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What to consider when building an extension Part 2: Planning and Build

In our previous blog, we looked at the budget and design considerations homeowners need to take into account when planning to build an extension. Whilst these stages are imperative for the success of your planning application and end result, they are by no means the be all and end all.

Once you know what you want and have worked out the affordability, you’re ready to proceed with your plans. For many, this is the daunting bit — but it needn’t be. In this post, we’re going to take a look at how to navigate through the planning application and build stages of your project as quickly and easily as possible.

Getting Planning Permission

If it does not fall within permitted development, building an extension on your existing property will need to apply for planning permission. The UK government’s planning department is essentially in place to control the way that land is used to ensure a certain level of uniformity in appearance, logistics (road access, etc.), and environmental impact.

Not all building work will require a planning application. However, it’s strongly advised to investigate this before undertaking any work. The government Planning Portal is a good place to start with your research, though generally speaking, you will need to obtain planning permission for your extension if:

  • The proposed building is taller than the tallest part of your original buildings
  • Any part of the proposed extension exceeds four meters in height and sits within two metres of your property boundaries
  • The ground area covered by the proposed extension covers more than half of the total property area
  • The total volume of original property is increased by more than 115 cubic metres
  • The total volume of original property is increased by more than ten per cent (or 50 cubic metres) for terraced houses, or any property in a conservation area

In most cases, Building Surveyors, architects and planning consultants can be hired to take care of the planning application process. Although this comes with a fee, homeowners are advised to seek expert council before they go ahead and make the planning application. Getting it wrong or missing out vital information could result in long and sometimes costly delays.

Getting onto the planning register

Once your plans have been received by the council, they will be placed on a Planning Register. This is so that they’re available for public viewing, and local residents will be advised of their existence so that they have the opportunity to speak up if they have any grievances with your proposition, before the final decision is made by a committee appointed by the local council.

This process generally takes around eight weeks and, if your application is approved, you then have up to three years to undertake the work.

If your application is rejected, on the other hand, then you have two options. Either you can go away and adjust your plans accordingly, and then resubmit them without any further charge, or you can appeal. Appeals can be lodged within three months of the council’s decision.

The Build

When your planning application is accepted, you’re finally ready to start work on your property. The first stage of the building process is once again application-based.
For almost all house-extension cases, it will be necessary to apply for approval from the government that your plans comply with set building regulations. These regulations are in place to ensure that the design and structure of your buildings meet with minimum standards for England and Wales for health and safety.

A major Building Regulation is Part L, which is the consideration of the energy efficiency of the Building. This is not always required on an extension but can be depending on the design, for example if the proposal is for a large glazed section, you may require SAP calculations. These should be carried out at the outset to avoid retrospective costs further down the line. Very simple and cost effective if carried out early in the process.

The process of applying for building regulations needn’t be a stumbling block, and we’ve covered the process in this blog post . However, it can help to seek the help of your builder or Building Surveyor both in the application stages and in making sure that any subsequent building work is met with approval.
Once you have received approval of your plans, it’s time to get down to work.


Depending on your budget and personal time constraints, you may wish to invest in a professional project manager. A project manager will oversee the entire project from start to finish in accordance with predefined terms set by you, including the acquisition of labour and supplies.
If you don’t have the budget, or if you’d rather put the time in to oversee the project yourself, then you will need to dedicate some time to hiring the right people.

When searching for a building contractor to undertake the work, it’s advisable to consult the Federation of Master Builders (FMB) to ensure you go with a reputable professional. It’s also a good idea to shortlist a few contractors and ask for quotes, making sure that all building supplies are included. Wherever possible, you may also want to arrange a face-to-face chat with each, just to double check that all parties understand the work to be carried out and get a feel for their knowledge and professionalism. Construction professionals are also a good source to receive a recommended Builder they use regularly.

Once you have decided which contractor to go with, you should always seal the deal with a formal contract. Though this might seem stuffy and unnecessary at first, laying out the terms on conditions from the outset keeps everyone on the same page and sets expectations for your contractor to work to — this could save a significant amount of time, money and hassle in the long run. Fundamentally, your contract should include two things: timescales and payment terms.

– Timescales

Before you start work, you should pre-define estimated dates to complete various milestones throughout the build, as well as agreeing on a completion date. Of course, you’ll need to keep this relatively flexible to account for things like availability of specialist materials, bad weather or changes you might make to the plans.

– Payment terms

Payment for building work is ordinarily made in stages of completion, and in the contract, you should detail exactly what elements of the build are included in each instalment. It goes without saying that once the work on your house is complete; you should fully ensure that you’re satisfied before making payment for any outstanding fees.

Generally speaking, you shouldn’t expect to pay any more for the first stage of the work in advance. Some contractors may insist that they require a large payment up-front in order to cover the cost of materials. However, most builders have a cash-flow and credit with local building suppliers so this shouldn’t usually be the case.

The bottom line

Undertaking any building work on your home can be a hugely rewarding but time intensive and costly pursuit. To keep stress levels to a minimum, you need to make sure you put the time in from the outset to make sure you have the right people working for you. Remember that cutting corners never pays off — but putting in the hours to ensure your work complies with government legislation and finding contractors you can trust almost certainly does.

If you need help or advice with your extension plans, Aldrock Surveyors can help. For more information about how our expert team can help you to build your dream extension, don’t hesitate to get in touch.

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  • 15th October 2014