Constructing a new home involves many decisions. We tried to make all the key ones before we started work on site, which is particularly essential when building a Passivhaus, and we have mostly been successful in this. But lots of small decisions remain to be made on site, and to keep things moving they have to be made quickly.
Finishing the Plasterboard
We have just finished installing the plasterboard (we’ve used Gyproc Habito from British Gypsum). By the time you read this, we will be pushing on towards completion. However, before we started fixing the plasterboard we had another major decision to make — to skim, or tape and joint?
Finishing plasterboard with a skim coat of plaster takes longer and introduces a wet trade into the project. However, it arguably gives a better finish for decorating. Taping and jointing plasterboard is quicker and suits a dry build system. But it is messier.
In the end, we decided to tape and joint; it’s what we’ve done in all our other showhomes, and it’s also what we recommend our customers do.
To make sure we were ready for the exclusive Homebuilding & Renovating Readers’ Day on 14 September, we had multiple trades working alongside each other for the first time. The tiling, for instance, is being shortly followed by decorating the following week. The kitchen installation is taking place at the same time.
Once the ceilings are finished then second fix electrics work will begin too, and we can think about installing the stairs. There’s plenty going on!
Bringing the Interior Scheme Together
Designing the interior of your own home is hard enough — creating the design for a showhome that will be visited by several thousand people every year is even more daunting and is something that needs careful thought and reflection.
So we opted to create, coordinate and curate the scheme using Terry Mahoney, a member of the Potton team. Terry retired many years ago as our national sales manager but continues to live and breathe self build, and now works as a consultant to the business.
The design he has pulled together is simple, stylish and sophisticated with some fun twists thrown in for good measure. I think he’s managed to pull off something that is simultaneously timeless and contemporary.
The interior design of the house is anchored by a few key feature elements, particularly the stairs and the central flexible ‘courtyard’ space. A decade ago we offered our customers a limited choice of staircase designs. Things have moved on somewhat since then and both Potton and our long-term supply partners at David Smith St Ives are much more flexible and ambitious.
The staircase in the showhome will move things on another step and will feature closed solid timber treads with glass balustrading. It will be constructed from American dark walnut. Walnut is more variable in figure and colour than oak or pine, and we believe that the completed assembly will provide a focal point for the rest of the interior design.
From a very early point in the design process I told everyone who wanted to listen, and probably plenty who didn’t, that the central ‘courtyard’ space under the large rooflight is the most important part of the design. The finished space will introduce great flexibility into how the ground floor of the house could be used and reconfigured on a daily basis — it could be used variously as a dining space, cleared of furniture for parties, but most importantly kitted out with an Eames chair for me to relax in at the end of a long day with a book and a glass of wine. (The Eames chair has been purchased and it won’t be too long before I get to try it out.)
Another of the key features is the large 3x8m feature window and doorset supplied by Kloeber — it will create a strong link between the interior and exterior. We have also strengthened this connection through our choice of materials. For instance, the external brick will also be used to create a feature wall inside the lounge area.
Lighting the Passivhaus
Our finished house will not lack for daylight with this large feature window to the rear, the substantial rooflight above the courtyard and the taller-than-average first floor windows. Indeed, one of the challenges throughout the design process was to manage the shading, size and specification of the windows and doors to prevent excessive solar gain and subsequent overheating in this airtight home. The PHPP (Passive House Planning Package) calculations have enabled us to achieve this successfully.
However, we have been guilty in the past, as have many others, of forgetting the artificial lighting design scheme and leaving it as an afterthought to be agreed on site between the electrician and project manager and/or customer. While these individuals invariably have many admirable qualities and experience, the ability to create a good lighting scheme design is not always one of them.
Clearly, there are specialist businesses that can design and install fabulous systems that will create a lighting mood appropriate to any occasion and setting, but these installations are frequently beyond the means and aspirations of many of our customers. So what we wanted to achieve within the Passivhaus was a low-energy design that had been thought about properly before the building was constructed, rather than being forced into an overly simple design revolving around picking the number and location of downlights.
Specifying Wall and Floor Finishes
Interestingly, Terry’s interior design calls for large areas of ceramic tiled floor. There are a few reasons for this beyond the aesthetic ones of following the general trend towards harder floor finishes; reflecting the contemporary external design of the property in the internal floor finish; and maintaining the stylish appearance of the rest of the design.
From a technical perspective, the hard flooring maintains the thermal mass provided by the screed beneath, which can be helpful in a building envelope that is otherwise lightweight in nature (built, as it is, in structural insulated panels, or SIPs). Tiled floors are also durable and easy to clean and great for those who suffer from asthma.
Our partners at British Ceramic Tile have supplied the products we have chosen; we’ve mostly selected tiles from their HD Technology range. The company is the largest manufacturer of ceramic and glass tiles in the UK and has a state-of-the-art factory situated on the edge of Dartmoor in Devon.
The interior design scheme is pulled together with feature walls of stunning wallpaper from Mockbee & Co and paint finishes provided by Brewers. These independently owned UK businesses have both been extremely helpful in guiding our selections and then matching specific paint colours within those selections.
Anchoring the design around a small number of key elements and pieces was deliberate. The house has interesting spaces that we want visitors to recognise and appreciate and we also wanted to develop a design that wasn’t reliant on expensive technology and fittings. One key element of this is the simple audio and media installation. Another is the kitchen…
Kitchen and Bathrooms Installation
Over the past few years we have developed an increasingly strong partnership with Callerton and Cambridge Kitchens and Bathrooms. Callerton is a kitchen system manufacturer based in the UK, and Cambridge Kitchens and Bathrooms is their retail partner closest to Potton’s Self Build Show Centre.
For the Passivhaus showhome, we agreed a design brief which required that the new kitchen would be simple, with materials selected to be stylish yet cost-effective. Callerton responded with a sleek handless design incorporating its new Monza matt cabinetry, Blum’s award-winning Legrabox drawer systems, Dekton’s innovative XGloss worksurfaces, and the very latest Bosch appliances.
The kitchen is regularly described as the heart of the home and while for many this is undoubtedly true, not everyone has the desire or inclination to spend an arguably disproportionate amount of their budget on the kitchen. Callerton wanted to make a clear statement that great kitchens don’t have to be monstrously expensive.
We also wanted to highlight that kitchen design should not be an afterthought and should instead be considered from an early stage of the design process. This is to ensure that the finished article properly meets the requirements of the occupiers.
It is also particularly important when designing a kitchen for a Passivhaus, as the interface between the mechanical ventilation heat recovery (MVHR) system in the house and the kitchen extract system is critical and the performance of the fittings will impact on the energy consumed by the house and therefore the PHPP analysis.
I stressed earlier that the interior design for the house is intended to be simple, stylish and sophisticated. We carried this through into the kitchen design and the next challenge was to make sure that the three bathrooms followed suit. The Passivhaus has two en suite bathrooms and a ground floor family bathroom.
Each has been designed by the team at our partners Sottini to showcase its latest products and complement the other elements of the interior design. Sottini believes that function dictates form and the best designs are those that are clean and simple. This was reflected in the brief that we gave to them and the designs that the company has created for us — as the stylish computer generated images on this page show.
Sottini has been at the forefront of water-efficient technologies since the business started over 40 years ago and continuously strives to minimise waste and improve efficiency in its products, something that was again key in the building of this Passivhaus.
The Importance of Landscaping
A self build is ultimately not finished until the landscaping work is complete and the garden planted out. We are delighted to be working with Brett Landscaping and Building Products to provide that crucial link between inside and outside.
The rear feature windows open on to a paved area on a level threshold, which is substantially covered by the projecting shade. The paved area will step down on to the minimalist- designed garden and then carry on around via an accessible ramp to the front door.
Much of this article has been about the lighter side of life, a long way away from the heavyweight technicalities of designing and constructing a Passivhaus. But the realities of constructing such a high-performance building are never that far from the surface and before we finally open up the house for business we will need to complete second fix plumbing and electrics, and ensure that the MVHR and hot water systems are properly commissioned. This is essential if we are to get the full performance benefits from the systems we have selected and installed.
Finally, we will need to carry out just one more airtightness test to ensure that we have at least maintained the level of performance already achieved.