What general contractors require of plumbing and HVAC subcontractors: the mechanical trades insurance exhibit and how to prove you meet it

What a general contractor requires of a plumbing or HVAC sub

QUICK ANSWER

A plumbing or HVAC subcontract typically requires general liability of $1M per occurrence and $2M aggregate per project with $2M products-completed operations, the GC and owner as additional insureds for ongoing and completed operations on a primary and non-contributory basis, waivers of subrogation on every policy, commercial auto of $1M combined single limit, statutory workers' compensation with $1M employers' liability, an umbrella of $2M to $5M, pollution liability for refrigerants and fuel, and an installation floater.

Reviewed by Michael LaBarbera, Licensed property & casualty agent, Provident Financial Group · Reviewed Oct 11, 2026 Updated Oct 14, 2026

Typical requirements and how to check them
Requirement	What they usually ask for	How to check what you have
Commercial general liability	$1M each occurrence / $2M general aggregate per project, $2M products-completed operations, occurrence form, with no action-over, no water-intrusion or mould exclusion that applies to the work, and no exclusion for the type of system installed	Dec page limits, per-project aggregate endorsement and the exclusions page; water damage from a failed fitting is the classic completed-operations claim for these trades.
Additional insured, ongoing and completed operations	GC and owner under ISO CG 20 10 and CG 20 37 or an equivalent blanket form, primary and non-contributory	Both forms on the policy; completed-operations status is the one GCs check for mechanical trades.
Waiver of subrogation	In favour of the GC and owner on general liability, auto, workers' compensation and umbrella	Waiver endorsement on each policy.
Contractors' pollution liability	$1M per claim for refrigerant releases, fuel and gas line work, hydronic fluids, and mould arising from the work	A contractors' pollution policy or an endorsement with its own limit; the standard general liability pollution exclusion removes these claims almost entirely.
Commercial auto	$1M combined single limit on any auto, including service trucks and trailers, with hired and non-owned	Auto dec page symbol and limit, with trailers scheduled where the carrier requires it.
Workers' compensation and employers' liability	Statutory for the project state plus employers' liability of $1M / $1M / $1M, with a waiver and the plumbing or HVAC class codes on the policy	Information page: Item 3.A state, Part Two limits, waiver endorsement and classification lines.
Umbrella or excess liability	$2M to $5M following form over general liability, auto, employers' liability and, where the exhibit says so, pollution	Umbrella dec page and underlying schedule; umbrellas often do not sit over pollution, so read the exhibit for whether it must.
Installation floater	Coverage for boilers, air handlers, condensers, piping and fixtures on site, in transit and in temporary storage before they are set and accepted	An inland marine installation floater with a per-location limit matching the largest equipment delivery; builder's risk often excludes a sub's uninstalled equipment.
Completed-operations tail and licence	Completed-operations coverage maintained for the statute of repose, commonly three to ten years; a current plumbing, HVAC or mechanical licence in the project state	Annual renewal of the general liability policy with the endorsement in force; the licence certificate kept with the certificates of insurance.

Requirement

What they usually ask for

How to check what you have

Commercial general liability

$1M each occurrence / $2M general aggregate per project, $2M products-completed operations, occurrence form, with no action-over, no water-intrusion or mould exclusion that applies to the work, and no exclusion for the type of system installed

Dec page limits, per-project aggregate endorsement and the exclusions page; water damage from a failed fitting is the classic completed-operations claim for these trades.

Additional insured, ongoing and completed operations

GC and owner under ISO CG 20 10 and CG 20 37 or an equivalent blanket form, primary and non-contributory

Both forms on the policy; completed-operations status is the one GCs check for mechanical trades.

Waiver of subrogation

In favour of the GC and owner on general liability, auto, workers' compensation and umbrella

Waiver endorsement on each policy.

Contractors' pollution liability

$1M per claim for refrigerant releases, fuel and gas line work, hydronic fluids, and mould arising from the work

A contractors' pollution policy or an endorsement with its own limit; the standard general liability pollution exclusion removes these claims almost entirely.

Commercial auto

$1M combined single limit on any auto, including service trucks and trailers, with hired and non-owned

Auto dec page symbol and limit, with trailers scheduled where the carrier requires it.

Workers' compensation and employers' liability

Statutory for the project state plus employers' liability of $1M / $1M / $1M, with a waiver and the plumbing or HVAC class codes on the policy

Information page: Item 3.A state, Part Two limits, waiver endorsement and classification lines.

Umbrella or excess liability

$2M to $5M following form over general liability, auto, employers' liability and, where the exhibit says so, pollution

Umbrella dec page and underlying schedule; umbrellas often do not sit over pollution, so read the exhibit for whether it must.

Installation floater

Coverage for boilers, air handlers, condensers, piping and fixtures on site, in transit and in temporary storage before they are set and accepted

An inland marine installation floater with a per-location limit matching the largest equipment delivery; builder's risk often excludes a sub's uninstalled equipment.

Completed-operations tail and licence

Completed-operations coverage maintained for the statute of repose, commonly three to ten years; a current plumbing, HVAC or mechanical licence in the project state

Annual renewal of the general liability policy with the endorsement in force; the licence certificate kept with the certificates of insurance.

What the GC is protecting

Plumbing and HVAC are the trades whose failures show up as water damage, mould, gas and refrigerant releases, often after completion. The exhibit answers each: completed-operations additional insured status, no water-intrusion or action-over exclusion, contractors' pollution liability, a tail for years after the job, and an umbrella above the primary layer.

The lines a mechanical subcontract names

General liability is judged on its exclusions and completed-operations aggregate. The two additional insured forms cover ongoing and completed work. Pollution liability answers for refrigerants, fuel and mould. Waivers appear on every policy. Auto covers trucks and trailers. Workers' compensation must show the trade class in the project state. The umbrella follows form, sometimes over pollution. The installation floater covers equipment before it is set, and the licence is a condition.

How to check your policies against the exhibit

Read the general liability exclusions against the scope, then match limits and the per-project aggregate. Confirm both additional insured forms and primary wording by number. Confirm pollution coverage and its limit. Check the waiver on each policy. Match auto, workers' compensation and umbrella, including whether the umbrella must sit over pollution. Confirm the installation floater limit and note the tail length.

Keep the certificate current

GCs track mechanical subs' certificates for the full tail. A live certificate link stays current as policies renew and shows the completed-operations and pollution lines, with the official PDF attached, so the tracker and the GC's project manager see the same status.

Questions people actually ask

A fitting we installed failed two years after the job and flooded three floors. Which policy responds?

The general liability policy in force when the claim is made, from its products-completed operations aggregate, provided the completed-operations additional insured endorsement protects the GC and no water-intrusion exclusion applies. That is why the exhibit insists on all three.

Why do HVAC subs need pollution liability?

Refrigerant releases, fuel oil and gas line work and mould arising from a condensate problem are all pollution claims under a standard general liability form, which excludes them. A contractors' pollution policy is the usual answer and GCs require it on mechanical scopes.

Our packaged units sit on the site for a week before the crane. Who covers them?

Your installation floater, unless the builder's risk policy expressly covers a subcontractor's uninstalled equipment, which it usually does not. Match the floater limit to the largest delivery you stage.

Does the umbrella have to follow the pollution policy?

Only if the exhibit says so; most umbrellas exclude pollution. Where the GC requires excess over pollution, the pollution carrier can usually write a higher limit instead.