What’s the Cost of Moving Drains for an Extension?

When building an extension, it’s often necessary to move drains.

Rerouting and moving drains is quite common.

The cost depends on the type of drain to be moved, and the type of movement that is required.

One might need to relay the drainage system in a completely new location, or simply need to move a drain to ensure it’s still in a place where it can be integrated with the existing pipework and sewers.

Below we outline what types of work is involved and the expected costs when moving drains for an extension.

Factors Affecting the Cost of Moving Drains

There are numerous factors that can affect the cost of moving drains.

If the drain is located where an extension is planned, the drain might need to be moved to avoid getting damaged or blocked during the construction works.

You need to bear in mind that there are some important restrictions as to where an extension can be built.

You will need to consider any public drains, and in most cases permission from your local authority is required before you commence such works.

In case there’s already a drain in the space where you intend to construct the extension, you will most likely need to move it outside of this area.

That’s why the cost of moving the drains varies considerably, as it depends on various factors and the type of work required.

The layout of the existing system is a prime consideration.

The cost will likely go up if the current system has a rather complex or unusual design.

Whether the foul and surface water drainage are combined or separate is another consideration.

Since heavy machinery is required for such work, the level of accessibility to the area is another critical point when it comes to the costs involved.

If there’s good access, the work should be completed much more quickly.

You may also need to consider whether restoration costs will be required once the moving process has been completed.

For instance, if an area of your garden has been dug out, you will need to factor in the landscaping works to be done afterwards.

The Cost of Moving Drains for an Extension

If you’re building an extension to gain a larger kitchen or a conservatory for example, you will probably need to move the drain.

As the extension works will take place outside the property, you’ill want to avoid having the drain right in the middle of the new space.

You’ll also have to make sure that there’ll be no problems with neighbouring properties either.

Hence the drain will need to be placed outside the area where the extension is going to be built upon.

Moving the drain calls for careful planning as well as research, and the process can be quite lengthy.

The most important point that needs to be made here is that there is definitely no one fixed price for moving a drain.

The costs will vary according to the type of drainage system one has, the distance that’s involved for the relocation, the size of the drain, as well as the features of the surrounding land.

However when it comes to moving drains for an extension, the costs can range somewhere between £4000 to £7500, depending on the complexity.

One will need to factor in materials, labour, the type of design of the relocation as well as the permission that will need to be obtained from the local authority.

The Cost of Moving a Main Drain

Moving a main drain will often be quite expensive when compared to the costs of only relocating the minor parts of the drainage system.

In such a case, it’s important to have a drainage specialist handle the planning of such a process.

Generally such a specialist will charge around £500 upwards for the drainage relocation drawings.

As mentioned earlier, permission from the local water authority will need to be acquired, especially if the drain will not be within the property’s boundary.

The Cost of Moving an External Drain

In cases where a drain is going to be moved outside, the process can be a bit simpler, since excavation is generally simpler with no foundations or existing structures to be concerned with.

The costs in this case will generally be around £4500 upwards, with half the cost covering materials required, 40% for man hours, and the other 10% for waste removal.

In more complex jobs, you might need to pay a bit more, often around £6000 upwards to relocate an external drain.

What to Expect When Moving a Drain

The process of moving a drain can be quite lengthy and it’s quite a complex process.

It’s important to check with the relevant authority to get any plans so that you can be more informed about the drainage system present underneath your property.

You may wish to hire a drain surveyor to ensure the information is up to date.

This could cost you from £250 upwards.

Permission from the local water authority will be required in most cases before the work commences.

You would need to ensure that you’re carrying out the work according to the UK Building Regulation H4.

In some cases there could be certain restrictions on the types of work that can be done.

If your drain is connected to multiple properties, there would also be building regulations that would need to be adhered to.

In such a case, it may be best to have a building inspector called in.

The Drain Moving Process Explained

The drain moving process is quite lengthy and complex.

The surface water drainage, that is the pipes and drains which carry rainwater to the nearest body of water will need to be seen to.

Moreover, there will be the foul water drainage to consider, that is, the water which comes out from appliances and sinks in your property to make its way in the drain.

Greywater systems may also be present, and in such a case these will be connected to storage tanks.

All of these systems will need to be taken into account when planning the drain moving process.

If it’s only a matter of modifying some gutters and drainpipes, the process will not be troublesome.

But in most cases the underground drains will need to be modified, with new junctions and inspection chambers being implemented.

In these cases, it’s of paramount importance to seek expert assistance.

FAQs

How Do You Locate Underground Drains & Sewer Lines?

You can locate them by lifting the manhole covers by using a manhole key.

Then, using drain dye, you can check which way the drain flows.

Based on this you can then try to plot where the manholes and the rest of the drains are situated.

Do I Need Permission from the Local Water Authority?

Permission is often required, but there are instances when there is no need to get it.

If the planned work is going to be within 3m of a public sewer or from a lateral drain, then permission will need to be sought.

Can You Build Over a Drain?

Theoretically yes you can build an extension over a drain.

However, ideally the number of lintels where a drain crosses a foundation are kept to just one, or two at most, as the structural integrity of the walls could be at stake.

Can I Move a Drain to Build an Extension?

Yes you can move a drain to build an extension.

However, such a task is best left in the hands of a specialist contractor.

Can I Move a Drain Myself?

Generally drainage systems can be quite complex, and hence it’s not recommended to take up such a job yourself.

A trained and qualified drainage specialist will be more suited for such a process.

Specialist equipment will be needed, as well as careful planning carried out to ensure that the job is done properly to avoid any problems.

How Long Does It Take to Move a Drain?

The answer to this question is not clear cut as it depends on the level of complexity of the job, as well as any issues or complications that could arise in the process.

In some cases, local water authority permission may take several months to be granted.

So make sure to factor this in to plan well ahead.

Also, drainage works could also go wrong, and hence the timescale to finish the job will increase, as would the costs.

Conclusion

While it’s a good idea to be informed about the process and the costs involved to move a drain, it is highly recommended to contact a drainage specialist to take care of the job.

This is a rather complex process, and definitely not a DIY job.

You will probably only end up making costly mistakes if you were to try to see to it on your own.