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Applications & Permissions

Section 1 of 3

Build Over Application.

In some instances, a 'Build Over Application' may be necessary, which will typically be with Thames Water Developer Services, due to the areas in which we operate.  Thames Water's opening line on their website sums up their request....


If you’re planning to improve your home by extending it, adding a conservatory, annex or garage it’s likely there will be pipes within your land. As well as checking the local authority's Building Regulations, it's important you work with us to make sure the pipework is protected and our access isn't restricted.

A link direct to the Thames Water website relating to this is given below. This will explain the process:

Hybrid Construction can make these applications for you upon request. The fees payable to the Water Authority are not included in our fees. Typically we would charge between £195.00 and £295.00 plus VAT for our involvement and submission of the application, depending on the complexity of the application/work involved.

As a basic rule, if you’re not building within three metres of a public sewer, or within one metre of a public lateral drain, you won't need approval to continue with works.

Q. What is a public Sewer?

A. A public sewer is a pipe that carries waste water from more than one property and is operated and maintained by the local sewerage undertaker, who must maintain it in line with its statutory duty under Section 94 of the Water Industry Act 1991. In this case, Thames Water is the sewerage undertaker.

Q. What is a public lateral drain?

A. All sewer pipes (that connect to the sewerage undertaker's network and were constructed before 1 July 2011) are now public sewers except where only one property is served by the existing pipe, which is known as a drain. ... Once it crosses the property boundary this pipe becomes the responsibility of the sewerage undertaker and is known as a public lateral drain.

Useful Information

This section below is from the Citizens Advice website and explains who is responsible for maintaining drains and sewers.

Generally speaking, you’re usually responsible for drains inside the boundaries of your property, while the sewerage company is responsible for lateral drains, which are usually outside of property boundaries, and sewers. Although most sewers are now publicly owned, there are still some private or unadopted sewers. If your property is served by one of these, you may be responsible for maintaining it.

What’s the difference between a drain and a sewer?

A drain is a pipe that drains water and waste from a building and other buildings which belong with it, for example a garage.

A lateral drain is a length of pipe which carries wastewater away from your property to a sewer. It’s usually located outside your property boundary, often under a public pavement or road. A lateral drain might run under your property if you share a sewer with your neighbour.

A sewer collects water and waste from the drains of a number of buildings. Most sewers are publicly owned and are maintained by your water company. However, there are still some privately owned sewers. Some people aren’t connected to a sewer but to a cesspool, septic tank or treatment plant. If you aren’t connected to a sewer, you won’t have to pay sewerage charges to a sewerage company.

Repairs to drains

You are responsible for maintaining or repairing any drains inside the boundaries of your property - these are your private drains. You don't have to maintain or repair lateral drains that you share with your neighbour - your water company is responsible for these

You will have to pay to get work done to your private drains, but you are free to choose whichever company you want to do the work. Alternatively, you may take out insurance to pay for work on private drains.

Sometimes, you might be required to have insurance for the drain to your property. You should check with your building insurance company whether this is the case.

In some circumstances, your local authority environmental health department can order you to carry out improvement work or replace a private drain. They might do this if, for example, they think your drain is too small for your property or if it’s causing a blockage.

If necessary, a local authority can carry out the work themselves and then charge you for it.

Section 2 of 3

Party Wall Notice

In brief, a homeowner has to give two months written notice on building works which affect a party wall or boundary, or one month's notice for excavations. Planning permission is not needed to serve a Party Wall notice, and once notice has been served, the homeowner has up to a year to start work.

When do I need a party wall agreement?

  • A party wall is the shared wall, usually between a terrace or semi-detached house, and divides the homes of two separate owners

  • It also includes garden walls built over a boundary and excavations close to a neighbour’s property (within three or six meters, depending on the depth of the new foundations).

  • In the home, Party Wall Agreements are most commonly needed for building works that involve loft conversions, the insertion of damp proof courses and the digging of new foundations (as would be required in building an extension).

Obtaining permission for party wall building works

  • Before party wall building works can start, the homeowner (Building Owner) needs a written Party Wall Agreement from all affected neighbours (Adjoining Owners). Many free templates are available online and we recommend you explore these to see if you are likely to want to undertake this initial agreement yourselves. This is a simple process if your neighbours give assent.

  • Or a surveyor has to be appointed to prepare a Party Wall Award (the agreed document outlining how the works should progress). Hybrid Construction can deal with all Party Wall Notices on your behalf using our Party Wall Surveyor. 

  • To start this process, the homeowner has to serve a Party Wall Notice on their neighbours, in writing, about the planned party wall works.

All projects vary in cost, depending on the complexity of the project and the work to be undertaken. Please do get in touch for your fee quote and we will be happy to help and quote? Use the form below if you prefer?

Gaining assent

Once notice is served, a neighbour has fourteen days to respond, after which, there are three possible outcomes:

i) The neighbour gives assent in writing providing the homeowner will put right any problems

  • In such straightforward cases, there is no need to appoint a party wall surveyor or have a Party Wall Award.

  • The homeowner should take dated pictures of the party wall and ideally have agreed written notes of any cracks, with copies for both.

  • Or a surveyor could be appointed to assess and prepare a schedule of condition to minimise the risk of disputes later. This should be done shortly before the work starts.


ii) If the neighbour dissents (or if they do not  NOT reply within 14 days, in which case, they are assumed to have dissented), a Party Wall Award is required

  • In this case, both homeowner and neighbour can appoint ONE Agreed Surveyor, usually within ten days, who can act impartially for both.

  • The agreed surveyor should be independent and NOT the same surveyor the homeowner might be using for their own works. Otherwise their neighbour is unlikely to view the surveyor as neutral.

  • The Agreed Surveyor produces an “Award” which details the works proposed and a schedule of condition, including pictures, of the neighbour’s home.

  • Surveyors’ rates vary between £150.00 and £200.00 per hour and a party wall award and surveyor costs approximately £1000.00 - £2000.00 plus VAT.

  • Some architects are also able to act as surveyors.

iii) Each owner appoints their own surveyor. However, this is expensive for the homeowner who is responsible for the costs of their neighbour’s surveyor as well as their own.

It is important that all these options available to the neighbour, are explained clearly in the notice.

Maintaining good relationships with your neighbours

  • Before posting a Party Wall notice through your neighbour’s letterbox, which can appear intimidating, have a friendly chat first.

  • A shared cup of tea fosters good will and allays fears. It is an opportunity to show sketches and explain the planned works.  It is worthwhile adding that a formal notice will be sent later.

  • It is reasonable for your neighbour to ask for the contact details of your surveyor and/or building company for further information and reassurance.

Common mistakes

i)  not providing adequate notice

ii) not informing all the affected neighbours. This includes the freeholder and anyone with a leasehold longer than a year. If you live in a terraced house, neighbours on both sides may be affected depending on the works.  A homeowner living next to flats, may need to serve notice on a number of different people. Check property ownership via the Land Registry.

iii) not describing the proposed work precisely enough or not including sufficient information. Notices about excavations, for example, need to include full structural details

iv) not using the standard, or wrong form of notice. The form of notice for excavating foundations is different from a party wall.

One building project may need more than one type of notice served on each affected neighbour.


  • Two months and one day later: building works can begin, assuming the party wall award has been agreed

  • One year and one day later: building works must have started

Section 3 of 3

Building Notice or Building Regulation Applications.

Hybrid Construction will gladly make any building notice or building regulations applications on your behalf upon request, typically for a fee of £99.00 plus VAT, although this can vary depending on the work involved.

A Building Notice is an application, which allows work to be carried out without the submission of full plans. However, in certain situations plans may be requested. This type of application can only be used in domestic proposals and in the following instances;

• Extension less than 10m2

• Garage conversions less than 10m2

• Roof space conversions less than 3m2

• Structural alterations

• Provision of services or installation of fittings.


A completed application requires the following information;

• A description of the work and its location

• Intended use of the building

• Means of drainage

• The size of the building and proximity to other buildings and boundaries.


Other information which may also be required are;

• Structural calculations

• Thermal performance specification, such as Co2 emissions and thermal calculations

• Certificate for cavity wall installation

• Manufacturer’s installation details for solar panels indicating loadings and fixings.


A Building Notice submission will only be considered valid if the building work it relates to be commenced within three years of the date it was submitted.

The link below will take you to the government website relating to Building Regulations, which you may find helpful?

Choosing a Full Plans or Building Notice application

The Building Regulations can be complied with by using either the 'Full Plans' or 'Building Notice' application route, both of which are described below. This guide offers comprehensive advice on the two different routes.


Please note that generally Building Control Officers can only communicate with the applicant or the agent. If you are the owner and you are not registered as the applicant or agent on the documents, you may not be entitled to information on the application.

Full Plans applications

  • A Full Plans application needs to  provide an application form and contain plans and other information showing all construction details. This needs to be made well in advance of when work is to start on site. It's usually used for larger projects like extensions and loft conversions.

  • This route can be used for any proposed project, but developments close to or over a public sewer need to apply to Thames Water. See above for guidance about building close to a sewer.

  • One copy of the plan(s) is required, or three copies if the plans relate to a commercial development. A site location and block plan

  • Payment for the Full Plans route is required upon application. A separate charge is then made for site inspections and this is payable by invoice, after the first inspection takes place by the appointed Building Control Officer'.

  • Plans are checked for compliance with the regulations and the need for building control to negotiate with your architect to resolve any problems before approving your application may be necessary.

  • You will have written confirmation that your proposals have been approved and comply with building regulations. On occasions a 'Conditional Approval' may be issued, which will basically be an approval but more information or specific details will need addressing/producing to achieve a full approval.

  • A Completion Certificate will be issued upon satisfactory inspection of the completed works. This must be retained by the building owner and is an important document. 

Building Notice applications 

  • A Building Notice application doesn't require detailed plans to be submitted.  It's generally quicker than the full plans application and is designed to enable some types of building work to get under way quickly. However, it tends to be best suited to small projects like wall removals etc.

  • A Building Notice can only be used for dwelling-houses. Buildings which are designated under the Regulatory Reform (Fire Safety) Order 2005 or built close to, or over a public sewer cannot use this route. Some financial lenders such as banks and building societies do not favour this type of application.

  • You will need to provide an application form and a site location and sometimes a block plan.

  • Payment for the Building Notice route is required upon application. No further charges are made.

  • You will NOT have written confirmation that your proposals have been approved and comply with building regulations, unlike a full plans application. There may also be limitations in the way a Building Notice application can be used.

  • A Completion Certificate will still be issued upon satisfactory inspection of the completed works. This must be retained by the building owner and is an important document. 

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