For some time now, ever since selling our house twice and failing to find another one we liked more, we have been planning an extension and remodel. When we first bought the house, back in 2012, we set about building an extension to provide a bigger kitchen, as well as a two-storey rear extension but, on reflection, we could have done more to expand the space.
Now that the toddlers are teens, we need more space and so are planning on building a further rear extension to provide a much-needed utility room. We also want to extend out over the flat-roofed kitchen in order to add another bedroom and bathroom upstairs.
Obviously this is going to cause a level of disruption and, as we plan on living in the house while work is carried out, we are keen to find ways to do this as harmoniously as possible. Equally, we would like to split the costs up a little, giving us time to save up for the upper storey section. However, I am questioning the wisdom of staggering an extension like this – is it actually better to just get it all done at once, accept the inevitable mess and disruption to daily life and pay the whole amount in one go? I put it to the experts.
What are the reasons for staggering an extension project?
For us, the main motivation for staggering our extension project is cost – quite simply, we want to get started but don't have the funds for the whole thing just yet. Additionally, we need to be able to live around the work as it takes place.
According to architect James Munro of Pace Architecture, our reasons are common, although not necessarily completely founded. "Usually, phasing an extension is not the most efficient way to deliver a build, and can actually carry more costs overall, so phasing is usually down to two key drivers.
"The first is living in the property during the works, with people keen to avoid having to find a rental property and incurring the costs that come with that," continues James.
"Secondly, there is the matter of financing. When the budget doesn’t match the overall extension costs, phasing can assist with that. It also allows more control over any financial risks, for example committing to one manageable phase first, and consolidating finances at the end of that phase, before proceeding."
Megan Ebanks, director of MEA Studio, agrees that budget is usually the biggest driving factor behind staggered extensions. "Most of the time phasing is a financial decision rather than a design one – it becomes a considered option when the full budget for the whole project isn't there at the beginning of the job. However, I'd encourage a homeowner to look hard at whether they can avoid it before committing."
Megan also highlights the toll a phased project can have on homeowners in terms of adding to the extension timescales. "The total period of disruption is much longer. Two shorter builds spread over multiple years can be more wearing on a family than one nine to 12 month job they move out for."
Finally, Scott Young, co-founder of K&S Bespoke Builds, points out that phasing an extension can get complicated for other reasons. "If your stages are a year or more apart then you might get a different team on the return visit which means they may do things differently, or might want to redo bits that are already done, which would add costs or give you a different result than originally planned.
"Also, planning typically lapses if you don't start the build within three years, and building regulations change so different stages might be subject to higher standards if you wait too long. Again, this might mean expensive reworks," adds Scott.
Pros of staggering an extension:
- Allows you to split payments into manageable chunks
- Easier to live around phased work
- Easier for those undertaking work on a DIY basis
Cons of staggering the work:
- Tends to cost more overall
- Project can lose a sense of momentum
- Delays likely in getting contractors back on site
- Stress of building work lasts for longer
James is an Architect with over 20 years experience working on homes for clients. He has delivered many complex large scale renovations, including new basements, swimming pools and multi-unit mixed used developments for commercial clients. His expertise includes working on listed buildings and obtaining challenging planning consents across all London Boroughs and the South-East. His ethos for a successful end result, is having a collaborative, customer-centric service with an emphasis on attention to detail, considered design solutions and high-quality materials and suppliers, as well as working with trusted partners in the construction industry.
Megan Ebanks (BA(Hons)DipArch RIBA), founded MEA, a RIBA Chartered Practice, in 2019. MEA is known for blending the historic with the contemporary, creating a sense of timeless luxury in heritage and modern buildings. Before founding MEA, Megan worked on high-profile projects for Foster + Partners and Bennetts Associates, including large-scale new build offices in the Kings Cross Development and the City of London, the refurbishment of significant listed buildings in an Oxbridge University and a new HQ for a prestigious Royal College.
Scott Young is the co-founder of K&S Bespoke Builds, a construction company in Reading, UK, specialising in conservatories and extensions.
Why is it better to carry out extension work all in one go?
Clearly then the experts favour getting the work all done at once – surprisingly, they all said that this a far more cost effective route than staggering.
"Completing in one go is more cost and time efficient for the actual contract with the contractor, and the reason is mostly preliminaries. Scaffolding costs, site set-up, welfare, skips, temporary protection and site management are priced per contract rather than per square metre, so phasing means paying for them twice," explains Megan Ebanks.
"Phase two also gets priced at a later date, so you lose your fixed price and the phase two price could include inflation. And, you pay for some items that are only in the schedule of works because the job is split, such as temporary weatherproofing, temporary propping, capping off services you'll uncap in two years' time.
"On top of that, you might lose the contractor," adds Megan. "By the end of phase one a build team knows the building and has their subcontractors lined up. If there's a gap and they've gone, and you re-tender from scratch, it could be a few months before anyone is back on site."
That said, Megan does point out that the 'all-in-one' route won't work for everyone. "Completing in one go means living on-site might not work so usually requires the homeowners to move out, which incurs some cost for the client, and that is the trade-off."
Pros of extending all at once:
- More cost effective
- Work gets completed faster
- Same build team for the entirety of the project
- Projects tend to run smoother without the stop-start that comes from phasing
Cons of extending in one go:
- Homeowners often required to move out
- Higher upfront costs
What is the best way to stagger an extension?
If you do decide to take a staggered approach to your extension project, there are ways of splitting it up that make more sense than others.
"We sometimes phase projects so that the shell and core are completed in phase one and the finishes are phase two, occasionally by the homeowners themselves," says Megan Ebanks. "More often though the phasing is to complete one part of a house and then do the other part in the next phase. It lets the homeowners live in the section of the house that isn't being renovated and extended, then move across to the completed half when phase two begins.
"We don't phase the design though – the whole project is designed at the outset, even when we only plan on building part of it in the first phase," adds Megan.
"Almost every phasing problem I've seen comes from a scheme that was only designed as far as phase one, so the drainage runs, the structure and the services positions were never set up for the future phase, and phase two then gets compromised or costs more as there is a need to change elements which were completed earlier."
"I'd recommend doing everything hard and disruptive in phase one – things like groundworks, foundations, steelwork and structural stuff, the roof and anything else to make it weathertight, drainage, service routes and so on. Then things like flooring, lights and the interior fit-out can come later," adds Scott Young.
"If phasing by stage, put everything dirty, structural and disruptive into phase one (steels, drainage, roof, rewiring, plumbing)," agrees Megan Ebanks. "And if phasing by area, set the boundary somewhere the building can actually be sealed – at a wall, a door or a compartment line, rather than part-way through a space.
"The main thing to think about if planning a phased project," she adds, "is to get the whole thing consented under one planning permission application."
FAQs
Is it a good idea to split a renovation into stages?
While the ideal scenario with both an extension and a renovation might be to move out in order to carry out all the work at once, it is not always possible. Interestingly though, if you are renovating a house, as opposed to extending, and are considering working in stages, there is one instance where a staggered approach can actually be a much better idea.
"There is one case where I think phasing is the right answer rather than a compromise which is when you can't finish the design until the building has been opened up," explains Megan Ebanks.
"We're running a Grade II listed house project in Belgravia in three phases for exactly that reason. Phase one is a soft strip out, taking the house back to brick so the whole structure is exposed and the structural engineer can confirm the assumptions their design rests on. Phase two is all of the structural work, taken to a watertight envelope. Phase three is the finishes.
"It is the right decision because, on a building of that age, a structural design always rests on assumptions until you can actually see the structure," she explains. "On a listed house I would far rather find the surprises during a strip out than part-way through a build."
While planning your new addition, do take the time to research whether a two-storey extension might work out to be more cost effective overall than a single storey design – you don't (as I am) want to be having to add to it later down the line if at all possible.
