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Bathroom Ventilation Ducts & Fans

1/29/2018

Bathroom ventilation systems are designed to exhaust odors and moist air to the home's exterior. Typical systems consist of a ceiling fan unit connected to a duct that terminates at the roof.

Fan Function

The fan may be controlled in one of several ways:

Most are controlled by a conventional wall switch.
A timer switch may be mounted on the wall.
A wall-mounted humidistat can be pre-set to turn the fan on and off based on different levels of relative humidity.

Newer fans may be very quiet but work just fine. Older fans may be very noisy or very quiet. If an older fan is quiet, it may not be working well. Inspectors can test for adequate fan airflow with a chemical smoke pencil or a powder puff bottle, but such tests exceed InterNACHI's Standards of Practice.

Bathroom ventilation fans should be inspected for dust buildup that can impede air flow. Particles of moisture-laden animal dander and lint are attracted

to the fan because of its static charge. Inspectors should comment on dirty fan covers.
Ventilation systems should be installed in all bathrooms. This includes bathrooms with windows, since windows will not be opened during the winter in cold climates.

Defects

The following conditions indicate insufficient bathroom ventilation:

moisture stains on walls or ceilings;
corrosion of metal;
visible mold on walls or ceilings;
peeling paint or wallpaper;
frost on windows; and
high levels of humidity.

The most common defect related to bathroom ventilation systems is improper termination of the duct. Vents must terminate at the home exterior.

The most common improper terminations locations are:

mid-level in the attic. These are easy to spot;
beneath the insulation. You need to remember to look. The duct may terminate beneath the insulation or there may be no duct installed; and
under attic vents. The duct must terminate at the home exterior, not just under it.

Improperly terminated ventilation systems may appear to work fine from inside the bathroom, so the inspector may have to look in the attic or on the roof. Sometimes, poorly installed ducts will loosen or become disconnected at joints or connections.

Ducts that leak or terminate in attics can cause problems from condensation. Warm, moist air will condense on cold attic framing, insulation and other materials. This condition has the potential to cause health and/or decay problems from mold, or damage to building materials, such as drywall. Moisture also reduces the effectiveness of thermal insulation.

Mold

Perhaps the most serious consequence of an improper ventilation setup is the potential accumulation of mold in attics or crawlspaces. Mold may appear as a fuzzy, thread-like, cobwebby fungus, although it can never be identified with certainty without being lab-tested. Health problems caused by mold are related to high concentrations of spores in indoor air. Spores are like microscopic seeds, released by mold fungi when they reproduce. Every home has mold. Moisture levels of about 20% in materials will cause mold colonies to grow. Inhaling mold spores can cause health problems in those with asthma or allergies, and can cause serious or fatal fungal infections in those with lung disease or compromised immune systems.
Mold is impossible to identify visually and must be tested by a lab in order to be confidently labeled. Inspectors should refrain from calling anything “mold” but should refer to anything that appears as mold as a material that “appears to be microbial growth.” Inspectors should include in their report, and in the inspection agreement signed by the client, a disclaimer clearly stating that the General Home Inspection is an inspection for safety and system defects, not a mold inspection.
Decay, which is rot, is also caused by fungi. Incipient or early decay cannot be seen. By the time decay becomes visible, affected wood may have lost up to 50% of its strength.
In order to grow, mold fungi require the following conditions to be present:

oxygen;
temperatures between approximately 45° F and 85° F;
food. This includes a wider variety of materials found in homes; and
moisture.

If insufficient levels of any of these requirements exist, all mold growth will stop and fungi will go dormant. Most are difficult to actually kill.
Even though mold growth may take place in the attic, mold spores can be sucked into the living areas of a residence by low air pressure. Low air pressure is usually created by the expulsion of household air from exhaust fans in bathrooms, dryers, kitchens and heating equipment.

Improper Ventilation
Ventilation ducts must be made from appropriate materials and oriented effectively in order to ensure that stale air is properly exhausted.

Ventilation ducts must:

terminate outdoors. Ducts should never terminate within the building envelope;
contain a screen or louvered (angled) slats at its termination to prevent bird, rodent and insect entry;
be as short and straight as possible and avoid turns. Longer ducts allow more time for vapor to condense

and also force the exhaust fan to work harder;
be insulated, especially in cooler climates. Cold ducts encourage condensation;
protrude at least several inches from the roof;
be equipped with a roof termination cap that protects the duct from the elements; and
be installed according to the manufacturer's recommendations.

The following tips are helpful, although not required. Ventilation ducts should:

be made from inflexible metal, PVC, or other rigid material. Unlike dryer exhaust vents, they should not droop; and
have smooth interiors. Ridges will encourage vapor to condense, allowing water to back-flow into the exhaust fan or leak through joints onto vulnerable surfaces.

Above all else, a bathroom ventilation fan should be connected to a duct capable of venting water vapor and odors into the outdoors. Mold growth within the bathroom or attic is a clear indication of improper ventilation that must be corrected in order to avoid structural decay and respiratory health issues.

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Anti-Scald Valve: What They Do To Protect You!

1/18/2018

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Anti-scald valves, also known as tempering valves and mixing valves, mix cold water in with outgoing hot water so that the hot water that leaves a fixture is not hot enough to scald a person.

Facts and Figures

Scalds account for 20% of all burns.
More than 2,000 American children are scalded each year, mostly in the bathroom and kitchen.
Scalding and other types of burns require costly and expensive hospital stays, often involving skin grafts and plastic surgery.
Scalding may lead to additional injuries, such as falls and heart attacks, especially among the elderly.
Water that is 160º F can cause scalding in 0.5 seconds.

Unwanted temperature fluctuations are an annoyance and a safety hazard. When a toilet is flushed, for instance, cold water flows into the toilet’s tank and lowers the pressure in the cold-water pipes. If someone is taking a shower, they will suddenly feel the water become hotter as less cold water is available to the shower valve. By the same principle, the shower water will become colder when someone in the house uses the hot-water faucet. This condition is exacerbated by plumbing that’s clogged, narrow, or installed in showers equipped with low-flow or multiple showerheads. A sudden burst of hot water can cause serious burns, particularly in young children, who have thinner skin than adults. Also, a startling thermal shock – hot or cold – may cause a person to fall in the shower as he or she scrambles on the slippery surface to adjust the water temperature. The elderly and physically challenged are at particular risk.

Anti-scald valves mitigate this danger by maintaining water temperature at a safe level, even as pressures fluctuate in water supply lines. They look similar to ordinary shower and tub valves and are equipped with a special diaphragm or piston mechanism that immediately balances the pressure of the hot- and cold-water inputs, limiting one or the other to keep the temperature within a range of several degrees. As a side effect, the use of an anti-scald valve increases the amount of available hot water, as it is drawn more slowly from the water heater. Inspectors and homeowners may want to check with the authority having jurisdiction (AHJ) to see if these safety measures are required in new construction in their area.

Installation of anti-scald valves is typically simple and inexpensive. Most models are installed in the hot-water line and require a cold-water feed. They also require a swing check valve on the cold-water feed line to prevent hot water from entering the cold-water system. They may be installed at the water heater to safeguard the plumbing for the whole building, or only at specific fixtures.

The actual temperature of the water that comes out of the fixture may be somewhat different than the target temperature set on the anti-scald valve. Such irregularities may be due to long, uninsulated plumbing lines or defects in the valve itself. Users may fine-tune the valve with a rotating mechanism that will allow the water to become hotter or colder, depending on which way it’s turned. Homeowners may contact an InterNACHI inspector or a qualified plumber if they have further questions or concerns.

In summary, anti-scald valves are used to reduce water temperature fluctuations that may otherwise inconvenience or harm unsuspecting building occupants.

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Kickout Flashing

1/12/2018

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Kickout flashing, also known as diverter flashing, is a special type of flashing that diverts rainwater away from the cladding and into the gutter. When installed properly, they provide excellent protection against the penetration of water into the building envelope.

Several factors can lead to rainwater intrusion, but a missing kickout flashing, in particular, often results in concentrated areas of water accumulation and potentially severe damage to exterior walls. InterNACHI inspectors should make sure that kickouts are present where they are needed and that they are installed correctly. Water penetration into the cladding can occasionally be observed on the exterior wall in the form of vertical water stains, although inspectors should not rely on visual identification. There may be severe damage with little or no visible evidence.

The kickout was never installed.

The need for kickout flashing developed fairly recently and the builder may not have been aware that one was required. The increased amount of insulation and building wrap that is used in modern construction makes buildings less breathable and more likely to sustain water damage. Kickout flashing prevents rainwater from being absorbed into the wall and is more essential than ever.

The following are locations where kickout flashing is critical:

anywhere a roof and exterior wall intersect, where the wall continues past the lower roof-edge and gutter. If a kickout flashing is absent in this location, large amounts of water may miss the gutter, penetrate the siding, and become trapped inside the wall; and
where gutters terminate at the side of a chimney.

The kickout was improperly installed.

The bottom seam of the flashing must be watertight. If it is not, water will leak through the seam and may penetrate the cladding.
The angle of the diverter should never be less than 110 degrees.
The kick-out was modified by the homeowner.
Homeowners who do not understand the importance of kickouts may choose to alter them because they are unsightly. A common way this is done is to shorten their height to less than the standard six inches (although some manufacturers permit four inches), which will greatly reduce their effectiveness. Kickout flashings should be the same height as the side wall flashings.
Homeowners may also make kickout flashings less conspicuous by cutting them flush with the wall.

In summary, kickout flashing should be present and properly installed in order to direct rainwater away from the cladding.

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Ice Dams: Prevention & Removal Methods

1/2/2018

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An ice dam is a ridge of ice that forms at the edge of a roof and prevents melting snow from draining. As water backs up behind the dam, it can leak through the roof and cause damage to walls, ceilings, insulation and other areas.

How do ice dams form?

Ice dams are formed by an interaction between snow cover, outside temperatures, and heat lost through the roof. Specifically, there must be snow on the roof, warm portions of the upper roof (warmer than 32° F), and cold portions of the lower roof (at freezing or below). Melted snow from the warmer areas will refreeze when it flows down to the colder portions, forming an ice dam.

Although the primary contributor to snow melting is heat loss from the building's interior, solar radiation can also provide sufficient heat to melt snow on a roof. For example, in southern Canada, enough sunlight can be transmitted through 6 inches (150 mm) of snow cover on a clear and sunny day to cause melting at the roof's surface even when the outside temperature is 14° F (-10° C), with an attic temperature of 23° F (-5° C).

Gutters do not cause ice dams to form, contrary to popular belief. Gutters do, however, help concentrate ice from the dam in a vulnerable area, where parts of the house can peel away under the weight of the ice and come crashing to the ground.

Problems Associated with Ice Dams
Ice dams are problematic because they force water to leak from the roof into the building envelope. This may lead to:

rotted roof decking, exterior and interior walls, and framing;
respiratory illnesses (allergies, asthma, etc.) caused by mold growth;
reduced effectiveness of insulation. Wet insulation doesn’t work well, and chronically wet insulation will not decompress even when it dries. Without working insulation, even more heat will escape to the roof where more snow will melt, causing more ice dams which, in turn, will lead to leaks; and
peeling paint. Water from the leak will infiltrate wall cavities and cause paint to peel and blister. This may happen long after the ice dam has melted and thus not appear directly related to the ice dam.

Prevention

Keep the entire roof cold. This can be accomplished by implementing the following measures:
- Install a metal roof. Ice formations may occur on metal roofs, but the design of the roof will not allow the melting water to penetrate the roof's surface. Also,snow and ice are more likely to slide off of a smooth, metal surface than asphalt shingles.
- Seal all air leaks in the attic floor, such as those surrounding wire and plumbing penetrations, attic hatches, and ceiling light fixtures leading to the attic from the living space below.
- Increase the thickness of insulation on the attic floor, ductwork, and chimneys that pass through the attic.
Move or elevate exhaust systems that terminate just above the roof, where they are likely to melt snow.
A minimum of 3" air space is recommended between the top of insulation and roof sheathing in sloped ceilings.
Remove snow from the roof. This can be accomplished safely using a roof rake from the ground. Be careful not to harm roofing materials or to dislodge dangerous icicles.
Create channels in the ice by hosing it with warm water. Because this process intentionally adds water to the roof, this should be done only in emergencies where a great deal of water is already flowing through the roof, and when temperatures are warm enough that the hose water can drain before it freezes.

Prevention and Removal Methods to Avoid

electric heat cables. These rarely work, they require effort to install, they use electricity, and they can make shingles brittle.
manual removal of the ice dam using shovels, hammers, ice picks, rakes, or whatever destructive items can be found in the shed. The roof can be easily damaged by these efforts, as can the homeowner, when they slip off of the icy roof.

In summary, ice dams are caused by inadequate attic insulation, but homeowners can take certain preventative measures to ensure that they are rare.

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Bathroom Ventilation Ducts & Fans

Anti-Scald Valve: What They Do To Protect You!

Kickout Flashing

Ice Dams: Prevention & Removal Methods

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