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House Extensions - Frequently Asked Questions


Q. How many years’ experience does Architecture First have?

A. We have been designing and building extensions, loft conversions and one-off new builds for over forty years. We have found that designing these projects in 3D helps our clients to get a better understanding of their project and have been producing designs of this type for over twenty years.

Q. What areas do you cover?

A. Architecture First are based in Derby Derbyshire and offer their services to clients within a twenty-mile radius. We frequently undertake work in Derbyshire, Nottinghamshire, Staffordshire, and Leicestershire and will take on projects further afield when requested to do so.

Q. How long does it take to produce the architectural drawings?

A. Once we have been instructed, we will arrange to undertake a measured survey of your property and produce architectural drawings that show the existing floor plans and external elevations. Following this we will build a 3D model of your property and use this to generate a conceptional design to include visuals, floor plans and elevations of the proposed alterations and extensions. These will be reviewed by you and further conceptional designs produced to show the requested design changes. Once you are happy with the design floorplans, elevations and sections will be completed for the next stage. This process will take 2-6 weeks depending on the complexity of the proposed project.

Q. Why should I pay to have architectural drawings?

A. Architectural drawings are a requirement for Planning Permission, Building Regulation Approval, Listed Building Consent, Build Over Agreements and sometimes Party Wall notifications. They provide the information that is required to build a compliant extension and allow building contractors to price the project accurately. Architectural drawings will be included in the information that forms the contract between you and the contractor. Having a set of professionally prepared drawings is essential to ensure that the extension fulfils your needs.

Q. How much do you charge for the architectural drawings?

A. Architecture First provide a detailed fee quotation based upon your requirements. In many cases this can be supplied once we have received the details of your requirements by email or the enquiry form. If the project is more complexed, we will contact you to arrange a site visit.

Q. What is included in your fee?

A. We have standard packages for extensions and loft conversions that just require Building Regulation Approval and those that also require Planning Permission.

Q. Will I need planning permission?

A. Permitted Development Rights will often allow houseowners to improve and extend their homes without the need for planning permission. This includes both single and double storey rear and side extensions if they are designed to meet the requirements of Permitted Development Rights for householders given in the Ministry of Housing, Communities & Local Government technical guidance September 2019. However, sometimes complying with these can restrict the design options. Extensions and alterations that do not meet the requirements will need planning permission. All extensions will need building regulation approval. Architecture First design extensions to comply with permitted development rights and extensions that need planning permission. When planning permission is required, we will complete the planning application including completion of the application form, supplying architectural floorplans elevations and sections, location plans and site plans.

Q. How can I reduce the cost of the extension?

A. Having a design that is functional, meets your needs and of standard construction will give you more value for money. Unconventional features and materials will raise costs whilst also in many cases make it more difficult to gain planning permission. Careful consideration needs to be given to where savings can be made. There shouldn’t be any compromise on the structure of the extension that needs to be built safely, to a high standard and for longevity. Removing walls can be expensive with new steel support being required to secure the retained structure. Wider openings cost more but clever design using smaller openings can make savings. When it comes to fitting out the interior there is scope for savings by using materials and fixtures from different manufactures and alternative ranges with this often giving the interior you desire. Be upfront with your budget and include a contingency then we will use this inform the design. Use one of our fixed price design packages to control costs at the initial stage. We can offer a design and build service so build costs can be secured within your budget.


Q. Will the new extension add value to my house?

A. If the design of the extension considers your budget and overspends are avoided on average an extension can add up to 20% to the value of your property. Consideration should also be given to the way an extension allows you to gain extra space and adapt existing spaces to your needs.

Q. What building regulations apply to an extension?

A. Building Regulations are a requirement for all extensions even those that can be built under Permitted Development. At a minimum they must comply with structural integrity, energy efficiency, fire safety, damp proofing, ventilation along with other key aspects that ensure the extension and existing house are safe. Prior to the building work starting Building Regulation Approval will have gained and during the construction a building inspector will complete inspections to certify the required standards have been met.

Q. How big should the extension be?

A. The size of the extension will be governed by aspects such as the available space, neighbouring properties, your requirements, the existing house design, and the budget. Bigger is not always better and an oversized extension can result in wasted space and money. Clever design can give you the feeling of more space whilst making use of what is already available.

Q. Will the extension make my house more thermally efficient?

A. The Building Regulations are increasingly raising standards for thermal efficiency and when you add an extension to your home the thermal envelope of the extension will help to reduce the heat loss from the existing structure.

Q. What do I need to know about the Party Wall Act?

A. Neighbours must be given notice If part of the extension is to be built on the line of junction or adjacent to it. There is also a requirement to notify the effected neighbours if the new extension foundations are going to be deeper than neighbouring structures or a certain distance away. Basic assistance with compliance with the Party Wall Act is included in the extension design package and when required we work alongside a Party Wall surveyor.

Q. Can I build over the drain?

A. Within restrictions it is fine to build over or near to private and public drains. Building over a public drain requires approval from the water company prior to the building work commencing. For both drain types we include basic details in our design package and when required structural engineer’s details will be incorporated.

Q. Will my house foundations need to be improved if I build upwards?

A. There are several options for building above exiting structures once the depth/type of existing foundation is identified. Often more recent extensions or single storey sections of a house will have foundations which meet the requirements for the additional loadings. When they don’t, strengthening of the existing foundations, forming new foundations, or demolishing the existing structure and rebuilding are options to consider.

Q. Will my existing boiler need to be replaced?

A. This will be dependent on the existing boilers output and the additional demand. During the design process the approx. new requirement can be calculated and an assessment made with changes to the heating system then incorporated. If the existing boiler is old, it is worthwhile considering the replacement and to also look at options for alternatives such as air source heat pumps. Heat pumps run at lower temperatures than traditional boilers so larger radiators, underfloor heating and improved insulation to the existing elements will have to be factored in.

Q. Have I got enough outside space to build an extension?

A. Generally there is always space around a property to extend but how much of the space is used will depend on how much you want to be given to outside and inside areas. Even small extensions can make a difference to a room allowing for more storage, seating, and working areas whilst providing the opportunity to introduce more natural light. Permitted Development rights allow for up to 50% of the total land around your house to be developed within certain conditions, but if the extension is two storey it can’t be within 7 metres of a boundary. Parking provisions also need to be considered with loss of a parking space sometimes restricting an extension size.

Q. How will the extension integrate with the layout of my house?

A. Integration of the extension with the existing house layout is one of the first elements in the design process. Extensions to create ground floor open plan living areas are very popular and usually include removing a large section of the existing wall or walls, however, this does reduce the number of rooms and wall space. Often remodelling of the existing ground floor layout is undertaken alongside this type of extension to create cloakrooms, utility rooms, an office, boot rooms, a wetroom and a bathroom. Linking first floor bedroom extension to existing landings is a requirement that can’t be overlooked along with ensuring that new bedrooms have windows. Creating ensuite bedrooms is a frequent request and these are often formed by remodelling existing areas.  

Q. I live in a Conservation Area, and will this restrict my extension design?

A. When houses are in Conservation Areas Permitted Development Rights can be removed or reduced by an Article 4 Direction or planning policy. Planning Permission (Conservation Area Consent) will be required in a Conservation Area for demolition of a building which exceeds 115 cubic metres, any wall, gate, or fence which is higher than 1 metre high when abutting a highway, or less than 2 metres high elsewhere. Often a Heritage Statement and/or a Design and Access Statement will be an additional requirement for the planning application. The extension will have to be of a high-quality design that does not introduce negative impact on the character of the conservation area and be subservient. Materials must be carefully chosen to be the same as or complement the existing and many councils will reject modern materials such as UPVC for windows and doors. Using traditional materials can often introduce additional costs that need to be factored into the budget.


Q. Will large amounts of glazing cause overheating?

A. When spaces are highly glazed there is the likelihood of introducing overheating by solar gain, but this will be dependent on factors such as the orientation of the extension and shading. Several measures can be incorporated in extensions that are going to be affected by solar gain to help to regulate the internal temperature. Mitigation measures include introducing cross ventilation, solar glass, shading externally (brise soleil) and internally, materials and coatings. When controlled solar gain can be advantageous in heating internal spaces.

Q. How big can the windows and doors be?

A. The current trend is for extensions that have large amounts of glazing often with bi-fold or sliding doors to garden areas. Part L of the Building Regulations does impose restrictions on the size of glazed areas to improve the energy efficiency of the new extension. To comply areas of glazing need to be limited to a maximum of 25 percent of the extension floor area and this can easily be used up when a small extension includes large doors and rooflights. When the limits are exceeded building control can reject the extension but usually ask for justification for an over-glazed extension. Often when existing glazing that is being covered over or lost is factored in the new glazing to the extension meets the requirement. When it doesn’t there are options for increasing the thermal efficiency of elements to compensate for the higher heat loss and the efficiency of the glazing can be improved. This method can allow extensions to have up to 50% glazing but going over will usually prompt building control to request a Standard Assessment Procedure (SAP). We use an accredited company for the calculations with costs being in the region of £200 and this option can allow extensions to be 100% glazed.

Q. Will I need planning permission to add an extension?

A. Planning Permission is not required for extensions that meet the conditions and limitations of Permitted Development. In many cases you will be able to achieve the extension you want under the Permitted Development Rights. Sometimes the restrictions imposed will mean compromises to the design, size, and materials so to avoid sacrifices gaining Planning Permission will be preferred.

Q. What type of roof should I have for the new extension?

A. Factors that can inform the roof choice include the size of the extension, the design of the existing house, planning policy and personal choice. The roof pitch of single storey extensions will be dependent upon the depth of the extension, the type of tile to be used, how the roof slopes and the cill height of the existing first floor windows. Sometimes this can restrict the size of the extension and either a compromise is needed, or a flat roof is used. The lowest pitch we would recommend for a pitched roof is 15 degrees though it is possible to have a pitch down to 12.5 degrees with some types of roof tiles. We will investigate all options for the roof design and advise you on the most appropriate.

Q. Can I remove walls between my house and the new extension?

A. Removing either supporting or non-supporting walls to link the new construction to the original is in many cases part of the alteration work this coincides with the new extension. When supporting walls are removed new support must be introduced and usually new steel members are used. For wider openings or those which are carrying large loads Building Control will request structural calculations that have been supplied by a structural engineer. We work alongside structural engineers and will provide quotations for the calculations. The structural details will then be incorporated into the architectural drawings that we supply.

Q. Can I extend my Listed Building?

A. Extensions can be added to Listed Buildings, but the design needs to consider the impact upon the significance of the heritage asset and its setting. The extension must be subservient to the historic building which often means that it will have to be lower and smaller. There are no rules to the percentage increase the extension introduces with this being dependent on the size, character, and the setting of the Listed Building along with how it has been extended previously. Not all Listed Buildings are suitable to be extended though sometimes extending a Grade II Listed Building can be more straight forward than extending a Grade II* or Grade I Listed Building. Linking the new extension to the historic building needs to be carefully thought through to minimise the loss of historic fabric and features. Any structural alterations should consider historic methods and materials to avoid creating problems to the existing building. All extensions will require Planning Permission, Listed Building Consent and Building Regulation Approval. There are no Permitted Development Rights for Listed Buildings. The application for Planning Permission and Listed Building Consent will need to include at a minimum scaled architectural floor plans, elevations, a location plan, an existing and proposed site plan, a Heritage Statement or a Heritage impact Assessment. Many Local Authorities will also request a Design and Access Statement, scaled section and detail drawings.

Q. Along with supplying Architectural Drawings do you obtain all permissions and approvals?

A. Architecture First will complete applications on your behalf to obtain Planning Permission, Building Regulation Approval, and Listed Building Consent.

Q. Does your team include other professionals?

A. When the new extensions are knocked through into the existing house or when other more complicated structural elements are included structural details are often required. We work with several Structural Engineers and will obtain quotations from these on your behalf. Their details are then included in the architectural drawings we provide. Occasionally the project requires further surveys and will make the arrangements for these to be completed.

Q. What areas do you offer your services?

A. Our standard fees cover a 20-mile radius of Derby, which includes areas of Derbyshire, Nottinghamshire, Staffordshire, and Leicestershire. We do undertake work outside of this radius, but the fee is slightly higher to include additional travelling costs.

Q. Can you recommend a building contractor?

A. We work with several contractors and will provide their contact details or if you prefer, we can include a tender package in our fee. When this is requested, we will send the tender to three of our approved contractors and supply the submitted prices for your review.

Q. Can you project manage the building work for us?

A. It is possible to extend our services to include project management along with contract administration.

Q. Should we have a contract between ourselves and the building contractor?

A. We would always recommend a written contract is used for the building work. These can vary from a simple contract that is compiled and agreed by both parties or an off the shelf contract. These are written by an organisation such as the Joint Contracts Tribunal, the Federation of Master Builders or RIBA. The contractual clauses included can be more complex for projects with higher contract sums with a more basic contract such as the JCT Homeowners Contract or Minor Works being better suited to most residential extensions. Using an independent contractor administrator can help building projects run smoother and when required we can provide this service.

If your question is not listed please contact us.
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