sketch up model of pod home

I beam timber frame construction

Structural solutions to producing passivhaus standard homes

We recommend using an ”I beams” structure for a timber frame home, so called because of their I shaped structure, which create a very strong core to the wall with the capacity to contain an ultra thick, super-high density volume of Warmcel insulation material.

Warmcel is made from recycled newpapers and it is pumped into the wall cavity under high pressure so provides superb insulation values and, being so dense, adds substantial thermal mass to the building’s structure.

This insulation is also one of the best acoustic insulators and can be installed between floors and in internal walls to provide even greater protection from noise pollution and heat loss. I beam frames also compartmentalise the wall studs into distinct bays, allowing the insulation material to be installed at higher density.

The beams themselves are made from wood grown on sustainable forest plantations. The wood is cut to plan on CNC machinery which allows each part of the structure to be precision cut for each individual section of the building. This enables us to create buildings of virtually any physical shape, and put each piece together as labelled for speed and efficiency on-site.

For improved overall airtightness, we would recommend installing an external airtight board to the structure, which creates a very robust solution which is far more efficient than the more traditional use of sticky tapes and membrane for the air-tight layer.

Another big advantage of an external sheathing system is that the ‘follow-on trades’, electricians and plumbers, have no need to cut into it to carry out their installations, so their workload is simplified and allows them to finish and be off site more quickly than they might be with more traditionally built homes.

 

Foundation diagram
Insulation diagram
Eaves diagram

...and so in implementing these we have:

Effective insulation

Cellulose fibre insulation is pumped into the walls. Our substantial I beams structures are the only successful way to achieve necessary density of insulation material. Cheaper twin wall systems are difficult to install with cellulose fibre to the required density.

Prevention of draughts

We cover the entire external surface of the build with our TG board, mastic sealed at all joints to form a long term robust air tight layer. We do not use cheap tapes and membranes.

Combated the issue of 'cold-bridging'

I beams have only the 9mm web passing through the structure, so minimal cold-bridging occurs.

This solid build structure is impenetrable to wind and rain and ensures a draft free home that requires very little heating. Even in the harshest weather, wind cannot blow through the dense insulation of our homes, making them far more comfortable and needing less energy to keep warm.  To obtain Passivhaus certification homes are tested for air-tightness and the maximum level must not exceed 0.6 ach. The typical air-tightness values  our build system achieves is 0.2 ach, which is considerably more efficient than required.

We usually build our walls and rafters from 300mm I beams, which provides a U value of 0.13, which is sufficient to achieve passivhaus certification for a design with a good form factor, however our system is flexible and if you require higher U values, we can also use 350, 400, or even 450 beam, for which our U values are 0.11, 0.10, and 0.09 respectively.