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  • Writer's pictureGlenn Thompson

4 Stages a Homeowner Should Know When Extending.

Updated: May 12

If you are considering extending your home please contact me for advice, no obligation. I would be more than happy to offer you my initial advice. The following guide will provide you with a basic understanding of the 4 key stages every homeowner should know when extending.

4 Stages a Homeowner Should Know When Extending | By GT Building Design
Domestic extension by GT Building Design incorporating a new Garden Room, Utility and sheltered Patio.

Initially to help me get a better understanding of your home and your wishes it would be very helpful if you could provide the following information, we can then discuss and I can advise you of my fees for helping you with your extension.

  • Confirm your full name and address including postcode.

  • Confirm your phone number and email address.

  • Provide a basic summary of what you wish to achieve.

  • Confirm your maximum spend, budget.

  • Take photos of your home and email them through to me, mainly around the location where you are thinking of extending.

  • If you have any existing drawings of your home that would be very helpful, email them to me. An Estate Agent may have prepared basic plans for instance or Building Control may have drawings from a previous application.

4 Stages a Homeowner Should Know When Extending | By GT Building Design
Your address will help me initially view your property, the garden space you have and the street view is very helpful to gain a quick understanding of your current home.

Architectural Fee Quotation:

When I have an understanding of your project and your ideas I will email you a Fee Quotation which will include my fees, stages and clarify any additional expenses that may be necessary on your project.

As an example, additional expenses may include the following: (Varies on each project)

  • Builders estimate (no charge) or Quantity Surveyors estimate (£150 - £300) You may prefer to obtain a construction cost estimate from the design drawings before moving on to the next stage.

  • Structural Engineers Fee (Payable to an Engineer if structural calculations are necessary)

  • Planning Application Fee (Payable to your local Council £327.00)

  • Building Control Plan and Inspection Fees (Payable to your local Council – varies and I will confirm, allow say £250 - £350 for an extension)

  • SAP Energy Calculations. Payable to others (approx. £150) and your Council may request this.

  • Large Scale Vector from Ordnance Survey (£57.00) to prepare Site Location Plan. (Required by both Planning & Building Control)



If you accept my written quotation I will carry out a measured survey of your home. This generally takes 2-3 hours. I will then produce existing plans and elevations using the latest CAD software.

On site I would also take many photos and these are used to help me produce the existing drawings and following on from this to prepare the initial Design Proposals.

Existing drawings are necessary for any Planning or Building Control Application.

4 Stages a Homeowner Should Know When Extending | By GT Building Design
A typical measured survey drawn by hand with measurements recorded, this would also include heights.

4 Stages a Homeowner Should Know When Extending | By GT Building Design
Typical drawing of an existing home prepared using the latest CAD software.



I will ask you to email me through your "Wish List". Ideally this would include your maximum budget, your must have's and what you would like if your budget allows (non-essentials). Based on your wish list I will then prepare initial design proposals to begin our discussions.

4 Stages a Homeowner Should Know When Extending | By GT Building Design
If you can prepare a "Wish List" for me that would be great

Often there are many ways to extend a home and the first option can be tweaked to meet your needs. On other occasions a second and third option is needed. Be assured that options can be easily tweaked or changed and we can keep working together until we have the option that you love ❤️

Note: At the completion of Stage 2 (Design Proposals) you may wish to obtain a construction estimate from a Builder and they would normally not charge for this. If needs be a Quantity Surveyor can also provide an estimate and will charge around £150 - £300.

I'm unable to provide estimates as construction costs fluctuate and vary on each and every project.

4 Stages a Homeowner Should Know When Extending | By GT Building Design
Typical Design Proposals prepared for approval by you.



A Planning Application would then be lodged, even if your project falls within permitted development rights. There are two routes for obtaining formal approval from the Planning Service.

1. Full Planning Permission.

2. Certificate of Lawful Development.

A certificate of Lawful Development is mainly used where a small extension falls within permitted development rights. This type of application requires the same amount of time and drawings to prepare but it has it's limitations on what you can and cannot do, it’s restrictive.

I would advise my clients to obtain either full permission or a certificate to keep you right with neighbour's and a Solicitor will ask for evidence of this in writing, should you or your family decide to sell the home at any stage.

I will prepare the planning application documents including existing and proposed plans / elevations, existing and proposed block plans, a Householders Design Statement (if required) together with a Site Location Plan.

I will submit and administer a planning application on your behalf and liaise with the Planning Service throughout. Once submitted a Planning Application for an extension often takes around 3 months or more.

4 Stages a Homeowner Should Know When Extending | By GT Building Design
Typical Planning Application drawing showing existing and proposed plans and elevations.
4 Stages a Homeowner Should Know When Extending | By GT Building Design
Planning Service may also ask for a Householders Design Statement and if required I will prepare this and submit to the Planning Service on your behalf.



This stage would involve preparing detailed construction drawings and a written Specification Booklet. Building Control have stringent regulations and both the drawings and specification will need to include all information that meets the current standards and regulations in construction.

I will submit and administer a full Building Regulations Application on your behalf. I will liaise with Building Control throughout providing any further information they request to obtain your Notice of Approval.

The approved drawings and specification will be a pricing package for a builder. When construction costs have been agreed these drawings and specification will form your contract between you and the builder.

4 Stages a Homeowner Should Know When Extending | By GT Building Design
Typical construction drawing including details to obtain Building Control Approval and form the contract between you and your builder.



My clients often mention that they are not aware of the stages and process when considering extending, I hope this guide clarifies and helps.

Please feel free to contact me if you have any questions, need advice, or discuss how we can work together on improving and extending your home.

Thank you, Glenn. 07719912695

GT Building Design | Chartered Architectural Practice | Donaghadee

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