Renovating
8 Common Mistakes to Avoid When Extending a Home
Check out advice from our experienced expert panel on what to consider when expanding your home’s footprint
“Nearly every homeowner we meet has similar questions and fears regarding a building project. Some clients don’t know how or where to start the process – there’s a lot to think about,” says Sam Holman of design and build company Project Nine Property Group.
Even seasoned renovators can come unstuck when taking on the major project of extending a house, and if you’re a first-timer, it can feel overwhelming. Let our panel of professionals guide you through some of the key common extension pitfalls to avoid in order to make the process run smoothly.
Professional advice from: Sara Slade of Sara Slade Interiors; Eilir Sheryn of VESP Architects; Sam Holman of Project Nine Property Group
Even seasoned renovators can come unstuck when taking on the major project of extending a house, and if you’re a first-timer, it can feel overwhelming. Let our panel of professionals guide you through some of the key common extension pitfalls to avoid in order to make the process run smoothly.
Professional advice from: Sara Slade of Sara Slade Interiors; Eilir Sheryn of VESP Architects; Sam Holman of Project Nine Property Group
2. Scrimping on planning
Undertaking a major renovation is exciting, but it’s important to temper any impatience to get going. “Understandably, some clients wish to get started with their project as fast as possible without the correct time being spent in pre-construction,” Sam says. “We prefer not to rush this stage and would advise all homeowners to think this way. We consider every aspect of a project before putting a spade in the ground.”
What sorts of things should you consider? “Think about the choice of materials, electrical layouts and interior products well in advance to give you clarity on what you’re getting and cost certainty,” he advises.
During preparations for a recent kitchen project, Sam’s client saved lots of photos into a Houzz ideabook. “The owner had done a lot of research, [including] on Houzz, and gave us loads of pictures to work with, which was great,” Sam says.
Eilir brings up an important, planning-related point – don’t assume you won’t need Planning Permission. “Often, an extension can be built under Permitted Development without you needing to apply for Planning Permission,” he says, “but pre-application enquiries with the local authority and early consultation with a planning consultant should establish whether an application is necessary or worth pursuing.”
Undertaking a major renovation is exciting, but it’s important to temper any impatience to get going. “Understandably, some clients wish to get started with their project as fast as possible without the correct time being spent in pre-construction,” Sam says. “We prefer not to rush this stage and would advise all homeowners to think this way. We consider every aspect of a project before putting a spade in the ground.”
What sorts of things should you consider? “Think about the choice of materials, electrical layouts and interior products well in advance to give you clarity on what you’re getting and cost certainty,” he advises.
During preparations for a recent kitchen project, Sam’s client saved lots of photos into a Houzz ideabook. “The owner had done a lot of research, [including] on Houzz, and gave us loads of pictures to work with, which was great,” Sam says.
Eilir brings up an important, planning-related point – don’t assume you won’t need Planning Permission. “Often, an extension can be built under Permitted Development without you needing to apply for Planning Permission,” he says, “but pre-application enquiries with the local authority and early consultation with a planning consultant should establish whether an application is necessary or worth pursuing.”
3. Lack of early interior design consideration
If you’re only thinking of the structure of your addition and not the details of how it will be decorated and furnished, you may end up regretting certain decisions.
“We find we’re often called in to help after the build work has started, because the homeowner has focused primarily on the structural aspects and adding square footage, leaving the interior design as an afterthought,” interior designer Sara Slade says. “This can lead to missed opportunities for cohesive material choices, optimal furniture layouts and lighting design.” She advises involving an interior designer from the start.
By way of example, Sara worked on the extension of this sleek bungalow from the outset and was able to ensure the structure and decor were perfectly synchronised.
She used Houzz Pro tools for this project and says, “One of the things we used that was really helpful was the Houzz Clipper tool. It means we can clip things from different brands or websites and put them all onto one board.
“We often have more than one option and the owner can go in and pick out the things they want,” she continues. This can be done with a simple click. “It’s brilliant.”
If you’re only thinking of the structure of your addition and not the details of how it will be decorated and furnished, you may end up regretting certain decisions.
“We find we’re often called in to help after the build work has started, because the homeowner has focused primarily on the structural aspects and adding square footage, leaving the interior design as an afterthought,” interior designer Sara Slade says. “This can lead to missed opportunities for cohesive material choices, optimal furniture layouts and lighting design.” She advises involving an interior designer from the start.
By way of example, Sara worked on the extension of this sleek bungalow from the outset and was able to ensure the structure and decor were perfectly synchronised.
She used Houzz Pro tools for this project and says, “One of the things we used that was really helpful was the Houzz Clipper tool. It means we can clip things from different brands or websites and put them all onto one board.
“We often have more than one option and the owner can go in and pick out the things they want,” she continues. This can be done with a simple click. “It’s brilliant.”
4. Overlooking lighting and atmosphere
It’s also important to think about how your new space will feel at different times of the day and evening before it gets built. Key to this is how your extension is lit.
“Often, we find extensions will have wall-to-wall glazed doors and rooflights to gain as much natural light as possible,” Sara says. “Then the evening comes and poor artificial lighting can make the new area feel cold and overly bright. If involved at the planning stage, an interior designer [can] design a lighting scheme that has a layered approach, to give ambient, task and accent lighting to create a warm and inviting atmosphere.”
Thinking of renovating? Find everyone you need, from interior designers to builders, carpenters and decorators, on Houzz.
It’s also important to think about how your new space will feel at different times of the day and evening before it gets built. Key to this is how your extension is lit.
“Often, we find extensions will have wall-to-wall glazed doors and rooflights to gain as much natural light as possible,” Sara says. “Then the evening comes and poor artificial lighting can make the new area feel cold and overly bright. If involved at the planning stage, an interior designer [can] design a lighting scheme that has a layered approach, to give ambient, task and accent lighting to create a warm and inviting atmosphere.”
Thinking of renovating? Find everyone you need, from interior designers to builders, carpenters and decorators, on Houzz.
5. Not factoring in the capacity of existing services
It might not be the most exciting part of your extension plans, but have you considered whether your plumbing system and electrics will cope with servicing all that new space?
Sam advises a pre-start survey. “Often, we’re asked to extend, renovate and add new services to an existing property. But before you rush to sign a big contract with a builder, it’s important to think about the capacity of your existing building services,” he says.
“Will adding new bathrooms, electrical services and heating elements overload the current system and what upgrades may be required to achieve your proposed project?” he continues. “Such elements can be costly and cause budgets to overrun.”
More: How to Cut the Cost of Your Extension Project
It might not be the most exciting part of your extension plans, but have you considered whether your plumbing system and electrics will cope with servicing all that new space?
Sam advises a pre-start survey. “Often, we’re asked to extend, renovate and add new services to an existing property. But before you rush to sign a big contract with a builder, it’s important to think about the capacity of your existing building services,” he says.
“Will adding new bathrooms, electrical services and heating elements overload the current system and what upgrades may be required to achieve your proposed project?” he continues. “Such elements can be costly and cause budgets to overrun.”
More: How to Cut the Cost of Your Extension Project
6. Underestimating the challenges of connection
The look of the connection between the original building and the new extension can often present a problem.
“One of the biggest challenges interior designers face is ensuring the new space blends seamlessly with the existing home,” Sara says. “Without careful planning, extensions can feel like a separate area with mismatched flooring, wall colours and overall design. A designer’s role is to create a smooth transition, using materials, colours and textures that complement the original space.”
“When older properties were originally constructed, there was less onus on Building Regulations and structural safety,” Sam adds. “For that reason, new designs will inevitably include larger structural elements, such as timber and steel, which is why you must think about how they will connect with the existing structure.
“Some clients want an open-plan space with flush ceilings connecting the extension to the old part of the house, but it may not be practical,” he says. “Exposed painted steels are a great way to overcome this and provide a unique finish [as in this design by Studio Fabbri]. It’s worth chatting to your design team and builder early on to discuss how this can be achieved.”
The look of the connection between the original building and the new extension can often present a problem.
“One of the biggest challenges interior designers face is ensuring the new space blends seamlessly with the existing home,” Sara says. “Without careful planning, extensions can feel like a separate area with mismatched flooring, wall colours and overall design. A designer’s role is to create a smooth transition, using materials, colours and textures that complement the original space.”
“When older properties were originally constructed, there was less onus on Building Regulations and structural safety,” Sam adds. “For that reason, new designs will inevitably include larger structural elements, such as timber and steel, which is why you must think about how they will connect with the existing structure.
“Some clients want an open-plan space with flush ceilings connecting the extension to the old part of the house, but it may not be practical,” he says. “Exposed painted steels are a great way to overcome this and provide a unique finish [as in this design by Studio Fabbri]. It’s worth chatting to your design team and builder early on to discuss how this can be achieved.”
The issue of connection is a huge consideration and all the pros had a lot of advice. “Inserting a glazed strip or margin achieves a purposeful ‘break’ and creates the most distinct declaration that the extension is clearly a different building,” Eilir says. You can see this idea in practice in this project, which he designed.
Some of Eilir’s other favoured architectural solutions include:
Some of Eilir’s other favoured architectural solutions include:
- Setting the extension back from the line of the existing house “It’s a deferential nod to the house being the more important building.”
- Using a contrasting material “It helps to distinguish between the two buildings.”
- Exposing the external materials internally “In some circumstances, further emphasis can me made by exposing the external materials – stone or brick – internally [also seen here].”
7. Failing to factor in contrast and variety
While you want that connection between old and new to look considered, that doesn’t mean the two spaces need to match. “A new extension is also an opportunity to add a new experience, not just more of the same accommodation, and often the most enjoyable houses are those that provide a variety of spaces,” Eilir says.
He suggests considering a pitched space if the rest of your existing house has a series of flat ceilings.
“Alternatively,” he says, “a more contemporary, highly glazed extension on the side of a listed building provides not only visual contrast to the elevation, but a different quality of light within, along with a better connection to the external spaces.”
While you want that connection between old and new to look considered, that doesn’t mean the two spaces need to match. “A new extension is also an opportunity to add a new experience, not just more of the same accommodation, and often the most enjoyable houses are those that provide a variety of spaces,” Eilir says.
He suggests considering a pitched space if the rest of your existing house has a series of flat ceilings.
“Alternatively,” he says, “a more contemporary, highly glazed extension on the side of a listed building provides not only visual contrast to the elevation, but a different quality of light within, along with a better connection to the external spaces.”
8. Rush-buying appliances, sanitaryware, tech and kitchens
Again, the advice is to slow down, do your research and get input from the right professionals.
“There are so many great products on the market and people can rush to choose their new kitchens, appliances, sanitaryware and smart home technologies without thought for how these will integrate into the existing property,” Sam says.
“New cabling, pipework, ducting or waste outlets may be required,” he says, adding that ceiling joists or steels may then obstruct routes through. “This means you could have to change products or design during the build, potentially causing delays and costly changes.”
The way to avoid such problems? “Working with a specialist contractor and interior designer to space plan and check product compatibility in advance will help to mitigate such risks,” Sam says.
Tell us…
Which of these tips have you found most useful? Let us know in the Comments.
Again, the advice is to slow down, do your research and get input from the right professionals.
“There are so many great products on the market and people can rush to choose their new kitchens, appliances, sanitaryware and smart home technologies without thought for how these will integrate into the existing property,” Sam says.
“New cabling, pipework, ducting or waste outlets may be required,” he says, adding that ceiling joists or steels may then obstruct routes through. “This means you could have to change products or design during the build, potentially causing delays and costly changes.”
The way to avoid such problems? “Working with a specialist contractor and interior designer to space plan and check product compatibility in advance will help to mitigate such risks,” Sam says.
Tell us…
Which of these tips have you found most useful? Let us know in the Comments.
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Being open about money can feel uncomfortable, but, the experts say, it’s vital for getting your project off to the best start.
“Having a realistic handle on your budget can be difficult to establish – and maintain – at an early stage,” architect Eilir Sheryn says. He advises being upfront with your architect about your position. “If you have a maximum amount of money you wish to invest, be sure to communicate this with your architect at the start. This should help to avoid abortive work, lost time and the almost inevitable ‘brief creep’,” he says.
Before you formally submit any applications, he says, “Have the provisional drawings priced by a builder or quantity surveyor. This will allow you and your architect to adjust the design to bring it down to an agreed budget before you get too far.”
Sam Holman agrees. To help make the process easier for homeowners, his design and build firm uses Houzz Pro’s Takeoff tool to quickly and accurately measure and mark up plans on screen, then turn them into Estimates. Referring to a recent kitchen extension project, he says, “The owners appreciated it, because we got everything priced from the start, so there were no later discussions or added extras and we avoided potential delays.”
Discover why you should hire a professional who uses Houzz Pro software.