10 Top Tips for Planning an Extension to Your Home

Extensions are a great way to maximise space. It is one of the biggest investments most people make so planning your extension thoroughly can save you serious pennies, not to mention ensure you have exactly what you had in mind once the builders pack up and go home.
Cook Brown Building Control are an independent Corporate Approved Inspector, licensed by the Construction Industry Council (CIC), to provide Building Regulation approval for all types of construction projects. From large commercial spaces to residential extensions. We’ve formulated ten top tips to help you navigate your way through the initial stages, giving you the guidance required to help the plans to go as smoothly as possible.

  1. Find the right Architect/Designer

    Make sure you chose someone with lots of experience. Ask for references or recommendations to be sure that they are competent with the type of project you are expecting.
    At the end of the day it is your responsibility to make sure that what you are building is safe. If you pass this to a consultant you need to make sure that they are safeguarding you with the designs they submit.
    The more detailed the specification and plans are the more accurate, and consistent the builders quotes will be.

  2. Consider what the purpose of your extension is

    By deciding the purpose of your extension you will be able to get a clearer idea for the scale of your budget as well as the type of designer you will need.
    Extensions come in all shapes and sizes, so the more specific you can get the better the end result will be. When deciding the type of extension you are after, consider who will use the space and at what time, for what function.

  3. Budget

    An extension could cost between £1,000-£2,000 per square meter depending upon specification and purpose so it is one is one of the largest financial commitment many people will commit to.
    It is worth allowing for an extra 10-20% contingency fund. Having said that, it never hurts to allow extra just in case. By issuing designers drawings to a quantity surveyor, you can get a step ahead as they will be able to provide you with an accurate cost.
    You will have to consider the designer/consultant’s fees, government VAT, local authorities fees for applications and of course the builders fees when estimating your budget.

  4. Talk to your neighbours

    Having your neighbours on board with your plans will be an enormous help when taking your proposal forward to the council.
    If planning permission is required your local council will write to your neighbours to let them know and give them an opportunity to look at the plans and comment, or even object – If they only find out what you are doing when they receive this letter it can cause anxiety which could lead to them submitting an objection.
    Talking through ideas beforehand can avoid the time-consuming process , and ongoing tensions of dealing with an objection.

  5. Get your approvals

    This is where the experts come in.
    They will be able to advise you on whether you will need to apply for planning and any other permissions. Each council is different, and their requirements will vary, but checking the local council’s website is a good place to begin outlining their policies.
    You can also look at the planning portal website for advice as to whether planning permission is required.
    Even if your extension doesn’t require planning permission it will likely need Buildings Regulations Approval, which is where we can help.

  6. Research different materials

    This stage is important as it can really make or break your extension as well as save you money on your energy bills.
    The local planning department will be interested in the appearance of the building based upon its surroundings. Finding a suitable material that compliments its surroundings is not only more likely to be approved, but it will also result in a beautiful addition to your home too.
    Some materials are more energy efficient than others too.
    Many people now choose to provide lots of glazing and light as part of their extension. Glazing is less thermally efficient than solid walls/roof and as such the Building Regulations limit the amount of glazing as a percentage of the floor area.
    There are solutions to this, such as SAP calculations and our Cook Brown Energy team will be able to advise you as to the minimum standards as well as any alternative products that are more energy efficient. Learn more about the energy efficiency of different materials >

  7. Party Wall Agreement

    This is in place to protect neighbouring properties from any building work that you undertake within 3-6 meters of their property.
    Learn more about Party Wall Agreements >

  8. Will your extension add value?

    Speak to a good local estate agent about your plans, they should be able to provide you with an estimation as to whether the extension will increase the property’s value. It is also worth considering that extensions can go up (lofts) and down (basements) as well as out!

  9. Choose the right builder

    So you have a design and are ready to start work.
    Once you have decided what type of extension you’re after, try to find a builder whose portfolio contains similar work. Try to obtain recommendations and chat to them extensively.
    You may be able to check their reviews online and don’t be afraid to ask for references from recent customers to ensure you are both on the same page.
    There is nothing wrong with obtaining quotes from more than one builder. Prices can vary, depending on the detail provided on the plans and specification.
    Alterations to your property are one of the largest capital investments you will make so always use a formal contract and consider stage payments.
    It is common in such contracts to retain a final payment for a period of time to cover defects or snagging items. Your designer/architect will be able to advise you with this regard.

  10. Commit!

    Finally, it is so important to be 100% about your plans. It is much easier to change the design on paper than when it has started on site.
    And lastly, enjoy! The extra space is always worth it.

Building Control and Approval across England and Wales with Cook Brown

Here at Cook Brown Building Control we are leading approved inspectors, providing a wide range of building control services across England and Wales. We have a vast amount of experience in fields such as design proposal assessments, checking design drawings, inspection regimes and issuing certification to oversee the compliance aspects of projects.
If you have gone through these tips and know you’re ready to get the ball rolling, get in touch today for bespoke advice tailored to your requirements, from a company who knows them best.