OSB) of a suitable thickness, and specifically designed airtight membranes. In addition to the materials that make up the building fabric, windows, doors, curtain wall systems and roof lights need to be airtight components.




What Airtight Construction is Not

Is airtight construction a problem for ventilation?



You can read other posts I have written about ventilation here.

Is airtight construction a problem for ‘breathing construction?

No. ‘Breathing Construction’ or ‘Breathing Wall’ type construction is the commonly used name for vapour permeable construction. It is entirely possible to have a building envelope that is both vapour permeable (allows the movement of water vapour through the construction) and airtight (draught-free). There are many examples of Passivhaus Standard buildings with a building envelope that is both ‘breathing’ and airtight.

For a more detail look at this subject read: Is a Passivhaus Building a 'Hermetically Sealed' box?



Why is Airtight Construction Required?

1. Airtight construction is required to protect the building envelope.


2. Airtight construction is required for energy efficiency.

Airtight construction prevents heat energy from escaping out through unintended gaps in the building envelope. The main reason why Passivhaus buildings require so little heating is because of the high-performance building envelope that reduces heat movement in and out of the building. Insulation plays a key role preventing unwanted heat-loss and so does airtightness. The air barrier preserves the performance of the insulation which would otherwise be reduced by draughts through it. The air barrier also keeps the warm air inside the building, preventing it being lost through gaps in the building envelope. There is more about this particular aspect in the accompanying article: The Passivhaus Building Envelope.

3. Airtight construction is required for comfort.


4. Airtight construction is required for efficient heat recovery ventilation.




What is Airtight Construction?  

Airtight construction is draught-free construction.




All of these aspects make airtight construction essential for any high-performance building, and indispensible for the Passivhaus Standard.

Some additional resources:




About the author:

Elrond Burrell is an Architect, Writer & Speaker with over 15 years experience in designing and delivering excellent buildings. His areas of expertise are Sustainable Design, Passivhaus, Timber construction, and Building Information Modeling (BIM). He is a passionate advocate of these subjects and loves writing and speaking about them, as he often does in the UK and around the world. You can connect with Elrond via his website.

Elrond Burrell is an Associate at Architype Ltd, however, this article is written in a personal capacity and represents his personal opinions, not those of his employer.