Getting The Builders In - How Long Is It Likely To Take? -

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Getting The Builders In – How Long Is It Likely To Take?

“Greg “Home

Top of the list of questions we get asked when quoting on loft conversions and home extensions – after ‘how much?’ – is ‘how long will a loft conversion / extension take?’ Generally we’re able to give a good estimate of the time it will take, barring any unexpected developments, because we’ve actually viewed the property and discussed the work that’s needed. Jeffery and Wilkes are London’s leading Building Contractors.

For you, our blog reader, thinking about converting your loft or adding an extension, it’s not so easy. I’ve no idea what you want done, what type of property is involved or where you are! So if you would prefer an alternative to ‘how long is a piece of string?’ the best bet is to get a quote from a specialist building firm like ours.

However, if you’re not quite ready to make that call, here are some rough guidelines that will help you estimate how long it’s likely to take.

Loft Conversions And Home Extensions: How Long Do They Take?

Planning Stage

First off you’ll want to get a few firms in to quote and talk through your plans. The time this takes will partly be down to how quickly those firms can respond to your request, and also down to how organised you are!

You want to get some recommendations first from friends or neighbours who have carried similar project on their homes, then draw up a shortlist and start booking some appointments.

Once the appointment has taken place those firms will get back to you with a formal quote and timescale on paper, although sometimes you may be provided with a rough estimate on the day.


Having decided on whom to use, you’ll now be relying on them being available to do the job when it suits you. If you’re planning to use a loft conversion company like ourselves – who do design and build – you’ll only be dealing with one person (a project manager). However, if you decide to use an architect for the design, and then a builder or firm for the work, you’ll need to juggle everyone’s availability. This can become a bit of a headache to organise, so often it’s less stressful & quicker to use one company to do everything.

Plans will also need to be drawn up for your project & generally we can send over initial designs within a week.

Planning Permission

Once you have your plans they may need to be submitted for planning permission. On average this could take up to 8 weeks although your Local Area Planning Office will be able to give you a better idea for your area.

Not all loft conversions or extensions require planning permission so this could be a factor in your design if you want quicker results. Many lofts/ extensions can be done under Permitted Development which still takes 8 weeks to get a certificate, but if you’re in a rush many will start works & allow this certificate to arrive during the build.

Building Stage

Depending on the complexity of your project the actual building time will vary considerably. A good company will give you a detailed timeline to show you exactly what’s happening & when. This will help manage your expectations & advise you of key stages to look out for.

Typically a rear dormer on a terraced house will take approximately six weeks, and a gable end with rear dormer on a semi-detached property, about nine weeks.  A small single story extension takes approximately six weeks, whereas a large extension could be over 3 months.

Note that these estimates are to complete the build, not decorate and fit out.

An effective way to either reduce these timelines or ensure that things do not get delayed is to use a firm that has al the trades in-house. They will be able to move different trades around their jobs so when your project needs a plumber they’ll already be lined up. This ensures that there are no hold ups during your build.

Decoration And Finishing Touches

Once the major work on your loft conversion or home extension is complete, it’s time to get on with the more decorative jobs. These may take a week or two depending on the size of your project and the kind of finish you require. Remember that if you want a particular wallpaper or handcrafted tiles, ordering and delivery can take some time. So make sure you finalise these design elements as soon as possible so you don’t have to wait around for them to arrive.

While naturally all home owners want their loft conversions or extensions to be completed as quickly as possible, if you want a great job that really gives you the wow factor you must allow sufficient time.

Taking shortcuts compromises the quality of the end result, so consider whether it’s more important to have the job completed quickly or get the perfect, beautiful space you desire.

If you’re ready to get a quote and estimate on the timescale for your project – and you live in West London, or Greater London – please call 020 819 3883 or email

Speak to one of our team about how we can design and build your space.