Build Phase


We will advise you of any access needed for plant and materials to conduct the initial groundwork’s. This enables us to work safely, store materials and remove debris and packaging. Sometimes we have to take these through your house if there is no alternative way. A skip will need to be located to the front or rear of your property to help facilitate this. This will usually be either in your driveway or on the road. We will discuss the location with you, and arrange any permits required to do this with your local authority. Your local council might charge you if Parking Bay Suspension is required. Groundwork’s and Excavation When building an Extension the ground works and excavation stage is among the most important elements we will plan and take care of. Based on your design we will advise you on the best foundations to lay down, the depth that these need to be placed at, we will ensure compliance with all building control regulations on these matters including oversight preparations. On occasion depending on the structure of your soil beneath, sometimes we have to build deeper foundation or even additional reinforcement, thouth this
can only be quoted for upon discovery.


Where concrete is concerned we most commonly lay the hardcore, sand, DPM and concrete slab finishing well below finished floor level. Once the house / extension is built, floor insulation and a screed layer of around 75mm (with UFH pipes if required) is then laid above the concrete slab. Alternativelly we can use structural plywood laid on family of joists with insulation. Tiles or floor finish of choice is then laid on the structural sub-floor if specified in a quote.


The trenches needed for your drainage will be carefully dug to the right depth and gradient to avoid huge amounts of bedding being necessary to support the pipes. We will also lay pipes at an even gradient and in straight lines avoiding bends whenever possible. Gravel will be used to a depth of a minimum of 100mm to 200mm thick for both bedding and surround material supporting and protecting the pipes at the correct fall. Inspection chambers are also provided for on-going maintenance. We will invite in the building inspections to ensure our compliance at this important stage of the build. At this stage we can also support in running in other services such as Gas and electric as requested, which will form part of an additional quote. Finally we will also
conduct a full drains test before final groundworks and drainage is complete. A comprehensive water or air pressure test will be carried out before drains are backfilled to ensure all the joints are watertight and everything works correctly.

Walls, Ceilings, Insulation

All exterior walls and ceilings will be lined with adequate insulations. All walls and ceilings are then plasterboarded and given a plaster skim coat, ready for decoration. The insulation panels retain room heat in winter, while reflecting the sun in summer to keep the space cool. They also enable creation of the 50mm air gap required by building regulations to ensure the timbers of your roof are properly ventilated. Exterior walls are then ready for either treatment or covering as per your design

Plumbing and Heating Installation

If your project includes a bath or shower room, or bedrooms with hand basins, all work required to install these will be carried out by our professionally qualified plumbers. Our Gas Safe registered heating engineers will extend your central heating installation into the new areas, and we will install high-output convector radiators in each new room. Gas Safe (which replaced CORGI in 2009) is the official register of engineers authorised to work
safely and legally on your boiler and other gas appliances.

Roof Construction

We will have our expert carpenters and roofers come to site to construct your designed style of roof, whether mono pitch, half hipped, parapet or gable end. We will also complete the look with your style of finish to the roof. This process will complete the exterior works and work to the inside and final fitting will now begin.

Electrical installation

All new electrical installation, as well as any modifications required to your existing installation, will be carried out by our NICEIC registered electricians, in line with the Institute of Electrical Engineers Wiring Regulations BS 7671. NICEIC is the leading UK regulatory body for electricians, and has been assessing their competence for over fifty years. Central ceiling lights, or recessed down-lighters, will be installed in your new extension or loft along with any extra requests you make and ask us to quote for.

Architraves, Door Handles, Flooring

Your project will be finished using quality door architraves and door furniture (handles, locks etc) to your specification. We will discuss your preferences with you. Your extension or loft will be constructed with its floor laid over a solid concrete base or structural plywood. This makes it extremely strong and enables the structure above carry very large loads, and will not be subject to vibrations.


We will help make the most of awkward spaces and additional requests that you may have along the way wherever possible. They will support you will our sister companies who may be installing Kitchens or bathrooms into your newly built extension to ensure every stage we undertake is to our standards.

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© Home Shape Ltd trading as London House Extension, Company Number: 8118027, VAT: 142 7996 78, Address: 10 Kedeston Court, Sutton, SM1 3JG, Tel: 020 8133 3610, 078 7749 7598, Email: