## 3.6 Additions and Alterations

|topic=Section 3.6-NR-Related Topics

The Energy Standards offer prescriptive approaches and a performance approach to additions and alterations but they do not apply to repairs. Relevant definitions from §100.1(b) are provided below:

A. Addition is a change to an existing building that increases conditioned floor area and volume. See §141.0(a) and §100.1(b) for a detailed definition.

When an unconditioned building or unconditioned part of a building adds heating or cooling so that it becomes conditioned, this area is treated as an addition.

B. Alteration is a change to an existing building that is not an addition. An alteration could include a new HVAC system, lighting system, or change to the building envelope, such as a new window. See §141.0(b) and §100.1(b) Roof replacements (reroofing) and reconstructions and renewal of the roof are considered alterations and are subject to all applicable Energy Standards requirements. For alterations, the compliance procedure includes:

1. The prescriptive envelope component approach.

2. The addition alone approach.

3. The existing-plus-alteration performance approach.

4. The existing-plus-addition-plus alteration performance approach.

C. Repair is the reconstruction or renewal of any part of an existing building for maintenance. Repairs must not increase the preexisting energy consumption of the repaired component, system, or equipment; otherwise, it is considered to be an alteration. See §141.0(b) and §100.1(b).

For example, a repair could include the replacement of a pane of glass in an existing multilite window without replacing the entire window.

Additions and alterations to the building envelope must meet the prescriptive insulation requirements in §141.0 or comply with the performance compliance approach.

### 3.6.1 Mandatory Requirements

3.6.1.1 Additions

All additions must meet the applicable mandatory measures from the following Standards sections:

• §110.6 - Mandatory Requirements for Fenestration Products and Exterior Doors

• §110.7 - Mandatory Requirements for Joints and Other Openings

• §110.8 - Mandatory Requirements for Insulation and Roofing Products (Cool Roofs)

• §120.7- Mandatory Requirements for Insulation.

3.6.1.2 Alterations

All alterations must meet the mandatory requirements stated for additions, with the exception of the insulation requirement of §120.7 for opaque envelope components (roofs, ceilings, walls and floors).

A. Wall Insulation

Insulation for walls that separate conditioned space from either unconditioned space or the exterior shall comply with the mandatory requirements of §141.0(b)1B. This section provides two options for wall insulation compliance: either a minimum insulation R-value or a maximum assembly U-factor. The mandatory requirements are determined by the wall type:

• Light mass and heavy mass walls do not have mandatory requirements for minimum R-value and maximum U-factor.

• Metal buildings - A minimum of R-13 insulation between framing members or an area-weighted average U-factor no greater than 0.113 is required.

• Metal-framed walls - A minimum of R-13 insulation between framing members or an area-weighted average U-factor no greater than 0.217 is required.

• Wood-framed walls and other wall types - A minimum of R-11 insulation between framing members, or an area-weighted average U-factor no greater than 0.110 is required.

• Spandrel panels and glass curtain walls - A minimum of R-4 insulation or an area-weighted average U-factor no greater than 0.280 is required.

B. Floor Insulation

Insulation for floors that separate conditioned space from either unconditioned space or the exterior shall comply with the mandatory requirements of §141.0(b)1C. This section provides two options for compliance with the mandatory requirements: either a minimum insulation R-value or a maximum assembly U-factor. For floors, the mandatory requirements are determined by both building type and floor type.

• Raised framed floors - A minimum of R-11 insulation between framing members, or the weighted average U-factor no greater than 0.071 is required.

• Raised mass floors in high-rise residential and hotel/motel guest rooms - A minimum of R-6 insulation or an area weighted average U-factor no greater than 0.111 is required.

• Raised mass floors in all other occupancies - No minimum U-factor is required.

### 3.6.2 Prescriptive Requirements

3.6.2.1 Additions

Prescriptive compliance for the building envelope of additions is addressed in §141.0(a)1 and §140.3. §140.3(a) provides prescriptive compliance alternatives for the building envelope including tradeoffs between roofing insulation and the solar reflectance of roofing products (cool roofs) in Table 140.3-A. Tradeoffs between other envelope components are not allowed in the prescriptive method. The performance method may be used for tradeoff for both new construction and alterations.

All additions must also comply with §140.3(c), Minimum Skylight Area for large enclosed spaces in buildings with three or fewer stories.

For more details on the prescriptive requirements for additions, see Section 3.2 for envelope requirements and Section 3.3 for fenestration requirements.

Alternatively, the addition may meet compliance by using the performance compliance approach of §140.1, which compares the TDV energy (space conditioning, lighting and water heating) of the proposed building addition to a TDV energy budget that complies with prescriptive requirements.

3.6.2.2 Alterations

In general, any alteration to an existing building that involves changes to a portion of the building envelope triggers the Energy Standards. The prescriptive requirements for alterations to building envelopes are in §141.0(b)2A and B of the Energy Standards.

The altered components of the envelope shall meet the applicable mandatory requirements of §110.6 and §110.8.

A. Fenestration

When fenestration is altered that does not increase the fenestration area, it shall meet the requirements of Table 141.0-A of the Energy Standards (Table 3-20 below) based on climate zone.

When new fenestration area is added to an alteration it shall meet the requirements of; §140.3(a) and Tables 140.3-B, C or D of the Energy Standards. Compliance with §140.3(a) is not required when the fenestration is temporarily removed and then reinstalled.

In cases where small amounts of fenestration area are changed, several options exist.

• If less than 150 ft² of fenestration area is replaced throughout the entire building, then the Energy Standards require that only the U-factor requirements in Tables 140.3-B, C, or D are met. The SHGC, RSHGC, or VT requirements need not be met.

• The same requirements and exceptions apply if 50 ft² or less of fenestration (or skylight) area is added. A typical example of this may be changing a door from a solid door to a glass door.

#### Table-3-20: Altered Window Maximum U-Factor and Minimum RSHGC and VT

Climate Zone | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16
U-factor | 0.47 | 0.47 | 0.58 | 0.47 | 0.58 | 0.47 | 0.47 | 0.47 | 0.47 | 0.47 | 0.47 | 0.47 | 0.47 | 0.47 | 0.47 | 0.47
RSHGC | 0.41 | 0.31 | 0.41 | 0.31 | 0.41 | 0.31 | 0.31 | 0.31 | 0.31 | 0.31 | 0.31 | 0.31 | 0.31 | 0.31 | 0.31 | 0.31
| Fixed Window | Operable Window | Curtain Wall/ Storefront | Glazed Doors
VT | Vertical |  |  | 0.42 | 0.32 | 0.46 | 0.17
|  |  | Glass, Curb Mounted | Glass, Deck Mounted | Plastic, Curb-Mounted
Skylights |  |  | 0.49 | 0.49 | 0.64
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

Energy Standards Table 141.0-A

Example 3-17

Question:

The envelope and space conditioning system of an office building with 120,000 ft² of conditioned floor area is being altered. The building has 24,000 ft² of vertical fenestration. Which of the following scenarios does the NFRC label certificate requirement apply to?

1. Existing glazing remains in place during the alteration.

2. Existing glazing is removed, stored during the alteration period, and then reinstalled (glazing is not altered in any way).

3. Existing glazing is removed and replaced with new site-built glazing with the same dimensions and performance specifications.

4. Existing glazing on the north façade (total area 800 ft²) is removed and replaced with site-built fenestration.

Answer:

NFRC label certificate or California Energy Commission default values requirements do not apply to Scenarios 1 and 2 but do apply to Scenario 3.

1. Requirement does not apply because the glazing remains unchanged and in place.

2. Exception to §110.6(a)1 applies in this case. (This exception applies to fenestration products removed and reinstalled as part of a building alteration or addition.)

3. Use either NFRC label certificate or use Table 110.6-A default values; applies in this case as 24,000 ft² (more than the threshold value of 1,000 ft²) of new fenestration is being installed.

4. Since the site-built fenestration area is less than 1,000 ft², use either the NFRC label certificate, the applicable default U-factor or SHGC set forth in Reference Nonresidential Appendix NA6, or California Energy Commission default values.

B. Walls and Floors

All nonresidential building alterations involving exterior walls, demising walls, external floors, or soffits must either comply as a component with the requirements in Tables 140.3-B, C, or D in the Energy Standards, or by approved compliance software following the rules of the ACM Reference Manual that demonstrates that the overall TDV energy use of the altered building complies with the Energy Standards.

C. Roofs

Existing roofs being replaced, recovered, or recoated for nonresidential, high-rise residential and hotels/motels buildings shall meet the requirements of §110.8(i). When the alteration is being made to either 50 percent of the existing roof area or when more than 2,000 ft2 of the roof is being altered, the requirements of this section apply. Thus, when a small repair is made, these requirements do not apply. For example, the requirements of regarding roof insulation would not be "triggered" if the existing roof surface were overlaid instead of replaced.

These requirements do apply to roofs over conditioned, nonprocess spaces even if the building has a portion that is a process space. These roof areas can be delineated by the fire separation walls between process areas and conditioned, nonprocess areas.

The California Building Code and local amendments place limitations on the number of new roof covering layers that are allowed to overlay an existing roof covering in accordance with CBC 1510. When this limit is reached, the existing roof covering must be removed down to the roof deck or to the insulation recover boards.

When a roof is exposed to the roof deck or to the roof recover boards, and alteration complies with the prescriptive requirements for roofing products, the exposed roof area shall be insulated to the levels specified in Table 141.0-C of the Energy Standards (Table 3-21 below).

The amount of insulation required varies by climate zone and building type. The requirements are given in terms of a continuous layer of insulation (usually installed on top of the roof deck) or an overall roof U-factor based on the default tables and calculation method in Reference Appendix JA4. The U-factor method provides the most flexibility, as insulation can be added continuously on top of the roof deck, below the roof deck between roof joists, or a combination of insulation above and below the roof deck.

#### Table 3-21: Insulation Requirements for Roof Alterations

| Nonresidential | High-Rise Residential and Guest Rooms of Hotel/Motel Buildings
Climate Zone | Continuous Insulation R-Value | U-Factor | Continuous Insulation R-Value | U-Factor
1 | R-8 | 0.082 | R-14 | 0.055
2 | R-14 | 0.055 | R-14 | 0.055
3-9 | R-8 | 0.082 | R-14 | 0.055
10-16 | R-14 | 0.055 | R-14 | 0.055

Energy Standards Table 141.0-C

For reroofing, when roofs are exposed to the roof deck and meet the roofing products requirements in §141.0(b)2Bi or ii, the exposed area must be insulated to levels specified in the Energy Standards Table 141.0-C. For nonresidential buildings, this level is R-8 continuous insulation in Climate Zones 1 and 3 through 9 and R-14 continuous insulation in Climate Zones 2 and 10 through 16. Several exceptions are provided:

1. No additional insulation is required if the roof is already insulated to a minimum level of R-7.

2. When insulation is added on top of a roof, the elevation of the roof membrane is increased. As shown in Figure 3-26, when insulation is added to a roof and the curb height (or reglet or counterflashing for walls) is unchanged, the height of the base flashing above the roof membrane will be reduced. In some cases when the overhanging edge of the space-conditioning equipment is very close to the side of the curb, this may also limit how far up the curb the base flashing may be inserted. Many manufacturers and the National Roofing Contractors Association (NRCA) recommend maintaining a minimum base flashing height of 8 inches above the roofing membrane.

Thus, when adding insulation on top of a formerly uninsulated or underinsulated roof, one must consider the effects on base flashing height. It may be desirable to increase curb heights or counterflashing heights to maintain the same or higher base flashing heights above the roof membrane. In other cases, where leak risk is low, one can ask the roofing manufacturer for a variance on installation requirements for a roofing warranty; this may require additional waterproofing measures to obtain the manufacturer’s warranty. Installing insulation under the roof deck when access is feasible doesn’t change the base flashing height and, in some cases, may be the least expensive way to insulate the roof.

#### Figure 3-26: Base Flashing on Rooftop Unit Curb Detail

In some circumstances it is costly or difficult to increase the curb or counterflashing height for maintaining the base flashing at a suitable height above the roof membrane. In the following situations, added insulation is limited to the thickness that will still maintain a base flashing height of 8 inches (20 cm) above the surface of the roof membrane.

If there is any space-conditioning equipment on the roof that is not disconnected and lifted during reroofing, the condition of this “undisturbed” equipment will determine how much, if any, insulation must be added to the entire roof. That is, if the equipment that is not disconnected and lifted is situated on a curb that is 9 inches above the roof membrane, only 1 inch of insulation must be added to the roof. If the undisturbed equipment is situated on a curb that is 8 inches (20 cm) or less above the roof membrane, no additional insulation is required.

If adding the required insulation will reduce the base flashing height to less than 8 inches at penthouse or parapet walls, the insulation added may be limited to the maximum insulation thickness that will allow a height of 8 inches from the roof membrane surface to the top of the base flashing. For the above exemption to apply, the following conditions must be met:

1. The penthouse or parapet walls are finished with an exterior cladding material other than the roofing covering membrane material.

2. The penthouse or parapet walls have exterior cladding material that must be removed to install the new roof covering membrane to maintain a base flashing height of 8 inches.

3. For nonresidential buildings, the ratio of the replaced roof area to the linear dimension of affected penthouse or parapet walls shall be less than 25 square feet per linear foot for Climate Zones 2 and 10 through 16, and less than 100 square feet per linear foot for Climate Zones 1 and 3 through 9.

4. For high-rise residential buildings, hotels, or motels, the ratio of the replaced roof area to the linear dimension of affected penthouse or parapet walls shall be less than 25 square feet per linear foot for all climate zones.

5. Increasing the elevation of the roof membrane by adding insulation may also affect roof drainage. The Energy Standards allow tapered insulation to be used that has a thermal resistance less than that prescribed in Table 141.0-C at the drains and other low points, provided that the thickness of insulation is increased at the high points of the roof so that the average thermal resistance equals or exceeds the value that is specified in Table 141.0-C.

For more details on the prescriptive requirements for alterations, see Section 3.2 for the opaque envelope assembly requirements and Section 3.3.2.2 for the requirements for fenestration.

Thermal Emittance and Solar Reflectance Prescriptive Requirements

§141.0(b)2B

For nonresidential buildings, the prescriptive requirements for roofing products are based on roof slope and climate zone:

• Low-sloped roofs in Climate Zones 1 through 16 have a required minimum aged solar reflectance of 0.63 and a minimum thermal emittance of 0.75, or a minimum SRI of 75.

• Steep-sloped roofs in Climate Zones 1 through 16 have a minimum aged solar reflectance of 0.20 and a minimum thermal emittance of 0.75, or a minimum SRI of 16.

For high-rise residential buildings and hotels and motels, the prescriptive requirements for roofing products are based on roof slope and climate zone:

• Low-sloped roofs in Climate Zones 10, 11, 13, 14 and 15 have a required minimum aged solar reflectance of 0.55 and a minimum thermal emittance of 0.75, or a minimum SRI of 64.

• Steep-sloped roofs in Climate Zones 2 through 15 have a required minimum aged solar reflectance of 0.20 and a minimum thermal emittance of 0.75, or a minimum SRI of 16.

There are three exceptions to the prescriptive requirements:

Nonresidential buildings:

1. An aged solar reflectance less than 0.63 is allowed, provided that additional insulation is installed.

High-rise residential buildings and hotels and motels:

1. For roof area covered by building integrated photovoltaic panels and building integrated solar thermal panels, roofing products are not required to meet the minimum requirements for solar reflectance, thermal emittance, or SRI.

2. For roof constructions that have thermal mass over the roof membrane with a weight of at least 25 lb/ft² roofing products are not required to meet the minimum requirements for solar reflectance, thermal emittance, or SRI.

Table 141.0-B (Table 3-22 below) has been added to the Energy Standards to simplify the process of making insulation/aged solar reflectance trade-off. The table expresses the trade-off requirements in terms of overall roof U-factors, rather than in terms of continuous insulation R-value.

#### Table 3-22: Roof/Ceiling Insulation Trade-Off for Aged Solar Reflectance

Aged Solar Reflectance | Climate Zone 1, 3-9 U-factor | Climate Zone 2, 10-16 U-factor
0.62 - 0.60 | 0.075 | 0.052
0.59 - 0.55 | 0.066 | 0.048
0.54 - 0.50 | 0.060 | 0.044
0.49 - 0.45 | 0.055 | 0.041
0.44 - 0.40 | 0.051 | 0.039
0.39 - 0.35 | 0.047 | 0.037
0.34 - 0.30 | 0.044 | 0.035
0.29 - 0.25 | 0.042 | 0.034

Energy Standards Table 141.0-B

U-factors measure the thermal performance of the entire roof assembly, both above and below the roof deck. Utilizing U-factors provides flexibility. Trade-offs can be made by installing additional insulation continuously above the roof deck, between the joists below the roof deck, or a combination of both approaches.

Simplified trade-off process:

• Locate in Table 141.0-B of the Energy Standards the maximum roof/ceiling U-factor that applies to the aged solar reflectance of the roofing products to be installed

• Locate the climate zone of the building.

• Consult the U-factor tables in Reference Appendix JA4 and then determine what configurations of above and/or below-deck insulation satisfy the trade-off.

o Reference Appendix JA4 contains U-factor tables for many common roof constructions (wood-framed, metal-framed, span deck, and concrete roofs, and others).

See the examples at the end of this section for illustrations of insulation/reflectance trade-offs.

Table 141.0-B of the Energy Standards not only takes account of the amount of insulation necessary to compensate for using a noncompliant roofing product, it also accounts for the minimum insulation requirements that apply to roof alterations generally.

Example 3-18

Question:

What are the Energy Standards requirements for cool roofs when reroofing an unconditioned warehouse containing conditioned office space? The warehouse has a low-sloped roof.

Answer:

Scenario 1.

In this situation (see picture below), there is either directly or indirectly conditioned space under the roof. The cool roof requirements apply to just the portion(s) of the warehouse roof over the conditioned space(s). The rest of the roof (over unconditioned warehouse space) is not required to be a cool roof.

The walls of the conditioned space go all the way up to the underside of the warehouse.

Scenario 2

The walls of the conditioned space do not reach all the way to the warehouse roof. (See picture below.) In this case, the roof requirements do not apply because the space directly below the roof is unconditioned and communicates with the rest of the unconditioned portion of the warehouse.

Example 3-14

Question:

I have a barrel roof on nonresidential conditioned building that needs to be reroofed. Must I follow the Energy Standards roofing product requirement?

Answer:

Yes, the roof would need to meet the aged solar reflectance and thermal emittance for a steep-sloped roof. The reason is that a barrel roof, although it has both low-sloped and steep-sloped roofing areas, has a continuous gradual slope change that would allow the steep-sloped section of the roof to be seen from ground level. This was the reason to allow barrel roofs to only meet the steep-sloped requirement for the entire roof area.

Example 3-20

Question:

40 percent of the low-sloped roof on a 500 ft by 100 ft retail building in Concord, California (CZ12,) is being reroofed. The roofing is removed down to the roof deck, and there is no insulation. The building has a stucco-clad parapet roof, and the current base flashing is 9 inches above the level of the roof. Must insulation be added before reroofing?

#### Figure 3-27: Plan View of Partial Building Re-roofing Project

Answer:

Yes, §141.0(b)2B requires when either 50 percent (or more) of the roof area or 2,000 ft² (whichever is less) is reroofed down to the roof deck or recover boards, that insulation be installed if the roof has less than R-7 insulation. Though the reroofing covers only 40 percent of the roof area, the requirements still apply because the 20,000 ft² of replacement roof area is greater than the threshold area of 2,000 ft². As stated in the question, the roof does not have any insulation and, therefore, is required to add insulation.

Concord, California, is in Climate Zone 12. As per Energy Standards Table 141.0-C “Insulation Requirements for Roof Alterations,” for nonresidential buildings in Climate Zone 12, the requirement for insulation is either R-14 continuous insulation or an effective roof U-factor of 0.055 Btu/h•ft²•°F. If the ratio of replaced roof area to affected clad wall length is less than 25 ft² of roof per linear ft of wall, then the insulation thickness is allowed to be limited to the maximum thickness that will maintain a base flashing height of no less than 8 inches above the roof membrane.

The ratio of the replaced roof to the affected wall area is 20,000 ft² / 500 linear ft = 40:1. Since this ratio is greater than 25:1, the full required insulation must be installed regardless of the existing base flashing height. This may require changing the height of the base flashing, removing some of the parapet wall cladding and moving the counterflashing (or reglet) higher up on the wall. Alternatively, the installer may ask for the roofing manufacturer to provide a variance in the warrantee to accept a slightly lower base flashing height above the roof surface. The specific risk of roof leakage at a given site has to be considered carefully before reducing the base flashing height. When access to the underside of the roof deck is available, an alternative method of compliance that does not affect base flashing heights is to add insulation below the roof deck to the overall U-factor levels given in Energy Standards Table 141.0-C.

Example 3-21

Question:

If the building in the question above was located in San Francisco, would the insulation requirements be different on the building?

Answer:

Yes. San Francisco (as shown in Reference Appendix JA2 ) is in Climate Zone 3. In Energy Standards Table 141.0-C from §141.0(b)2B, the insulation requirement for roof alterations for nonresidential buildings in Climate Zone 3 is R-8 or a U-factor of 0.081.

The criteria for limiting the insulation thickness based on the existing base flashing height are different for Climate Zone 3 than for Climate Zone 12. For nonresidential buildings in Climate Zone 3, if the ratio of replaced roof area to affected clad wall length is less than 100 ft² of roof per linear foot of wall, then the insulation thickness is limited to the thickness that will maintain a base flashing height of no less than 8 inches above the roof membrane. The ratio of the replaced roof to the affected wall area is 20,000 ft² / 500 linear ft = 40:1. Since this ratio is less than 100:1, only the amount of insulation (and recover board) that will still maintain a base flashing height of 8 inches above the roofing membrane is required. Thus, one could still add 1 inch of insulation board.

Example 3-22

Question:

A nonresidential building is having 5,000 ft² of roofing replaced. During roofing replacement the roof deck will be exposed. This building has a rooftop air conditioner that is sitting on an 8-inch-high curb above the roof membrane level. The roof is uninsulated. If the rooftop air-conditioner unit is not disconnected and not lifted off the curb during reroofing, is adding insulation required?

Answer:

No, the exception to §141.0(b)2Biii, specifically exempts reroofing projects when space-conditioning equipment is not disconnected and lifted. In this case, the requirements for adding insulation are limited to the thicknesses that result in the base flashing height to be no less than 8 inches above the roofing membrane surface, Adding insulation increases the height of the membrane surface and thus for a given curb would reduce the base flashing height above the roof membrane. Since the base flashing height is already 8 inches above the roof membrane, no added insulation is required.

Example 3-23

Question:

What if the rooftop air conditioner from Example 3-22 is lifted temporarily during reroofing to remove and replace the roofing membrane? Is added insulation required?

Answer:

Yes, insulation is required.

The exception to §141.0(b)2Biii specifically applies when the space-conditioning equipment is not disconnected and lifted. Since the roof membrane level will be higher after the addition of insulation, the base flashing height will no longer be 8 inches above the roof membrane. When the rooftop unit is lifted as part of the reroofing project, the incremental cost of replacing the curb or adding a curb extension is reduced.

Thus to maintain the 8-inch base flashing height, one can replace the curb or add a curb extension before reinstalling the roof top unit. Alternatively, one can ask for a roofing manufacturer’s variance to the warranty from the typical minimum required 8 Inches base flashing height above the roof membrane to the reduced amount after the roof insulation is installed. The specific risk of roof leakage at a given site has to be considered carefully before reducing the base flashing height. An alternative method of compliance that does not affect base flashing heights is to add insulation below the roof deck to the overall U-factor levels given in Table 141.0-C of §141.0(b)2B.

Example 3-24

Question:

A nonresidential building is having 5,000 ft² of roofing replaced. During roofing replacement, the roof deck will be exposed. This building has several unit skylights that are sitting on an 8–inch-high (20 cm) curb above the roof membrane level. The roof is uninsulated. Is added insulation required?

Answer:

Yes, insulation is required. The exception to §141.0(b)2Biii specifically applies when space-conditioning equipment is not lifted. Unit skylights are not space-conditioning equipment; thus, the exception does not apply. Removing a unit skylight and increasing its curb height is substantially less effort than that for space-conditioning equipment.

Example 3-25

The rooftop unit with the 9-inch base flashing is disconnected and lifted during reroofing. However, the rooftop unit on the curb with the 14-inch (36 cm) base flashing is not lifted. In this situation, is the insulation added limited to the amount of insulation that will result in an 8-inch base flashing on the unit with the lower curb?

#### Figure 3-28: Building with Two Roof Configurations

Scenario 1:

A building has low-sloped roofs at two elevations (Figure 3-28). One roof is 18 feet above grade and has a total area of 5,000 ft²; the other roof is 15 feet above grade and has a total area of 3,000 ft². Both roofs are uninsulated and are above conditioned space. If 1,800 ft² of the 3,000 ft² roof is being reroofed and the roof deck is exposed, is that portion of the roof required to be insulated and be a “cool roof” (high reflectance and emittance)?

Answer:

Yes, the reroofed section of the roof must be insulated and have a “cool roof”. Section 141.0(b)2B requires insulation and cool roofs for low-sloped roof alterations if the alteration is greater than 2,000 ft² or greater than 50 percent of the roof area. Since 1,800 ft² is 60 percent of 3,000 ft², the cool roof and insulation requirements apply.

Scenario 2:

If the 1,800 ft² of roofing being replaced was on the 5,000 ft² uninsulated roof, would the portion of the roof replaced be required to have “cool roof” radiative properties and have insulation installed?

Answer:

No. The 1,800 ft² retrofit is 36 percent of the 5,000 ft² roof. Thus, the 1,800 ft² retrofit is less than 50 percent of the roof area and it is less than 2,000 ft²; thus, it is not required to comply with the insulation and cool roof requirements in §141.0(b)2B.

Example 3-26

A 10,000 ft² building in Climate Zone 10 with an uninsulated roof above conditioned space is having roofing removed so that the roof deck is exposed. There are two rooftop units on this section of the roof that is being altered. One rooftop unit has a curb with a 9-inch base flashing, and the other has a modern curb with a 14-inch base flashing. Consider the following three scenarios:

Scenario 1:

Answer:

No. The unit with the 9 inches base flashing was disconnected and lifted and thus it does not qualify for the exception to §141.0(b)2Biii:

“Not be disconnected and lifted as part of the roof replacement.” One could add as much as 6 inches or more of insulation before the base flashing height would be reduced below 8 inches on the unlifted rooftop unit with a 14-inch curb. The Climate Zone 10 roof insulation requirement is R-14. The thickness of rigid insulation that provides this amount of R-value is substantially thinner than 6 inches. Thus, the full R-14 insulation would be required.

Scenario 2:

The rooftop unit with the 9-inch base flashing is not disconnected and lifted during reroofing. In this situation, is the insulation that must be added limited to the amount of insulation that will result in an 8-inch base flashing on the unit with the lower curb?

Answer:

Yes. The unit with the 9-inch (23 cm) base flashing was not disconnected and lifted, and thus it qualifies for the exception to §141.0(b)2Biiia. One could add only 1 inch (2.5 cm) of insulation before the base flashing height would be reduced below 8 inches (20 cm) on the unlifted rooftop unit with a - inch (23 cm) base flashing. The insulation requirement is R-14, but the thickness of rigid insulation that provides this amount of R-value is greater than 1 inch (2.5 cm). Therefore, only 1 inch (2.5cm) of additional insulation is required because adding any more insulation would reduce the base flashing height below 8 inches (20 cm) on the unlifted rooftop unit with a 9-inch (23 cm) base flashing.

Scenario 3:

In Scenario 2 above, does this reduced amount of required insulation apply only to the area immediately surrounding the unlifted unit or to the entire roof?

Answer:

The added insulation for the entire roof would be limited to 1 inch (2.5 cm) so that the base flashing of the unlifted unit is not reduced to less than 8 inches (20 cm). However, if a building has multiple roofs, the limitation would apply only to any roof with a rooftop unit that was not disconnected and lifted and that has a low curb.

Example 3-15

Question:

In reroofing, is existing roofing that is a rock or gravel surface equivalent to a gravel roof over an existing cap sheet, and therefore qualify for the exception discussed in the previous question?

Answer:

No, the two roofs are not equivalent (rock or gravel roofs do not perform the same as gravel roofs over an existing cap sheet), and, therefore, the gravel roof over existing cap sheet may not qualify for the exception.

Example 3-16

Question:

If I am doing a reroof, would Exceptions 1 through 4 to §140.3(a)1Ai apply to reroofing and roof alterations?

Answer:

Yes, these exceptions apply to reroofing and alterations, and the roofs that meet one or more of these exceptions are exempt from the cool roof requirements.

Example 3-17

Question:

What happens if I have a low-sloped roof on most of the building but steep-sloped on another portion of the

roof? Do I have to meet two sets of rules in §141.0(b)2Bi and ii?

Answer:

Yes, the low-sloped portion of the roof must comply with the requirements for low-sloped roofs, while the steep-sloped portion of the roof must comply with the requirements for steep-sloped roofs. These requirements are climate zone-based and vary based on the density of the outer roofing layer.

Example 3-18

Question:

A low-sloped nonresidential building in Santa Rosa needs to be reroofed. It has a wood-framed rafter roof. The rafters are 2 x 4’s spaced 16 inches on center. The owner wants to install a roofing product with an aged reflectance of 0.60, which is less than the prescriptive standard of 0.63. Can I install additional insulation to make up for the shortfall in reflectance?

Answer:

Yes. There are two ways to make an insulation/reflectance trade-off when reroofing a low-sloped nonresidential building.

Scenario1:

The Simplified Performance Tradeoff Approach has been modified for the 2013 Standards. It is a software tool that allows users to make roof insulation/reflectance trade-offs through a simplified process. The user enters a limited number of inputs, such as building type, building vintage, roof insulation, and reflectance details. The software analyzes the inputs and generates for the user a range of compliant design options. The software does all the work. There is no need for the user to consult reference appendices or make manual calculations. The software tool can be accessed on the Energy Commission’s website at http://www.energy.ca.gov/title24/2013standards

Scenario 2:

Another way to make an insulation/reflectance trade-off is to use Table 141.0-B. First, look up in the table the maximum roof/ceiling insulation U-factor for the aged solar reflectance of the roofing product and the climate zone in which the building is located. In this case, the roofing product has an aged reflectance of 0.60, and Santa Rosa is in Climate Zone 2, so the appropriate U-factor is found in row 1, column 2 of the table. It is 0.052.

Next, consult Section 4.2 (Roofs and Ceilings) of Reference Appendix JA4 to find the U-factor table for the type of roof in question. Reference Appendix JA4 can be accessed on the Commission’s website at http://ww.energy.ca.gov/title24/2016standards/

The appropriate table in this case is Table 4.2.2, U-factors of Wood Framed Rafter Roofs. Locate the section of the table that pertains to 2 x 4 rafters spaced 16 inches on center. There are several U-factors in this area of the table that are equal to or less than 0.052. A combination of R-11 cavity insulation and R-8 continuous insulation, for example, has a U-factor of 0.050. Similarly, a combination of R-13 cavity insulation and R-6 continuous insulation has a U-factor of 0.052. Any U-factor that is equal to or less than 0.052 represents a combination of above- and below-deck insulation that complies with the requirements for the proposed trade-off.

Example 3-19

Question:

There several exceptions to the minimum insulation requirements for roof alterations. Can these be used to limit the insulation required to make a trade-off under Table 141.0-B?

Answer:

No. The exceptions to §141.0(b)2Biii do not apply to trade-off situations. They apply only when a compliant roofing product is being installed and no trade-off is involved.

### 3.6.3 Performance Requirements

A. Additions

The envelope and indoor lighting in the conditioned space of the addition, and any newly installed space conditioning system or water-heating system serving the addition, shall meet the applicable requirements of § 110.0 through §130.5; and either 1 or 2 below:

1. The addition alone shall comply with §141.0(a)

2. Existing plus addition plus alteration. The standard design building is the reference building against which the altered building is compared. The standard design building uses equivalent building envelope, lighting and HVAC components when those components are not altered. For components that are altered or added, the standard design uses either the prescriptive requirements for new construction or the envelope baseline specified in §141.0 of the Standards. The proposed design energy use is the combination of the unaltered components of the existing building to remain and the altered component’s energy features, plus the proposed energy features of the addition.

EXCEPTION to Additions - Performance Approach: Additions that increase the area of the roof by 2,000 square feet or less are exempt from the requirements of §110.10.

B. Alterations

The envelope and indoor lighting in the conditioned space of the alteration, shall meet the applicable requirements of §110.0 through §130.5; and either A or B below:

1. The altered envelope, space–conditioning system, lighting and water heating components, and any newly installed equipment serving the alteration, shall meet the applicable requirements of §110.0 through 110.9, §120.0 through 120.6, and §120.8 through 130.5. EXCEPTION to §141.0(b)3A Window Films. Applied window films installed as part of an alteration complies with the U-factor, RSHG and VT requirements of Table 141.0-D.

EXCEPTION to §141.0(b)3A: Window Films. Applied window films installed as part of an alteration complies with the U-factor, RSHGC and VT requirements of Table 141.0-D (Table 3-23 below).

The standard design for an altered component shall be the higher efficiency of existing conditions or the requirements stated in Table 141.0-D. For components not being altered, the standard design shall be based on the existing conditions.

2. The proposed design shall be based on the actual values of the altered components.

Notes to Alterations – Performance Approach:

1. If an existing component must be replaced with a new component, that component is considered an altered component for determining the energy budget and must meet the requirements of §141.0(b)3.

2. The standard design shall assume the same geometry and orientation as the proposed design.

#### Table 3-23: The Standard Design for an Altered Component

Altered Component | Standard Design Without Third Party Verification of Existing Conditions Shall be Based On | Standard Design With Third Party Verification of Existing Conditions Shall be Based On
Roof/Ceiling Insulation, Wall Insulation, and Floor/Soffit Insulation | The requirements of §141.0(b)2.
Fenestration The allowed glass area shall be the smaller of the a. or b. below: a. The proposed glass area: or b. The larger of: 1.The existing glass area that remains; or 2.The area allowed in §140.3(a)5A. | The U-factor and RSHGC requirements of TABLE 141.0-A. | The existing U-factor and RSHGC levels.
Window Film | The U-factor, RSHGC and VT shall be based on TABLE 140.1-A The existing fenestration in the alteration shall be based on Table 110.6-B Third Party verification not required.
Roofing Products | The requirements of §141.0(b)2B.
All Other Measures | The proposed efficiency levels.
Energy Standards Table 141.0-D

### 3.6.4 Historical Buildings

§100.0(a), Exception 1, states that qualified historic buildings, as defined in the California Historical Building Code (Title 24, Part 8 or California Building Code, Title 24, Part 2, Volume I, Chapter 34, Division II) are not covered by the Energy Standards. However, nonhistorical components of the buildings, such as new or replaced space-conditioning, plumbing, and electrical (including lighting) equipment, additions and alterations to historic buildings, and new appliances in historic buildings must comply with the Energy Standards and Appliance Efficiency Regulations, as well as other codes. Additions and alterations to historical buildings must also meet applicable requirements of the Energy Standards. For more information about energy compliance requirements for historical buildings, see Section 1.7.1, Building Types Covered.