CHAPTER 9. BUILDING ENVELOPE

PERFORMANCE OBJECTIVES

9-1. GENERAL. The building envelope (consisting of walls, roofs,

accessory construction, windows, finishes and attachments) of

residential and nondwelling buildings shall be consistent

with the MPS and provide for:

a\. Protection of interior building components and materials

from the entrance of excessive water, moisture, dust and

air;

b\. Health and safety for tenants;

c\. Strength and stability to carry and withstand anticipated

loads;

d\. Fire resistance;

e\. Prevention of corrosion, decay and infestation by the use

of materials appropriate for local climatic conditions;

f\. Anchorage to building structure as required;

g\. Reasonable durability against abuse; and

f\. Energy efficiency.

9-1 2/85

CHAPTER 9. BUILDING ENVELOPE

SECTION 1: MANDATORY STANDARDS

9-2. GENERAL.

a\. Construction and installation of materials during

rehabilitation shall be accomplished in a manner that

does not promote galvanic action. Dissimilar metals

shall not make contact without protection to prevent

deterioration. All ferrous (iron or steel) pipes shall

be protected. Architectural features, such as cornices,

railings and shutters, shall be present as designed, in

sound condition and anchored.

b\. Wood elements used on the building exterior, including

siding or trim, shall be constructed of naturally

resistant species, such as redwood or cedar, or treated

for weather and moisture resistance. For technical

requirements, see paragraph 10-6.

c\. Use of brittle or otherwise easily damaged exterior

materials shall be restricted to 7 ft. or more above

grade where large numbers of children are anticipated or

where the probability of damage due to abuse is expected.

9-3. EXTERIOR WALLS. Exterior walls shall support imposed live

and dead loads and shall be pointed as necessary, and

weatherproofed to prevent the entrance of water and moisture.

Openings and projections through exterior walls shall be

watertight and flashed where required.

a\. Vents, air conditioning sleeves and other openings shall

be close fitting and properly caulked or otherwise sealed

to prevent excessive air infiltration. Walls shall be

free of evidence of buckling, deflection, splitting or

settlement. Joint material including caulking and

sealants shall function as designed, and shall not have

shrunk, dried or pulled away from adjacent members.

Exterior walls shall be retrofitted with energy

conservation opportunities that are cost-effective, such

as:

o Wall insulation to optimal level;

o Passive solar retrofit; or

o Other.

2/85 9-2

b\. Exterior joints between walls, foundation, roofs,

around window and door frames, between wall panels,

penetrations through the wall and all other such openings

in the building envelope shall be caulked, gasketed,

weatherstripped or otherwise sealed with non-staining

materials that will remain pliable during use. Thermal

conductivity (U-values) for new walls shall meet or

exceed requirements of the CABO Model Energy Code, 1983

Edition as referenced in the Minimum Property Standards

Section 607-1.l when cost-effective.

9-4. ROOFS.

a\. Low-Sloped Roofing Systems. Low-sloped roofing systems

are either built-up roofing (BUR) or non-conventional

roofing (single-ply and others) and where the slope is

less than 2 in l2. These systems are defined as an

assembly of 4 or less interacting components designed to

weatherproof and normally to insulate a building top

surface. The components of a roof system consist of:

o a structural deck;

o a vapor retarder (where required);

o thermal insulation (where required); and

o a waterproof membrane.

\(1\) New or Replacement Low-Sloped Roofing Systems. In

the selection of a new or replacement roofing

system, the following shall be considered:

\(a\) Satisfactory record of performance in the

location of intended use, which includes

durability, i.e., resistance to physical,

chemical and biological factors when tested in

accordance with accepted material standards.

\(b\) A single source warranty issued by the membrane

manufacturer for the roof system performance

which includes wind blow-off resistance, fire

classification and durability, for a minimum of

l0 years for labor and materials. The

manufacturer shall be liable for the roof

system performance warranty. This warranty

shall include an evaluation by the manufacturer

(or approved representative) of

9-3 2/85

the existing roof system for acceptability as a

substrate for the new roofing system. Also,

the warranty shall include all flashings,

seaming (for single-ply and other non-

conventional roofs), wood and metal work,

sealing, access walks and other work to make a

complete watertight roof membrane system.

Application of the roof system shall be by

contractors approved by the manufacturer.

Construction shall be in accordance with the

manufacturer\'s printed specifications,

architectural detail and installation

instructions.

\(c\) As an alternative to replacing or partially

replacing a roof with a hot BUR or a single-ply

membrane, one of the following cold-applied

products may be used for remedial work:

recoatings; cutbacks; or emulsions. Coal tar

pitch and asphalt are incompatible; therefore,

consult with the cold product manufacturer

before using these products. There are

normally no warranties associated with this

remedial work.

\(2\) Roof Evaluation Survey. The failure to find and

correct minor roof defects and deterioration in the

earliest stages is probably the greatest cause of

premature roof problems. This is particularly true

of BURs built on low-sloped roof decks. Periodic

inspection and remedial maintenance can mitigate

these problems. Premature roof failure (within the

first two years of roof completion) is usually due

to improper application, improper storage of

building products (especially felts) and improper

design; and normal weathering and lack of periodic

maintenance may age a roof in a time frame less than

the warranted period. Roof evaluation, maintenance,

application and repair should be performed by

qualified personnel only. Evaluation should be

conducted by a roof consultant or a person well

versed in roof failure. Manufacturers can supply

this service if their product is used. (See

subparagraph a(l)(b) regarding roof warranty.)

There are non-destructive methods for determining

the water content of a roof, i.e., Infra Red

capacitance and Nuclear Meter. Minor maintenance

and repair work, emergency work (required to provide

immediate protection against water damage) is best

performed by PHA staff, if available. Major repairs

and reroofing projects should be performed by

qualified roofing contractors. Where the

deterioration

2/85 9-4

of the structural members is found to be extensive

and beyond repair as technically determined by an

architect/engineer on the PHA\'s staff or under

contract through a roof survey, and/or where repeated

and frequent membrane failures justify alternate

roofing design, a comparative cost analysis shall be

used to determine the best type of roof design for the

structure.

\(3\) Performance Criteria for Low-Sloped Roof Systems.

\(a\) Wind. The new roof system (or re-roof system)

shall withstand the wind up-lift requirements of

the HUD/MPS, i.e., ANSI A-58.l 1982. Tests shall

be in accordance with Factory Mutual 1-90 or 1-60

test procedures or equal.

\(b\) Fire. A class A fire rating (or local code

requirement) shall be achieved via Underwriters

Laboratories, Inc. Test procedures shall be in

accordance with UL 790 or ASTM E-l08 or equal.

\(c\) Slope. Positive slope to drain, i.e., 1/2\" in

12\", shall be attained by use of tapered

insulation or separation boards on top of the

existing roofing structure or membrane.

Resulting top surface shall be a smooth plane;

ponding and other depressions shall be

eliminated.

b\. Steep Slope Shingle Roofing. Where slopes are greater than

2 in 12, organic or inorganic asphalt shingles shall be

used. When strip self-sealing shingles are used, they

shall measure approximately 12\" x 36\". Class \"A\"

(fiberglass) shingles shall weigh a minimum of 240 pounds

per square; Class \"C\" (organic) shingles shall weigh a

minimum of 260 pounds per square. All shingles shall carry

a 25-year materials warranty, plus a 3-year up-front

warranty for labor and materials.

\(1\) Performance Reguirements for Steep Sloped Roofs.

\(a\) Fire resistance - shingles shall meet

Underwriters Laboratories, Inc., test UL-790 for

Class A or Class C fire ratings.

9-5 2/85

\(b\) Wind resistance - shingles shall meet

Underwriters Laboratories, Inc., test UL-997 for

wind resistance. Shingles shall resist a full

gale force wind, as defined by the Asphalt

Roofing Manufacturers Association (ARMA).

\(c\) Shingle packages shall be UL labeled and also

listed by UL as meeting these requirements.

\(2\) Installation. Installation of shingle roofing

materials and flashing shall be in accordance with the

ARMA roofing manual.

\(3\) Reroofing. Depending on local codes, a maximum of

three (original and two reroofs or original and one

reroof in heavy snow load areas) roofs may be

installed before tear-off is mandatory. However, the

decision to reroof shall depend on the structural

integrity of the supporting roof structure and the

condition of the existing shingled roof. Substrate

for reroofing shall be firm. If not available,

ventilation shall be provided concurrently with the

reroofing. Ridge and soffit ventilation is

recommended.

\(4\) Roofing Underlayment Felts.

o Roofing underlayment felts applied to a minimum

sloped roof of 4 in l2 shall be 15 pound asphalt

non-perforated saturated felt (or equal).

o Low-sloped shingle roofs (2 in 12 to 4 in 12)

require 2 layers of 15 pound non-perforated

saturated felt.

o Some local codes may require 30 pound felt

regardless of the slope.

o Wherever there is a possibility of creating an

ice dam along the eaves, the underlayment shall

be cemented to the substrate and to each other to

a point at least 24\" beyond the interior wall

line of the building. Ice damming frequently

occurs where the slope of the roof is between 2

in l2 and 4 in 12.

\(5\) Roof Ventilation. Roof and roof structures shall have

natural or mechanical ventilation as required in the

HUD MPS. Proper ventilation will prevent dampness and

minimize

2/85 9-6

the effect of conditions conducive to decay,

deterioration and excessive heat build-up. Exterior

ventilation openings shall be screened to prevent

unauthorized entry or the penetration of rodents or

other infestation. Roof venting systems shall be in

operable condition. Vents shall not be clogged or

painted over or missing proper strainers.

\(6\) Maximum slope considered suitable for normal shingle

application is 2l in 12. Applications above this

slope require special nailing and cementing (i. e.,

Mansard roof). Use manufacturers\' instructions.

c\. Roof and Attic Insulation. Existing insulation and its

installation shall comply with relevant fire codes and

shall be anchored as required. Gaps, holes or other

passages shall be effectively filled so that air will not

escape from interior spaces into the attic. New or

additional roof or attic insulation shall be provided if

determined to be cost-effective and shall perform as

follows:

o Meet applicable fire-resistance standards and comply

with local fire codes;

o Not be toxic when in exposed locations;

o Settlement will not reduce insulating material to

below agreed upon R value;

o Not deteriorate when wet; and

o Dry within a reasonable amount of time when exposed to

moisture.

NOTE: Light fixtures or electric fans exposed on

attic floors for use in spaces below shall have

the insulation kept back a minimum of 3 inches.

d\. Drainage from Roof. Buildings shall have a controlled

method of disposal of water from roofs to prevent water

penetration, property damage or public hazard. Drainage

systems shall be connected to available storm sewers or

provided with suitable splash blocks or empty at acceptable

locations onto landscaped or paved areas. Systems shall be

of size and placement to efficiently accommodate

anticipated rain and snow. Drains shall be protected from

the intrusion of foreign matter. Gutters and downspouts

shall be securely anchored to the

9-7 2/85

building and shall be free of holes, cracks, rust or

material deterioration. Gutter and leader systems,

diverters, or other suitable means of systemized drainage

shall be present in locations where internal systems are

not provided and the following occurs:

\(1\) Adequately sized roof overhangs are not present to

prevent drainage along exterior wall that could lead

to building penetration or staining of walls, windows

and doors;

\(2\) Ground erosion of expansion has occurred due to

excessive soil saturation;

\(3\) Water drains on uncovered entrance platforms or steps;

or

\(4\) Drainage patterns create hazardous areas for occupants

or public.

e\. Skylights. Where existing, skylights shall be weather-

tight and shall be fitted to frames so as not to be a

safety hazard to life or property. For technical require-

ments, see paragraph 9-7. In areas where unauthorized

entry is a problem, skylights shall be secured with

tamperproof grills, bars or other means of security. No

new skylights are permitted.

9-5. CHIMNEYS. Chimneys shall be in safe and structurally sound

condition. Chimneys shall be smoke-tight, capable of

withstanding the action of operational temperatures and flue

gases, and of sufficient height to allow proper draw for venting

as required. Masonry chimneys shall not have major open mortar

joints or cracks, permitting smoke or flame to be discharged

into the building. Unlined masonry chimneys with deficient

mortar or joints shall be either removed or made safe by the

installation of a flue liner or corrosion-resistant pipe 1 inch

less in diameter than the interior of the chimney.

9-6. EXTERIOR ACCESSORY STRUCTURES. Stairs, platforms and other

structures accessible to tenants that extend 24 inches or more

above grade shall be continuous, enclosing walls or railings at

least 40 inches high. Enclosures of balconies shall be designed

to prevent the passage of a spherical object measuring 5 inches

in diameter or greater. Porches, balconies, canopies and roof

overhangs shall be sloped for

2/85 9-8

safe drainage. For technical requirements, see paragraph 9-4.

Exterior accessory structures shall be in safe and structurally

sound condition, anchored and capable of supporting anticipated

loads. All exposed surfaces shall be protected from decay and

moisture, and shall be free of splintering, rust and material

deterioration.

9-7. WINDOWS. Windows shall have required glazing that is free of

holes, cracks or missing portions and shall be supported by

frames that provide secure and sealed connections to the wall.

Glazing, sashes and frames shall connect securely to limit the

infiltration of water, moisture and air in accordance with the

HUD MPS. These elements shall be free of splintering, rust or

other material deterioration. Operable windows shall be easy to

open, hold open, close and lock securely. Weatherstripping

shall be durable when in contact with the window sash and shall

prevent excessive infiltration of water, moisture, wind, sound,

light and dust. Windows shall be retrofitted with energy

conservation devices that are cost-effective, such as:

o Storm windows;

o Thermal shutters;

o Caulking;

o Weathestripping;

o Window shading;

o Replacement windows; or

o Other.

NOTE: Improper fit of window sashes in frames may indicate

structural problems. For further information, see Chapter 8.

a\. Security. All operable windows shall have keyless sash

locks such as \"clam shell\" or equivalent interior

fastener.

b\. Accessory. Insect screens shall be provided for all oper-

able windows in areas where they are needed and customarily

provided. Screens shall be in safe and sound condition,

and fit firmly into appropriate frames.

9-9 2/85

SECTION 2: PROJECT SPECIFIC STANDARDS

9-2B. RESERVED.

9-3B. RESERVED.

9-4B. ROOFS.

a\. Surface Materials. When replacement is necessary,

wood shingles and shakes should be replaced with fire-

resistant materials. When repairing or replacing

major portions of the roofing system, whenever

possible, the color, texture and character of the new

material should be compatible or matching to the

existing.

b\. Reserved.

c\. Reserved.

d\. Reserved.

e\. Roof Drainage. New gutters and leaders should be

consistent with successful existing systems and

should be durable and resistant to deterioration by

the elements. In determining which material to use,

the following should be considered:

\(1\) Aluminum is an acceptable gutter/leader material

except in locations where aluminum-corrosive

vapors (such as those present in salt air and

industrial areas) are present. In these cases,

plastic (vinyl) systems may be used.

\(2\) Exterior wood gutters and leaders should not be

used because of leakage and repainting

requirements. When the drainage system is an

integral part of the roof, the gutter may be

lined with aluminum or other durable metal.

\(3\) Copper gutters and leaders shall not be used

except for repair work of existing systems

because they are prime targets for theft.

\(4\) A steel boot that extends 72 inches above the

ground should be provided when leaders are

subject to abuse.

2/85 9-10

\(5\) The following should be considered when clogging

has been a major problem.

\(a\) Increase gutter/leader diameters;

\(b\) Provide basket strainers at the head of the

leader; or

\(c\) Provide screens across gutter heads.

\(6\) Leaders may be connected to underground storm

drainage systems or dry walls (when granular soil

is present) where soil erosion or flooding has

been a problem. The expense of this change makes

conversion a possibility only when unsatisfactory

conditions are severe and where other diversion

methods have proved unsuccessful. The existing

storm system must also have the capacity to

receive the additional load.

f\. Reserved.

9-5B. RESERVED.

9-6B. RESERVED.

9-7B. WINDOWS.

a\. Security. In areas where security is a problem, windows

affording easy access to the premises, such as ground floor

and basement windows, windows opening onto fire escapes,

stairways, porches, terraces, balconies right under roofs,

etc., may be provided with a better security system than

keyless clam shell or equivalent sash locks. Systems may

include:

\(1\) Security screens, grills, or window guards. Security

screens and gates should be easy to open in case of

emergency or when used by the elderly or the disabled.

Sliding gates which afford excellent protection and

can be easily pushed aside or opened for emergency

may be provided. These gates should be set in tracks

on top and bottom to prevent them from being pulled or

pried from the window. When wire mesh is used, the

metal should be a minimum of 1/8 inches in diameter

and the opening should not exceed 2 inches. The

grills should be attached to the window frame with

machine or round head bolts which cannot be removed

from the outside. If bars are used, they should be a

maximum of 5 inches apart and set at least 3 inches

into the framing wall.

9-11 2/85

NOTE: Mechanisms shall comply with relevant fire

codes regarding use of windows for secondary

egress. Security screens shall not be

permanently fixed when windows are required means

of egress or interfere with the ability of

residents to open or close windows for

ventilation and dwelling unit comfort.

\(2\) Keyed window locks.

\(3\) Local window alarms in management, maintenance

and community spaces, such as contract switch,

foil strips and motion detectors, or central

alarms connected to security personnel or the

police. Prior to the installation of alarm

systems, the following should be considered:

\(a\) Test of reliability of current products on

the market;

\(b\) Commitment of security/police to respond to

systems; and

\(c\) Problems involved with false alarms by

residents.

\(4\) Tempered, laminated or wire glass, or other

break-resistant materials on ground floor

windows that are frequently vandalized.

b\. Reserved.

c\. Child Guards. Where required by relevant codes in

multi-family projects, window guards shall be provided

on exterior windows of dwelling units that are above

the second floor. Installation child guards shall be

in compliance with relevant fire codes.

d\. Window Replacement. New windows should have the

following features:

\(1\) Sashes and frames of the kind and quality that

will withstand intense use and do not require

repeated maintenance. Class A wood, vinyl clad

wood, steel with baked enamel finish or A-2

aluminum may be used;

\(2\) Removable sashes for shop glazing when

maintenance capacities exist;

2/85 9-12

\(3\) Insulation and with thermobreak frames if

determined cost-effective;

NOTE: Windows conforming to the recommendations

of AAMA 1502.6 are considered to meet this

requirement. Where wood is used as the

insulator, it should be treated with a

water-repellant preservative;

\(4\) Limited infiltration into or from the building

envelope, meeting MPS requirements;

\(5\) Maximized winter heat gain through no shading of

glazed areas during the heating season. The

ratio of south window to floor area should not

exceed 25% without adequate interior thermal

storage; and

\(6\) Minimized summer heat gain through such measures

as horizontal overhangs for south orientations,

combination horizontal and vertical overhangs for

east-west orientations or tinted/reflective glass

that allows pentration of winter sun.

NOTE: To take advantage of the winter heat gain,

south-oriented windows should not have tinted

glass or over-sized overhangs.

9-13 2/85