House on a hill – Crafford residence
Making the most of nature’s canvas, the compact Crafford home and art studio in Pretoria uses local materials, works with the site and climate, and accentuates views to create an inspirational living and working space.
Architect Abre Crafford’s father-in-law bought a rocky and semi-arid 3.2-hectare site against a koppie in Pretoria in 1979. In 1988, Crafford and his wife, Carla, started planning a house that would reflect their shared dream of living responsibly in nature and adding to, rather than destroying, nature through human use.
The couple’s dream included working from a self-sufficient property that would eventually expand to include spaces and studios for like-minded artists and creatives. Almost 30 years later, and having searched unsuccessfully all over Gauteng for a house that would suit their personalities and living/work requirements, daughter Lala Crafford and her musician partner, Louwrens Ferreira, recognised the viability of investing in a new owner-built home on the same site as the first house.
“Our initial idea was a place that is comfortable to live in where we can produce art and music, that pays homage to nature, from which we draw inspiration. As the project developed, it became apparent that it was all about the environment – about seeing the structure of the earth in some of the rooms and using materials from the site,” says Lala.
Built on a modest R1.5million budget and with the option to add more phases at a later stage, the new house is small, compact (less than 90m2) and simple in character, providing a blank canvas for the art that will be created there. Essentially a one-bedroom apartment upstairs and a shared studio/exhibition space downstairs, the house capitalises on the mild climate and lofty site with a large open veranda opening off the living area to offer spectacular views over the city and its hills to Hartbeespoort Dam in the distance.
A site to behold
From concept design to detailed resolution, everything started with the site. “We wanted to use nature as the garden and to allow the building to blend by using natural colours and materials found on-site,” Crafford recalls. “Both houses have been influenced by the impact of nature on building.”
“Materials should be able to take habitat, provide habitat, and become habitat. Because of the density of indigenous trees, there is very active bird life in the area as well as small wildlife, bats and snakes. So we are shaping the land with packed retaining stone walls that can become their habitat, and trying in every way to restore what is moved during construction,” says Crafford.
With a slope ranging from 30º to 50º, the first phase of construction, which took place over a six-month period, involved creating access to the site from the road and preparing the site in a way that would honour the existing ecosystem as much as possible. This included developing a suitable process of casting an in-situ concrete driveway in a way that would teach unskilled labourers skills such as batch mixes, water content and lining up casting, all while gathering and controlling the movement of stormwater down a steep hill in order to avoid soil erosion.
A system of sorting and saving soil, seeds and plants was planned and executed. This included moving vegetation for later propagation to a nursery during the construction period; replanting smaller plants and aloes; separating topsoil from deeper soils and saving it as seed stock; separating and grading gravel and small rocks for filling; and separating the various stone types on-site into those suitable for cladding, solid walls, paving and steps.
A strategic decision was taken to spend money on people, not machines, because, as Crafford puts it, “manual labour feeds families”. This included digging trenches by hand, packing stone walls, and building up the fill behind the stone walls carefully with layered strata of gravel and excavated soil. Carrying out the earthworks by hand meant excessive damage to the site and sensitive steep slope could be avoided, and the very limited space and small footprint could be carefully managed to preserve the sensitive growth on the hillside. While this process took longer, crafts and detailing skills like carpentry and stonework were transferred, and although more expensive initially, Crafford believes the end result has a higher value both aesthetically and socially.
Embracing the elements
Following the same design principles as the original house, the plan is based on a mandala, turned through 90º to accommodate the steep slope. Circular and curved elements are introduced through the tower in the middle of the building, to which everything connects and which encloses the feature spiral staircase; and the leaf-shaped roof, which forms the basis of a water harvesting system.
Rainwater run-off is collected at the front of the leaf-shaped roof and taken down to ground level through a series of stepped containers to separate out leaves and sediment; and at the back of the leaf through the tower. Currently the water is channelled into the lower house’s stormwater collection system, but, the intention is to eventually build a dam to increase the property’s water storage capacity.
In terms of temperature and light control, windows have been placed in such a way as to guarantee privacy without the need for blinds or curtains, while allowing sufficient light in. Slightly smaller windows have been used to retain light with minimal heat gain, while the massive veranda allows a panoramic view around the house for both relaxation and security purposes.
Generous wall thicknesses are achieved with single brick walls clad in stone from the site for insulation purposes. Acting like trombe walls, these release heat into the house at night. Massive overhangs and strategically placed windows around the building allow for maximum cross-ventilation, while the veranda doubles as an outdoor sleeping and living space.
The house has two electrical circuits – one for solar, which will power essentials such as lights and computers, and one that runs off the municipal grid. A large shed has been planned below the house as phase two, which will eventually accommodate a larger studio and exhibition space, and will also house a solar PV installation on its roof. This should allow sufficient solar energy to be generated in future for the house to function off-grid. Currently, both the original and this second house on the property use solar water heaters and gas ovens as alternative energy sources.
Crafford says the materiality of the building is critical – this is what forms and informs building. Nothing was imported and as little as possible was manufactured. The house has no finishes apart from the cement floor, sealants and some textured plaster. Concrete slabs and brickwork are exposed; and, where possible, the rock face that was excavated has been left exposed. Pathways are clad in stone and will imitate nature by allowing moss and plants to grow in between, thereby naturally allowing water back into the soil.
Following the principle that everything has a use, most construction waste was stored and separated, including broken bricks for paving and steel for reuse by local artists. In terms of ongoing waste management, all organics will be used in the garden, while non-biodegradables will be recycled. In addition, the sewage line has been split in two for grey and blackwater recycling.
Such a detailed and complex project was not without its challenges. Jock Pretorius, structural engineer with Struct Africa Com, says the site required terracing with high retaining walls, and, as the brief was to use packed natural stone, strengthening fin walls had to be built – horizontally of concrete and vertically of brickwork. In addition, the challenges of building on a hill with no easy access for cement trucks necessitated hand packed rib-and-block slabs that could be installed on-site.
“Because we had to excavate into the mountain on top of shale rock, and we employed labour intensive systems, construction took a while,” Pretorius says. “But overall it worked very well. The project was well planned around the site, and it was interesting to be involved in project like this where one is required to think beyond the normal bounds of structural engineering.”
Future work includes adding density to the endemic plants, bio-filters for stored rainwater, more tanks for storing clean and greywater, a solar PV farm, composting and worm farms and developing concepts around access and sculpture gardens.
“It’s a great space to work site-specifically, and we have learned a lot about the environment through this process,” reflects Lala.
“I hope that, ultimately, we will be able to open the building up as a cultural hub for exhibitions and performances, so that other people can experience the site for its own beauty and the inspiration it offers.”
By Karen Eicker
See earthworks Issue 36, Feb-Mar for the full feature.