Barber chair and split trunks: what the sources say

This page reports what the named codes, regulators and makers say. It is not training and does not teach the work. This page reports what the official source says. It is not legal advice: ask the office named here. It sets out five sources that name a trunk splitting during or before a felling. All pages were read on October 9, 2026. The courses that teach felling are in the guides on chainsaw tickets and certifications by country, and the UK awards are on the pages for medium trees and large trees. Each place's felling rules are on the page about felling rules by country, and trees that stop short of the ground are on the page about hung and lodged trees.

Credits. Wording from HSE is adapted from pages licensed under the Open Government Licence v3.0. Wording from the SafeWork NSW Tree works code of practice is adapted under the Creative Commons Attribution 4.0 licence, with sentences shortened and reworded. Wording from the WorkSafe New Zealand code is adapted with the source and copyright status acknowledged. OSHA and University of Georgia Extension are described in our own words with links.

The definition: University of Georgia Extension

The University of Georgia Extension circular Chainsaw safety: preventing common tree felling accidents, published on November 15, 2022, gives barber chair its own heading. In its words, a barber chair is a trunk that splits lengthways because the forward pull on it is strong enough to crack the wood yet too weak to bend the hinge. It names a heavy, forward-leaning tree as the usual cause, and a rope pulled too hard with mechanical advantage as another. It likens the result to a barber's chair tipped back, with the base rising and the crown dropping, and says the saw operator can be hit by the swinging trunk or crushed by it as it falls.

The circular's prevention list, reported here as its own advice and not the site's, names a five step felling plan, looking for lean and cracks that raise the chance of a barber chair, a planned escape route at 45 degrees from the direction of fall, a changed felling direction where lean is excessive, and correcting undercutting or bypassing before the back cut. It also says an open-faced notch followed by a bore cut places less force on the fibres along the trunk, and that a sharp chain shortens the time the wood is under tension.

OSHA: the undercut that stops a split

OSHA's logging standard, 29 CFR 1910.266, defines the undercut as a notch cut in a tree to guide the direction of its fall and to prevent splitting or kickback. Paragraph (h)(2)(v) says an undercut is made in each tree being felled unless the employer shows that felling that tree without one creates no hazard, and that the undercut is of a size so the tree will not split and will fall in the intended direction. Paragraph (h)(2)(vi) says the back cut leaves enough hinge wood to hold the tree to the stump during most of its fall.

HSE: over-tensioned control lines

HSE's page on working with chainsaws lists control line problems to avoid. It says an over-tensioned line may put considerable tension on the rear of the tree, which may cause the hinge to sever early, the tree to split, and injury to the chainsaw operator. It also names free-hand pulling with no anchor, where swaying the tree opens and closes the back cut, and making the back cut while a workmate puts tension on the line.

WorkSafe New Zealand: the scarf

Section 3.4.3 of the WorkSafe New Zealand arboriculture code says scarf cuts are 45 degrees or greater and large enough to guide the fall of trees and trunks and prevent splitting. The same section says the two cuts forming the scarf do not cross where they meet, that the depth does not exceed one-third of the diameter, and that the back cut does not penetrate the predetermined hinge area.

SafeWork NSW: trunks that split before the cut

The SafeWork NSW Tree works code of practice does not use the term barber chair. Its table of assessment and visual inspection factors lists decay at the base of the tree, trunk or branch forks as a reason a tree may split or collapse when climbed or under the combined weight of the worker and equipment. The same table lists species with potential for branch splitting and names willows, coral trees and poplars as ones that may fail easily.

Where each source names a split

Source	Term used	What the source links it to
University of Georgia Extension circular 1243	Barber chair	Heavy forward lean, too much rope force, cracks, cuts that bypass or undercut
HSE working with chainsaws	Tree to split	Over-tensioned control line
OSHA 1910.266	Splitting (undercut definition and rule)	Undercut size
WorkSafe NZ code 3.4.3	Splitting (scarf cuts)	Scarf angle and size
SafeWork NSW code	Tree may split	Decay at the base, trunk or forks; species