Structures 101 – What You Should Know About The “Bones”

"This house isn't going anywhere." Or is it!?

Serious structural problems in houses are not very common, but when they occur they are never cheap to fix. Some can’t be fixed at all. This report won’t turn you into a home inspector, but it will give you some of the common indicators.

Uneven Floors

Uneven floors are typical, particularly in older homes. Here is a trick to help distinguish between a typical home with character and a structural problem. It’s not unusual for an older home to have the floor sag in the middle. On the other hand, if the floor slopes toward an outside wall, there is a good chance that the house has a significant structural problem.

Leaning House

While no house is perfect, this is one area where you should be very careful. Take a look at the house from across the street. If the house appears to be leaning one way or the other, there may be a structural problem. It may help to line up a front corner of the house with the back corner of an adjacent house just for reference. The corners should be parallel. Stepping back from the house to take a look is always a good idea. It is easy to miss something major by standing too close to it! If there is a lean that is detectable by eye, don’t take any chances. Get it checked out.

Horizontal Foundation Cracks are Bad

It is not uncommon to find cracks in the foundation. This goes for new houses as well as old ones. While there is a great deal of engineering that goes into “reading” these cracks, there is one rule that you should never forget. “Horizontal cracks are a problem”. Of course not all vertical cracks are acceptable, but they are generally not as serious as a horizontal crack.

Harmless Cracks

Shrinkage cracks in a new house: Most new foundations will develop small vertical cracks. These cracks are a result of the concrete shrinking as it cures. These cracks are about 1 /8 inch wide or less. They don’t affect the structure. The only concern is leakage. If you see small cracks in a new foundation, don’t panic. In fact, in a new home, some builders will pre-crack the foundation and fill the crack with flexible material.

Plaster Cracks:

Few things are more misunderstood than plaster cracks on the inside of the house.

The following crack types are not generally related to structural movement -

• a small crack (less than 1/4 inch) that follows the corner of the room where two walls meet
• small cracks that extend up from the upper corner of a door opening

The following cracks may be related to structural movement –

• large cracks (larger than 1/4 inch in width)
• cracks that run diagonally across the wall
• cracks on the interior finish that are in the same vicinity as cracks on the exterior of the house.

Line drawings are from the Carson Dunlop Home Inspection Training Program and Home Inspection Software Tool – Horizon

Carbon Monoxide – What You Need To Know

What is Carbon Monoxide (CO)?

• CO is a colorless, odorless, tasteless gas
• It is a by-product of incomplete combustion (unburned fuel such as gas, oil, wood, etc.)
• Low concentrations of CO can go undetected and can contribute to ongoing, unidentified illnesses. At high concentrations, it can be deadly.

Why is it Dangerous?

If there is CO in the air you breath, it will enter your blood system the same way oxygen does through your lungs. The CO displaces the oxygen in your blood, depriving your body of oxygen. When the CO displaces enough oxygen, you suffocate.

What are the Symptoms?

Continued exposure or high concentrations can result in –

• Confusion
• Severe headaches
• Cardiac problems
• Breathing difficulties
• Brain damage
• Dizziness
• Death

Long term exposure to low concentrations –

• Slight headaches
• Fatigue
• Shortness of breath with only moderate exertion
• Nausea
• Dizziness and confusion

Why is it called "The Great Imitator"?

• Symptoms of CO poisoning are very similar to the flu
• Illness in pets preceding illness in a family member may suggest CO poisoning

Who is at Greater Risk?

• Senior citizens
• Unborn babies
• People with respiratory or coronary problems
• Infants
• Pregnant women
• Young children

Note: Vulnerable people who are exposed even to low levels of CO for long time periods may have similar health affects as those exposed to high concentrations of CO.

What can Produce CO in our Homes

Anything that burns fuel or generates combustion gases including -

• Gas Stoves
• Fireplaces
• Automobiles
• Barbecues
• Furnaces
• Ranges
• Boilers
• Space heaters
• Water heaters
• Portable generators

Solid fuels, such as wood, always produce carbon monoxide when they are burned. Gas and liquid fuels may produce no CO or very little.

What are the most common sources of Carbon Monoxide?

1. Automobile exhaust in attached garages.
This is responsible for 60% of all CO alarms. People who warm their cars up in the garage are trapping CO inside the garage. The CO can find its way into the home.

2. Gas cooking appliances.
This is reported to account for 20% of CO alarms. It may be a result of a misused, poorly maintained, poorly installed, or unvented cooking appliance.

3. Poor draft/venting for fuel burning appliances.
This is one of the most common and serious causes for CO build-up and has been reported to account for up to 19% of CO alarms. The products of combustion are not being safely expelled to the exterior. This could be due to venting problems, such as blocked chimney flues or inadequate venting for appliances or fireplaces. Other problems include poor installation and negative air pressure in the house, causing backdrafting, often due to exhaust fans.

Other problems include poor combustion at furnace. Inadequate combustion air to the furnace can result in incomplete combustion. If the furnace has a cracked heat exchanger, it is possible to get CO into the circulating air. It is also imperative that we do not deprive our heating equipment and fuel burning appliances of air; especially in air-tight homes where running exhaust fans can result in a shortage of combustion air. Combustion air is essential for safe operation of furnaces, water heaters, and other fuel burning equipment.

There can also be a leak in a chimney or flue pipe.

Ventilation issues are very common as a result of barbecues or gasoline powered equipment operating in an attached garage, basement, or enclosed area.

Are there more problems with carbon monoxide today than 30 years ago?
Yes, this is due to:

• More energy-efficient, air-tight homes
• Less natural ventilation

How can I guard against carbon monoxide poisoning?

The first line of defense is to have your home heating systems, fuel burning appliances, flues and chimneys checked and/or cleaned annually.

Here is the inspection checklist. Specialists should check for:

• Blocked openings to flues and chimneys
• Cracked, rusted, or disconnected flue pipes
• Dirty filters
• Rusted or cracked heat exchanger
• Soot or creosote build-up inside fireplaces and chimney flues
• Exhaust or gas odors
• Attached garages require gas proofing and automatic closers for doors into the home
• Adequate combustion air
• Adequate venting on indoor combustion appliances (i.e-gas stoves)

The second line of defense is a CO detector.

Carbon Monoxide Detectors

Background

It’s a relatively new technology introduced in the early 1990s. It is designed to warn homeowners when CO reaches dangerous levels within the home.

How do they work?

CO detectors sample the air at specific time intervals. A microchip inside the detector stores the reading and keeps track of the level of CO that the detector is exposed to over time

Types of sensors:

Residential

• Biometric (Oldest type of sensor)
• Metal Oxide Semi-conductor
• Electrochemical (The best of the three types for a residential sensor)

Industrial

• Infrared – Highly advanced, very expensive. Not something you would find at a typical hardware store.

The detectors are supposed to sound an alarm when exposed to a set level of CO (measured in parts per million) over a specific time period. These levels or standards are set by UL (Underwriters Laboratories).

Old Standard (Units manufactured between October 1, 1995 and October 1, 1998) - First Generation CO detectors.

Exposure	CO (ppm)	Time
To a low level for a prolonged period of time	15	Alarm after 30 days
To a low level of CO for an extended period of time	100	Alarm within 90 minutes
To a moderate level of CO for a shorter period of time	200	Alarm within 35 minutes
To a high level of CO for a short period of time	400	Alarm within 15 minutes

The UL Standard was revised and any detector manufactured after October 1, 1998 must conform to the new Standard.

Exposure	CO (ppm)	Time
To a low level for a prolonged period of time	30	Alarm after 30 days
To a low level of CO for an extended period of time	70	Alarm within 189 minutes
To a moderate level of CO for a shorter period of time	150	Alarm within 50 minutes
To a high level of CO for a short period of time	400	Alarm within 15 minutes

Also included in the new Standard is:

• CO detector should ignore a CO level reading of 70 for at least 1 hour without alarming
• CO detector should ignore a CO level reading of 150 for at least 10 minutes without alarming
• Must only signal under alarm or trouble. No low-level warning signal is allowed
• Must have a SILENCE button to shut it off. Must re-alarm after 6 minutes if CO levels persist
• Must meet the specificity test referencing non-alarm status at specific concentrations of certain gases and vapors

To put levels into perspective:

CO Level (ppm)	Health Effect
0	Desirable level
9	Maximum outdoor air quality level as per EPA
50	Maximum concentration for a continuous exposure in an 8-hour time period (OSHA standard)
400	Headaches in 1 to 2 hours, life threatening after 3 hours
800	Nausea and convulsions, death within 2 hours
1600	Nausea within 20 minutes, death within 1 hour
12,800	Death within 1 to 3 minutes

Note: These studies are generally done on young, healthy people. These symptoms can change drastically depending on age, sex, weight, habits (e.g. smoking), and most importantly, your health.

The Controversy

• Reliability of the detectors

The Issue

• CO detectors are supposed to alarm at certain levels as indicated in the tables above
• Recent testing suggests that many of these devices are not nearly as reliable as they should be
• There has been regular television coverage that focused on false alarms and the reliability of CO detectors

Example

• In 1994, Chicago was the first major city to make these detectors mandatory in the living space
• In the last three months of 1994, the Chicago Fire Department responded to 8,600 CO alarms
• In almost every case there was no dangerous level of CO found during follow-up investigations

Result

• Laboratory testing was done
• Up to 1/3 of the alarms tested, failed to alarm

Reasons

1. Technology

• Technology for residential CO detectors is very primitive.
• Industrial detectors have a different set of standards and more sophisticated technology. As a result, they are very expensive.
• Different detectors have large variances on the levels at which they are supposed to alarm. The sensor technology used in home alarms is not designed to measure and display low level, short term concentrations of CO. Substantial differences exist in the sensitivity of different sensors at low levels. As a result, they may go off too soon or not soon enough.

2. Humidity

• Standards require these devices to be tested at a humidity of 50%.
• Testing revealed that many devices failed to respond when humidity levels were low even though they are supposed to work within a large humidity range. See your CO detectors manual.
• In colder climates, humidity levels can fall well below 50% (in fact the humidity should not be higher than 40%) during the cold season when furnaces and other fuel burning appliances are in full operation.

3. Effect of Other Gases and Vapors

• Other gases such as Carbon Dioxide can also trigger a CO alarm. The UL 2034 Standard requires that CO alarms do not alarm when certain concentrations of other gases and vapors exist in the vicinity of a CO detector. The level for Carbon Dioxide in the old standard was low, which may have contributed to many false alarms with first generation CO detectors.

Conclusions

• CO detectors are designed to protect the average healthy human from death or serious injury under the current standards; however –
• People who are more susceptible cannot depend on these devices for total protection. In this case, more sensitive CO detecting equipment should be used.
• Several groups are working with UL to improve the standards. October 1999 revisions have already been drafted.
• There is room for improvement by imposing stricter standards as well as technological development.
• It is critical that people understand the dangers of CO and that the people who investigate it are properly trained and are using CO testing equipment properly.

Where to install a CO detector?

• One or more CO detectors in accordance with the manufacturer’s recommendations. Usually one per floor.
• Maintain and test regularly as instructed by the manufacturer.

Things to look for when buying a CO detector?

1. Type of sensor (electrochemical)
2. Certification-UL 2034
3. Conforms to new standard
4. IAS 6-96 is a supplementary standard to the UL 2034 which includes reliability testing. This standard may not be visible on the box.
5. Other considerations include digital display, sensor life, power source, and warranty.

How does all of this relate to your home inspection?

A home inspection may reveal a potential Carbon Monoxide source.
Common deficiencies found during inspections include:

• Venting deficiencies
• Damaged or rusted flue pipes
• Dirty or blocked chimney flues
• Cracked heat exchangers
• Gas proofing deficiencies
• Inadequate combustion air
• Poorly installed equipment

Limitations –

• Visual Inspection
• Equipment available

There are other ways to test CO levels in a home. These tests go beyond the scope of a standard home inspection.

Line drawings are from the Carson Dunlop Home Inspection Training Program and Home Inspection Software Tool – Horizon

Vermiculite Insulation – Should You Be Concerned?

What Is It?

If you have never seen vermiculite insulation in an attic, you may have seen it in potting soil. Vermiculite is a naturally occurring mineral worldwide. When heated rapidly to high temperatures, this crystalline mineral expands into low density, accordion-like, golden brown strands.

In fact, its worm-like shape is what gives vermiculite its name. The worms are broken into rectangular chunks about the size of the eraser on the end of a pencil. In addition to being light, vermiculite chunks are also absorbent and fire retardant. These characteristics make it great as an additive, for example to potting soil. It also makes a good insulating material.

Where Was It Used?

Sold under various brand names, such as Zonolite Attic Insulation, the insulation came in big bags. Thousands of homeowners simply opened the bags and poured the vermiculite onto their attic floor and sometimes down exterior walls. It was generally not used in new construction.

When Was It Used?

Worldwide, vermiculite has been used in various industries as long ago as 1920. With the upsurge in home ownership during the baby boom, vermiculite insulation was a popular material in the 1950’s, and continued with the energy crisis into the late 1970’s. In Canada, it was one of the insulating materials allowed under the Canadian Home Insulation Program from about 1976 to the mid-1980’s. The CHIP program provided grants to homeowners to increase insulation levels, reducing energy consumption.

What Is The Problem?

The majority of the vermiculite used worldwide was from a mine in Libby, Montana, owned and operated since 1963 by W.R. Grace. The mine was closed in 1990. As well as being rich in vermiculite, this mine had the misfortune of having a deposit of tremolite, a type of asbestos. When the vermiculite was extracted, some tremolite came in with the mix.

For Canadian use, the raw product from the Libby mine was shipped to Grace subsidiary F. Hyde processing plants in Montreal, St. Thomas, Ajax and Toronto, and Grant Industries in western Canada. At these plants, it was processed and sold as Zonolite.

What Is The Risk?

Asbestos minerals tend to separate into microscopic particles that become airborne and are easily inhaled. People exposed to asbestos in the workplace have developed several types of life-threatening diseases, including lung cancer. Workers in and around the Libby mine developed serious health problems.

Like any hazards, length and intensity of exposure are major factors in the risk of asbestos-related respiratory illness. To assess the risk of asbestos exposure at a house, a sample of the vermiculite would need to be analyzed by a lab. Since most of the vermiculite used in Canada was taken from the Libby mine, the odds are quite good that there is asbestos in the vermiculite in Canadian attics.

The good news is that we don’t live in our attics. In addition, as long as it is undisturbed, neither the asbestos fibers bound up in the vermiculite chunks nor the dust will be released into the air. According to the National Institute for Occupational Safety and Health in the U.S., “Most people who get asbestos-related diseases have been exposed to high levels of asbestos for a long time.” Lastly, most of the time the air in your house flows from the house into the attic, rather than into the house from the attic.

The bottom line is, like most household products that may contain asbestos, and there are many, doing nothing is often the best approach. Naturally, the risk of exposure increases with the amount of time spent in the attic.

Recommendations

If the attic or walls of a house contain vermiculite insulation, leave it alone. Avoid disturbing the material. Do not sweep it or vacuum it up. Do not store belongings in the attic.

If work is planned that involves these areas, for example installing recessed lights in a room below the attic, send a sample of the vermiculite to a private lab. Send several samples, and use a lab specializing in asbestos analysis. If it is found to contain asbestos, or if you just assume it does, precautions should be taken. The safest approach would be to have the insulation in the affected areas removed by a qualified environmental contractor.

For smaller jobs it may be sufficient to isolate work areas with temporary barriers or enclosures to avoid spreading fibers, use disposable protective clothing, and use proper respiratory protection. An important note – disposable respirators or dust masks are not appropriate for asbestos. Again, it is best to consult a qualified contractor.

Line drawings are from the Carson Dunlop Home Inspection Training Program and Home Inspection Software Tool – Horizon

Truss Uplift - An Uplifting Experience

Truss uplift is a phenomenon common in homes built with roof trusses as opposed to rafters.
If a house suffers from truss uplift, the top floor ceilings literally lift off the interior walls in the winter. They drop back down in the summer. Needless to say, this is a tad disconcerting to the homeowner. At first glance, one might assume that the floors have settled. Actually the ceiling has gone up - sometimes creating a gap of as much as two inches where interior walls meet the ceilings.

What is a Truss?

Trusses are prefabricated structural assemblies which hold up the roof and the top floor ceilings. Trusses tend to be a stronger, lighter and less expensive approach to roof framing. Trusses are strong because they make use of the most efficient geometric shape we know of - the triangle. Trusses are a series of triangles fastened together with gusset plates. The outside members of a truss are called chords while the inner pieces are known as webs.

Why Truss Uplift?

Houses have changed over the years. Attics of newer houses have lots of insulation and ventilation. They also have roof trusses instead of rafters and ceiling joists. The bottom chord of a truss is buried below a deep blanket of insulation. Even on the coldest days the bottom chord is nice and warm. The top chords however, are above the insulation and get very cold in a well ventilated attic.

While the bottom chord is warm and is drying out, the top chords are doing just the opposite. The cold winter air has very high relative humidity. The top chords absorb moisture from the air causing them to elongate. With the top chords growing and the bottom chord shrinking, the truss arches up in the middle causing the ceilings to lift off the walls. In the summer, the cycle reverses itself.

What Is The Problem?

No problem really - from a structural point of view. But cosmetically it's another story. No one has yet solved the problem, but some builders mask it by securing the ceiling drywall to the top of the walls and not to the trusses for a distance of 18 inches away from the walls. The drywall flexes and stays fastened to the walls while the trusses lift above it.

Others use a decorative molding where the walls meet the ceilings. They fasten the moldings to the ceilings but not to the walls. As the ceilings move up, the moldings go with them hiding the gap.

One little tip to remember. If you're redecorating, always do it in the winter when the ceiling is at its highest point. Otherwise you'll have a stripe around the room below the molding next winter!

Line drawings are from the Carson Dunlop Home Inspection Training Program and Home Inspection Software Tool – Horizon

Priority Maintenance for Home Buyers

There are so many home maintenance and repair items that are important; it can be confusing trying to establish which are the most critical. To simplify things, we have compiled a short list of our favorites. These are by no means all-inclusive, nor do they replace any of the information in a home inspection report. They should, however, help you get started on the right foot. Remember, any items marked as priority or safety issues on your home inspection report need immediate attention.

One-Time Tasks

1. Install smoke detectors and carbon monoxide detectors as required, according to manufacturer’s recommendations. Know the requirements in your area.
2. Make any electrical improvements recommended in the home inspection report.
3. Remove any wood/soil contact to prevent rot and insect damage.
4. Change the locks on all doors. Use a dead bolt for better security and to minimize insurance costs.
5. Correct trip hazards such as broken or uneven walks and driveways, loose or torn carpet or uneven flooring.
6. Correct unsafe stairways and landings. (Railings missing, loose, too low, et cetera.)
7. Have all chimneys inspected before operating any of these appliances.
8. Locate and mark the shut-offs for the heating, electrical and plumbing systems.
9. Label the circuits in electrical panels.
10. If there is a septic system, have the tank pumped and inspected. If the house is on a private water supply (well), set up a regular testing procedure for checking water quality.

Regular Maintenance Items

11. Clean the gutters in the spring and fall.
12. Check for damaged roofing and flashing materials twice a year.
13. Cut back trees and shrubs from the house walls, roof and air conditioning system as needed.
14. Clean the tracks on horizontal sliding windows annually, and ensure the drain holes are clear.
15. Test ground fault circuit interrupters, carbon monoxide detectors and smoke detectors using the test button, monthly.
16. Service furnace or boiler yearly.
17. Check furnace filters, humidifiers and electronic air cleaners monthly.
18. Check the bathtub and shower caulking monthly and improve promptly as needed.
19. If you are in a climate where freezing occurs, shut off outdoor water faucets in the fall.
20. Check reversing mechanism on garage door opener monthly.
21. Check attics for evidence of leaks and condensation and make sure vents are not obstructed, at least twice a year. (Provide access into all attics and crawl spaces.)

Line drawings are from the Carson Dunlop Home Inspection Training Program and Home Inspection Software Tool – Horizon

Wet Basements – A Homeowner’s Biggest Concern

The words are all-too-familiar to many homeowners. It is said that more than ninety-eight percent of all houses have had, or will have, basement leakage at some point.

Identifying the Problem:

The presence of efflorescence, a whitish mineral deposit on the interior of foundation walls, indicates moisture penetration. It should be noted that the severity of the problem, or whether the problem is active, is not indicated by the amount of efflorescence. Other clues are rusty nails in baseboards, rotted wood near floor level, rusted metal feet on appliances, mould and mildew, lifted floor tiles, storage on skids, peeling paint and the presence of dehumidifiers.

Corrective Action:

Poor surface drainage is one of the main causes of basement leaks. The ground should slope away from the house a rate of one inch per foot for at least the first six feet. As a preventative measure, seal where the driveway and sidewalk meet the foundation walls. The gutter and downspout systems must also perform properly. If downspouts are ever suspected of being disconnected, broken or clogged below ground level, they should be redirected to discharge above grade at least six feet away from the house. Also, gutters should be kept clear of debris.

Localized low areas including basement stairwells, window wells, et cetera, may allow water to collect. Drains should be provided in the bottom of these. Where there are no drains, plastic dome covers over the window wells allow light into the basement while minimizing water and snow accumulation.

More Extreme Measures:

In the vast majority of cases, basement leakage is not significant from a structural point of view and can be controlled relatively inexpensively, as discussed above. However, the presence of foundation cracks, damaged perimeter drainage tiles, a high water table or underground streams may call for more extreme corrective measures. These measures are used when chronic flooding occurs.

Sealing foundation cracks can be performed several ways with the cost of repairs varying. The approach taken depends on the specific crack; however, the most successful approach is sealing from the outside (Cost $500 - $900). Urethane or epoxy injection repairs can be done from the interior on poured concrete walls only (cost $400 - $600).

Excavating, dampproofing and installing drainage tiles should be used as a last resort. Dampproofing on the exterior typically involves parging a masonry foundation wall with a one-quarter inch layer of mortar covered with a bituminous or plastic membrane which extends down to the footings.

The drainage tile laid beside the footing is covered with gravel and filter paper. These tiles can often be damaged or clogged by roots and some localized repairs may be required.

Because excavating on the exterior is expensive ($8,000 - $15,000 typically), an alternative is an interior drainage system. The cost of this approach is one-third to one-quarter the cost of exterior work. There are many cases where this proves satisfactory, although this must be judged on a case by case basis.

Where underground streams and/or a high water table are present, sump pumps are usually required.

Line drawings are from the Carson Dunlop Home Inspection Training Program and Home Inspection Software Tool – Horizon

The Importance Of Ground Fault Circuit Interrupters

Ground fault circuit interrupters (GFCI’s) are outlets with the colored "Test" and "Reset" buttons specially designed to better protect people than ordinary outlets. GFCI's have been used in houses since the 1970's.

Why Are They Used?

GFCI's are designed to shut power off if there is a very small leak of electricity (a ground fault) which ordinary outlets wouldn't notice. Normal outlets are shut off by a fuse or breaker if more than 15 amps flow. This prevents fires, but since people can be killed by 1 amp or less, fuses may not protect people from shock. GFCI's shut off power if a leak as small as .005 amp occurs.

How Do They Work?

A GFCI detects a leak by comparing how much electricity comes back through the white wire to how much was sent in the black wire. When everything is working correctly, the current flow is the same. If a little electricity is leaking out, it may be going through a ground wire or through part of the house. If this happens, the black wire will have more electricity than the white wire. Electricity, like most people, will follow the path of least resistance. If a person touches a leaky electrical system, they may present a better route to ground for electricity, since they may offer very little resistance.

Another way of saying this is that the person may be a very good conductor or the person may not be well insulated. The electricity will flow through the person, giving them a shock. Without a GFCI, this can be fatal. With a GFCI, the little leak would be detected and the power would be shut off.

Where Are They Used?

In Canada, GFCI's are now required by Code for outdoor outlets, bathroom outlets and whirlpool outlets. Electrical systems for swimming pools are also GFCI protected. In the United States, kitchen outlets within six feet of the sink must also be GFCI protected.

Can The Outlet Be GFCI Protected If There Is No Button?

Yes, if for example, the circuit breaker back at the panel has a "Test" button, it is a GFCI breaker. This will protect everything on that particular circuit. Any outlets wired downstream of a GFCI outlet are also protected if the GFCI is wired correctly.

Can They Be Added To Older Houses?

Yes, GFCI's can be added to any electrical system. They are more expensive than regular outlets ($15-$20 vs. $1-$2), but are inexpensive insurance. While they do not replace grounding systems exactly, some Codes do allow GFCI's in lieu of grounding in some cases. It is safe to say that a circuit protected by a GFCI is better protected than one without.

Line drawings are from the Carson Dunlop Home Inspection Training Program and Home Inspection Software Tool – Horizon