Water Intrusion 101. Presented by: Michael D. Spensieri, P.E. Regional Engineering Manager Office: Ext:

Transcription

1 Water Intrusion 101 Presented by: Michael D. Spensieri, P.E. Regional Engineering Manager Office: Ext:

2 Goals Open environment Interactive discussion PLEASE ask questions TCB as needed while respecting others Let s learn about water intrusion and foundation problems!

3 Outline I. Site study guideline II. Roof water intrusion issues with Case Study No. 1 III. Roof system components with Case Studies Nos. 2 & 3 IV. Building penetrations and construction issues V. Site drainage with Case Study No. 4 VI. Foundations walls with Case Study No. 5 VII. Retaining walls with Case Study No. 6 VIII.Moisture/water-intrusion surveys

4 General Site Study Guideline Initial Gather firsthand background information Study the general characteristics of the building exterior Study the topography (slope) of the ground around the property Study the physical damage Is the water-damaged material (if any) wet or dry Determine the extent or limits of the damage Is the water source above, below or both Is the damage short-term or long-term (e.g., wood rot present, historical) Investigate Follow where the data/evidence and your observations lead

5 Water, water, everywhere

6 How does water get in? Water intrusion issues: Ponding water on roofs Leaking roof coverings Roof penetrations Eaves / overhangs / vents Exterior envelope failure (e.g., design flaws, construction, damaged, lack of maintenance) HVAC systems (e.g., overflow, condensation) High humidity / condensation Storm damage (e.g., wind, tornado, hurricane) Surface or runoff water (e.g., rainwater, roof downspouts) Subsurface water (e.g., basements, crawlspaces)

7 MANY places water can get in 1. Scupper & rainwater leader 2. Parapet cap flashing 3. Control joint 4. Wall / Window interface 5. Balcony door threshold Diagram provided by CMHC publication: Building envelope rehabilitation consultant guide and owner/property manager guide.

8 MANY places water can get in 6. Balcony rail attachment 7. Vent hood 8. Rainwater leader attachment 9. Saddle detail 10. Deck drain Diagram provided by CMHC publication: Building envelope rehabilitation consultant guide and owner/property manager guide.

9 MANY places water can get in 11. Junction between materials 12. Window head / jamb 13. Window sill 14. Overflow scupper 15. Planter 16. Wall / concrete slab interface 17. Balcony / wall interface Diagram provided by CMHC publication: Building envelope rehabilitation consultant guide and owner/property manager guide.

10 How does water get in? What is vital to any roof drainage system?

11 How does water get in? Debris around a roof drain - Maintenance issue Standing water due to debris covering a drain - Maintenance issue

12 Standing water on a flat roof How does water get in?

13 How does water get in? Failed roof seam (material failure) - Maintenance issue

14 How does water get in? Failed / deteriorated rubber plumbing boot - Maintenance issue

15 How does water get in? Leaking roof penetration no boot! - Improper construction and maintenance issue

16 How does water get in? Parapet wall with inappropriate covering - Shingles are not to be used on vertical walls

17 How does water get in? Failure of 3-tab shingle roof covering from low winds - Displaced shingles due to vertical racking installation

18 Vertical Racking Installation Shingles are installed in columns, beginning at the eave. Vertical racking almost always results in some damage to the sealant strip on the lifted tab, affecting its long-term performance. Not recommended by the National Roofing Contractors Association (NRCA) or the American Roofing Manufacturer s Association (ARMA). Commonly chosen by installers due to a general increase in efficiency and ease, and decreased waste.

19 Vertical Racking Installation

20 Vertical Racking Installation

21 Case Study No. 1 Unsealed Shingles Claim: Water intrusion at 19-year-old house Location: Westborough, MA

22 Case Study No. 1 Unsealed Shingles

28 Case Study No. 1 Unsealed Shingles Claim: Water intrusion at 19-year-old house Location: Westborough, MA O/C & Conclusions: Unsealed shingles are present on the roof above the observed water staining in the attic and living room. Some of the unsealed shingles have slid, creating gaps around the nails. The water intrusion in the living room is the result of water entering from under the unsealed roof shingles and into the stretched nail holes. The water intrusion only occurs during winter months as the buildup of snow and/or ice is required to back up the shedding water under the unsealed shingles and into the stretched nail holes.

29 it s no joke! FLASHING!!!

30 Roof Construction - Typical

31 Chimney or Wall Flashing A common place for chimney leaks is along the flashing and sealants It is common for leaks to occur at wall interfaces on roofs Proper flashing must include counter flashing

32 Case Study No. 2 Chimney Flashing Claim: Water intrusion at 13-year-old house due to wind damage to chimney Location: Saco, ME

33 Case Study No. 2 Chimney Flashing

38 Case Study No. 2 Chimney Flashing Claim: Water intrusion at 13-year-old house due to wind damage to chimney Location: Saco, ME O/C & Conclusions: No wind-related damages to the roof or chimney. The depressed roof shingles on the north side of the chimney allows water to pond. Proper roof penetration flashing and detailing would prevent any water intrusion and/or ponding water at the chimney. The water intrusion at the chimney is the result of inadequate construction in the form of improper flashing and detailing of the chimney roof penetration and inadequate maintenance.

39 Flashing Along Walls Built-up commercial roof shown with, Installation issues and/or Material failures (e.g., membrane shrinkage)

40 Historical wear and tear with prior repairs Unsecured Flashing

41 Case Study No. 3 Roof water intrusion / Flashing Claim: Water intrusion at 173-year old church Location: Canandaigua, NY

42 Case Study No. 3 Roof water intrusion / Flashing

46 Case Study No. 3 Roof water intrusion

48 Case Study No. 3 Roof water intrusion / Flashing Claim: Water intrusion at 173-year-old church Location: Canandaigua, NY O/C & Conclusions, Caused by the combination of improper installation of the EPDM rubber roof laying in reverse over the metal roof, failing sealants and inadequate maintenance on the valley rubber roof overlay. Based on the degree of wood rot to the subject wooden arch, the water intrusion is an on-going issue and not a sudden occurrence.

49 Roof Construction - Typical

50 Roof Construction Drip Edge

51 Roof Construction Drip Edge

52 Door-Threshold Opening

55 Deck Flashing Prevents water from entering structures between deck and interior Flashing must extend under the exterior siding or covering

56 Wall Sheathing Wrap

57 Window Flashing Nailing Fins and Peel & Seal Tape

58 Window Flashing Long-Term Damage

59 Kickout Flashing

60 Kickout Flashing

61 Kickout Flashing - Issues

62 Kickout Flashing - Issues

63 Flashing, Brick & Weep Holes The International Building Code (IBC) requires that flashing be installed at the first course of masonry above finished ground level above the foundation wall, at lintels, above windows, and below sills. The IBC requires weep holes in brick veneer immediately above the flashing. The IRC states that the maximum spacing of weep holes is 33-inches. Brick veneer is not intended as a waterproof covering of the house; the brick and mortar joints are permeable. Water can enter around windows and other openings in the wall. The purpose of the flashing is to direct water away from the house, and weep holes allow the water to exit the wall cavity. Flashing and weep holes should be installed above and below the windows and near the ground line. Without weep holes, any water that intrudes behind the brick veneer cannot exit the wall. The Brick Industry Association (BIA) specifies that brick window sills should slope down away from the house/building at an angle 15 degrees from horizontal. This equates to a slope of approximately 28 percent.

64 Weep Holes Exterior Wall Drainage

65 Weep Holes Exterior Wall Drainage

66 Break time back in 10

67 Drainage! Drainage!! Drainage!!!

68 Ground Slopes and Drainage The International Building Code (IBC) Section , as well as good construction practices, requires a minimum of a 6-inch vertical drop in 10 feet of horizontal length (5- percent slope) around building foundations. If physical obstructions or lot lines prohibit 10 feet of horizontal distance, a 5-percent slope shall be provided to an approved alternative method of diverting water away from the foundation. Ground swales used for this purpose shall be sloped a minimum of 2 percent where located within 10 feet of the building foundation. Impervious surfaces (e.g., parking lot, asphalt pavement) within 10 feet of the building foundation shall be sloped a minimum of 2 percent away from the building.

69 Ground slopes toward the building. Ground Slopes - DRAINAGE

70 Ground Slopes - SETTLEMENT Moisture in Soil The key to loading earth with a foundation is to control the moisture in the soil. Well-compacted and maintained soil has two physical properties that allow it to hold together: cohesion and shear resistance. Cohesion is the attractive nature of the particles. Moisture in the soil can neutralize this attraction. Shear resistance has to do with their shape of individual soil particles and how they rub against one another to lock into place. As the soil moisture increases, the soil s ability to carry weight decreases.

71 Ground Slopes - SETTLEMENT

72 Differential Settlement Single crack pattern holds at sides and crack develops in middle that is more open at the bottom

73 Differential Settlement Single crack pattern one side settles more than the other; crack is wider at the top

74 Differential Settlement Most common multiple cracks due to differential settlement

75 Differential Settlement Shear crack due to differential settlement on one side

76 Grading - Siding Issues

77 Grading - Siding Issues

78 Water in Crawlspace Groundwater Ground drainage (i.e., surface runoff) Roof drainage Failed mechanical device (i.e., sump pump) Reoccurring event (i.e., water stains to CMU block)

79 Water in Crawlspace / Basement

80 Case Study No. 4 Basement Water Intrusion Claim: Water intrusion at ~64-year-old house Location: West Springfield, MA

81 Case Study No. 4 Basement Water Intrusion

86 Case Study No. 4 Basement Water Intrusion Claim: Water intrusion at ~64-year-old house Location: West Springfield, MA O/C & Conclusions: The origin of the basement water intrusion is the NE house corner. The cause of the basement water intrusion is the inadequate ground drainage that leads surface runoff water to gather adjacent to and up against the house at the northeast house corner. This condition allows the water to enter the basement. The basement sump pump functions as intended. The lack of water staining on the pit interior walls indicates that little to no water has entered the pit since installation on 3/21/2014. The need for the sump pump is in question since the cause of the basement water intrusion is the inadequate ground drainage adjacent to the northeast house corner.

87 Foundations and Retaining Walls Unless properly designed, and more importantly properly constructed, foundation and retaining walls can leak, hold water and/or fail. Drainage behind all earth-retaining walls (e.g., basement, landscaping, etc.) is vital to the functionality of the wall and its service life.

88 Foundation Issues/Failures Common causes: Hydrostatic pressure behind wall Inadequate or absent drainage Excessive loading adjacent to wall Unreinforced walls Design and/or construction defects

89 Hydrostatic Pressure Behind Walls Groundwater and rainwater exerts its own pressure on walls as it seeps into the ground. Hydrostatic pressure is the pressure/weight of water against a basement wall when the soil is saturated. It can force moisture through pores in the basement wall and can crack and/or buckle walls.

90 Bending Wall Failure Commonly the result of: Too much backfill against an unreinforced wall Inadequate drainage behind wall Hydrostatic pressure Lateral earth pressure Even if the damaged wall is repaired, proper drainage is the long-term solution to the problem basement wall and can crack and/or buckle walls. Lateral Force CMU Wall CRACK

91 Case Study No. 5 Basement Wall Failure Claim: Basement wall failure at ~60-year-old commercial structure Location: White River Junction, VT

92 Case Study No. 5 Basement Wall Failure

96 Case Study No. 5 Basement Wall Failure Lower portion (2/3) of wall leans 3.5% or 2 degrees inward

97 Case Study No. 5 Basement Wall Failure Upper portion (1/3) of wall leans 9.7% or 5.5 degrees inward

101 Case Study No. 4 Basement Wall Failure Claim: Basement wall failure at ~60-year-old commercial structure Location: White River Junction, VT O/C & Conclusion, The wall failure was due to the combination of heavy commercial vehicle traffic and horizontal earth pressure. The wall failure occurred gradually with the crack originating at least 2 years ago, per Mr. Richards, and got worse over time.

102 Block Retaining Wall Design

103 Block Retaining Wall Design

104 Case Study No. 6 Retaining Wall Failure Claim: 166-feet long 5½-feet tall retaining wall failure Location: Charlotte, NC

105 Case Study No. 6 Retaining Wall Failure

109 Case Study No. 6 Retaining Wall Failure Claim: 166-feet long 5½-feet tall retaining wall failure Location: Charlotte, NC O/C & Conclusions, The fallen section of the retaining wall overturned due to the lack of tiebacks, vertical or horizontal reinforcement, and a water drainage system. The wall was designed inadequately to resist the lateral earth pressure of the materials behind it. The retaining wall has no drain system to remove water from collecting behind the wall within the soil.

110 Moisture Surveys Common uses, Inspecting for water damage in roof structures and in wall cavities Delineating damage once found to avoid the butcher-knife demolition process Pipe leak detection

111 Roof Moisture Surveys Three methods to perform roof-moisture surveys: A. Infrared B. Nuclear C. Capacitance

112 Moisture Surveys - Infrared

113 Moisture Surveys - Infrared Most common method as it utilizes an infrared camera that detects invisible infrared radiation or heat. The survey is performed around or after sunset following a sunny, dry day. During the day, dry insulation on the roof reflects the heat while the wet insulation absorbs it. After dark when the roof s surface cools, the wet insulation retains heat longer than the dry insulation. This heat is visible through the infrared camera.

114 EPDM Rubber Roof Example: Moisture Surveys - Infrared Through the naked eye Through the infrared camera

115 Moisture Surveys - Infrared Built-up Roof (BUR) with gravel surface Example: Through the naked eye Through the infrared camera

116 Moisture Surveys - Infrared Infrared surveys map the subsurface moisture over the entire roof area A survey map with affected roof areas can be created (image) Wet insulation areas on the roof are outlined with paint for identification and removal purposes

117 Moisture Surveys - Infrared Other uses for Infrared surveys: Water intrusion into walls Finding leaking pipes Detect missing insulation Electrical problems

118 Moisture Surveys - Nuclear

119 Moisture Surveys - Nuclear Nuclear roof moisture surveys are primarily used on ballasted single-ply roof systems. The nuclear gauge emits neutrons into the roof system. When the neutrons strike a water molecule, they are slowed and reflected back to the gauge where they are counted. Nuclear gauges are heavily regulated by state and federal agencies. They are expensive to own and are difficult to transport across state lines. Each user must be licensed.

120 Moisture Surveys - Nuclear

121 Moisture Surveys - Capacitance Capacitance meters emit a weak electrical current into the roof system, then measure its strength. Wet materials conduct electricity more readily than dry materials and the gauge detects the difference.

122 Moisture Surveys - Summary INFRARED Pros, Cons, 1. Relatively inexpensive (~$200-$4k) 1. Cannot be used on some roof types 2. Examine entire roof 2. Must be performed at night (safety) 3. Wet insulation outlined on roof 3. Trouble reflective coatings 4. FAST results 4. Weather dependant NUCLEAR Pros, Cons, 1. Can be used on all roof types 1. Highly regulated 2. Not weather dependant 2. Expensive (~$2,000) 3. Not affected by rooftop equipment 3. Time consuming CAPACITANCE Pros, Cons, 1. Realatively inexpensive (~$700) 1. ONLY used on EPDM or similar 2. No special training required 2. Does not test 100% of roof area 3. Not affected by rooftop equipment 3. Not as accurate as other methods

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