Answers and Analysis

No. The language of Section 1101.11.1 requires roof drains (flat roofs) or gutters (pitched roofs) for all structures. The only mention of one and two family dwellings (Section 1101.1) is in regard to allowable
points of surface discharge from these specific structures.

Section 302.0 stipulates that “iron, steel, brass and copper pipe shall be standard weight iron pipe size (I.P.S.) pipe.” Standard weight steel pipe is considered to be Schedule 40 wall thickness.
Sections 1101.3, 1102.1 and 1102.2 reference these same piping materials as being acceptable for use
within a building for rainwater drainage.
Table 14-1 (Plumbing Material Standards) references the ASTM standards for both A-53 and A-120
steel pipe. Each of these classifications offers a variety of wall thicknesses, but none are less than
Schedule 40.
All steel pipe used within a building which conveys products which are covered by the UPC (potable
water or waste water) must have a minimum wall thickness not less than Schedule 40.

No, the primary and secondary roof drains and horizontal piping may be sized at the normal rainfall amounts. Only at the point where the two connect to the common vertical stack does the mandatory double
rainfall rate go into effect.

Yes. Rainwater piping must be provided with cleanouts as required by Sections 719.0, 1101.12.1 and 1101.12.2 (2003/2006/2009/2012).

"Leaders" are defined by Section 214.0 as "exterior vertical drainage pipe for conveying storm water from roof or gutter drains.” Section 1102.2.1 list the materials approved for leaders and include among others
aluminum, copper and galvanized sheet metals, and all materials approved for above ground waste and
vent pipe. That would include the use of ABS and PVC pipe. Installation Standard IS-9 and IS-5, if adopted,
prohibits installing these materials in direct sunlight and would therefore require that if used that they be
protected from sun rays in a manner approved by the AHJ.

Section 1102.4 addresses storm water piping which commences “two feet from the exterior of a building,” and which by definition therefore becomes a storm sewer (see Section 221.0, 2003/2006/2009/2012). Piping
materials which would be suitable for a sanitary sewer installation would be equally suitable for transporting
storm water (see Table 14-1(2003/2006/2009) Table 1401.1 (2012), Drains – Storm).

What should be the size, shape, and depth of a job-fabricated sheet metal roof drain, including its flange or flashing? How are the various seams and parts of a job fabricated sheet metal roof drain properly
joined?

Approvable connections can be effected in all three conditions by fitting the drain sumps with standard threaded, ferrule, or spigot outlets during their fabrication. Conventional adapter fittings can then be utilized
in making transitions to the various rainwater piping systems.

Yes, an overflow drain is still basically a roof drain in the event a primary drain becomes plugged, and therefore, the strainer requirement of Section 1105.2 applies.
The only time an overflow drain would normally come into use would be due to a blockage of the
strainer on the primary drain. This blockage could be caused by accumulation of debris on the roof which
could enter the drainage system through an unprotected overflow, rendering the entire storm drainage
system inoperative.
The strainer requirement would be the same, whether the overflow were installed on either a vertical
or a horizontal plane.

Yes, secondary roof drains must connect in a vertical section of the downspouts for the primary roof drains and would be allowed to connect on a 45 degree angle and shall be connected below all portions of any horizontal piping below the roof. The horizontal offset in the garage ceiling would not be considered an offset below the roof. The code considers horizontal offsets below the roof to be the horizontal piping that would connect to the primary roof drains before they connect to the vertical sections of the downspouts.

The calculation for a single side wall would be 50% of the total square footage area. This would be added to the roof square footage area, or “canopy” square footage area for which the rain from the wall would collect and be drained away. Using Table 11-2 (2009), 1101.11(2012), 1101.12 (2015), use the column of rainfall rate for their area (see Appendix D), then follow down the column that is equal to or exceeds the calculated square footage area. Next, follow to the left column to determine the roof drain and vertical piping sizing. The size of the horizontal drain should be determined by Table 11-2 (2009), 1101.7 (2012), 1101.8 (2015).

The intent of Section 1102.1.1 (2009/2012), 1101.4.2 (2015) is to describe to the user/installer what materials are acceptable to use in regards to conductors, above ground inside of the building.

Section 1102.1.1 (2009/2012) reference to “standard weight” steel piping is additional language for section 1102.1 (2009/2012). Thus the reference to Table 701.1 (2012) in Section 1102.1 (2009/2012) would include the requirement to use schedule 40 or better steel piping that meets the ASTM A53 standard.

The language in the 2015 UPC was revised with better clarity,

1101.4.2 Conductors. Conductors installed aboveground in buildings shall be in accordance with the applicable standards referenced in Table 701.2 for aboveground drain, waste, and vent pipe. Conductors installed aboveground level shall be of seamless copper water tube, Type K, L, or M; Schedule 40 copper pipe or Schedule 40 copper alloy pipe; Type DWV copper drainage tube; service weight cast-iron soil pipe or hubless cast-iron soil pipe; standard weight galvanized steel pipe; stainless steel 304 or 316L [stainless steel 304 pipe and fittings shall not be installed underground and shall be kept not less than 6 inches (152 mm) aboveground]; or Schedule 40 ABS or Schedule 40 PVC plastic pipe.

No. If the Rainwater leaders and conductors can go by gravity then they must go by gravity. If a power outage were to occur during a rain storm, disabling the sump, the rainwater would quickly backup to the roof and could cause overloading of the roof system. There are unique situations that won’t allow them to go by gravity and therefor you must comply with section 1101.14. If the building is for public use than you must install a dual pump similar to the requirements as an ejector system for sanitary drainage.

3” is the minimum common size for Table 1102.5 MATERIALS FOR SUBSOIL DRAIN PIPE and FITTINGS which list the applicable standards for pipe fittings material.

1. Section 1101.4 of the 2018 Uniform Plumbing Code states, “Pipe, tube, and fittings conveying rainwater shall be of such materials and design as to perform their intended function to the satisfaction of the Authority Having Jurisdiction”. Pipe and fittings for building storm sewers are required to meet applicable standards referenced in Table 701.2, per Section 1101.4.5. Since the UPC is mute on this subject, the configuration of fittings approved for building storm sewers rests with the AHJ.
2. See answer #1.

Note: SDR 35 PVC, unless approved by the local jurisdiction, is not an acceptable material for sanitary sewers (Section 715.1) or storm sewers (Section 1101.4.5) as prescribed in Table 701.2

1. No. Section 1101.11.1 Primary Roof Drainage, of the 2012 Uniform Plumbing Code, states “roof areas of a building shall be drained with roof drains or gutters”. Scuppers are addressed in the Section 1101.11.2 as a method of secondary drainage.
2. No. The sizing of scuppers, per Section 1101.11.2.1, shall have an opening not less than 4 inches high and have a width equal to the circumference of the roof drain required for the area served.

1. Yes. Per Section 101.2 of the 2018 Uniform Plumbing Code, “the provisions of this code shall apply to erection, installation, alteration, repair, relocation, replacement, addition to, use, or maintenance of plumbing systems* within this jurisdiction”. The devices in question would be considered plumbing fixtures**, and are installed as part of the storm sewer system, which is used to convey rainwater, surface water, condensate, cooling water, or similar liquid waste to an approved point of disposal.
2. Yes. Section 301.2 (Minimum Standards) requires all “pipe, pipe fittings, traps, fixtures, material, and devices used in a plumbing system” to be tested to applicable standards and certified by an approved third party listing agency.
3. No. The staff for IAPMO’s Standards Development Department could not find a current standard that would apply to this product. They did indicate that a standard could be developed for the product.
4. Yes. The piping for storm sewers, per Section 1101.4.5, shall comply with the applicable standards referenced in Table 701.2 for building sewer pipe.
5. No. As stated in answer 2, all material connected to a plumbing system shall be tested to applicable standards and certified by an approved third party listing agency.

*Plumbing System. Includes all potable water, alternate water sources, building supply, and distribution pipes; all plumbing fixtures and traps; all drainage and vent pipes; and all building drains and building sewers, including their respective joints and connections, devices, receptors, and appurtenances within the property lines of the premises and shall include potable water piping, potable water treating or
using equipment, medical gas and medical vacuum systems, liquid and fuel gas piping, and water heaters and vents for same.
**Plumbing Fixture. An approved type installed receptacle, device or appliance that is supplied with water or that receives liquid or liquid-borne wastes and discharges such wastes into the drainage system to which it may be directly or indirectly connected. Industrial or commercial tanks, vats, and similar
processing equipment are not plumbing fixtures, but may be connected to or discharged into approved traps or plumbing fixtures where and as otherwise provided for elsewhere in this code.

1. Yes. The lowest “non-perforated” piping in a storm water drainage system, located within a building, is considered the storm water building drain. It remains a storm water building drain until it connects to the storm water building sewer which begins 2 foot outside the building. Sizing and slope of a storm water building drain is based, per Section 1106.2 of the 2012 Uniform Plumbing Code, on the requirements found in Table 1101.7.
2. Yes.

1. The 45° roof cant strip located at the junction of the roof to the parapet wall reduces the stress on the roofing membrane by providing a smoother and less acute horizontal to vertical transition.
2. Section 301.2 of the 2012 Uniform Plumbing Code permits the “use of systems, methods or devices of equivalent or superior quality, strength, fire resistance, effectiveness, durability and safety over those prescribed by this code”. This section also gives the Authority Having Jurisdiction the power to approve or disapprove the system or installation depending on the technical documentation of equivalency supplied by the manufacturer.

1. Yes. Section 1101.13 of the 2012 Uniform Plumbing Code states that “Rainwater sumps serving “public use” occupancy buildings shall be provided with dual pumps arranged to function alternately in case of overload or mechanical failure”.

2. Yes. Groundwater is water that exists beneath the Earth's surface. It originates as rainfall or snow, and then moves through the soil into the groundwater system, where it remains below grade in aquifers or makes its way back to the surface to streams, rivers or lakes. It is naturally replenished from precipitation or streams and rivers that infiltrate into the ground.
3. No. A multi-family occupancy is considered residential per Table 422.1.

The term “public use occupancy” is not defined in either the Uniform Plumbing Code or the building code. “Public use” and “private use” as defined in Chapter 2 of the 2012 UPC refers only to plumbing fixtures in a public or private setting, not to a type of building occupancy. Finding no supporting Code language in the UPC, it is the opinion of this Committee that a building having mixed-use occupancies would be considered a “public use occupancy” and would therefore have to comply with the requirements found in Section 1101.13 of the 2012 Uniform Plumbing Code.

1. No. Section 1101.11.1 Primary Roof Drainage, of the 2012 Uniform Plumbing Code, states “roof areas of a building shall be drained with roof drains or gutters”. Scuppers are addressed in the Section 1101.11.2 as a method of secondary drainage.
2. No. The sizing of scuppers, per Section 1101.11.2.1, shall have an opening not less than 4 inches high and have a width equal to the circumference of the roof drain required for the area served.

A scupper cannot be used as a primary roof drain.

Yes, the connection of the secondary drain to the primary drain stack must remain separate until the last horizontal offset of the primary roof drain located below the roof as illustrated below.

No, 3” is the minimum horizontal size according to Table 1103.2, however the system may be submitted under Section 1106.0, Engineered Storm Drainage System, 1106.1, General.

Yes, secondary roof drains shall be a minimum 2 inches above the roof surface at its assembly. Location and height of secondary drain is also important so that in the event primary drain becomes clogged or overwhelmed, ponding/puddling on roof does not exceed the roof design capacity.