Designed by Passivhaus member Sarah Small Architects, the 216m² contemporary new build home accommodates 4 people and received Passivhaus certification in March 2017. The south facing site has far reaching views across Weymouth Bay and is the first Passivhaus in the region.
Sarah Small Architects gained planning approval to demolish a 1960’s bungalow and rebuild a two-storey detached house. The approval to demolish and rebuild gave the client the opportunity to achieve something different and the design was then developed to meet Passivhaus standards.
After going out to tender to four local builders, which all came back over budget, the decision was taken by the client to go down the self-build procurement route. Sarah Small Architects was employed to measure and order materials, act as cost consultant, to provide daily on site supervision, and to obtain quotes for each element and ensure suitability of all trades.
It was necessary to be on site everyday to make sure each contractor knew about building to Passivhaus standards. We found this to be important when installing the airtight layer. Sometimes it was necessary to pick up the tape and demonstrate how the membrane should be taped, especially around the window reveals. We under estimated the amount of tape needed, and the time it takes to carefully cover every inch of the building.
Building Performance
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n50 ACH@50pascals (≤0.6ach@50pascals)
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0.4
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Thermal Energy demand (≤15kWh/m2.yr)
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10.3 kWh/(m2.yr)
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Thermal Energy load (≤10W/m2)
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10 W/m2
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Primary E demand (≤120kWh/m2.yr)
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110 kWh/(m2.yr)
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Sleepy Dorset Weymouth passivehouse https://www.sleepydorset.com
Details of construction
Timber frame I joists made by James Jones, Lockerbie, cut in Gloucester.
Underfloor heating
EPS underfloor insulation (polystyrene)
I-frame floor joists with pre-cut holes for ducting.
Timber frame covered with DWD vapour permeable boards externally http://www.bischoff-
schaefer.de/en/products/boards-panels/dwd-boards.html?L=0
Membrane over Agepan DWD, then battens and cladding
Touchwood Homes. http://www.touchwoodhomes.co.uk/index.php/portfolio/21-
weymouth-passivhaus-3
Pro Clima Solitex Quattro membrane (black) for the walls which are also lapped and taped
using the Tescon Vana Tapes.
Pro Clima Solitex Plus membrane (blue) for the roof provides superior protection against
condensation risk and extreme resistance against driving rain.
sheets of birch ply to the roof battens ready for the final roof covering.
balconies each have a beautiful box gutter made of birch ply set within the structure. These
will eventually be covered over with the membrane to allow the balconies to drain properly.
Render board with silicon render outside Jubizol.
1500 linear meters cedar cladding
triple glazed Internorm windows and doors, ordered in July, not arrived in January
zzinc fascia roof
The window frames are a combination of timber on the inside and powder coated
aluminium on the outside. They have excellent thermal insulation (Ug=0.5W/m2K
Uw=0.69W/m2K) and soundproofing values up to 46dB.
Proclima Tescon Profil airtight tape around the window frame internally, filling the gap with
Illbruck F330 expanding foam and Extoseal Encors to the external wall & frame (especially
under the cills).
six large triple glazed Fakro roof lights ref: FTT U6. We specified Fakro because they offer the
best thermal efficiency on the market, Uw(W/m2K = 0.81. Two out of the six roof lights will
have an automated opening system, which means when the internal temperature of the
house reaches a certain temperature the windows will automatically open and allow the
internal temperature to cool. An outside rain censor will then tell them when to close.
two high level windows at ground floor to open (and be locked in the open position)
Back to Earth in Exeter for a box of Udi tapes. We think the Udi tapes have more stickiness
than the Tescon tapes.
MVHR PAUL NOVUS 300
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