Guest Blog – DOW Floormate Hill Barn Case Study

Posted on October 26, 2016 by CCF


Dow Floormate – Product Information

Floormate -AP products are manufactured in the UK using technology that takes CO2 from industry and uses it as a blowing agent in order to create blue extruded polystyrene foam with a Global Warming Potential (GWP) of less than five.

The process of extruding polystyrene foam generates a mass of small, homogeneous closed cells which give the final product high design loads, low water absorption and excellent insulating properties. Such features mean the material can be installed outside the waterproof envelope, the right design choice when aiming for an ‘envelope’ of continuous insulation that minimises heat loss.

Case Study – Hill Barn

Located in the heart of the English Cotswolds, Hill Barn was a derelict 300-year old barn situated in a prominent and beautiful location on a hillside in an Area of Outstanding Natural Beauty (AONB). Designed to safeguard an important local environment, the AONB designation made the prospect of obtaining planning permission for any development of the barn a daunting prospect.

To address this challenge, architect Helen Seymour-Smith developed a bold and ambitious proposal which involved a breakthrough building. This was Under hill House. Constructed underneath and adjacent to the barn. Therefore itself would be carefully restored and used as an office for Helen’s architectural practice.

In contrast, the house – set to be home for Helen, her husband and young son – would be strikingly modern. Dug into the hill and invisible from the surrounding countryside. This development was designed to have minimal visual and environmental impact.


Not only is the external form of Underhill House designed to minimise environmental impact. Also the interior form and construction materials were carefully chosen. This is to make the building as environmentally sustainable as realistically possible. The structure of the underground house is constructed entirely from concrete. Much of which has been left exposed internally to exploit the benefits of the thermal mass of the material. The basement walls, floors, and roof are all insulated with FLOORMATE-AP and waterproofed externally for the same reason. As a result of this carefully thought-through design, no manufactured energy is required to heat the building.



FLOORMATE™ 300-AP proved to be the real star of the show when it came to insulating Underhill House. Because it resists moisture and has a high compressive strength, FLOORMATE™ 300-AP is ideal for below-slab insulation. A growing practice in residential buildings and one which could support more energy efficient buildings in future.


Using the insulation in this way helps to avoid thermal bridges at floor and wall junctions. This means concrete can be left exposed internally. This makes the most of its thermal mass properties. Exposed concrete absorbs heat in warm weather, effective cooling the buildings; and releases stored heat during cooler weather to provide a natural heating regime.