5.3 Valves, Shutoffs, and Required Valve Locations

Full-open valves versus shutoff valves

The IPC distinguishes two valve classes, and the distinction drives the required locations.

• A full-open valve offers essentially unobstructed flow when open — a gate, ball or butterfly valve. It is used where the whole system or a major branch must be isolated without throttling normal flow.
• A shutoff valve simply stops flow — the angle stop under a lavatory is the classic example.

Where full-open valves are required — IPC 606.1

Learn this as a list of eight:

1. On the building water service pipe from the public water supply near the curb.
2. On the water distribution supply pipe at the entrance into the structure.
   • 2.1 In multiple-tenant buildings with a common water supply system serving other than one- and two-family dwellings, a main shutoff valve for each tenant.
3. On the discharge side of every water meter.
4. On the base of every water riser pipe in occupancies other than multiple-family residential occupancies two stories or less in height, and other than one- and two-family residential occupancies.
5. On the top of every water down-feed pipe in occupancies other than one- and two-family residential occupancies.
6. On the entrance to every water supply pipe to a dwelling unit, except where supplying a single fixture equipped with individual stops.
7. On the water supply pipe to a gravity or pressurized water tank.
8. On the water supply pipe to every water heater.

Item 8 dovetails with IPC 503.1, which adds that the water heater's cold water branch valve must be near the equipment, serve only that heater, not disrupt the rest of the cold water system, and have access on the same floor level.

Note what items 4 and 5 exclude. In a single-family house you do not need a full-open valve at the base of the riser; in a four-story apartment building you do.

Where shutoff valves are required — IPC 606.2

Three locations:

1. On the fixture supply to each plumbing fixture, other than bathtubs and showers in one- and two-family residential occupancies, and other than in individual sleeping units provided with unit shutoff valves in hotels, motels, boarding houses and similar occupancies.
2. On the water supply pipe to each sillcock.
3. On the water supply pipe to each appliance or mechanical equipment.

The bathtub-and-shower carve-out is the exception everyone remembers wrong. It applies only in one- and two-family residential occupancies. In a hotel, an apartment building common bathroom, or a gym, the tub and shower supplies need stops unless the sleeping unit itself has a unit shutoff.

Access and identification

• IPC 606.3: access shall be provided to all full-open valves and shutoff valves. A valve buried behind unbroken drywall fails, no matter how correct its location.
• IPC 606.4: service and hose bibb valves shall be identified. Other valves installed in locations not adjacent to the fixture or appliance served shall be identified, indicating the fixture or appliance served. This is why a mechanical room valve tag set is not optional.
• IPC 604.10.2 repeats the idea for manifolds: individual fixture shutoff valves at a manifold must be identified as to the fixture supplied.

Water pressure booster systems — IPC 606.5

IPC 604.7 triggers the requirement: wherever pressure from the street main or other source is insufficient to provide the flow pressures of Table 604.3, a booster system conforming to Section 606.5 must be installed. IPC 606.5.1 lists the three permitted approaches: an elevated water tank, a hydropneumatic pressure booster system, or a water pressure booster pump.

The Section 606.5 subsections carry several very testable numbers:

Overflow pipe sizing from Table 606.5.4, keyed to the capacity of the water supply line to the tank:

606.5.5 is the safety rule to remember. A booster pump that keeps running as suction pressure collapses creates negative pressure on the street side — precisely the backsiphonage condition Chapter 7 of this guide exists to prevent. The low-pressure cutoff is a cross-connection control device as much as a pump control.

Worked layout: a four-story mixed-use building

A four-story building has retail on the ground floor and three floors of apartments, served by a 2-inch water service and a 2-inch meter, with an upfeed riser.

Full-open valves required:

• At the curb on the service (606.1 item 1).
• At the entrance into the structure on the distribution supply pipe (item 2).
• A main shutoff for each tenant, because this is a multiple-tenant building with a common supply serving other than one- and two-family dwellings (item 2.1).
• On the discharge side of the meter (item 3).
• At the base of the riser — the building is four stories, so the "two stories or less" exclusion does not apply (item 4).
• At the entrance to each dwelling unit (item 6).
• On the supply to each water heater (item 8).

Shutoff valves required:

• At each fixture supply. The apartments are not one- and two-family occupancies, so the tubs and showers need stops too.
• At each sillcock and at each appliance, including the clothes washer boxes and the rooftop makeup air unit.

All of them must be accessible (606.3), and the mechanical room and roof valves must be tagged with what they serve (606.4).