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Extension Plans - Extension Over A Sewer

Updated: Sep 15, 2022 recently gained approval for a single Storey extension for our client Mr Owen based in Staffordshire.

Extension Planning Drawings
Extension Planning Drawings

The first step in all planning applications is to understand what our client needs. In this particular project our client was looking at constructing a single storey flat roof extension to the rear of his property. The property was extended previously but like many families now, they are looking to extend their home to create a larger kitchen dining area.

One issue with this project was that there was a sewer that runs beneath the proposed extension. We have come across many horror stories of when people have gone through the process with Architects to create their planning drawings for extensions and then when it comes to the build they find out that there is a sewer running underneath their property and the build is abruptly stopped. Sometimes people only find this out when the builders come in to prepare the foundations.

The first step when potential clients reach our website is to obtain your quotation. We have fixed costs from the start for all planning drawings.

Step 1 - Send us the information for your Extension Plans

There are many ways for us to obtain the information we need to create extension planning drawings. In this case our client put together some hand drawings with measurements using our survey sheet which we provided.

This means that we did not need to come to the property to measure which reduces costs. It is really easy to measure your own property if you are able to. We can assist you with any questions you may have. If you are in the position where you are unable to measure your property then we do have a service where we will come to site to do this for you. You can contact us anytime for this.

Extension Planning Drawings
Extension Planning Drawings

It was very important that our client told us that there was a manhole within his property boundary. This is why we always ask all of our clients to disclose this. We openly ask for this so that we cover all aspects in planning drawings for extensions.

After discussing his requirements for the extension planning application. We then advised our client on what we would need. Some examples of what was provided to us are shown here.

As you can see from these drawings, they show a lot of detail. The drawings clearly shows all the measurements, door openings and window locations. As you can see in the top left of the drawing, the manhole itself has been included. The proposed location of the extension has also been put on the drawing. The external elevations of the building also need to be included on planning drawings for extensions. This is a specific requirement by all councils. This is for them to review the external modifications to the building. In some proposals this can be strictly scrutinised, especially for properties that fall withing a conservation area or are a Listed Building. In this case it was relatively simple as the client was using materials that were already incorporated into the main building and the previous extension which meant that the change to the building was minimal.

Extension Planning Drawings
Extension Planning Drawings

Step 2 - Creation of you Extension plans

Once all the information was provided we reviewed all the information to ensure that we had everything we need. This includes the measurements that were discussed in Step 1 along with photographs of the property.

We then worked away in the background creating all the planning drawings required for an extension application. This includes;

- Location plan.

- Block plan.

- Existing and Proposed Ground and First Floor.

- Existing and Proposed External Elevations.

We have created another blog which goes into planning drawings in more detail. This includes what is actually included on a planning drawing as well as the scales required. We will come back to the creation of these planning application drawings later in this blog

Step 3 - Build Over Agreement

It was at this point that we must take into account the sewer that runs beneath the extension. This must be incorporated into the design an onto the extension planning drawings. the sewer belonged to Severn Trent Water. When the water board owns pipework beneath your property, you are required to obtain permission from them to build near or on top of them. failure to do so can cause SERIOUS financial and structural issues.

The easiest option to take is to submit a build over agreement application. This is an application whereby you tell your water company your proposal and they will look at it and decide if you can build over the sewer without causing damage or if they would ask you to relocate the pipework. This build over agreement can then be supplied to building control and to your builder to ensure that all steps have been followed. we can help take care of this build over agreement for you. Usually at no extra cost as we are creating the drawings for you anyway. Extension planning drawings can be included with your build over agreement application. The cost for the build over agreement in this case was around £150. Such a small price to pay to ensure you are compliant.

We advised our client and it is important to know if you are reading this blog that you must supply a drainage survey as well as extension planning drawings for a build over agreement when it comes to building an extension over existing sewer. Drainage surveys can range from £150-300 depending on the size, location etc. The drainage company will then provide information regarding to the pipe work itself such as diameter depth and any turns or junctions. we have included a sample from the drainage survey to give you an idea of what you will receive.

This allowed us to put the exact measurements onto the drawings itself. If you have any questions about these types of applications you can contact us anytime

Step 4 - Receive your Extension Plans

Once the build over agreement was set up and submitted. it was time to finalise the extension planning drawings. All of the drawings were created in accordance with UK government planning regulations in terms of sheet size, scale and level of detail. All have of these drawings were provided at a Low Fixed Cost from the Start! You can get an instant quotation from us anytime.

Extension Planning Drawings
Extension Planning Drawings

Step 5 - Submit your Extension Plans to the council.

When the drawings have been approved by our client, it is time to set up the planning application. As with all of our quotes we can set up and submit the planning application on your behalf. We can then liaise with the council with any issues (if any) that you may have. it is important to remember that all modifications are included in your original quotation. Unlike many other Technicians and Architects, We will never charge anymore than our initial quote.

For this extension planning application the council requested the completion of the community infrastructure levy form. The UK government states this as a charge which can be levied by local authorities on new developments in their area however some developments as in this case, may be eligible for relief or exemption from the levy this includes residential extensions. this is a form that is relatively common but it is nothing to worry about.

Once all the information is provided the council will validate the application. we have more information on this on one of our other blogs.

Extension Plans Online

This is just one in a long list of extension planning drawings that we create here at We support our clients from initial drawings stage all the way to approval at a Low Fixed Costs from the Start!

You can view more information about extension planning drawings here. you can also find more information about planning drawings on our website.

We are preparing another block which will include the building regulation application when it came to this extension.

We pride ourselves on creating low cost planning drawings for extensions Quick, Easy and Completely Online. if you have any questions about your project please contact us or obtain a fixed quote here

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