Want to know how to stop building work damaging your drains?
Thousands of homeowners fit out their houses every year only to find that their underground drainage has been damaged. Butts extensions, loft conversions and landscaping projects can all cause serious damage to underground pipes without homeowners even realizing.
The issue is…
Very few homeowners spot the damage until it’s too late. Pipes can stay cracked, joints can be left displaced and seals can be broken for months before anything starts to go wrong.
Except, that doesn’t have to be the case.
You can identify drain damage early on if you know what you’re looking for. Spotting those warning signs after building work will allow you to get the issues fixed before they become serious (and expensive) problems.
You’ll learn:
- Why Building Work Is Bad News For Your Drains
- Tree Roots Make Drain Damage Worse
- What To Look Out For Down There
- How To Keep Your Drainage Safe In The Long-Term
Building Work Is Bad News For Your Drains
You’d be amazed at the damage building work can do to underground drains. Excavation, heavy machinery and ground vibrations can shift pipes, crack seals and even collapse old drainage that was perfectly intact before work began.
Here’s the kicker…
Your drains are usually the last thing homeowners think about when doing building work. Walls, roofs and decorations take priority whilst underground the drainage network suffers.
Four common ways building work damages drains:
- Driving heavy vehicles over underground pipes
- Excavating too close to existing drainage runs
- Settlement after foundations have been laid
- Poor reinstatement of trenches and backfill
Tree root ingress also becomes more of an issue after construction work. Pipelines that have been damaged will start to attract tree roots looking for water. Even the smallest crack will allow roots inside, multiplying the problem every single year.
That’s why post-construction CCTV drain surveys are so important after building work completes. A professional survey can spot cracks, root ingress and displaced joints before they turn into blocked drains and serious structural damage.
Tree Roots Make Drain Damage Way Worse
Tree root ingress is already one of the most common causes of drainage issues across the UK. But here’s the thing… tree roots cause far more damage after building work has gone on.
Why? Let’s find out…
Healthy drains rarely experience problems with trees. Most root ingress occurs when trees search out cracks and begin to break through pipes from the outside. Water leaking from poorly sealed joints or cracks caused by building work invites every tree root nearby to feed.
What’s worse is that stats from the Arboricultural Association reveal that over 90% of tree roots grow within the top 60cm of topsoil. That puts them right at ground level with the majority of domestic drains.
Once roots begin invading drains they will continue to grow at an alarming rate. What may begin as a tiny crack can soon lead to a drain which is blocked up completely with tree roots.
Thankfully, identifying tree roots inside drains is easy with a drain survey.
The worst culprits for tree root ingress are:
- Willow Trees
- Oak Trees
- Poplar Trees
- Sycamore Trees
Know The Warning Signs Of Damaged Drains
While drains don’t normally rupture or collapse overnight, there will be tell-tale signs that something is amiss with your drainage system. Here are the common signs to look out for which suggest your drains have been compromised:
- Sink, bath or toilet drains slowly away
- You hear gurgling noises from your plumbing
- An unpleasant smell is present around drains or manholes
- Damp walls/floors that seem to come out of nowhere
- Unusually healthy patches of grass on your lawn
Don’t ignore that last one. One of the most common, yet obvious signs that a drain is leaking underground is patches of healthy grass. As nutrients pass through broken pipes and leak into the soil, you’ll notice patches of your lawn become greener than the rest.
Another not so obvious issue that comes hand in hand with broken pipes and tree roots is subsidence.
Here’s a stat you’ll unlikely know…
Subsidence claims caused by damaged drains reached £153 million in the first half of 2025 alone. According to the ABI, more claims involved tree roots absorbing moisture from the soil than any other cause.
Missing the signs won’t just leave you with a blocked drain. Left unchecked, broken drains can lead to your property experiencing subsidence.
Keeping Your Drains Safe In The Long-Term
Completing building work on your house is fun. Checking your drains are okay after the project finishes is dull but just as important.
Here’s what you should do:
Invest In A Professional Drain Survey
While CCTV drain surveys can be carried out at any time, doing one after building work is the best move. Small cameras are fed through drains to check for cracks, blockages, tree roots and joints that have become displaced.
This is particularly important when trees are close to your property. Tree roots can start damaging drains within weeks of a pathway being created. Discovering it sooner rather than later will save you a lot of hassle.
Keep An Eye Out For Settlement
Even if your drainage was okay after work completes, they could be damaged over time due to settlement. When building work is carried out, the ground will settle as time goes on which can cause pipes to shift or joints to separate.
Monitoring your drains between 6-12 months after building work completes is a sure fire way to catch problems early.
Watch Those Trees
Don’t worry, you don’t have to start chopping down trees that get too close to your drain runs. But, you should be aware of which trees are located near your pipes.
Installing root barriers is a great way of protecting drains that are near trees. Prevention is always better than cure when it comes to tree root damage.
Keep Records Of Drain Surveys
By keeping old drain surveys, you have a better idea of what state your drains were in at the time of survey. If a problem occurs in the future and you need to make an insurance claim, having prior evidence that the drain wasn’t already damaged can only help you.
Here’s the bottom line…
Underground drainage doesn’t tend to cross people’s minds until there’s a problem. But if you’ve just had building work completed on your property, your drainage has now become at risk.
Factor in invasive tree roots and you’ve got a recipe for disaster.
So long as you know what to look for after building work completes, you can stop minor drain damage becoming a serious problem.
Keep an eye out for drain problems, get your drains surveyed and keep those trees in check.
Until then…
Your drainage system might be out of sight, but it should definitely not be out of mind.