We use concrete free, or minimal concrete foundations to minimise the ground disturbance and the embedded carbon associated with cement and concrete. For a 5m x 3m garden room, this saves around 570kg of CO2e, that’s the same as taking over 100 cars off the road. Our foundations also save time, money and mess which is a nice bonus. Exactly which foundation system we use will depend on the building and the site, but may be steel screw piles, limecrete or packed stone.

To reduce the impact of the timber we use, it will all be from sustainably managed forests. Our large section, softwood structural timber will be from British woodlands via local sawmills with whom we have a good relationship to ensure quality and traceability.

These same sawmills supply our oak beams and cladding, however this often comes from France or Eastern Europe where they have oak forests large enough to extract timber from sustainably. Treated framing timber, and sheet goods will always carry an FSC or PEFC sustainability stamp and may be from the UK or Europe.

We use a range of different insulation materials throughout the building. In the walls and roof, we use wood fibre insulation, a great heat and sound insulator which retains heat and helps manage moisture and indoor air quality. Under the floor we use rigid foam PIR insulation, for example Kingspan or Celotex, which is a great insulator, it provides a barrier to moisture coming up from the ground and will not degrade in the damp. Due to the amount of energy needed to make PIR foam (high ‘embodied energy’), and difficulties around recycling it, we are looking for alternatives to PIR foam.

We have recently made a commitment to no longer using gypsum plasterboard and plasters in our building. Instead we will be using wood based carrier boards and lime plaster. This again reduces the embodied carbon in our buildings and means we are locking up more carbon in the fabric of our buildings.

These materials also mean that our buildings ‘breathe’- moisture vapour from inside the space is able to pass through the wall. This maintains a stable, comfortable and healthy moisture level, preventing mould growth and ensuring superior indoor air quality.

There are some aspects of building where natural, sustainable alternatives are not yet available. Things such as breather membranes and airtightness tapes and PIR subfloor insulation. We use these materials when necessary to greatly improve a building’s efficiency, reduce the energy needs of the finished space and extend the lifespan of the building.

Also, we use metal fixings (nails, screws, strapping etc) in all our builds. However, as is the case for all materials we use, we use them in a considered fashion, only using as many as we need and reusing them where possible.

As of writing this there doesn’t exist feasible sustainable alternatives to these products. However, technologies are constantly being improved and developed and Square Peg is always looking for more ecologically sound alternatives. We attend courses, read journal papers and are members of professional organisations to stay up to date.

Yes, but not as much as you might think. A garden room built to a high spec using well considered, sustainably sourced materials is likely to cost slightly more (about 5-10%) than the equivalent built with standard materials from the local builder’s merchant. A Square Peg garden room or cabin will be a healthier space, and will come with the peace of mind that you are minimising the impact of your build, as well as locking up as much carbon as possible in the process.

We are a company driven not just by profits, we are driven by creating quality, sustainable spaces for as many people as possible. This means we are still competitive on price, and excel in quality and customer service.