Hiring an arborist: what the trade bodies say to look for

This page reports what the official source says. It is not legal advice: ask the office named here. The bodies below are trade and professional bodies, and each one describes its own schemes. A name on any list is not a ruling on the quality of a company, and none is named here.

What a certified arborist is, as ISA describes it

On the site run by the International Society of Arboriculture (ISA), the TreesAreGood page on hiring an arborist calls an ISA arborist certification a voluntary process, outside government, through which individuals document what they know. It says certified arborists must continue their education to keep the credential. The page lists the services an arborist can provide: pruning, tree removal, emergency tree care, planting, plant health care, cabling and bracing, and soil aeration.

Separately, the ISA false advertisements page says ISA credentials are earned by individuals, never by a company, and that an advertisement for a credential holder is required to list the person's name and ISA certification ID number. The Find an Arborist page describes a directory where the public can find and verify ISA-credentialed tree care professionals. It says listing is voluntary, so a credential holder may not appear in it.

What TCIA tells owners

The Tree Care Industry Association (TCIA) page Hiring a Tree Care Company says the credentials of someone calling themselves an arborist can vary widely. It names several things to look at when reviewing a company: years in business, professional affiliations, licences and certification. It says some cities license arborists and points owners to city hall to ask. It describes TCIA Accreditation as a voluntary program that credentials companies meeting criteria for professionalism, employee training, safety regulations, business ethics and customer satisfaction.

For a first meeting, the same page lists these items: current certificates of liability and workers' compensation insurance where it applies, references, estimates in writing, a written work order, a signed contract covering cost, dates and exactly what is to be done, and a question about ANSI standards. It also says not to pay in advance. Quotes and contracts are covered on the page about reading a tree quote.

What the Arboricultural Association tells owners in the United Kingdom

The Arboricultural Association's page Choosing your Arborist sets out a six-step process. It names five questions to put to a contractor:

whether they are insured, with public liability and, if they have employees, employers' liability, and a recommended minimum public liability cover of £5m;
whether the people working hold qualifications for the type of work, typically chainsaw and tree climbing awards from NPTC or Lantra, shown by a card or certificate;
whether they work to a recognised standard, normally British Standard 3998;
whether they belong to a professional organisation, which the page says shows commitment to professionalism but does not cover standards of work;
whether they can give details of someone who can give a reference.

The page says the Association keeps a directory of ARB Approved Contractors, businesses assessed on health and safety procedures, business practices and the quality of tree work. It says some contractors claim to be Approved Contractors when they are not, and that a business not on the online register is not an Approved Contractor. Other schemes are compared in the guide on approved contractor and credential-check schemes.

What the New Zealand Arboricultural Association tells owners

The NZ Arb page Why Hire An Arborist lists steps for selecting an arborist: check membership of NZ Arb or ISA, check ISA certification, ask for proof of insurance and phone the insurer if unsatisfied, check permits and licences, ask for references, get more than one estimate, and get it in writing. It says a reputable arborist carries personal and property damage insurance as well as professional indemnity insurance. It names topping, removing an excessive amount of live wood and using climbing spikes on trees that are not being removed as practices that violate industry standards. NZ Arb also runs a Registered Master Arborist list by region.

What a regulator asks of its own contractors

The Health and Safety Executive in Great Britain gives landowners who hire tree contractors a list of questions on its page Are you a ...?. The list covers experience and references, whether employees hold certificates of competence for chainsaw use, tree climbing, aerial rescue, chippers and mobile elevating work platforms, membership of a trade or professional body, and how the contractor manages health and safety. It says an employer who hires contractors has a legal duty to make sure they are competent.

At a glance

Body	Country	What the body lists for hirers
Arboricultural Association	United Kingdom	Insurance, qualifications, standard, membership, reference, written quote
HSE	Great Britain	Experience, certificates of competence, safety management
International Society of Arboriculture	United States and international	Individual credentials, found through its directory
New Zealand Arboricultural Association	New Zealand	Membership, certification, insurance, permits, references, written contract
Tree Care Industry Association	United States	Insurance certificates, references, written estimates, signed contract, accreditation

The guide on checking a tree company lists the public registers and licence lookups by country. The guide on licensed, certified, accredited and insured explains each of those words.

Who to call

ISA Find an Arborist: finding and verifying individuals who hold an ISA credential
Arboricultural Association, ARB Approved Contractor Directory: the register of Approved Contractors in the United Kingdom
New Zealand Arboricultural Association, find an arborist: the Registered Master Arborist list by region
Public registers and licence lookups: state, provincial and national lookups for licences, cover and safety records