Concrete the mold solution: outlines the cause for mold and the solution with concrete

1. Concrete Masonry and Mold
NCMA Program #: 000515
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2. AIA Disclaimer Notice
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Education This program is registered with the AIA/CES for
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continuing professional education. As such, it does not
include content that may be deemed or construed to be an
approval or endorsement by the AIA of any material of
construction or any method or manner of handling, using,
distributing, or dealing in any material or product.
Questions related to specific materials, methods, and
services will be addressed at the conclusion of this
presentation.

3. Is Concrete Masonry the Solution to Mold?
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4. Benefits of Concrete Masonry
•Form and function
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•Versatile designs
•Long-term durability
•Fire-resistant
•Energy efficient
•Sound insulation
•Strength
And - does not provide a
source of food for mold
growth.

5. Overview
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•What is mold?
•Why the fuss?
•How should concrete masonry be
designed and constructed to limit mold
growth potential?

6. What is Mold?
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• Members of the Fungi Kingdom –
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Neither plant nor animal.
• Mold Spores – They are everywhere!
Sizes from 3 to 40 Microns (human hair
is 100- 150 microns). 250,000 can fit on
head of a pin.

7. Types of Mold
Continuing
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Services • More than 100,000 known species
worldwide.
• Most types found in homes and buildings
are not harmful to people. Black mold - requires high
levels of moisture, and
• Harmful types include: cellulose containing materials.
– Stachybotrys Chartarum Greenish-black. Slimy and wet
to the touch.
– Aspergillius versicular
– Various species of penicillium
• Most harmful when they become airborne
(such as in air handling systems).

8. Requirements for Mold Growth
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Education • Food Source – Any
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organic substance.
• Moisture – Free water or
high relative humidity
(greater than 70%).
• Hospitable Growing
Conditions –
Temperature between 40
and 100F, oxygen,
darkness, etc.
• Mold Spores – Located
everywhere.

9. Health Effects
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Services • Possible reactions:
– Runny nose, headaches, sinus infections, coughs,
watery eyes, breathing difficulties, and general
discomfort.
– Asthmatic symptoms: labored breathing, chest
constriction and coughing.
– Rash
• Prolonged exposure reactions
– Chronic fatigue, dizziness, shortness of breath,
headaches, and nosebleeds. Also muscle cramps,
inability to concentrate, and edema.

10. Litigation Issues
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• As many as 60,000 outstanding cases.
• About $780 million in claims paid in 2001
(75% in Texas).
• Basis for lawsuits:
– professional malpractice and negligence for
construction defects and defective designs
– fraud and failure to disclose problems at time
of sale of the property

11. Insurance Response
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“The costs of cleaning up mold caused by water from a
burst pipe are covered under the policy because water
damage from a burst pipe is a covered peril. But mold
caused by water from excessive humidity, leaks,
condensation or flooding is a maintenance issue for the
property owner, like termite or mildew prevention, and is
not covered by the policy.”
- Dr. Robert Hartwig
Insurance Information Institute
Also, insurance companies in many states
are not writing new policies.

12. Learning Curve
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Why the recent increase in observed mold
infestation…
• Media/public awareness?
• Tighter construction?
• Use of more moisture-sensitive
materials?
• Non-uniform pressurization of buildings?
• Increased construction pace?

13. Mold in Schools
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Chavez Elementary School - Madison, Wisconsin
• First new public elementary school in Madison in 30 years.
• Air quality complaints led to finding sizeable mold blooms in 1/3 of
the school’s rooms.
•$1.5 million mold and remediation program

14. Building Code Requirements
For controlling mold, esoteric at best…
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Keep in mind building codes address
minimum life safety requirements.

15. Building Code Requirements
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Services • Model codes do not contain words “mold
resistant”
• Codes do address minimum conditions which
could produce mold and associated effects.
– Proper ventilation required.
– Exterior envelopes must have vapor retarders, water-
resistive barriers, and flashings.
• International Property Maintenance Code
includes requirements for maintaining viability
and safety.

16. Options for Limiting Mold Growth
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Education • Limit Food Source – Nearly impossible.
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Reduce use of paper and wood - but still can
grow on oil and dust on non-food surfaces.
• Limit Moisture – A logical strategy. Good
construction details to reduce free water.
Reduce humidity since people prefer 40-50%
anyway.
• Provide Inhospitable Conditions – Tough.
Hospitable environments provide the
temperatures and oxygen. Darkness enables
growth in areas that can no be seen.
• Eliminate Mold Spores – Impossible.

17. Options for Limiting Mold Growth
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• A/C selection • Repair small leaks
• A/C sizing • Water damage
• Thermostat set point/ceiling fans • Moisture condensation
• Interior doors • Exhaust fans
• Space pressurization • Closets
• Measure RH in home • House plants
• No vinyl wallpapers • Construction moisture
• Return air pathways • Unvented attics
• Bathrooms • Central dehumidification
• No open windows or whole • Consider a/c with variable
house fans during humid speed air handlers and with
weather (esp at night) enhanced dehumidification
• A/C maintenance mode

18. Mold
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19. Is Mold Present?
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Services • Musty smell
• Pink or yellow splotches on vinyl wall
cover

20. Eliminate the Moisture
Continuing
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Services Keeping indoor
relative humidity low
Exterior Interior will decrease dew-
• Rain • Vapor point temperatures,
• Vapor • Air reducing chance of
condensation.
Also - ensure
continuation of
insulation and air and
vapor retarders.

21. Moisture in Building Materials
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Be careful of
sealing in moisture
that is present
within building
materials.

22. Associated Effects of Moisture
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• Efflorescence
• Corrosion of Metals & Reinforcing
• Staining/Mold/Mildew
• Leaks
• Rotting & Disintegration of
Insulation/Wood/etc.

23. Keys to Providing
Moisture Penetration Resistance
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• Quality Materials
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• Good Design and
Detailing
• Good Construction

24. Construction Materials:
Concrete Masonry Units
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ASTM C 90 Properties Properties Not in C 90
• Compressive – Color
Strength – Texture
• Absorption – Density
• Dimensional – Water Repellency
Tolerances – Fire Ratings
• Density – Thermal Properties
Definitions – Sound Properties
• Linear Drying
Shrinkage

25. Which Mortar is the Best?
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Services Sand/Lime Optimum Cement/Sand
Mortar Range Mortar
O N S M
•Workability •Strength
•Water Retentivity •Early Setting
•Late Strength •Bond
•Autogenous Healing •Durability
ASTM C 270 Mortar Selection Guide:
• Exterior walls – Type N (alternatively S or M)
• Below grade – Type S (alternatively M or N)

26. Design Considerations:
Basic Concrete Masonry Wall Types
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Barrier Single-Wythe Cavity

27. Barrier Wall
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• Collar joint
between wythes
acts a barrier to
moisture along
with the thickness
of the wall
• Examples
– Brick and Block
Composite Wall
– Solid Grouted
CMU Wall

28. Cavity Wall
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29. Rain Screen Wall
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• Equalizes pressure within cavity
• Vents at top and bottom of wall or panel
• Flashing and weep holes
• Compartmentalized
• Allows for ventilation and evaporation

30. Components for Moisture Mitigation
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• Flashing Successful
• Weeps Mitigation
• Vents Requires
• Water Repellent Admixtures Consideration
• Sealants & Coatings of ALL
• Vapor Retarders Components

31. Best Performance Is Achieved
By Redundancy
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Level of
Defense Defense Mechanism
1 Surface Protection
• Mortar Joints
• Sealants /Coatings
Vapor 2 Internal Protection
Barriers • Integral Water Repellents
3 Drainage
• Flashing, weeps and vents

32. Surface Protection:
Clear Surface Treatments
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• Acrylics - form elastic film over surface.
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Quick drying. $
• Silicone Resins - good penetration.
Drying time 4-5 hours. $
• Silanes - good penetration. More volatile.
Can be applied to damp surfaces. $$
• Siloxanes - similar benefits of silanes.
Effective on wider variety of surfaces. $$

33. Surface Protection:
Opaque Surface Treatments
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Services • Portland Cement Plaster (Stucco) - Cementitious
coating. $$
• Cement-Based Paint - good durability (including
alkalis). Fills small voids. $
• Latex Paint - water based. Good durability
(including alkalis). Breathable. Applied to damp
or dry surfaces and cure quickly. Good hiding
characteristics. $
• Alkyd Paints - Durable, flexible, quick dry. Low
alkali resistance. $

34. Internal Protection:
Integral Water Repellents
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Services If the surface barrier compromised, moisture
can move through the wall by:
• gravity
• pressure
• capillary action

35. Integral Water Repellents
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• Polymeric material which does not alter
the finished appearance of the block.
• Lasts the lifetime of the unit.
• Cuts down on possibility of
efflorescence.
• Incorporate a compatible integral water
repellent admixture into the mortar.

36. Drainage:
Flashing Material Options
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• Sheet Metals
• Composite Materials
• Plastic and Rubber Compounds

37. Flashing Materials
Metals
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Stainless Durable, Hard to form
Steel non staining
Cold-Rolled Flexible, durable, Damaged by
Copper easy to work with excessive flexing
and can stain
Easy to paint and
Galvanized durable Corrodes early in
Steel acidic and salty air

38. Flashing Materials
Plastic and Rubber Compounds
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EPDM Flexible, easy to Aesthetics, full
form, non-staining support
recommended
Rubberized Fully adhered, self Full support
asphalt healing, flexible, required, degrades
in UV light, metal
easy to form and drip edge required
join

39. Flashing Materials
Plastic and Rubber Compounds
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Material Advantages Disadvantages
PVC Easy to form and Easily damaged,
join, non- full support
staining, low cost required, metal
drip edge
required,
questionable
durability

40. Flashing Locations
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Needed anywhere the downward vertical
path of water to the weeps is interrupted:
• Base and foundation
• Lintels
• Bond beams
• Parapets
• Intermediate roofs

41. Flashing Detail at
Reinforced Cell
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Architectural unit
with inside faceshell
and part of webs cut
off to fit (typ. a & c)
3 in. (76 mm) unit for
8 in. (203 mm) wall,
4 in. (102 mm) unit for
> 8 in. (203 mm) wall

42. Flashing Detail at
Unreinforced Cell
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hell (typ. b & c)
cut
& c)
Weep holes @
2 ft. 8 in. (813 mm)
t for o.c. partially open
all, "L-shaped" head
nit for joints
wall
1 in. (25 mm)

43. Detail at Inside Face Shell
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Edge of flashing Stop flashing at
sealed by mortar inside of faceshell
from joint
Cavity filter*
Solid unit or
filled hollow unit
to support flashing Flashing
Typical detail at inside of faceshell

44. Optional Flashing Detail at
Unreinforced Cell
Mortar net*
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#5 (#16) min. @
48 in. (1219 mm) o.c.
4 in. (102 mm) unit
Drip edge (typ.)

45. Good Flashing Detail
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46. Poor Detail
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47. Drip Edge
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48. End Dams
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49. Weep Holes
At 32 inches max.
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50. Weep Holes
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• Cotton sash cord
for drainage path
(remove after wall
is laid up)
• Partially open
head joints
(preferred)

51. Products & Workmanship
Tying it all Together
Continuing
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Services • The quality and compatibility of material
components and care in installation are key to
wall performance.
• The recommended specification
for products and workmanship
for masonry construction are
covered in the latest edition of
Masonry Standards Joint
Committee ACI 530.1/ASCE
6/TMS 602

52. Mold Susceptibility
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Building Susceptible to Provides food Deterioration
Material mold growth? source for mold? from mold?
Concrete Masonry Yes No No
Gypsum Wallboard Yes Yes Yes
Wood surfaces Yes Yes Yes
Vinyl, linoleum Yes No (except for Yes
adhesisves)
Plastics, metals Yes No No

53. Mold Remediation
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Concrete Masonry Wet vacuum or HEPA vacuum
Gypsum Wallboard Remove and discard if possible, or HEPA vacuum
Wood surfaces Wet vacuum, damp-wipe or scrub surfaces, HEPA
vacuum, or remove and discard if a large area is
affected or if there is significant occupant exposure
during remediation.
Vinyl, linoleum Same as for wood surfaces
Plastics, metals Wet vacuum, damp-wipe or scrub surfaces, or HEPA
vacuum
HEPA = high-efficiency particulate air vacuum

54. Summary
NCMA
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Masonry is a good
choice!
Simply choosing
masonry is not
enough - attention
needed for design,
construction and
maintenance.