Permitted developmentand trees

Building and tree work are separate questions

Permitted development is about buildings: whether an extension, loft or garden room needs a planning application. Cutting down or pruning a tree isn't development at all, so permitted development has nothing to say about it. Trees have their own protections, and they apply whether or not your building work needs permission.

That catches people out. A full planning permission can authorise felling or pruning a protected tree where it's needed to carry out the approved work. Permitted development rights don't. Building under permitted development next to a protected tree means getting consent for the tree work separately.

Which trees are protected

• —A tree with a Tree Preservation Order (TPO): you need the council's consent before cutting it down, pruning it, or doing anything that damages it, roots included.
• —Any tree in a conservation area with a trunk over 7.5 cm across, measured 1.5 m above the ground: you must give the council six weeks' written notice first.
• —A tree kept by a condition on the planning permission that built your house: the condition applies to every later owner.
• —Your neighbour's tree: you can't damage it, and roots and branches crossing the boundary still belong to it.

Roots count as tree work

Most of a tree's roots are in the top 60 cm of soil and spread well beyond its branches. Digging foundations, laying a slab for a garden room, changing ground levels or parking a skip over the roots can all harm a protected tree. If the harm is serious, it's treated the same as cutting the tree without consent.

For a protected tree, ask an arboricultural consultant to set out a root protection area before you design the footprint. Screw piles or a raised base can often take a garden room closer to a tree than strip foundations would.

Plan for six weeks' notice in a conservation area

• —Give notice to the council in writing, or through the Planning Portal. It's free.
• —Describe the tree, where it is and exactly what you want to do. A photo and a sketch plan help.
• —Don't start until the six weeks are up, unless the council tells you in writing that it won't object.
• —The council can use those six weeks to protect the tree with a TPO. If it does, you'll need consent instead.
• —Do the work within two years, or give notice again.

Trees also affect your foundations

Building regulations apply to an extension even when planning permission doesn't. On clay soil, trees nearby, including ones you've recently removed, can shrink or swell the ground under new foundations. Building control will usually expect deeper foundations close to trees, which can add noticeably to the cost. Ask your builder or engineer early.