6 minute read -
Cutting Tree Roots: The Right Saw and a Safe Approach
The easiest way of cutting tree roots that are fairly thin is with a pruning saw or a cordless reciprocating saw fitted with a coarse wood blade. For thick roots a chainsaw works, but only once you've dug the root out properly, because sand and stones will blunt the chain in seconds.
Never cut too close to the trunk of a living tree. That can weaken the tree or make it unstable.
What will you learn in this article?
- Why would you cut tree roots?
- Which saw should you use for tree roots?
- How close to the trunk can you cut roots?
- Step by step: cutting tree roots
- Can you cut roots from a neighbour's tree?
- How do you remove a stump and roots without a stump grinder?
- Working safely with a saw in the ground
- Frequently asked questions about cutting tree roots
- In short: cutting tree roots
Why would you cut tree roots?
Roots go looking for water and space. As a result they grow under paving, along foundations, into drains or across the boundary. The most common reasons to cut roots are:
- Relaying paving slabs or block paving that has been pushed up
- Making room for a fence, shed, pond or pipe
- Removing a tree stump after the tree has been felled
- Roots from a neighbour's tree causing problems in your garden
With a living tree you want to remove as few roots as possible. With the stump of a felled tree it doesn't matter, and you can cut freely.
Which saw should you use for tree roots?
| Root | Suitable saw | Watch out for |
|---|---|---|
| Up to about 3 cm | Secateurs or loppers | Quick and clean, no power needed |
| About 3 to 10 cm | Pruning saw or cordless reciprocating saw | Use a coarse wood blade, preferably bi-metal or one designed for wood with nails and dirt |
| Thicker than 10 cm | Chainsaw | Dig the root out completely and hose the cutting line clean first |
Cordless reciprocating saw
For most roots a reciprocating saw is the handiest option. It fits into a narrow hole, it can take a knock and you can swap a blunt blade in seconds. With a reciprocating saw from the Maxxpack 18V range you don't need a cable or fuel in the garden. Take a few spare blades with you: soil in the root wears these blades down faster too.
Chainsaw
A chainsaw cuts thick roots fastest, but it doesn't cope well with soil. Touch the tip into the ground once and the chain is blunt. Dig the root out generously, brush or hose the cutting line clean and never cut with the tip of the guide bar, as that can cause kickback. Only use a chainsaw if you have experience with one and are wearing the right protective clothing.
Hand saw and axe
A coarse pruning saw or a root saw with large teeth works well for exposed roots. An axe can be used on thick roots of a stump, but not near stones, pipes or foundations.
How close to the trunk can you cut roots?
With a living tree, the further from the trunk the better. A rule of thumb used by tree surgeons is to keep roughly 15 to 30 cm away from the trunk for every 2.5 cm of trunk diameter. For a trunk 30 cm across, that works out at 1.8 to 3.6 metres.
Cut any closer and the tree takes up less water and may start to lean or blow over in a storm. Removing more than a quarter of the root system is too much for most trees. If you're unsure, or it's a large tree close to your house, call in a qualified tree surgeon.
Step by step: cutting tree roots
Check for cables and pipes
Find out where underground cables and pipes run before you dig. Ask your utility companies for plans or use a cable detector, especially if you're digging with machinery.
Dig the root out
Dig around the root until you have plenty of room to saw. Remove any stones.
Clean the cutting line
Clean the area where you'll cut with a brush or garden hose.
Cut on the tree side first
Make the first cut on the side nearest the tree for a neat, clean wound. Then cut the section you're removing free with a second cut.
Pull out the cut section
Pull the cut piece out. If the root is still stuck, cut a little further along.
Backfill the hole
Fill the hole with soil and, if you like, add root barrier membrane to slow new root growth towards paving or foundations.
Can you cut roots from a neighbour's tree?
In the UK you are generally allowed to cut back roots that grow over the boundary into your garden, up to the boundary line. Talk to your neighbours first, though. If cutting the roots kills the tree or makes it unsafe, you could be held liable for the damage. Check with your local council before cutting near a tree with a Tree Preservation Order or in a conservation area, as extra rules apply.
How do you remove a stump and roots without a stump grinder?
After felling, you can leave the stump to rot down. Saw or drill deep criss-cross cuts into it and fill them with compost or manure. Keep the stump moist and cover it. This takes a number of years but involves very little work. If you want it gone faster, dig around the stump and cut through the roots one by one, or hire a stump grinder. A grinder removes the stump to below ground level, and the thin roots then rot away on their own. Our guide to tree stump removal goes into more detail.
Working safely with a saw in the ground
- Wear work gloves, safety glasses and ear protection.
- With a chainsaw: chainsaw trousers, safety boots and a helmet with a face shield.
- Keep a stable footing and don't saw at full stretch in a deep hole.
- Remove the battery before freeing a jammed blade.
- Make sure someone is nearby when you work with a chainsaw.
Frequently asked questions about cutting tree roots
Will a tree die if you cut its roots?
Usually not, if you remove a few side roots well away from the trunk. If you cut large roots close to the trunk, or more than a quarter of the root system, the tree may weaken, dry out or blow over.
Can you cut tree roots with a jigsaw?
We don't recommend it. The blade is too short and too thin for roots and bends easily. A reciprocating saw or pruning saw works much better.
Why does my saw blade go blunt so quickly on roots?
Roots are full of sand, grit and clay, which grind down the teeth. Dig the root out properly and clean the cutting line before you start.
Do roots grow back after you cut them?
With a living tree, new roots grow from the cut. Root barrier membrane in the ground slows growth towards paving or foundations. With a felled tree the roots usually don't come back, although some species do send up new shoots.
In short: cutting tree roots
Choose your saw by the thickness of the root: secateurs or loppers for thin roots, a reciprocating saw or pruning saw for medium roots and a chainsaw for thick ones. Always dig the root out and clean it first. With a living tree, keep well away from the trunk and call in a tree surgeon for large trees.
