Extensions & Alterations

We design house extensions and alterations in all common structural materials i.e. timber, steel, masonry and concrete. 

We produce comprehensive structural engineering calculations for checking by Building Control and clear design details for use by your contractor. We pride ourselves on producing thorough and well considered designs which minimise problems and delays during construction and therefore represent excellent value for money.

On appointment we will work closely with your Architect to provide a structural engineering solution that is sympathetic to your budget and requirements as well as the existing building. If you do not currently have an Architect we can refer you to several that we work with on a regular basis for your consideration.


Our services are flexible to suit your budget and requirements and we can discuss these with you before submitting our fee proposal. However, we find that most of the structural engineering services that we provide fall into one of the following categories:

1. Preliminary Feasibility Advice

You may just need some advice on the engineering feasibility of your proposal and are not yet ready to commission detailed design work. If so we can visit you to look at the building, discuss your proposals, assess their engineering feasibility and give verbal advice. Our fee for this service is £150 plus VAT and includes up to 3 hours of our time, including time spent travelling from our offices near Ashford, Kent. 

2. Design Only

If you have already commissioned an Architect or other designer please send a copy of their drawings to us at contact@epsdesign.co.uk . We will then provide you with a detailed fixed price quotation for the structural engineering design, provided that the drawings contain sufficient information for us to be able to quantify the design work needed.

 3. Survey and Design 

If you have not commissioned an Architect or other designer, we may still be able to carry out the necessary structural work for you provided that the works are purely structural, internal only, do not involve an application for Planning Permission and do not require agreement under the Party Wall Act. This service is normally carried out in two stages:

First Stage - Survey

We visit the property to establish the existing structural arrangement e.g. roof, floor and ceiling spans, wall details etc. and discuss the proposed works with you, including any specific requirements you may have. We then produce a set of structural drawings showing the existing and preliminary proposed structural arrangement which contain sufficient information for the detailed structural design work to follow. Our fee for this first stage survey  will depend on many factors including the size and location of the property, the extent of work proposed and whether you already have any drawings. Please contact us for a quotation.

Second Stage - Design

We cannot assess the amount of engineering design work necessary until we have completed the survey. We therefore provide fixed price quotations for the design after the survey has been completed. You can then seek alternative competitive quotations from other engineers before deciding who to commission the design work from. The drawings we produce in the  survey will contain sufficient information for other engineers to be able to quote for the design work. If instructed to carry out the design, we will produce a package of information comprising structural calculations, a design statement and drawings sufficient for checking by Building Control and construction purposes. The package can also be used to obtain competitive tenders from contractors.

4. Minor Alterations

For minor alterations, such as the creation of a new opening in a wall or the widening of an existing opening, we offer a combined survey and design service. This service only applies where the arrangement of the existing structure is straightforward and can be established by visual and dimensional survey, without the need for ‘opening up’ to establish hidden details such as joist spans. Our standard fee is £415 plus VAT for properties in Kent and East Sussex and includes the survey and structural engineering design of a single beam and its supports. However, if on arrival we see that the proposed structural alteration is more complicated than described to us, we would discuss this with you and perhaps change to the two stage Survey and Design service described above. 



We specialise in engineering design and a range of project management, surveying and detailing services. We have knowledge of many other areas of construction but are not experts in them. If you need advice in any of the following areas, you will need to seek advice from an appropriate professional. Please refer to us if you need assistance as we may have contacts we can refer you to.

· architecture and all non-structural aspects of the Building Regulations

· geotechnical engineering and complex ground investigations

· the Party Wall Act

· general building surveys for house sale or purchase

· asbestos

· cost estimating


For queries or to appoint us please contact us
by phone: 01233 224986
or by email: contact@epsdesign.co.uk