When carrying out any building works, drains can be an all-too-common problem, however it’s possible to reroute and move them. The big question is how much this would cost. If you want to build on an extension to your home, you’ll have a few hurdles to overcome before being able to enjoy your new space, and one of those is the drains since they’ll be in the way of your planned extension’s foundations if you don’t relocate them.
The drains form part of the complex network of sewers, manhole covers, and pipework, so often you can’t move only a single drain – you may instead have to rebuild an entirely new drainage system somewhere else, ensuring it’s at the correct depth (possibly deep underground). You may need to obtain the local water authority’s permission too, adding still further to the costs.
The Average Cost Of Drain Relocation
There’s no single price for relocating a drain. Rather, the cost will depend on which kind of drainage system is in place, how far it needs to be relocated, the drain’s size, and the surrounding land’s features. A more complex job will, of course, cost more.
On average, you can expect the costs of moving a drain to be as follows:
The materials required – £2700
Labour costs – £1800
Relocation designs – £500
Water authority permission – £750
Overall, the average cost of moving a drain to complete your extension will be about £4500, with a more complex job costing as much as £6000. Ensure you’ll allowed about £1000 for moving manholes and refinishing too, since this job often makes a mess of your garden and returfing and relandscaping may be necessary.
Access is another consideration too, since if a mini or micro-digger is able to get onto the property it will be cheaper and easier to complete the job rather than having to dig by hand.
Consider, too, the ground over the drain. In many gardens, the space will be filled with aggregate, whereas if the ground is a driveway, concrete may be needed to surround the drain, which raises the costs.
Obtaining the local water authority’s permission for moving the drain also increases costs by around £750, although this may not always be necessary if the drain is located within the boundary of your property. All new drains have to be witnessed by a building inspector and signed off during the building regulation approval process.
In most cases, relocating a main drain will cost more than a relocation of the more minor components of the drainage system. The work has to be carefully and properly planned by a specialist, and they will charge about £500 for their services.
Moving An Outdoor Drain
If you’re relocating a drain outside, the job will be easier than digging around the foundations and lifting floors. Your construction team will already be building your extension’s foundations, so carrying out alterations to the drains simultaneously makes sense.
When you’re working out the cost of moving your outside drain, materials will make up around half of the entire cost, with 40% of the cost being for labour and 10% for waste removal. You can expect to pay around £4500 for relocating an outdoor drain, or £6000 for a more complex relocation.
Will I Need To get Local Water Authority Permission?
If you are planning to carry out building works within three metres of a lateral drain or public sewer, you are required under the UK’s building regulations to obtain the local water authority’s approval. Even when this doesn’t apply to your project you should still carry out checks with the authority before beginning work.
If you do need permission from the local water authority, bear in mind that this can take some time to obtain, especially if the job is very complex or if any complications or issues arise during the job itself.
Is It Possible To Relocate The Drain Myself?
It isn’t a good idea to move a drain yourself, since drainage systems are incredibly complicated. You should always use the services of a qualified, trained drainage specialist instead. Remember that sometimes, drainage works go wrong, too, and while that will add onto the length of time it takes to finish the job, if you’re doing the works yourself, it could scupper your entire project.
Is It Possible To Move A Drain Cover Inside My Garden?
Normally, it’s possible to move drain covers in your garden, but if this is something you want to do solely for aesthetic purposes, remember that it can be very costly. Hiding the drain cover with an ornament will be far more affordable than paying to have it moved. Drain covers have to sit on top of the drain, since they cannot be offset.
Although, in theory, it’s possible to build your extension over the drain, most architects will try to avoid this situation arising, and will minimise how many lintels have a drain crossing the foundation, so the walls’ structural integrity won’t be adversely affected.
Moving a drain is a fairly speedy job for a skilled team of groundwork professionals, taking around 1 or 2 days to complete.
How Do I Determine Where The Underground Sewers And Drains Are Located?
Determining where the underground sewers and drains are located on your property is very important when you’re planning to build an extension to your home. The first step is to work out where the manhole covers are located then lift them up with a manhole key (you can buy one of these from a builders’ merchants or DIY shop).
Once you’ve raised the cover, use drain dye which will show you the direction in which the drain is flowing, so you can then plot where the drains and manholes will need to be after you complete the extension. If the drain runs beyond your own property, you’ll need to either speak to the local authority, utility or water provider, or drain specialist who will hold the maps of the area’s public sewers.