June 2017

Mitchell Evans Architects are delighted to have been shortlisted for the CIAT Award for Excellence in Architectural Technology 2017 with their new build private residence, the winner will be announced and presented at an awards ceremony held in East London on 15th September.

We were appointed to design a contemporary new build house to be located on the site currently occupied by a dated bungalow.

The brief was to provide a dwelling with 2 bedroom suites, an open plan kitchen, dining/living area, study and utility room, the house was to take advantage of the open meadow to the rear and far reaching views of the North Downs.

The design gave the impression the clean crisp lines of the building were perched over a natural meadow and rough stone base.

Once planning approval was gained, Chartered Architectural Technologist, Colin Miller MCIAT, lead the project from the creation of the construction documentation, on site supervision to the client hand over.

Colin co-ordinated and liaised with all the consultants to produce highly detailed drawings, including plans, elevations, sections and large scale details, this ensured the contractor had a clear understanding of how to assemble the building, what labour and sub-contractors were required and how this was to be programmed, it also meant accurate costings could be produced for the client.

The project was undertaken by KM Grant under a JCT Prime Cost contract which allowed the client to keep a close watch on the budget and ensure the contractor was obtaining competitive costs for materials and labour.

Due to the high water table and ground conditions traditional foundations were ruled out with an Abbey Pynford ground slab /piling system being selected, this removed potential deep excavations and de-watering and proved to be both cost and time efficient.

The building’s superstructure was designed by Finite Design Ltd with the ground floor formed in pre-cast concrete planks cantilevered over reinforced “stepoc” shuttering walls, back filled with top soil to create a sloping meadow with a small section clad in natural split stone.

The open plan accommodation and large glazed areas led to a steel frame superstructure being selected, with infills of insulated timber framing and insulated cavity blockwork. The timber frame is finished externally in zinc with standing seams continuing over timber rafters to form the roof. The blockwork section between the perpendicular wings is finished in through coloured render with a concealed flat roof having a GRP finish.

The client’s brief included sustainable energy, high thermal insulation and an air tight house, this was also imposed on us via a planning condition (Code 4 –thermal / water usage), therefore careful detail design was undertaken to ensure all of the steel frame was within the insulation barrier and no cold bridging throughout the house occurred. Energy performance and heat loss calculations were carried out by Thermenergy.

The glazing elements were carefully looked at, and after much research we selected Burckhardt’s Soreg Glide triple glazed frameless system giving a U-Value of 0.8W/m²K, this system features a GSK extruded material for the entire frame eliminating cold bridging and linear thermal movement, this was to be the UKs first installation of this system undertaken by Ecohaus Internorm.

The system featured integrated frameless glass balustrades and fly screens, in addition concealed automated roller blinds were installed to provide both privacy and solar shading. Secret gutters within the Zinc roof slope we designed along with recessed flat roof lanterns, all RWPs were run internally in highly insulated boxing, the RWPs were installed in one length from outlet to the bend within the underfloor void to minimise potential leaks.

We liaised with a Civil Engineer, Martin J. Harvey to deal with the high level water table and the dispersion of rainwater from both the building and the hard landscaping.

The solution was a water attenuation tank allowing the rainwater collected from the building to be discharged at a given rate into a drainage ditch adjacent to the rear boundary preventing the ditch breaching in heavy rainfall, stored water will be used to provide irrigation to the soft landscaping around the building. The driveway was finished in a locally sourced gravel to provide a permeable finish.

To provide an energy efficient house an airtight and highly insulated fabric was designed, reducing heat loss and the energy required to maintain a comfortable living environment

A mechanical ventilation and heat recovery system was installed, removing warm moist air from the en suites and utility room and suppling the living accommodation with pre-warmed fresh air via the heat exchanger in the plant room. This MVHR system was configured to provide air changes throughout the day with a boost function when the moisture levels rose in the en suites.

Our client wanted renewable energy to supply the hot water and heating, we therefore employed an energy consultant, Mesh Energy, to prepare costs and performance comparisons between the available technologies.

The solution selected was a ground source heat pump fed by 2No. 110m deep borehole collectors to provide 100% of the houses requirements, this system supplied the entire underfloor heating via a NIBE 8Kw heat pump and 300l pressurised HWC.

We also installed 8No. 270kWp PV panels giving a total of 2.16kWp output, this generated enough electricity to provide the day to day electrical demands, additional demands being topped up by mains electricity, conversely any excess electricity would be fed back to the mains grid.

The PV panels are located on the concealed flat roof and with careful positioning are not visible from ground level.

Internally our client worked closely with an interior designer to continue the house’s theme, this included selecting the en suite’s sanitaryware, tiling and bespoke fitted furniture, the internal joinery was also specified and included lacquered high gloss internal doors.

All the materials selected are traditional and by careful design detailing and innovative use have been able to utilise the contractors experience and skilled trades to deliver the project without relying on specialist sub-contractors, this will also provide ease of maintenance in the future.

We are extremely pleased with the end result and are proud to be involved with such an exciting project. For photos see here.