House Extensions 

Design and Build package 
Price starts from as low as £30,000

If you are considering a rear, side or a wrap-around extension project in London or the Home Counties, our Engineers and project managers will be pleased to impart with years of experience.  


Our team will take care of everything, including planning permission, party wall, structural design and construction. Our aim is to provide you with exclusive services like no other, and you will benefit from the following services:  

Fixed price:

Following our site visit, you will receive a detailed quote, including a breakdown of all costs associated with the house extension. We are providing fixed quotes that will not change during the progress of the construction. The payment plan is in accordance with the work completed hence you so you will never pay any money upfront.  

All-Inclusive package: 

We offer including all-inclusive design and build package from obtaining planning permission, building regulation approval, statutory authority fees for planning and building control, acting as your agent fees, project management and contract administration and party wall to construction that includes fire regulation compliance, electrical certificate, plumbing, tiles, flooring, window and skylight sourcing and fitting and maintenance. Our Qualified Professionals will take care of everything including planning permission, party wall awards, structural design and construction eliminating the bottlenecks in designer/builder collaboration. 

Project management:

All our clients have their own dedicated project manager that will report weekly and monthly for the progress of works, liaise with you to order the required materials such as tiles, flooring, architrave and lighting to make sure the finished product is what you dreamed. You will be able to ask any questions and may have at any given point during design and construction. 

Client Management Dashboard:

We have a dedicated management system to keep track your project at any given point, including a program of works, deadlines, RFIs, drawings, documents and certificates. It's a simple central system to include all the information required for the team of project managers, designers and building team and for you to monitor the progress of the house extension.

Dedicated customer service and aftercare:

We offer a dedicated hotline for all your enquiries alongside the project manager. Our team will be available to answer all your questions and chase the relevant authorities and suppliers on your behalf for a headache-free process. 



We created a simple yet all-inclusive package to suit all your needs for the house extension, including planning permission, building regulation approval, structural design, party wall agreements and notices, building regulation-off, and construction. 

Our all-inclusive package 

Our all-inclusive package start from £30,000 including all costs from designing the house extension, building regulation approval, statutory authority fees for planning and building control, acting as your agent fees, project management and contract administration, construction cost including fire regulation compliance, electrical certificate, plumbing, window and skylight sourcing and fitting and maintenance. 

Request a Free Quote

To obtain a free quote fill in the form and upload floor plans if available. We will send you a detailed quote within 24 hours. 


Modern Room Decor

Extension and finished products 

We are specialised in sourcing internal fittings 


To apply for a job at Ritzi Structural Engineering Consultants, please send a cover letter together with your C.V. To:


Useful Links



New Build

Rear and Side Extension

Loft / Basement Conversion 



Project Management 

Clients Representative 


We have extensive experience of designing large-scale structures in the United Kingdom with a wide understanding of the technical and procurement issues that may arise.

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