An example of some of the drawings required to gain planning permission.

After Marble has surveyed the site and took down all the measurements, the information is combined with the design brief which will have been constructed after discussions with the customer.

The customer is then given preliminary drawings and plans. Unlike other companies, with Marble Construction this process can be repeated up to three times without additional charge if modifications to the plans need further tailoring to the customer’s needs.

It is vital that the plans are exactly what the customer wants as revisions to the plans during the construction process are likely to be more expensive and may even require additional planning permission applications.


Design Factors

The Customer should consider these factors when communicating their needs with the architect:


The single story room on the right is an example of a hipped roof


Flat roofs are the most common choice for single story extensions because they are cheap and quick. However they rarely look attractive, are prone to leaking and require more upkeep and repair than a pitched roof. Also remember that it is important that the extension fits in with the existing style of the house for planning permission reasons.

For double story extensions a pitched roof is usually the more viable option, but this still leaves a lot of different options such as whether all sides will slope downwards (hipped) or a triangular shaped roof (gable). Another decision is what covering to use with options as varied as slate, thatched, standard tiles, Aluminium or even glass.


Natural Light and Ventilation

Unless using an extension as a photo developing suite, windows are an important consideration. To meet building regulations, the extension will also need to be ventilated therefore doubling the importance of getting this right.

Marble Construction has a massive variety of windows and doors to choose from. Important considerations when choosing windows include:

This window has been chosen and fitted in a way suiting to the existing building style
  • Will the direction of the window impede a neighbor’s privacy?
  • Will the window only allow light in at certain times of the day due to it’s direction?
  • Will the height of the windows be un-practical? i.e will it be in the way of kitchen or bathroom units?
  • Are the window tops aligned? (if they are not it will look jarring).
  • Are sky lights or light tubes (reflective channeling of light from the roof) more practical?
  • Are the windows in keeping with the existing property?


Most extensions require the relocation and modification of downpipes and gutter systems either because it is in the way of the build or the new extension would over work the existing system. Downpipes obviously need to be away from windows, doors and boiler flues.



Any existing wall shared by the new extension and a neighbor’s property is subject to the party wall act 1996. any excavations within three metres of an adjoining property are also subject to this. Luckily all that is need to resolve this is the permission of the neighbor. If this is not possible, it might be worth considering offsetting the extension by 3 metres from the neighbor’s walls.


Creating Designs and Drawings

Mistakes in the design stage can be very costly, coupled with the fact that many people may struggle with third angle orthographic projections to scale, it is advisable to allow Marble’s highly skilled architects generate the plans. However any sketches the customer gives in may help to give the designer a better idea of what the customer wants.

Important things to look for in designs include:

  • Correct use of scale.
  • All necessary measurements.
  • Clear annotations and detail on the design.
  • A range of drawings showing different scales, cross sections,different elevations, floor plans and 3d simulations to help explain and visualize the project to planning permission.
  • Lots of detail, a separate specification as well as on the designs is usually necessary to satisfy planning permission.

Most extension guide books will stress the importance of choosing the right designer. Most of Marble Construction’s contracts come from recommendations  from very satisfied customers and for a construction company there is no bigger compliment than this. Coupled with the fact our designer has over 1,000 domestic projects under his belt and has a  BSc (Hons) in civil structural engineering, there is nobody more qualified to design than Marble.


Submitting Drawings for planning permission

these are the following drawings needed for submission

  • Existing front side and rear elevations of property (1:50/1:100 scales)
  • Elevations of how the property will be after construction (1:50/1:100 scales)
  • Existing floor plans for each story with each room’s purpose detailed (1:50 scale)
  • Floor plans of how each story will be after construction with each room’s new purpose (1:50 scale)
  • Location plan of local area with the construction site outlined in red (1:1250 scale)
  • Site Plan of the construction area with a smaller scale than the location plan (1:500/1:200 scale)
  • 3D sketch or graphic design of how the new extension will look (not necessary but useful for wooing planning permission)
  • Section Plan drawing with vertical cross sections of the new extension (1:20/1:50 scale)
  • Elevation and plan drawings along with a specification and details
  • Structural calculations




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