Insulation and Ventilation

Question 1

INSULATION
Stationary air is actually a good insulator. and is how most insulation achieves its R-value

True or False

Answer 1

True

Question 2

Air barrier:

any material or combination of materials that prevents the flow of air from unconditioned areas into the thermal envelope.

(True or False)

Answer 2

True

Question 3

Basement wall:

a wall with at least (≥) 70% of its area below grade (covered by earth on the outside) and encloses conditioned space.

True or False

Answer 3

False

(≥) 50%, not 70

Question 4

Building thermal envelope:
(Choose the INCORRECT answer)

a) the conditioned (heated and cooled) area of the building.
b) The envelope boundary between conditioned and unconditioned space includes walls, ceilings, floors, basement walls and slab-on-grade foundations.
c) The thermal envelope may include the attic and the crawl space if these areas are designed and built as conditioned space.
d) none of the above

Answer 4

d) none of the above

Question 5

Dew point (temperature):

the temperature at which water vapor in the air may condense into liquid water. A higher dew point temperature indicates that the air contains more water vapor.

True or False

Answer 5

True

Question 6

Fenestration:
Which of the following openings in the wall and roof of a house are not Fenestrations:

a) windows
b) doors
c) skylights
d) garage door

Answer 6

d) garage door

Question 7

Humidity, relative:
(Choose the INCORRECT answer)

a) the amount of water vapor that is actually in the air compared to the amount of water vapor that could exist in the air at a given air temperature, expressed as a percentage.
b) More moisture can exist in warm air than in cold air, so raising the air temperature while keeping the water vapor constant reduces relative humidity.
c) Lowering the air temperature and keeping the water vapor content constant reduces relative humidity.
d) none of the above

Answer 7

c) Lowering the air temperature and keeping the water vapor content constant INCREASES (not reduces) relative humidity.

Question 8

Mass wall:
Which of the following is not a component of mass walls:

a) concrete,
b) brick or adobe
c) brick veneer
d) solid timber logs.

Answer 8

c) brick veneer

Question 9

Permeability:
(Choose the INCORRECT answer)

a) the ability or property of a material to resist or allow the diffusion of water vapor through the material.
b) Permeability (perms) is expressed as a number greater than five.
c) For example, glass is a very low permeability material and fiberglass batt insulation is a high permeability material.
d) none of the above

Answer 9

b) a number greater than ZERO, not 5.

Question 10

R-value:
(Choose the INCORRECT answer)

a) the ability or property of a material to slow heat transfer.
b) A higher R-value number equals a higher ability to slow heat transfer.
c) R-value is expressed as a number greater than five.
d) R-value is used to compare the insulation value of materials.

Answer 10

c) R-value is expressed as a number greater than zero (not 5).

Question 11

Solar heat gain coefficient (SHGC):
(Choose the INCORRECT answer)

a) a measure of the amount of solar radiation that passes through a window.
b) A lower SHGC means that less solar radiation passes through a window.
c) both a and b)
d) none of the above

Answer 11

d) none of the above

Question 12

U-value (factor):

Answer 12

the ability or property of a material to allow heat transfer. U-value is the inverse of R-value (R-value = 1/U-value). U-value is expressed as a number greater than zero. A larger number equals a higher rate of heat transfer and a lower R-value. U-value is primarily used in residential construction to compare the thermal performance of fenestration. For example, metal such as aluminum has a high U-value; this is why higher quality aluminum windows have a thermal break in the frame to slow heat transfer.

Question 13

Vapor barrier:

Answer 13

a technically questionable term often used when the term vapor retarder is intended. Class I vapor retarders are effectively vapor barriers, but the term vapor retarder is preferred.

Question 14

Vapor diffusion:

Answer 14

the process by which water vapor passes through a permeable mate-rial from an area of greater vapor pressure to an area of lower vapor pressure.

Question 15

Vapor drive:

Answer 15

a condition that occurs when heat and vapor pressure cause increased vapor diffusion. One example is when water vapor diffuses through permeable building materials from heated interior areas in the winter. Another example is when solar radiation heats wet bricks forcing water vapor through permeable building materials in the summer. Vapor drive is usually less of a factor than vapor flow by convection through openings in the building envelope.

Question 16

Vapor retarder:

Answer 16

a material that restricts the flow of water vapor. A Class I vapor retarder is rated at 0.1 perms or less. Polyethylene sheeting is an example. A Class II vapor retarder is rated at between 0.1 and 1.0 perms. Kraft paper used as the facing on some batt insulation is an example. A Class III vapor retarder is rated at between 1.0 and 10.0 perms. Latex and oil paints are examples.

Question 17

Ventilation (building):

Answer 17

the process of supplying outside air to a house or removing inside air from a house by natural or mechanical means; ventilation can be random and uncontrolled (air leaks), or it can be designed and controlled (outside air ducts, heat recovery ventilators, energy recovery ventilators).

Question 18

HOW INSULATION WORKS

Answer 18

•Heat energy transfers from some place hotter to some place colder.
•Hotter air is lighter than cooler air and will rise (stack effect).
Air moving across or through insulation reduces its resistance to heat flow (its R-value).
Insulation that has more, but not too many air pockets, that completely fills the space in which it is installed, and that does not have air moving around or through it has a higher resistance to heat transfer (a higher R-value)
Insulation that is compressed, even a little, loses R-value because it contains less air to slow heat transfer. Conversely, insulation that is “fluffed” also loses R-value because it is not dense enough to keep the air in the insulation stable
Wet insulation loses R-value because heat transfers more effectively through water. Wet insulation also retains water that can provide moisture for fungal growth.
Because insulation works primarily by slowing conductive heat flow, insulation must be in contact with an air barrier that is adjacent to conditioned space
All conditioned spaces should have insulation installed at the surface closest to the conditioned space.
Moisture stains or mold growth near these areas or near baseboards can be an indication of an insulation or air sealing defect.
The ideal insulation installation has an air barrier on all six sides of the insulation to eliminate convection around and through the insulation, a phenomenon sometimes called wind washing. Insulation that is not in direct contact with an air barrier at the insulated area is practically worthless.
Air that flows between the insulation and conditioned space, and air that flows through or around the insulation, can reduce the R-value of the insulation to almost zero.
Relatively poor R-value of wood. You can see this using an infrared camera. This phenomenon is called thermal bridging. One effect of thermal bridging is to reduce the total R-value of the assembly
The other effect is to provide a surface on which water vapor in the assembly can condense.
Strategies for reducing thermal bridging include using fewer framing members and installing insulating exterior sheathing.

Question 19

HOW VAPOR RETARDERS WORK

Answer 19

• Water vapor in the air flows (diffuses) from a place with more water vapor to a place with less water vapor.
• More water vapor can exist in warm air than in cool air.
• Water vapor in the air may condense into liquid water if the air temperature decreases to the dew point.

The ease with which this happens depends on the permeability of the material.
Brick, wood and vinyl siding, #15 building felt, and insulation are vapor permeable, meaning they allow water vapor to pass easily. Most house wrap material is vapor permeable. Drywall, OSB and plywood sheathing, and insulation sheathing (1 inch or less thick), are moderately vapor permeable and are not considered vapor retarders. Polyethylene and foil sheeting, Kraft paper, and vinyl and foil wallpaper are vapor impermeable, meaning they do not allow water vapor to pass easily. These materials and others are considered vapor retarders, although wallpaper is not supposed to be used as a vapor retarder.
A vapor retarder was installed on the interior side of exterior framed walls in all climates
We now know that this one size fits all approach causes problems, especially in warm/humid climates.
The humidity divisions are (A) moist, (B) dry, and (C) marine. Most of the continental US is in zones 2 - 7

Question 20

Vapor Retarders in Walls

Answer 20

A vapor retarder is not required, nor is it recommended, on either side of walls in climate zones 1 - 4.
A wall cavity should be designed to dry toward at least one side, so a vapor retarder should not be installed on both sides of a wall cavity.
A Class I or II vapor retarder is usually required on the interior side of walls in climate zones 5 - 8 and Marine 4. There are several exceptions to this requirement that allow a Class III vapor retarder. These exceptions involve using specific types of wall cladding and sheathing material.
A vapor retarder is not required in an adequately ventilated attic.
in climate zones 6 - 8 as an alternative to the 1/150 attic ventilation ratio. If a vapor retarder is installed, it should be installed in contact with the conditioned space.
A vapor retarder installed above the insulation can create a moisture trap.

Question 21

THE HOUSE AS A SYSTEM

Answer 21

House systems and components, house occupants, and the environment in which the house exists are constantly acting on each other.
This makes the house, occupants, and its environment one complex interdependent system.
The easiest way to think about the house as a system is in terms of pressures and holes.
Air and water vapor will remain motionless without pressure (a force) to move them. This is an expression of NEWTON’S FIRST LAW OF MOTION. Air and water vapor will remain in the same space unless there is a hole through which they can pass.
Pressure comes in many forms.
Holes can be visible.
Holes can be microscopic.

Mold and Rot in the Attic.
Several systems contribute to the situation.
The current crawl space ventilation rules have no scientific or empirical basis and were developed before the widespread use of air conditioning.

Question 22

COMMON TYPES OF INSULATION

Answer 22

BATT (blanket) insulation comes in rolls that are usually installed between framing members. Some batts have a vapor retarder on one side and are called FACED BATTS. Some have NO VAPOR RETARDER and are called UNFACED BATTS. The vapor retarder is usually a heavy paper called KRAFT PAPER.

The most common type of batt insulation is made from FIBERGLASS. MINERAL WOOL is another less common insulation type. Mineral wool is made from natural minerals (rocks) or from waste products from steel production (slag). Batts made from cotton are marketed as eco-friendly insulation, but are uncommon. Batts made from recycled plastic are also marketed as eco-friendly, but are uncommon.

Fiberglass batts range between about R-3 (standard) to R-4 (high density) per inch. Mineral wool batts are about R-3.7 per inch. Cotton batts are about R-3.7 per inch. Plastic batts are about R-4 per inch.
Unfaced batt insulation is not an air barrier nor is it a vapor retarder.

Question 23

Loose Fill/Blown-in Insulation

Answer 23

Loose fill (also called blown-in or blown) insulation comes in bags.
Loose fill insulation is usually installed on the attic floor. The material can be blown into fabric suspended from the rafters in unventilated attics.
Cellulose loose fill can be blown into wall cavities.
Most loose fill insulation is usually made from fiberglass or cellulose.
Loose fill fiberglass, like fiberglass batts, is available in low and high density versions.
Low density fiberglass R-value is about R-2.2 per inch.
High density fiberglass is heavier and is less easily moved. High density fiberglass R-value is about R-2.7 per inch.
Loose fill mineral wool R-value is about R-3.1 per inch
A blown-in fiberglass system called Blown-in Batts (Blankets) is also available, but is less common. Its R-value is about R-3.8 per inch. Loose fill insulation is not an air-barrier, nor is it a vapor retarder.

Question 24

Sheet/Rigid Insulation

Answer 24

Sheet insulation is most commonly available in 4 foot wide sheets of various lengths (8 to 10 feet are the most common).
Many types of sheet and spray foam insulation may need protection from ignition because they are flammable and because they produce toxic smoke when they burn.
Expanded Polystyrene (EPS) is usually white and looks like a sheet of white beads stuck together (which is what it is).
The R-value of EPS sheets is about R-4 per inch
he permeability of 1 inch of EPS is about 5.0, which makes it a Class III vapor retarder. EPS is an air barrier if the seams are sealed. EPS is also available as a loose fill material with an R-value of about R-2.5 per inch.
Extruded Polystyrene (XPS) is usually pink, blue, or green depending on the manufacturer.
Its R- value is about R-5 per inch..
The permeability of 1 inch of XPS is about 1.1, which makes it a Class III vapor retarder but very close to a Class II vapor retarder. XPS is an air barrier if the seams are sealed.
Polyisocyanurate and polyurethane are usually a light orange or a light yellow color.
Both often have a foil vapor retarder or radiant barrier on both sides which makes them Class I vapor retarders.
Both lose some R-value over time as the gas inside escapes.
They may start with an R-value around R-8 per inch, but the long term r-value is about R-6 per inch. These sheets are air barriers if the seams are sealed.

Question 25

Spray Foam Insulation

Answer 25

Most spray foam insulation is either polyisocyanurate or polyurethane.
Cementitious foam (such as Air Krete) is available, but is uncommon. Latex foam is primarily a consumer product that is sold in cans for small sealing projects. Latex foam is an open cell product and should not be used as a substitute for caulking where water sealing is required.
Polyisocyanurate and polyurethane foam come in two types, open cell (½ pound) and closed cell (2 pound).
Both types are effective air barriers.
The R-value of open cell is about R-3.7 per inch; closed cell is about R-6 per inch.

Question 26

Other Insulation Types

Answer 26

Vermiculite has an R-value of about R-2.4 per inch.
much of the vermiculite used in residential insulation came from a mine that also contained asbestos.
Vermiculite insulation is, therefore, a possible asbestos containing material.
Loose fill perlite insulation has an R-value of about R-2.4 per inch.
Perlite is not a possible asbestos containing material.
Urea-Formaldehyde Foam (UFFI) is no longer used in residential applications because of formaldehyde off gassing.
It is no longer a health concern because the off gassing has subsided.

Question 27

Typical Insulation Defects

Answer 27

1. Insulation R-value is less than current standards
2. Insulation depth is less than the normal depth for the material or less than the stated depth on the insulation card.
3. Insulation is absent at conditioned space
4. Insulation is compressed or disturbed
5. Insulation is not in contact with the air barrier at conditioned space
6. Strands of batt insulation are hanging from insulation in a crawl space
7. Insulation is blocking ventilation openings
8. Insulation is not cut to fit into the space
9. Insulation is not cut around obstructions: insulation should be cut to fit around obstructions.
10. Chases are not fireblocked and are not insulated.
11. Insulation is in contact with heat-generating components
12. Vapor retarder is installed facing unconditioned space.
13. Multiple vapor retarders are installed.

Question 28

ENERGY EFFICIENCY AND MOISTURE MANAGEMENT COMPONENTS

Answer 28

A water-resistive barrier is now required under all exterior wall cladding. These are also called weather-resistant barriers. A WRB has not always been required.
The original WRBs were asphalt saturated Kraft paper (Grade D paper) and asphalt saturated felt (usually #15).
Correct installation was (and still is in many cases) uncommon.
These include house wraps, liquid coatings, and wall sheathing with an integrated wRB.
Experience and testing indicates that liquid water and water vapor will penetrate through all wall claddings whether through holes or gaps in the cladding or by vapor drive.

Question 29

Radiant Barriers

Answer 29

Radiant barriers are not insulation and provide no R-value.

A radiant barrier is intended to reflect infrared radiation (heat) so that it does not enter the house.

Question 30

Fenestration

Answer 30

A typical single pane wood window has an R-value around R-1. A typical double pane wood window has an R-value around R-1.8. The best (very expensive) triple pane inert gas filled windows are only about R-4.5. A typical wood door is about R-2

Question 31

Recommended Energy Efficiency Values

Answer 31

The following table presents current (2018) minimum R-values and U-factors for residential building insulation and fenestration

Question 32

MECHANICAL VENTILATION AND EXHAUST

Answer 32

Ventilation involves bringing (fresh) outside air inside the house and removing (polluted) inside air to outside the house.

Heat Recovery Ventilation System (HRV) and
Energy Recovery Ventilation System (ERV)

The HVAC connected outside air duct method: An automatic damper that closes when the system is not active should be installed in the duct system

HRVs and ERVs may provide ventilation by operating continuously or intermittently.
The difference between an HRV and an ERV is that HRVs transfer only heat between the incoming supply and outgoing exhaust air, while ERVs transfer heat and some moisture.
HRVs and ERVs are installed in one of three duct configurations:
The fully ducted configuration uses exhaust ducts connected to grilles in bathrooms, the kitchen, and laundry to remove pollutants and uses supply ducts to provide outside ventilation air to the living areas.
The partially ducted configuration uses exhaust ducts connected to grilles in bathrooms, the kitchen, and utility rooms to remove pollutants and provides outside ventilation air to living areas through the HVAC return duct.
The simplified duct configuration draws some pollutants from the HVAC return duct, and provides outside ventilation air through the HVAC return duct by connecting the outside ventilation air further downstream from where the exhaust air duct connects to the return duct.
HRVs may be installed in any climate and are recommended for cold climates. ERVs are recommended for mild climates and are not recommended for cold climates.
It is not possible to determine if HRVs and ERVs are properly balanced and operating as intended during a home inspection.

Question 33

Typical Defects. Typical defects that home inspectors should report include:

Answer 33

1. Air intake exterior opening too close to a vent or exhaust.
2. Exhaust exterior opening too close to a building opening.
3. No screen or protection at air intake or exhaust exterior opening.
4. Blocked exterior openings.
5. No filter on air intake.
6. Crimped or damaged ducts.
7. Lack of recommended maintenance.

Question 34

Whole-house fans

Answer 34

A traditional whole-house fan is a large (usually 24 to 36 inch diameter) fan that is installed in the ceiling, usually in a central hallway.
The primary occupant complaint about whole-house fans is noise, especially traditional models. Another problem is that they allow large amounts of conditioned air to escape into the attic during the winter.
A ratio of 1 square foot of net free ventilation openings per 750 cubic feet per minute of fan air flow is a common recommendation.
A fan should not be used when a combustion appliance draws combustion air from inside the house.
A fan should not be used when the attic has possible asbestos containing substances such as vermiculite insulation, or any other potentially toxic substance.

Question 35

Typical Defects of Whole-House fans that home inspectors should report include:

Answer 35

1. fan does not operate using normal controls,
2. damaged louvers, some or all do not operate,
3. loose or worn fan drive belt,
4. winter cover damaged or not available,
5. attic ventilation openings inadequate in area or blocked.

Question 36

Local Exhaust Systems

Answer 36

Local exhaust systems include those for the kitchen, bathrooms, laundry, and the clothes dryer.
The preferred term is exhaust because it more accurately describes the function of these systems, and it distinguishes them from other systems, such as appliance vents and plumbing vents.
Install a screen on the outdoor air intake and exhaust openings to restrict vermin entry.
The screen should have openings between ¼ and ½ inch. Install a damper in the air intake and exhaust system that automatically closes when the system is not operating.

Question 37

Clothes Dryer Exhaust

Answer 37

Proper installation of the clothes dryer exhaust system is important for safety and for efficient clothes dryer operation
Lint is flammable and if ignited can cause a fire.
The clothes dryer exhaust duct should be 4 inch diameter, minimum 28 gauge, smooth wall metal (usually galvanized steel).
The duct should be supported at least every 12 feet (4 feet for gas clothes dryers).
The duct should not exceed 35 feet developed length.
Developed length means the straight length of the duct plus additional length to account for the reduction in air flow caused by fittings that change duct direction.
Add 5 feet for most 90° bend fittings and 2½ feet for most 45° bend fittings.
Duct developed length does not include the transition duct.
The transition duct is the (usually) flexible duct between the clothes dryer and the exhaust duct.
The transition duct should not be more than 8 feet long.
It may not be run through walls, floors, or ceilings and may not be concealed.
Clothes dryers exhaust a lot of air.
When a clothes dryer is located in a closet and the doors are shut, there is probably not enough makeup air to allow effective dryer operation
An opening of at least 100 square inches should be provided for gas dryers located in a closet

Question 38

Typical Defects, Clothes Dryer Exhaust Typical defects that home inspectors should report include:

Answer 38

1. Duct too large or too small
2. Duct terminates inside an enclosed space including the attic or crawl space
3. Duct disconnected before the exterior termination hood:
4. Duct terminates within 3 feet from a door, window, mechanical air intake, or crawl space ventilation opening
5. Duct terminates within 3 feet from a condenser
6. Duct terminates into a bucket
7. Duct blocked by lint
8. Excessive lint behind the dryer or at the termination hood
9. Screen installed at the termination hood
10. Exterior damper stuck open or shut
11. Damaged or absent exterior damper
12. Transition duct penetrates a floor, wall, or ceiling
13. Constricted or damaged transition duct

Question 39

Kitchen Exhaust

Answer 39

An exhaust fan is not required in a kitchen if mechanical or natural ventilation is provided.
If installed, the fan should exhaust at a rate of at least 100 cubic feet per minute.
Kitchen exhaust fans are available in two general types. The most common is a hood or a microwave oven with an exhaust fan installed above the cooktop. These exhaust fans can usually be installed as an externally exhausted fans with an exhaust duct, or as a recirculating fan. The less common type is the downdraft in which a fan and duct are installed under the cooktop.
The duct material for under-slab ducts may be Schedule 40 PVC.
Round ducts are usually at least 6 inches diameter.
The duct should be air tight from the fan to the termination hood.
A backdraft damper should be installed. The damper may be installed at the termination hood or at the fan.

Question 40

Typical Defects, Kitchen Exhaust Typical defects that home inspectors should report include:

Answer 40

1. Duct constructed using non-metallic materials
2. Duct not air tight
3. Absent or damaged screen or protection at exterior opening.
4. Blocked exterior opening
5. Exterior damper is stuck open or shut
6. Small duct or exterior terminal
7. Absent or blocked grease filters
8. Duct terminates inside the building

Question 41

Bathroom Exhaust

Answer 41

A local exhaust fan is not required in a bathroom if mechanical or natural ventilation is provided. Current best practice is to install an exhaust fan in all bathrooms including those with an operable window.
Bathroom exhaust fans should be exhausted to the exterior.
2018 IRC effectively eliminates the use of 3 inch diameter flexible duct. Typical duct material is flexible foil covered 3 or 4 inch diameter

Question 42

Typical Defects, Bathroom Exhaust Typical defects that home inspectors should report include:

Answer 42

1. fan exhausted into the attic, crawl space, soffit or other location that is not to the exterior,
2. damaged, kinked, or crushed duct,
3. duct connected to another system such as a plumbing vent or the clothes dryer exhaust duct,
4. absent, damaged, stuck shut or stuck open damper at exterior termination hood,
5. fan does not function,
6. unusually noisy fan,
7. grille blocked by dust,
8. water staining near fan or duct, sometimes caused by condensation.

Question 43

ATTIC VENTILATION

Answer 43

Attic ventilation includes roof structures where there is no accessible attic.
Including low slope roofs that preclude an accessible attic. Attic ventilation also includes attics above unconditioned spaces such as an attached garage.
The alternative to a ventilated attic is to completely seal the attic from the outdoors and turn the attic into conditioned space.
Attic ventilation that functions properly involves more than just installing the required ventilation area.
Equally important to good attic ventilation is avoiding ventilation openings and devices that compete with each other.
An important part of achieving the benefits of attic ventilation is addressing the entire attic system.
Sealing openings between the attic and the house is important.
The default attic ventilation area requirement is 1 square foot of net free area for every 150 square feet of attic floor area or other ventilated space.
This default ventilation area requirement is almost always reduced to 1 square foot of net free area for every 300 square feet of ventilated space by installing the prescribed ratio of openings near the ridge and at the eaves.
Screens should have a maximum opening of ¼ inch.
A reasonable assumption is that screens reduce the gross opening area by at least 25% and screens combined with louvers or grilles reduce the gross opening area by at least 50%.

Question 44

Ventilation Installation

Answer 44

At least 40% and not more than 50% of the opening area should be at the ridge with the remainder in the eaves.
Properly ventilating vaulted ceilings where the finish material (drywall) is installed directly on the rafters is a common problem.
Insulation often blocks ventilation unless baffles are installed. Baffles should be continuous from the eaves to the ridge. Skylights are another obstruction that block continuous ventilation in vaulted ceilings. Installing ventilation openings above and below the skylight is one method of providing continuous ventilation. Notching the trimmer rafters on each side of the skylight is another method; but care must be taken not to impair the structural integrity of the rafters.
This staining could be caused by condensation, not by roof leaks, so evaluation by a roofing contractor and an insulation contractor may be prudent in this situation.

Question 45

Ventilation Devices and Opening Covers

Answer 45

Attic ventilation openings consist of intakes at and near the eaves and exhausts at and near the ridge.
Rectangular louvers are often 8x16 inches or 4x16 inches. Round louvers are available in various diameters.
Continuous opening covers are usually between about 2 and 4 inches wide.
Dormer covers are raised above the roof with louvered openings that are mostly vertical with respect to the roof; they get their name by looking like dormers projecting from the roof. O’Hagin covers are flat or rounded covers. Dormer and O’Hagin covers are popular with tile roof coverings.
Gable ventilation openings are installed in gable end walls. They can be triangular, rectangular, or round.
Water stains and water-compressed insulation are often found near gable ventilation openings.

Question 46

Typical Defects of Ventilation Systems that home inspectors should report include:

Answer 46

1. eave openings blocked, usually by insulation or poorly installed baffles,
2. ventilation opening covers (usually at the eaves) blocked, usually by paint,
3. damaged or absent ventilation opening covers,
4. ventilation opening covers, such as ridge covers, installed where no opening has been cut, or the covers are not installed directly over the opening, or openings are too small,
5. turbine ventilator does not turn,
6. powered attic ventilation fan does not function (service life can be as short as five years),
7. evidence of water infiltration near ventilation openings (usually at gable openings),
8. inadequate total ventilation opening area,
9. improper ventilation opening area distribution between eave and ridge openings,
10. improper ventilation opening location.

Question 47

Unventilated (Closed) Attic

Answer 47

A closed attic is conditioned space even if it has no HVAC supply or return duct openings. Insulation and vapor retarders should be installed above or below the roof sheathing, and at gable walls in a similar manner to walls and ceilings in other conditioned parts of the house.
Three methods exist for installing closed attic insulation and vapor retarders. Attention to details is essential for effective installation of all closed attic methods.
The home inspector should report this limitation to the client and recommend evaluation if the client wants more information about the installation details and the condition of the closed attic system
A Class I vapor retarder (such as polyethylene sheeting) should not be installed on the attic floor or at the ceiling above the closed attic space. Doing so would mean that vapor retarders are installed on both sides of the assembly and would trap any moisture entering the assembly.
Sealing the joints is necessary to form a complete vapor retarder.
A vapor diffusion port is required in closed attics located in climate zones 1, 2, and 3 when air-permeable insulation is installed.
Air-impermeable insulation may be installed either above or below the roof sheathing.
Air-impermeable insulation is installed above the roof sheathing, and air-permeable insulation is installed below the roof sheathing.

Question 48

Typical Defects of Unventilated Attics that home inspectors should report include:

Answer 48

1. openings to the exterior not sealed,
2. vapor retarder installed in the wrong location or not installed,
3. ventilation not provided for roof coverings when required,
4. thermal barrier or ignition barrier not installed to protect foam insulation,
5. damaged insulation,
6. absent or improperly installed vapor diffusion port where required.

Question 49

CRAWL SPACE VENTILATION

Answer 49

The current majority opinion is that passive crawl space ventilation as specified by current standards is not a good idea in most areas.
Passive ventilation can bring more warm and humid air into a crawl space during the summer than is removed by the passive ventilation.
Attempts to correct crawl space moisture problems using sump pumps, interior foundation drains, and dehumidifiers often address the symptoms instead of providing a cure.
The default crawl space ventilation area requirement is 1 square foot of net free area for every 150 square feet of crawl space floor area. This default ventilation area requirement may be reduced to 1 square foot of net free area for every 1,500 square feet of crawl space floor area by installing a Class I vapor retarder (usually 6 mil polyethylene sheeting) on the crawl space floor.
The crawl space vapor retarder is frequently poorly installed. While not required in a ventilated crawl space, the vapor retarder seams should be sealed and the edges should be sealed to walls and piers for maximum effectiveness.
Calculating the crawl space ventilation area is out of scope of a home inspection.
Screens should have an opening of not less than ¼ inch.
Ventilation openings should be located so that cross ventilation of the crawl space is possible. At least one opening should be located within 3 feet from each corner of the house.

Question 50

Typical Defects of Crawl Space Ventilation that home inspectors should report include:

Answer 50

1. ventilation openings blocked or are stuck shut,
2. damaged or absent ventilation opening covers,
3. inadequate total ventilation opening area,
4. improper ventilation opening location,
5. vapor retarder poorly installed and may not function properly,
6. dark areas or efflorescence on crawl space walls indicate water infiltration,
7. evidence of active water infiltration such as liquid water and wet soil,
8. damp insulation or strings of insulation hang down from the insulation,
9. significant fungal growth on framing materials,
10. evidence of past or current attempts to correct water infiltration are observed such as waterproofing material on the crawl space walls, interior foundation drains, and dehumidifiers.

Question 51

Unventilated (Closed) Crawl Spaces

Answer 51

The current majority opinion is that most crawl spaces should be closed.
The minimum vapor retarder thickness is usually 6 mil, but this material will not last long if the crawl space has much traffic. Ten to 12 mil (or better) reinforced material is more realistic, especially if there are appliances that require service in the crawl space.
Ventilation air should be provided to the crawl space.
The rate should be 1 cubic foot per minute for every 50 square feet of crawl space floor.
Crawl space walls, including framed walls and the band joist or rim board, should be insulated. Insulation may be installed on the interior or the exterior side of the walls. Crawl space access doors should be weather stripped and insulated like other doors to the exterior.
A small gap in the insulation (2 to 3 inches) is usually required in areas where termites are a problem, so that termite tubes can be seen

Question 52

Typical Defects to Closed Crawl Spaces that home inspectors should report include:

Answer 52

1. openings to the exterior not sealed,
2. damaged vapor retarder or seams not sealed,
3. thermal barrier or ignition barrier not installed to protect foam insulation,
4. damaged insulation,
5. insulation or vapor retarder not adequately fastened to foundation walls,
6. access door not insulated and weather stripped.

Question 53

BASEMENT WALL INSULATION

Answer 53

Insulating a full-height framed basement wall is relatively easy
The danger comes from liquid water and from water vapor that can diffuse through the wall and condense. Considerable damage and fungal growth can occur before the problem is discovered.
A common method of insulating and finishing basement foundation walls was to build a stud wall inside the basement foundation wall and insulate the framed wall using fiberglass batts.
This method can work if two conditions are satisfied; however, both conditions have significant practical limitations:
(1) the foundation wall is dry; meaning no liquid water flows and little or no water vapor diffuses through the wall. Dry foundation walls are an unusual situation in some areas.
(2) water vapor entering the framed wall cavity can dry toward conditioned space. This means not installing a vapor retarder on the interior side of the wall.
All fiberglass batt insulation methods are no longer recommended in any climate as a way to insulate concrete and masonry foundation walls.
The current recommended methods for insulating basement foundation walls involve installing vapor impermeable insulation either on the interior or the exterior of the foundation wall.
A basement should not be insulated and finished until there is reasonable certainty that all liquid water intrusion has been stopped.
A home inspector who is inspecting a finished basement should pay special attention to evidence of moisture problems behind the wall and in the basement. Evidence includes:
•water stains and fungal growth, especially near the floor,
•rust on drywall and trim nails and rust on exposed metal columns,
•musty smells,
•presence of a dehumidifier, especially if it appears to be constantly running,
•stained or loose floor coverings (lifting carpeting at a corner to observe the tack strip can provide good evidence).