Sally Godber, a Director at WARM consultancy explains why reducing the risks on her own Passivhaus project was so important, what that entailed and how it enabled her to deliver a healthy, comfortable and energy-efficient home on budget.
Interview with Sally Godber
Sally is a Chartered Mechanical Engineer and Passivhaus certifier who co-founded WARM consultancy with her father Peter Warm. She grew up with her dad building different houses, always experimenting with designs and construction systems to improve energy efficiency. It was never her intention to work in this field but somehow it had seeped in by osmosis, and after university and her growing awareness of the climate crisis she wanted to work in sustainability. With her engineering background she had gone into building service design, but it wasn’t rounded enough for her as it only dealt with a small part of the building process. Combining her experience from the commercial sector with her dad’s hands on practical experience and knowledge of domestic builds resulted in WARM energy consultancy. Their services include Passivhaus consultancy and certification, focusing mainly on commercial building projects. They also offer training through their sister organisation, Coaction.
The juxtaposition of her work and her home situation became too much
The driver for taking on a project came after living in a large, damp, Victorian house, whilst working on Passivhaus projects for other people. Initially Sally and her husband Mikey had started looking for a new home, but they found themselves wanting to change everything other people had done, which felt pointless. Either they needed to find somewhere that required a lot of renovation or to start from scratch.
Managing risk became an integral part of taking on a project
For Sally the prospect of taking on a new build or retrofit was exciting, but her husband Mikey was not so sure. So when they sat down at the beginning to discuss their priorities, risk came up. For Mikey, above anything else he did not want to be crippled financially by chasing the self build dream. Luckily a large part of Sally’s professional life is spent de-risking projects and also having had ‘the big house’ experience she was after the polar opposite.
Scaling down a project scales down costs
With a tight budget one of the most important decisions you’ll ever make is setting the size of the project. If you make it too big then it will be impossible to get the quality you desire. Sally and Mikey wanted to build to Passivhaus standard, but beyond that they just wanted a modest sized, warm and comfortable family home.
“We had a young family, I had my business going on, and my husband was not totally sold into this. We really needed something that was going to be low risk. So all of the design work that we did was about being able to manage the budget.”
Risks can often be identified
Sally outlines multiple risks and how many of them can be reduced through good design. She explains that some risks start with our expectation about how a project is going to go and then the reality of what actually happens. We might be faced with cost increases or there might be a failure during construction, for example, through something not being protected on site, which results in water damage. In terms of the energy performance, the airtightness, the insulation continuity and the build quality are key. Sally sees projects go wrong when the contractor is not clear about the expectation for the build, or the design contains many complex details, which have been hard to price in advance. Although it’s a quantity surveyor’s job to cost up projects, when the design is complicated it’s much harder to work out accurately the time and effort needed to complete the build to a decent quality. So, the difference between the client’s expectation and reality could be quite significant.
Reducing the number of ‘unknowns’ reduces the overall risk
Sally will always look to pay a fair price for building work which has got the least of number of unknowns within it. She explains that it is impossible to take some guesswork out of retrofit projects because you can’t know what you are going to find. Likewise, there are always some unknowns around groundworks, but for a new build, once you are out the ground, the risks come from the things that you’ve added into the design.
Complexity increases risk
This means that the amount of risk you have on your project is down to how complex you’ve made the design. These risks can come from the geometry of the building or the construction choices. Sally explains that making good decisions during the design process may not save you money on paper, but reduce the risks of you having to build to a poorer quality and it not being what you wanted.
“The amount of risk that you have on your project is about how complex you’ve made the design.”
Know your absolute price when buying at auction
Sally and Mikey considered a few plots and existing dwellings, before spotting a dilapidated pub at auction. Key opportunities included it being in a great location in Plymouth, which was at the entrance to the historic naval victualling yard and near to the WARM office, and having a sizeable garden with a beautiful old Holm oak tree in it. So they decided to bid for it.
A top tip that Sally received from a friend is to work out your absolute maximum offer in advance of attending the auction and then not to go above it! While this may seem basic advice, as a novice it’s easy to get swept along in the moment.
Sally also gets the feeling that most people at auctions are professionals, who are representing investors, so you will be competing in this arena. However, overall she thought it was a great way to buy a building, particularly because it’s so quick. Their last bid was their absolute maximum, so the adrenaline levels were high but they secured the property.
Living in the pub gave them a better understanding of the work that was needed
The pub had a flat upstairs, so they decided to live in it for a year to help get an idea of the space and make sure they understood what the retrofit required. They quickly realised that the pub was more dilapidated than they had thought, it wasn’t well connected to the garden and the refurbishment would cost a lot more than they were planning to spend. So they explored another option instead, which was to build a new home in the garden and then refurbish the pub at a later date.
Achieving planning permission was an emotional roller coaster
Sally has a lot of empathy for people who have been through the planning process or are going through it, as it was a real headache. It didn’t seem to matter that they wanted to build a good quality, high performance building that would fit into the local environment and last for generations. It felt like a lottery, particularly when they’d had a positive response to their pre-application, only to be turned down on their full application. Luckily their architect Jae Cotterell got involved and was able to present a good case for why it should be granted, and the planning department eventually saw sense and gave it the green light.
Working with one company for the design and build was part of their original de-risking strategy
Sally tells us that part of their de-risking strategy was to get Passivhaus Homes involved. Not only did they supply a kit that was tried and tested, and would easily reach the Passivhaus standard, but at the time they were also doing the construction work. So keeping the design and build with one company was a way to get cost certainty.
With her second child on the way, however, Sally was keen to get moving as soon as possible. Unfortunately the time frame for Passivhaus Homes to carry out construction didn’t work out, so they considered another option.
Their simple design made it easier to engage with another timber framing company
The positive side of all the work they had carried out in the design stage to de-risk the build meant they could approach a more standard timber framing company.
A simple design reduces the risks during construction
The house has a simple rectangular form with a pitched roof. On one side there’s a single storey element with a flat roof to provide a view for their neighbours. This added some complexity to the detailing and being close to their neighbours also meant they had to lower the eaves on one side of the roof.
The floor area internally is 120m² and it was a priority for Sally to make this space work hard. Downstairs is an open plan living room and kitchen, which has been designed so that a wall could be added later if they ever want to separate the rooms. There is also a spare bedroom downstairs, along with a utility room and a downstairs bathroom. Upstairs, there are three bedrooms and one bathroom.
The emphasis was on making the spaces work, with Jae encouraging them not to scrimp everywhere! For example, creating a welcoming and spacious hallway was something they didn’t appreciate at first, it felt like a waste of space, but over time they have realised how valuable this is.
There were challenges using a standard timber frame
Sally explains that Passivhaus Homes use a portal timber frame, which doesn’t require a ridge beam and allows you to create spans without any supporting beams. Unfortunately, standard timber frame manufacturers are not used to doing the lift of the ground floor and first floor in one which is what you do with a portal frame. Separating it into a ground floor timber frame and a first floor timber frame meant that they needed steel beams to provide support. Sally hadn’t wanted to use steel as a material in the build and this then created some difficult detailing for the airtightness. This is where the standard timber frame suppliers really struggled and if it hadn’t been so late in the design process Sally would have changed the design to break up the spans, so they could still have used timber. She feels it’s really important for designers to understand the natural limitations of different materials rather than relying on engineers having to solve problems because you’ve created a span that’s too wide.
Allwood Timber supplied the twin stud frame, which was then filled with Warmcel insulation. They have insulation under the slab and the roof is treated the same way as the walls, with blown-in cellulose. The structure is I beams, with OSB board on the inside.
Another advantage of a simple design is that you can run your eye over everything to see it’s all in order, such as making sure the airtightness line is continuous.
Remedial work enabled them to achieve the airtightness target
They did some of the taping themselves, along with the timber framer and after a poor first air test (1.2 air changes per hour at 50 Pascals) they realised they hadn’t pressed down the tapes enough. As soon as they did this and activated the glues, they saved another 0.2 on their air test. There was also air leakage around the steel beam. If she’d done the project today Sally would have used an airtightness paint to sort this out, but back then she had to spend a late night putting a lot of tape on it. Their final air test achieved 0.56 which meets the Passivhaus standard performance criteria.
Their windows and doors are from Rationel, because Sally had used them before and knew they were relatively cheap in comparison to others. They also designed all the windows so that they could be openable with a single span, with a lot of them being top hung so they could leave them open at nighttime. They’re a simple design with easy detailing, which all helped during construction. Sally feels it was still hard to achieve good airtightness when they didn’t have a lot of time themselves to check things and weren’t working with people with experience of this type of build.
They achieved a better airtightness with the pub retrofit a few years later, working with a local contractor called Greenacre Design and Build who had an amazingly skilled team. They were great problem solvers and fantastic at detailing, so they did exceptionally well even though it was their first time doing a Passivhaus retrofit project. But sometimes you don’t have those teams, and so being able to keep the details simple is really helpful.
Sally took over managing the build as soon as it was watertight
Sally made the decision to take over the project once the building was watertight. This meant they could project manage, be in control of the individual contractors and communicate directly with them. For example they got a contractor in to do the plastering and did all the services themselves, apart from the final electrical bits. They brought in a friend, a carpenter, to do the internal finishes and he refused to use soft wood! This really put quality into the build and is now much appreciated by Sally and her husband. It did take longer to complete the build as they were quite restricted with the time they could make noise in the evenings and at weekends, but it was good to feel more in control.
“We found that once it’s watertight, it feels like you can just breathe a bit, and it’s a bit easier to manage.”
It’s worth taking the time to get things right
It took two years from the point where they bought the pub to them being able to start construction and one year to do the build. The first year was deciding what they wanted, going from the pub renovation to a new build, then another year designing and getting planning permission. At the time all the faffing felt frustrating, but seven years on she can see that it was worthwhile and meant they ended up with a better home that will last them much longer as a family.
Sally had also learnt from her parents’ projects that it’s best not to move in until the house is finished as the work just doesn’t get done after that. One of the things they hadn’t done was tile the kitchen, which was only done six years later!
The house was delivered on budget, but the time put in hasn’t been calculated
It was a real success for them to deliver the project on budget, but with a self-build the amount of time put in is huge and something Sally doesn’t want to calculate.
There were some complications during the build, not necessarily associated with the design and things that they would definitely do better next time. They were very careful and conservative to achieve their budget and there are some things they might want to be different. Luckily noticing the faults wears off with time and over the whole project there is just one window that Sally wishes was larger. She was worried during the build that they were being too careful and maybe the building would feel mean, but it doesn’t.
“If you are on a tight budget, it makes a huge amount of difference feeling in control and that was ultimately why we took on the self-build.”
Managing the contractors themselves meant there was no middleman, they could negotiate individual prices and have conversations about the materials they were using.
Sally describes herself as a Passivhaus geek, but even so there was so much she didn’t know. This has given her a huge appreciation of all the different skills needed in a team to complete a build project.
She tells us how she really enjoyed the whole experience, both stretching her mind and also physically doing stuff. She doesn’t think there’s enough of that crossover, with designers getting practical hands-on experience. With the pub finished three years ago she’s definitely ready for another project but has nothing particular in mind.
Sally got to appreciate Passivhaus certification from a client’s perspective
They had designed the house to Passivhaus standard but hadn’t discussed certification until they were just about to start the build. Sally tells us that at the time she was absolutely exhausted and didn’t think she had the energy for it; it would be just too much hassle. Her dad, who doesn’t often tell her what to do was very clear that not doing it wasn’t an option, particularly considering her job!
They employed Will South of Etude to do the certification so that they had someone independent looking at the project. In the end, the certification process proved incredibly valuable for Sally as she knew there was a second pair of eyes checking on the project details. She was doing her best to check things but was incredibly busy and Will picked up on a few things that were wrong. Will had identified that they’d got their shading wrong, which they were able to correct, but it was too late to change the insulation, which was not the right specification. They had enough margin in the calculations for this not to matter, but by identifying it early they could have made adjustments elsewhere if they’d needed to.
It also gave Sally a real appreciation of just how hard it is as a client getting everything together for certification and the need to find the right level of checking. She is still a massive advocate for certification and as there’s very little quality control it’s good to have someone whose sole job is to check that you’ve built what you said you were going to build.
Sally’s husband is now an advocate of Passivhaus!
Sally says her husband wasn’t totally onboard with MVHR, triple glazing or even achieving the Passivhaus standard, but she was clear that these things would be worth it. They’d moved from a large Victorian house that was uncomfortable and difficult to manage into a tiny pub flat where she was cleaning mould off the walls. The flat was just 60m² and inevitably there were arguments and conflict. So, the experience of moving into somewhere that was a lot bigger was obviously like a revolution for the family. Sally tells us that it was so warm in the house that the kids wouldn’t believe they needed to put on coats to go outside. She had been spouting the theory to everyone, but it was still amazing to experience the comfort and warmth for herself. Her husband was quickly converted to this way of living. They also realised how they’d stopped inviting people round to the pub flat because it was so damp and at the time Sally hadn’t realised just how much inherent stress the mould and the dampness were giving her. She admits to being a total snowflake now, finding it very difficult to stay in other people’s houses.
Try to enjoy the whole house-building journey
In hindsight Sally reflects on the self build journey as a really lovely process, but this is not always how it feels at the time. She gives an analogy of when you have young kids you can feel like your hair is on fire, you’ve got sick down your front, and you’ve just stepped in something you’d rather not have. But when you look back, you think that was an absolutely incredible experience. She says to find ways to bring your family together through the process and the same with your wider building team. The relationship side of a building project is really important. So, as much as possible try to enjoy the sick down the front feeling!
Find out more
Transcript
Download a transcript of this episode.
Please connect with us
Subscribe, rate and review us on Apple Podcasts
