Water Intrusion, Vapor Transport and Vapor Diffusion in Buildings. Mark Scott P.E. LEED ap Wiss Janney Elstner Associates

Transcription

1 Water Intrusion, Vapor Transport and Vapor Diffusion in Buildings Mark Scott P.E. LEED ap Wiss Janney Elstner Associates

2 Water is essential 70 percent of the earth is covered with water The human body is 60 percent water We can live without water for 3 days If there's mold there's water To solve the mold problem solve the water problem

3 Solid Forms of Water

4 Liquid Forms of Water

5 Vapor Forms of Water

6 Forms of Water Water doesn t tend to stay in one state it moves around

7 Movement of water in buildings Water Intrusion Vapor Transport Vapor Diffusion

8 Water Intrusion Water from outside the building leaks into the building from above, below or the side. Roof leak Ice dam Failed flashing Failed shingles Wall leak Windows (the number one source) Below grade leak Ground water Storm water Plumbing Frozen pipe, failed fitting Sprinkler pipe failure Waste and vent pipe

9 Drain it away

10 Vapor Transport Air that moves across the building envelope carries water with it. As the vapor cools it turns to liquid water at it s Dew Point

11 Vapor Transport Air that moves across the building envelope carries water with it. As the vapor cools it turns to liquid water at it s Dew Point A one square inch hole can move 30 Quarts of water per year (70F 40% RH)

12 Typical Site Conditions A plague of air leakage paths

13 Psych Chart WET WATER VAPOR LIQUID WATER COLD HOT DRY

14 Psych Chart WET WATER VAPOR LIQUID WATER COLD HOT DRY

15 Psych Chart WET WATER VAPOR LIQUID WATER COLD HOT DRY

16 Psych Chart WET LIQUID WATER WATER VAPOR COLD HOT DRY

17 Winter Summer outdoor design

18 Temperature Gradient Analysis Wall systems that promote problems

19 Psych Chart WET DEW POINT WATER VAPOR LIQUID WATER COLD HOT DRY

20 Psych Chart WET AIR WATER COLD HOT DRY

21 Vapor diffusion Water in vapor form moves through the material of the building envelope.

22 Vapor diffusion Water in vapor form moves through the material of the building envelope. A 4x8 sheet of gypsum Will move 1/3 of a Quart Per year (70F 40%RH)

23 Vapor diffusion Water in vapor form moves through the material of the building envelope. A 4x8 sheet of gypsum Will move 1/3 of a Quart Per year (70F 40%RH)

24 Vapor diffusion Water in vapor form moves through the material of the building envelope. A 4x8 sheet of gypsum Will move 1/3 of a Quart Per year (70F 40%RH)

25 Vapor diffusion Water in vapor form moves through the material of the building envelope. A 4x8 sheet of gypsum Will move 1/3 of a Quart Per year (70F 40%RH)

26 Why is vapor transport significant Vapor transport The amount of water moved by transport is directly proportional to the amount of air transported

27 Why is vapor transport significant Air Moved Is the product of the velocity of the air and the size of the hole The velocity of the air is proportional to the difference in pressure across the hole We can not build air tight buildings.

28 Why is vapor transport significant Air Moved Is the product of the velocity of the air and the size of the hole The velocity of the air is proportional to the difference in pressure across the hole We can not build air tight buildings if we don t ask for and test for air tightness.

29 Why is diffusion insignificant We know how to and can build buildings to limit diffusion Diffusion is a function of the perm rating of the wall or roof, holes don t matter.

30 Why is diffusion insignificant We know how to and can build buildings to limit diffusion Diffusion is a function of the perm rating of the wall or roof, holes don t matter much

31 Vapor Barrier.No Problem

32 Vapor Barrier.No Problem

33 Vapor Barrier.No Problem 12 x =.15 square inches per shoe

34 Vapor Barrier.No Problem.15 square inches x 7 = 1.05 square inches or.007 square feet sq ft x.06p = sq ft x 250p = = 37.74/600 sq ft =.062 Perm = gr/hr. ft2.in hg

35 ASTM E96 Standard Test Methods for Water Vapor Transmission of Materials Water Vapor Transmission Test procedure for vapor retarders: ASTM E-96 Test Method Class I: 0.1 perm or less vapor impermeable Class II:.1 perm to no greater than 1.0 perm vapor semi-impermeable Class III: 1.0 perms to no greater than 10 perms vapor semi-permeable 10 perms and greater vapor permeable

36 Performance Requirements AIR BARRIER Prevent air flow Continuous, supported Durable or serviceable Transfer loads Resist creep Flexible VAPOR BARRIER Resist vapor diffusion. L/s. m 2 (cfm/ft 2 ) ng/pa. s. m 2 (perms)

37 States with Air Barrier Codes

38 Massachusetts Energy Code Model for Future Codes? Air leakage rates Materials identified as being the air barrier must allow not more than CFM/ft 2 at a pressure difference of 0.3 of water. Metric is 0.02 l/m 2 75 Pa. (1.6 psf, 10mph wind load, etc.)

39 Diagnostics

40 Water moving rules Water runs downhill by.. gravity Vapor is transported from high air pressure to low air pressure by..pressure difference Vapor diffuses from warm to cold by. thermal gradient Vapor diffuses from moist to dry by..vapor pressure Water runs uphill? By capillarity

41 Capillarity

42 Water Detective Intrusion, the best time to diagnose intrusion from rainwater is when its raining. If its not raining, use a hose, spray lightly Water will go through a brick wall in about 30 seconds. Look for the puddle

43 Water Detective Vapor Transport, where is the moisture inside or outside?

44 Winter Summer outdoor design

45 Sources of indoor moisture Plants Dishwasher Clothes Dryer Shower House keeping Humidifier Swimming Pool

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48 Water Detective Vapor Transport, where is the moisture inside or outside? What's causing the pressure difference?

49 Sources of Air Pressure Air barriers must resist these combined forces

50 I think I have a mold problem Where in the country do you live? How old is your house? Does the roof leak only in the winter? Do you have lights in a sloped ceiling? Do you have an indoor pool? Do you have a humidifier? Do you have air conditioning? Where is your furnace? Is it a brick house? Do you have EIFS?

51 I think I have a mold problem Where do you live?

52 I think I have a mold problem Where do you live? Where it rains a lot?

53 I think I have a mold problem Where do you live? Where it rains a lot? How old is your house?

54 I think I have a mold problem Where do you live? Where it rains a lot? How old is your house? Concrete has 400 lbs of water per cubic yard, half of which is released as vapor over the first year or two.

55 I think I have a mold problem Where do you live? Where it rains a lot? How old is your house? Concrete has 400 lbs of water per cubic yard, half of which is released as vapor over the first year or two. Does the roof leak only in the winter?

56 I think I have a mold problem Where do you live? Where it rains a lot? How old is your house? Concrete has 400 lbs of water per cubic yard, half of which is released as vapor over the first year or two. Does the roof leak only in the winter? Probably not a roof leak but may be condensation or an ice dam

57 I think I have a mold problem Where do you live? Where it rains a lot? How old is your house? Concrete has 400 lbs of water per cubic yard, half of which is released as vapor over the first year or two. Does the roof leak only in the winter? Probably not a roof leak but may be condensation or an ice dam Is your ceiling sloped?

58 I think I have a mold problem Where do you live? Where it rains a lot? How old is your house? Concrete has 400 lbs of water per cubic yard, half of which is released as vapor over the first year or two. Does the roof leak only in the winter? Probably not a roof leak but may be condensation or an ice dam Is your ceiling sloped? Vapor Transport problem

59 I think I have a mold problem Where do you live? Where it rains a lot? How old is your house? Concrete has 400 lbs of water per cubic yard, half of which is released as vapor over the first year or two. Does the roof leak only in the winter? Probably not a roof leak but may be condensation or an ice dam Is your ceiling sloped? Vapor Transport problem Do you have an indoor pool?

60 I think I have a mold problem Where do you live? Where it rains a lot? How old is your house? Concrete has 400 lbs of water per cubic yard, half of which is released as vapor over the first year or two. Does the roof leak only in the winter? Probably not a roof leak but may be condensation or an ice dam Is your ceiling sloped? Vapor Transport problem Do you have an indoor pool? The pressure in the pool room must be negative to the outside.

61 I think I have a mold problem Where do you live? Where it rains a lot? How old is your house? Concrete has 400 lbs of water per cubic yard, half of which is released as vapor over the first year or two. Does the roof leak only in the winter? Probably not a roof leak but may be condensation or an ice dam Is your ceiling sloped? Vapor Transport problem Do you have an indoor pool? The pressure in the pool room must be negative to the outside. Do you have a humidifier?

62 I think I have a mold problem Where do you live? Where it rains a lot? How old is your house? Concrete has 400 lbs of water per cubic yard, half of which is released as vapor over the first year or two. Does the roof leak only in the winter? Probably not a roof leak but may be condensation or an ice dam Is your ceiling sloped? Vapor Transport problem Do you have an indoor pool? The pressure in the pool room must be negative to the outside. Do you have a humidifier? Do you have air conditioning?

63 I think I have a mold problem Where do you live? Where it rains a lot? How old is your house? Concrete has 400 lbs of water per cubic yard, half of which is released as vapor over the first year or two. Does the roof leak only in the winter? Probably not a roof leak but may be condensation or an ice dam Is your ceiling sloped? Vapor Transport problem Do you have an indoor pool? The pressure in the pool room must be negative to the outside. Do you have a humidifier? Do you have air conditioning? Cause of condensation in the summer

64 I think I have a mold problem Where do you live? Where it rains a lot? How old is your house? Concrete has 400 lbs of water per cubic yard, half of which is released as vapor over the first year or two. Does the roof leak only in the winter? Probably not a roof leak but may be condensation or an ice dam Is your ceiling sloped? Vapor Transport problem Do you have an indoor pool? The pressure in the pool room must be negative to the outside. Do you have a humidifier? Do you have air conditioning? Cause of condensation in the summer Where is your furnace?

65 I think I have a mold problem Where do you live? Where it rains a lot? How old is your house? Concrete has 400 lbs of water per cubic yard, half of which is released as vapor over the first year or two. Does the roof leak only in the winter? Probably not a roof leak but may be condensation or an ice dam Is your ceiling sloped? Vapor Transport problem Do you have an indoor pool? The pressure in the pool room must be negative to the outside. Do you have a humidifier? Do you have air conditioning? Cause of condensation in the summer Where is your furnace? Fans outside of the envelope move air across the envelope.

66 I think I have a mold problem Where do you live? Where it rains a lot? How old is your house? Concrete has 400 lbs of water per cubic yard, half of which is released as vapor over the first year or two. Does the roof leak only in the winter? Probably not a roof leak but may be condensation or an ice dam Is your ceiling sloped? Vapor Transport problem Do you have an indoor pool? The pressure in the pool room must be negative to the outside. Do you have a humidifier? Do you have air conditioning? Cause of condensation in the summer Where is your furnace? Fans outside of the envelope move air across the envelope. Is it a brick house?

67 I think I have a mold problem Where do you live? Where it rains a lot? How old is your house? Concrete has 400 lbs of water per cubic yard, half of which is released as vapor over the first year or two. Does the roof leak only in the winter? Probably not a roof leak but may be condensation or an ice dam Is your ceiling sloped? Vapor Transport problem Do you have an indoor pool? The pressure in the pool room must be negative to the outside. Do you have a humidifier? Do you have air conditioning? Cause of condensation in the summer Where is your furnace? Fans outside of the envelope move air across the envelope. Is it a brick house? Masonry stores water (reservoir cladding)

68 I think I have a mold problem Where do you live? Where it rains a lot? How old is your house? Concrete has 400 lbs of water per cubic yard, half of which is released as vapor over the first year or two. Does the roof leak only in the winter? Probably not a roof leak but may be condensation or an ice dam Is your ceiling sloped? Vapor Transport problem Do you have an indoor pool? The pressure in the pool room must be negative to the outside. Do you have a humidifier? Do you have air conditioning? Cause of condensation in the summer Where is your furnace? Fans outside of the envelope move air across the envelope. Is it a brick house? Masonry stores water (reservoir cladding) Do you have EIFS?

69 I think I have a mold problem Where do you live? Where it rains a lot? How old is your house? Concrete has 400 lbs of water per cubic yard, half of which is released as vapor over the first year or two. Does the roof leak only in the winter? Probably not a roof leak but may be condensation or an ice dam Is your ceiling sloped? Vapor Transport problem Do you have an indoor pool? The pressure in the pool room must be negative to the outside. Do you have a humidifier? Do you have air conditioning? Cause of condensation in the summer Where is your furnace? Fans outside of the envelope move air across the envelope. Is it a brick house? Masonry stores water (reservoir cladding) Do you have EIFS? From What year?

70 As we move forward Common to all water movement some form of energy is required The amount of energy moving through walls and roofs is decreasing significantly due to the energy codes and 2030 net zero goal With less and less energy lost through the envelope, things that get wet will tend to stay wet.and that s a problem

71 CONCLUSION Expect to see more water problems as more insulation is added to new and existing building.

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