Outhouse, Forest of Dean

Outhouse follows Loyn & Co’s Manser Medal-winning Stormy Castle in Gower, Wales, which also featured a contemporary, concrete-led aesthetic. But while both respond to Areas of Outstanding Natural Beauty settings with earth-sheltered designs that make the most of the fantastic prospects, there are also great differences.

The new single-storey building needed to function not only as a home for the two artists but as a workspace, with both requiring their own studio. The solution was to push the 490m² new building to the rear of the site against the hill and provide a green roof that continues the surrounding field over the house and greatly minimises the impact of the new build when seen from the road above. A gallery spine runs through the building from east to west, with north-facing top-lit studio space and guest rooms to the rear, and domestic living space at the front overlooking the valley. The configuration is also driven by the decision to leave “memories” of the previous buildings on the site as outlines forming a series of sheltered courtyards serving both the domestic and studio spaces.

Concrete was the obvious choice for the structure. The sustainability of the material was considered and 33% of the cement was replaced with fly ash. The concrete was also sourced from a local plant – Bardon Concrete – just four miles away. Added to this was the clients’ love of the concrete aesthetic, which they felt created the best backdrop for their art. The result is extensive use of exposed concrete for the floors, walls and ceiling both internally and externally, with the exception of areas of vertical strips of charred timber used for facing on non-loadbearing infill panels.

The slab for the rear portion of the house is ground-bearing while the front is suspended. The majority of the concrete was cast in situ. Reinforced retaining walls were 250mm thick with a further 300mm of insulation externally, while internal loadbearing concrete walls were 200mm thick. However concrete panels – precast on site – were used to form the 800mm-high, 150mm-thick fascia that runs 53m across the front of the house.

In order to allow the courtyard walls that define the location of the original buildings to read differently to the new work, Loyn & Co introduced a black pigment into the concrete mix, which the practice was advised would work better with self-compacting concrete. These walls were a total of 550mm thick, consisting of two skins of concrete with 225mm of insulation in between. To avoid visible formwork bolt holes, Thermomass low-conductivity ties were used to hold the insulation in place and enable both the outer and inner skins of the wall to be cast in one operation.

Great attention was paid to the quality of the finishes, with architect and clients visiting the University of the  West of England to research various surface textures and grades of finish as well as referring to the then on-site Stormy Castle before arriving at the final design.

Apart from the stone floor of the gallery, floors are power-floated and buffed to achieve a highly reflective finish. This contrasts with the walls and ceiling, which have a self-finish from the phenolic-faced boarding. A great deal of thought was given to how to fix the art to the 2.4m-high walls without drilling into the concrete. The solution was a cast-in recessed detail at the top of the walls that created a contemporary picture rail for stainless steel hangers to ensure that pictures can be hung anywhere along the gallery.

Aside from its structural and aesthetic uses, concrete also contributed to Outhouse’s A+ EPC rating, and not only through its thermal mass.Outhouse’s sustainability credentials also include use of local contractors along with triple glazing, LED lighting, ground source heat pump, MVHR, and solar thermal and photovoltaic panels.

Featured in CQ Winter 2016 (pg 10)