How to Determine the Age of a Building

 

Building technologies and fashions have followed well-known trends that  allow those interested to roughly determine Crude, square nails may be hundreds of years oldwhen  particular buildings were constructed.  Here are some methods based on a  building’s materials, components and styles.
 
Estimates of Building Age Based on Building  Materials
 

Nails

  • Prior to the 1800s, nails were hand-made by blacksmiths and nail makers  and appear crude compared with modern nails. They are often squared rather than  rounded, and have a beaten look on the top of the head.
  • Type A- and Type B- cut nails were used from 1790 to 1830. They were  made from wrought iron and are squared.
  • Wire nails, used from 1890 through today, are modern, machine-made  nails that are rounded and more practical to use than the earlier designs.

Wiring

  • Aluminum wiring was used extensively from 1967 till 1975, a  period during which copper was prohibitively expensive. Aluminum use  was generally discontinued when its potential as a fire hazard become  publicized.
  • K&T or knob-and-tube wiring was an early method of electrical  wiring installed in buildings from 1880 to the 1940s. The system is considered  obsolete and can be a fire hazard, although much of the fear associated with it  is exaggerated.

Electrical ReceptaclesModern electrical receptacles are polarized and grounded

Electrical receptacles evolved from earliest to most recent in the following  order:

  • non-polarized:  These early receptacles are made up of two slots  of equal size, with no ground slot.
  • polarized:  These receptacles are two-slotted, one of which is wider  than the other to allow for proper polarity.
  • grounded, polarized:  Modern receptacles were changed to permit  grounding of an appliance or device. They can be identified by the round hole  beneath the center of the polarized slots.

Flooring

  • In the late 19th century (1890), linoleum became common for  use in hallways and passages, but it became better known for its use in kitchen  floors in the 20th century, up through 1960. Originally valued for  its water-resistance and affordability, it was surpassed by other floor  coverings by the mid-20th century.
  • Asphalt tile was used for floor tiles starting around 1920 through  the 1960s. The earliest tiles are darker because they contained more asphalt,  unlike later tiles that had higher levels of synthetic binders.Old linoleum floor
  • Vinyl asbestos tiles became popular in response to consumers who wanted  lighter-colored tiles of varying color patterns.

Structural Panels

  • Plywood’s use began around 1905.  It is made from thin sheets of veneer  (layers of wood that are peeled from a spinning log) that are cross-laminated  and glued together with a hot press. Since it is made from whole layers of logs  rather than small strands, plywood has a more consistent and less rough  appearance than oriented strand board (OSB).
  • Waferboard or particle board was developed in the 1970s and, like plywood,  is still used today. This material appears similar to OSB, except the wooden  strands from which it is composed are not aligned.
  • OSB was developed the 1980s and is manufactured from heat-cured  adhesives, and then rectangularly shaped wood strands that are arranged in  cross-oriented layers. Produced in large, continuous mats, OSB is a solid-panel  product of consistent quality with few voids and gaps. While OSB was  developed fairly receDutch-style Colonial housently,  it became more popular than plywood in North America by 2000.

Keep in  mind that houses, especially older ones, have evolved over many years. It can be  very difficult to reliably date a building based on the presence of a single  material or component. The majority of a house might be newer than its  18th century foundation, for instance, especially if there was a fire  that destroyed the rest of the structure.

Estimates of Building Age Based on Architectural Style 
  • American Colonial (1600 to 1800):  North America was colonized by  Europeans who brought with them building styles from their homelands. This broad  category includes the following regional styles and their characteristics:
    • New England style (1600 to 1740):  These homes feature steep roofs  and narrows eaves used in simple timber-frame houses, usually located in  the northeastern United States, primarily in Massachusetts, Vermont,  Connecticut, New Hampshire and New York.
    • German (1600 to 1850):  Most often found in New York,  Pennsylvania, Ohio and Maryland, these buildings generally feature thick,  sandstone walls.
    • Spanish (1600 to 1900):  Located in the American South, Southwest,  and California, these houses are simple and low, built from rocks, stucco,  coquina and adobe brick, with small windows and thick walls.
    • Other home styles from the American Colonial period include Georgian,  Dutch, French and Cape Cod.
  • Classical style houses (1780 to 1860):  Many houses built during  the founding of the United States are a throwback to ancient Greece, emphasizing  order and symmetry. Among the styles common to this era are Greek Revival,  Tidewater and Antebellum.
  • Victorian (1840 to 1900): With the technological innovation  of mass production came the ability to produce large homes affordably.  Queen Anne, Gothic Revival, Folk and Octagon are some of the architectural  styles common to this era.
  • Gilded Age (1880 to 1929): The “Gilded Age” is a term popularized by Mark  Twain to describe extravagant wealth. This era saw the construction of large,  Mcmansions are hastily-built and often too large for their plot of landelaborate homes owned  by a class of suddenly-rich businessmen who enjoyed grandiose displays of their  new wealth.
  • Early 20th Century homes:  Homes built during this period  were compact and economical, somewhat smaller and less pretentious than earlier  Gilded Age homes.
  • Post-War homes (1945 to 1980):  Very simple and affordable, some  critics believe they have no style at all. Soldiers returning from the World War  II spurred the construction of these homes, which emphasized utilitarianism  over style more than preceding periods.
  • “Neo” houses (1965 to present):  Theses houses borrow styles from  previous architectural eras, such as Victorian, Colonial and Mediterranean.  “McMansion” is a word used to describe large, quickly-constructed, flamboyant  and poorly-designed neo-eclectic homes.

Other Ways to Determine a Building’s Age:

  • Check the meter reader. Sometimes, the meter reader will bear a date stamp.
  • Check the inside of the toilet. Toilet manufacturers often stamp the inside  of tanks or lids with the year the toilet was made. Toilets are usually  installed right after construction, so you can often determine a newer home’s  age by inspecting a toilet.
  • In log homes, it may be possible to tell the building’s age by analyzing the  tree rings in a piece of timber removed from the building. The science on which  this is based, dendrochronology, does not arrive at an age based on the number  of tree rings, but rather focuses on patterns of tree rings and compares these  with known pattern ages for a specific region. This method is destructive and it  requires a specialist.
  • Local town, county, or state tax records usually indicate the date or  year a building was constructed.
  • Historical real estate listings may include indications of building age.
  • Census records can prove that a house was present at the time the census was  taken.
  • Papers found inside the building will often indicate when the building was  present. A house will probably be at least as old as, for instance, newspapers  from the 1920s found in a crawlspace.
  • Employ an architectural investigator to date the house by studying its wood,  plaster, mortar and paint.
  • The aluminum spacers within thermal-paned windows often bear the year of  production, which can at least provide an approximate date of  installation.
  • Sewer grates are sometimes stamped with the year they were manufactured,  which may provide an age for the neighborhood.

by Nick Gromicko

 

Engineered Wood Flooring

Engineered wood flooring is an alternative to solid hardwood flooring made entirely out of real wood.  It’s currently the most popular type of flooring in the world.  North America is the only area left where traditional, solid wood floors still outnumber engineered floors, but engineered wood flooring is quickly catching up, with the rate of use for new builds, as well as remodels, increasing steadily every year for the past few decades.  Inspectors and homeowners alike may be interested in how this product is manufactured and installed, and what its advantages are compared to older, more traditional forms of flooring.

Brief History

The beginnings of mass-produced wood flooring can be dated as far back as 1903, when an E. L. Roberts mail-order catalog offered “wood carpeting.”  This flooring consisted of 1½ x 5/16-inch wooden strips that were glued to heavy canvas that was then installed by tacking it down with brads.  The wood was then sanded and finished.  The varnishes used were usually slow-curing tung oils from China.  These were not durable in themselves, so the floors were hot-waxed and buffed to a shine with a floor brush.

Early examples of the “wood carpet” eventually evolved into more modern iterations, such as laminate flooring, which consists of melamine-infused paper as its upper layer, and wood-chip composite beneath.  Laminate flooring typically features a printed or embossed top layer meant to approximate the look of real hardwood.

The current incarnation of engineered wood flooring has been available since the 1960s, and has steadily increased in quality, leading to improved advantages over traditional hardwood flooring.

Composition

Engineered wood flooring is most commonly made with a plywood-core substrate and a real hardwood veneer or skin, which comes pre-finished from the factory.  The top veneer, which looks just like the top of a traditional solid wood plank, is called the lamella. 

Some engineered flooring utilizes a finger-core construction, with a substrate comprised of small pieces of milled timber running perpendicular to the lamella.  This can be made with an additional layer of plywood running parallel to the lamella, which gives it added stability.  Fiberboard-core flooring is also available, but it’s generally considered to be an inferior option.

Engineered wood flooring is meant to be indistinguishable from traditional hardwood floor once it’s installed, and only the lamella is visible.  The lamella veneers available are made from nearly every type of common wood, as well as many more exotic ones, in order to provide the same variety of aesthetics typical of quality hardwood floors.  The substrate that the veneer is attached to is just as strong and durable as hardwood — if not stronger — and the finish applied at the factory often outlasts one applied on-site to solid wood flooring.  Even surface effects are available that can be applied to the finish to give the flooring a time-worn look, such as light distressing.

Engineered flooring runs the gamut from the low end, starting at $3 per square foot, to the high, at $14 and more. To judge quality, check the thickness of the lamella, the number of layers in the substrate, and the number of finish coats.  Typically, the more layers, the better. Listed below are descriptions of the advantages of adding layers to the construction in the common classes of engineered boards:

  • 3-ply construction: 1- to 2-mm wear layer; five finish coats; 10- to 15-year warranty; 1⁄4-inch thick; current price is about $3 to $5 per square foot.  Options for lamella veneer are limited to common species, such as oak and ash, and just a few stains are available;
  • 5-ply construction: 2- to 3-mm wear layer; seven finish coats; 15- to 25-year warranty; 1⁄4-inch thick; about $6 to $9 per square foot.  More species, such as cherry, beech, and some exotics are available for lamella, as well as all stains, and a few surface effects, such as distressing; and
  • 7-ply or more: 3+-mm wear layer, which can be sanded two or more times; nine finish coats; 25+-year warranty; 5/8- to 3⁄4-inch thick; average price is about $10 to $14 per square foot.  The widest selection of species is available for lamella, including reclaimed options.  More surface treatments are also available, such as hand-scraped and wire-brushed.

The cost of engineered flooring can be around 20% more than that of traditional flooring, but the difference can be offset or recouped by saving on installation, staining and sealing.

Installation

Installation of engineered wood flooring is generally quite simple compared to the installation of traditional hardwood, and can often be accomplished by a homeowner without the help of a professional flooring contractor.  If the services of a professional are enlisted, the job can be done more quickly and cost-effectively than if solid hardwood were to be installed.  Engineered flooring can be fastened in place with screws or nails, glued down, or left to “float,” relying on its mass to hold it in place.  Listed below are several installation methods:

  • A bead of glue can be applied to the tongue of each board, which is then tapped into place with a block. The floor floats, unattached to the sub-floor except by force of gravity.
  • A floor stapler and compressor can be used to rapidly secure the boards to the existing floor, without having to deal with any glue.
  • Boards can be laid in a bed of adhesive, as is done with tile.  This approach works particularly well over cured concrete, which precludes the use of staples.
  • Some types of engineered floor are designed with milled tongues and grooves that lock together without glue or fasteners. It’s the quickest and cleanest installation method.

Advantages of Engineered Flooring

While solid hardwood is a great traditional building material that provides aesthetically pleasing and structurally sound flooring, it does have its limitations.  For example, it cannot be installed directly on concrete or below grade, such as in basements.  It is generally limited in plank width and is more prone to gapping, which is excessive space between planks, and cupping, which is a concave or “dished” appearance of the plank, with the height of the plank along its longer edges being higher than the center with increased plank size.  Solid hardwood also cannot be used where radiant-floor heating is in place.
Engineered wood flooring, on the other hand, can actually provide some distinct advantages over traditional hardwood in many instances and applications.  Some of these include:
  • Lamella veneer is available in dozens of wood species.
  • Surface effects can be applied to further enhance its appearance.
  • The factory finish can outlast site-applied finish on solid hardwoods.
  • Drying time for the finish is eliminated because it’s pre-applied at the factory.
  • It can be used in basements and over concrete slabs.
  • Installation is quick and easy.
  • It can be used over radiant-heat systems.
  • It can be refinished to repair normal wear and tear.
  • The core layer can expand and contract more freely without warping.
  • The flooring can be removed and re-installed elsewhere, if desired.
Engineered wood flooring is increasingly the first choice for floor installations, and its advantages, in many circumstances, can be exceptional.  Homeowners with a little DIY experience can usually install it themselves.
by Nick Gromicko and Ethan Ward

Abrasive Blasting for Mold Remediation

 Mold in the Home

Health concerns related to the growth of mold in the home have been featured heavily in the news.  Problems ranging from itchy eyes, coughing and sneezing to serious allergic reactions, asthma attacks, and even the possibility of permanent lung damage can all be caused by mold, which can be found growing in the home, given the right conditions.

All that is needed for mold to grow is moisture, oxygen, a food source, and a surface to grow on.  Mold spores are commonly found naturally in the air.  If spores land on a wet or damp spot indoors and begin growing, they will lead to problems.

Molds produce allergens, irritants and, in some cases, potentially toxic substances called mycotoxins.  Inhaling or touching mold or mold spores may cause allergic reactions in sensitive individuals.

Allergic responses include hay fever-type symptoms, such as sneezing, runny nose, red eyes, and skin rash (dermatitis).  Allergic reactions to mold are common.  They can be immediate or delayed.  Molds can also trigger asthma attacks in people with asthma who are allergic to mold.

In addition, mold exposure can irritate the eyes, skin, nose, throat and lungs of both mold-allergic and non-allergic people.

As more is understood about the health issues related to mold growth in interior environments, new methods for mold assessment and remediation are being put into practice.  Mold assessment and mold remediation are techniques used in occupational health.  Mold assessment is the process of identifying the location and extent of the mold hazard in a structure.

Mold remediation is the process of cleanup and/or removal of mold from an indoor environment.  Mold remediation is usually conducted by a company with experience in construction, demolition, cleaning, airborne-particle containment-control, and the use of special equipment to protect workers and building occupants from contaminated or irritating dust and organic debris.  A new method that is gaining traction in this area is abrasive blasting.

Abrasive Blasting

The first step in combating mold growth is not to allow for an environment that is conducive to its growth in the first place.  Controlling moisture and assuring that standing water from leaks or floods is eliminated are the most important places to start.  If mold growth has already begun, the mold must be removed completely, and any affected surfaces must be cleaned or repaired.

Traditional methods for remediation have been slow and tedious, often involving copious amounts of hand-scrubbing and sanding.  Abrasive blasting is a new technique that is proving to be less tedious and time-consuming, while maintaining a high level of effectiveness.

Abrasive blasting is a process for cleaning or finishing objects by using an air-blast or centrifugal wheel that throws abrasive particles against the surface of the work pieces. Sand, dry ice and corncobs are just some of the different types of media used in blasting.  For the purposes of mold remediation, sodium bicarbonate (baking soda) and dry ice are the media commonly used.

Benefits of Abrasive Blasting

Abrasive (or “media”) blasting provides some distinct advantages over traditional techniques of mold remediation.  In addition to eliminating much of the tedious labor involved in scrubbing and sanding by hand, abrasive blasting is extremely useful for cleaning irregular and hard-to-reach surfaces.

Surfaces that have cross-bracing or bridging can be cleaned more easily, as well as areas such as the bottom of a deck, where nails may be protruding.  Areas that are difficult to access, such as attics and crawlspaces, can also be cleaned more easily with abrasive blasting than by traditional methods.

The time saved is also an advantage, and the typical timeframe for completion of a mold remediation project can often be greatly reduced by utilizing abrasive blasting.

Soda-Blasting

Soda-blasting is a type of abrasive blasting that utilizes sodium bicarbonate as the medium propelled by compressed air.  One of the earliest and most widely publicized uses of soda-blasting was on the restoration of the Statue of Liberty.
In May of 1982, President Ronald Reagan appointed Lee Iacocca to head up a private-sector effort for the project.  Fundraising began for the $87 million restoration under a public-private partnership between the National Park Service and The Statue of Liberty-Ellis Island Foundation, Inc.  After extensive work that included the use of soda-blasting, the restored monument re-opened to the public on July 5, 1986, during Liberty Weekend, which celebrated the statue’s  centennial.

The baking soda used in soda-blasting is soft but angular, appearing knife-like under a microscope.  The crystals are manufactured in state-of-the-art facilities to ensure that the right size and shape are consistently produced.

Baking soda is water-soluble, with a pH near neutral. Baking-soda abrasive blasting effectively removes mold while minimizing damage to the underlying surface (i.e., wood, PVC, modern wiring, ductwork, etc.).  When using the proper equipment setup (correct nozzles, media regulators, hoses, etc.) and technique (proper air flow, pressure, angle of attack, etc.), the process allows for fast and efficient removal of mold, with a minimum of damage, waste and cleanup.  By using a soda blaster with the correct-size nozzle, the amount of baking soda used is minimized. Minimal baking soda means better visibility while working, and less cleanup afterward.

Dry-Ice Blasting

Dry ice is solidified carbon dioxide that, at -78.5° C and ambient pressure, changes directly into a gas as it absorbs heat.  Dry ice pellets are made by taking liquid carbon dioxide (CO2) from a pressurized storage tank and expanding it at ambient pressure to produce snow.  The snow is then compressed through a die to make hard pellets.  The pellets are readily available from most dry ice suppliers nationwide.  For dry-ice blasting, the standard size used is 1/8-inch, high-density dry ice pellets.

The dry-ice blasting process includes three phases, the first of which is energy transfer.  Energy transfer works when dry ice pellets are propelled out of the blasting gun at supersonic speed and impact the surface. The energy transfer helps to knock mold off the surface being cleaned, with little or no damage.

The freezing effect of the dry ice pellets hitting the mold creates the second phase, which is micro-thermal shock, caused by the dry ice’s temperature of -79º C, between the mold and the contaminated surface.  This phase isn’t as much a factor in the removal of mold as it is for removing resins, oils, waxes, food particles, and other contaminants and debris.  For these types of substances, the thermal shock causes cracking and delaminating of the contaminant, furthering the elimination process.

The final phase is gas pressure, which happens when the dry ice pellets explode on impact.  As the pellets warm, they convert to CO2 gas, generating a volume expansion of 400 to 800 times.  The rapid gas expansion underneath the mold forces it off the surface.

HEPA Vacuuming

A HEPA vacuum is a vacuum cleaner with a high-efficiency particulate air (or HEPA) filter through which the contaminated air flows.  HEPA filters, as defined by the U.S. Department of Energy’s standard adopted by most American industries, remove at least 99.97% of airborne particles that are as small as 0.3 micrometers (µm) in diameter.  HEPA vacuuming is necessary in conjunction with blasting for complete mold removal.

While abrasive blasting with either baking soda or dry ice is an effective technique, remediation will not be complete until HEPA filtering or vacuuming has been done.  Abrasive blasting removes mold from contaminated surfaces, but it also causes the mold spores to become airborne again.  The spores can cover the ground and the surfaces that have already been cleaned.  So, the mold spores need to be removed by HEPA filters.

Additionally, while some remediation companies claim that there will be no blasting media to remove after cleaning, especially with the dry-ice method, there will be at least a small amount of visible debris left by the blasting that must be removed before HEPA vacuuming can occur.  HEPA vacuuming removes all invisible contaminants from surfaces and the surrounding air.  When HEPA vacuuming is completed, samples at the previously contaminated areas should be re-tested to ensure that no mold or mold spores remain.

by Nick Gromicko and Ethan Ward

Anti-Scald Valves

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. Anti-scald valves are used to regulate water temperature in buildings

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 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.

by Nick Gromicko and Rob London

Electrical Safety: Some Thoughts on Knob and Tube Wiring and Insulation

Knob and tube electrical wiring was an early method of electrical wiring in buildings and was commonly used in North America from about 1880 to the 1930s.  While it was replaced with other electrical wiring methods decades ago, home with energized knob and tube electrical wiring still exist.

Knob and tube wiring consists of single-insulated copper conductors run within wall or ceiling cavities, passing through studs and ceiling/floor joists through protective porcelain insulating tubes.  The wires are supported along their length by porcelain knob insulators that have been nailed in place.

Knob and tube wiring runs at a higher temperature than modern wiring materials and requires a minimum of three inches of air space around the length of the wire.  This requirement adds an additional challenge to home owners wishing to add insulation in order to increase the comfort and energy efficiency of their older home.

If you have knob and tube electrical wiring in your home and plan to add insulation, first have a qualified electrical contractor inspect your wiring to ensure that it is safe prior to adding insulation.  Ensure that all connections are enclosed in appropriate protective boxes, that the wiring insulation is intact and in good condition and that it has not been modified in any manner since its original installation (addition of non-metalic sheathed cable wiring circuits, for example).

The next step, prior to insulating attics or floors where knob and tube wiring is present, is to identify and seal air leakage points.  This is an important step that will maximize the efficiency of the insulation, extend its life and assist in providing a comfortable and healthier living space.

Do not insulate wall cavities containing knob and tube wiring.

Knob and tube wiring in attics may be isolated by building a barricade around it with R-30 unfaced batts.  Ensure that the batts are at least three inches away from the knob and tube wiring.

While the presence of the older knob an tube wiring does not, in itself, violate national electric codes (though some regions forbid it), the best solution for knob and tube wiring is to replace it, if economically possible.

I’m sure that there are electrical contractors and weatherization folks who could add much to this topic and  I hope they will chime in.  Home owners should always consult a professional electrical contractor prior to adding insulation in the presence of knob and tube electrical wiring.

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