Welcome to Ventus Design & Build!

How much does it cost to build an extension / conversion?

Industry Experts in Home Extensions, Kitchen Extensions and Loft Conversions - Customised for your Budget and Unique Style

We at Good Design and Build are industry experts in creating beautifully elegant spaces that you will love. From adding an extra room for your growing family or converting your loft to extending your kitchen, we have you covered!

With a great eye for detail and spaces built to the highest specification, we offer designs with a clear understanding of your taste as well as your budget – whether it’s managing the cost of your loft conversion, planning for the cost of a house extension or ensuring the kitchen extension costs stays within your means, our team will ensure that the project is delivered based on your needs without compromising on quality or style.

Loft Conversions

Velux Loft Conversion

Velux loft conversion includes installing Velux windows in the loft space without making any structural changes. This allows the natural light to flood in and make the space bright and fresh, perfect for a modest bedroom, reading nook or even a home office.

Estimated Cost
Starting from £35K

Dormer Loft Conversion

A Dormer loft conversion involves constructing a box-shaped extension on a slanted roof, resulting in walls that form a right angle with the floor. This clever addition not only increases the available headspace but also expands the overall floor area.

Estimated Cost
Starting from £50K

Double Mansard Loft Conversion

A double Mansard loft conversion is the most spacious and extensive option available. This type of conversion involves constructing both a front and rear Mansard, adding an entire new storey to the property.

Estimated Cost
Starting from £65K

Velux Loft Conversion

Velux loft conversion includes installing Velux windows in the loft space without making any structural changes. This allows the natural light to flood in and make the space bright and fresh, perfect for a modest bedroom, reading nook or even a home office.

Estimated Cost
Starting from £35K

Dormer Loft Conversion

A Dormer loft conversion involves constructing a box-shaped extension on a slanted roof, resulting in walls that form a right angle with the floor. This clever addition not only increases the available headspace but also expands the overall floor area.

Estimated Cost
Starting from £50K

Double Mansard Loft Conversion

A double Mansard loft conversion is the most spacious and extensive option available. This type of conversion involves constructing both a front and rear Mansard, adding an entire new storey to the property.

Estimated Cost
Starting from £65K

Bespoke Design & Planning

Over 16 Years of Experience

Free Consultation & Itemised Quotes

Full Cost Transparency & Project Management

Insurance Backed Warranty

Frequently Asked Questions

We’re committed to delighting our clients, as much with our approach as with our solutions. Our values run through every aspect of what we do – from the moment you commission us, to the moment we hand over the keys.

There are many different types of loft conversions and home extensions that we offer depending on your property and budget. In terms of loft conversions, you have the choice of selecting a standard loft conversion as well as other additions such as a roof terrace or a skylight. Furthermore, you can also expand your home through Double Mansard loft conversions, dormer loft conversions or even include a pod room.

A home extension will also allow you to expand other areas of your home such as the kitchen or garage. Please note that the overall house extension costs can depend on your specifications, but we will work with you to ensure the project stays within your budget. For instance The cost of pod extensions and utility room extensions may vary based on the size of the area, features, materials and style you opt for.

How we deliver projects

Our process is simple and divided into two distinct phases with separate contracts: Design and Build. As a client you only commit to one phase at a time depending on what stage of the process you are in. Each phase consists of three stages as described below.

1. Design

This is the kick-off point for your project. We carry out a complete architectural measured survey of the property. This allows us to create accurate CAD design drawings. This is followed by a design meeting to start discussing your ideas in more detail.

2. Planning

At this stage we finalise the designs with you and start preparing planning applications as needed. We place a high priority on ensuring that plans, designs and schedules are all based on a thorough and detailed understanding of planning guidelines. We co-ordinate with local authorities until the decision is made, and the planning approval is secured.

3. Technical

Once the planning consent is secured, we translate the design drawings into more detailed technical drawings for the purposes of building control and construction. This also includes specifications and structural calculations. At this stage, we will also submit to you our ‘no obligation’ quote for the build phase.

4. Pre-build

90% of our clients decide to stick with us after the design phase is completed. Once the build contract is signed, we kick off the process by making sure all the pre-build processes are complete. These include assistance with party wall agreements, Thames Water build over agreement, submitting building control application, and preparing method statements etc as needed. This stage ends with a pre-start meeting with your foreman before the actual build begins.

5. Build

One of our foremen will be dedicated to your project and will be on-site to manage everyday works. Our project managers will be overseeing the works to make sure they are completed to high standards, within your budget and on time. Throughout the process we will keep you updated with the progress and coordinate the works with third parties such as kitchen or flooring suppliers. We will also advise and guide you to choose any suppliers if needed.

6. Handover

As the build draws to finish, we will help to iron out any ‘snags’ to make sure everything is completed to your satisfaction. We will put together all necessary certificates such as gas, electricity and building control completion along with warranties for glazing, boiler etc. At the final completion meeting, we will hand you these documents, together with the keys to your house. Needless to say, you can contact us any time after this, if you want us to look at something.

Featured Projects

Harlesden

Sellons Ave NW10 4HJ The project included creating a master bedroom in the loft with an adjoining .

Fulham

Orbain Road SW6 7JZ This project was completed in 2023 and the approximate budget was £101,000.

Lambeth

Hetherington Road SW4 We completed this stunning project for our client Angus in Lambeth.