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How to Build a Passivhaus 2 weeks – Passive Kit Home Build package

Fully Engineered Timber Frame Design

Our Kit Homes design and build process provides total assurance and peace of mind for the self-builder, or commercial client, looking to achieve a low energy build or Passivhaus standard . We take architects plans and develop realized kit house designs using the latest CAD software, all structural loading calculations are undertaken by our in house engineers.

Site Preparation

Prior to delivery of the kit home and passive slab foundation system the client or groundworks contractor strips the site to the required levels and installs the first 150mm of hardcore. At this time it is also advisable to install the drainage connections and services for the building, along with the footings for the roadway or paving and any retain walls or structures that are required.the required levels and installs the first 150mm of hardcore.

Passive Slab Foundation

Our kit home build team will arrive and install the next 50-100mm of blinding material and pack it down to ensure that the building is built on an entirely level platform. Unlike conventional build methods we aim for tolerances of 2mm or less. At this time our passive slab contractors will install pipework or drainage connections to your design. By feeding build services though the foundation this enables the most airtight and neat solution possible, an essential choice for an airtight Passivhaus or low energy kit builds.

Our foundation is formed from structurally reinforced Expanded polystyrene (EPS) which is machined offsite. This then forms a permanent insulated raft foundation for the Passive kit home and achieves a u-value of 0.10w/m2k. We then install a radon barrier that also acts as a damp proof membrane.

If your self-build house or commercial project has a masonry exterior we will also install a reinforced ring beam. Once all is prepared the concrete pour can begin. Our eco builders take extra care to ensure that the passive slab is power floated to be flat as a billiard table. We require these extremely fine tolerances to be adhered to so that when the flat pack timber frame kit home arrives almost no settlement occurs.This is essential when precision engineering a kit home in this way using modern methods of construction (MMC).

Flat pack Kit Home – Superstructure

The beauty of our kit home system is that the foundation passive slab and flat pack timber frame walls can undergo manufacture simultaneously

The Timber frame wall cassettes are manufactured from engineered European softwood in our factory in county Tipperary. This form of kit build construction enables great speed as well as precision and minimal waste and can typically cut down you build time from 4-8 weeks.

The unique twin-wall timber frame design enables an extremely low u-value 0.12w/m2k as more insulation fills the gaps and repeating thermal bridges are minimised. The timber frame is clad with engineering grade OSB on the internal face and battens to form the 38mm service cavity. On the external face we use Panel vent and a breather membrane for added vapour protection.

The timber frame flat pack cassettes are loaded on to low loaders and transported to site. The kit home erection team make short work of unloading the flat packs, and begin to erect the ground floor. Typically two to three stories of the building can be erected in one day. The timber frame is clad with engineering grade OSB on the internal face and battens to form the 38mm service cavity. On the external face we use Panel vent and a breather membrane for added vapour protection.

The floor is made up from metal webbing joist that help provide sound insulation and allow mechanical and electrical services or MVHR to pass through the floor. We also provide all internal studs loose to enable boarding of the ceilings to use full boards and superior sound protection between rooms.

Warm roof kit home cassettes can be lowered into position with ease. Or where the roof is cold typically we use our own engineered roofing trusses, both achieve 0.10w/m2k We finish the roof by providing waterproof felt an batten ready for tiling slating or a green or metal roof finish.


Once the timber frame kit house superstructure is complete, Passivhaus triple glazed windows can be installed.

We specify triple glazed Passivhaus certified windows as standard <0.8w/m2k. These units come in a range of price points from UPVC, Solid aluminium, Alu-timber clad and solid timber options.

These high performance Passivhaus windows are an essential component of our low energy kit builds as windows and doors loose a great deal of heat. We specify Passivhaus certified windows that are very affordable and are manufactured in the UK.


Once windows are installed our kit home build team then pump high density cellulose Warmcell insulation into every void and space in the timber frame kit shell. Studies have shown this insulation method has less of a thermal performance gap caused by air spaces than conventional insulation slabs and batts, where gaps are more common.

‘Therm’ Modelling of Passivhaus Detail showing Insulation Properties


Our kit build team undertake highly diligent airtightness detailing, using lifetime guarantee SIG and Intello tapes and membranes. We guarantee after first fix works are complete by us that the building will achieve Passivhaus airtightness standards of <0.6 ach/hr @ 50 Pa, and we include the blower door test as part of our build package.

Next Steps

Once the Passive Build frame package is complete the finishing contractors can undertake the internal and external fit out. We have a range of main contractor partners depending on you region and can discuss a turkey solution to your low passive kit home.

Building is air and water tight with insulation and windows installed within 2 weeks of start on site

Contact us to find out more

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