A Blog

A Blog

Using an Isotherm to Detect Potential Condensation Sites

Tip written by: Infraspection Institute

Condensation on interior building surfaces can lead to a variety of problems including conditions conducive to mold growth. Used properly, the isotherm feature found on many infrared imagers can be utilized to spot potential condensation sites.

Simply put, dew point is the temperature at which water vapor in the air will cause condensation to form on a surface. When interior building components are cooled to dew point temperature or lower, water vapor will precipitate out of the air causing water to form on the subject component.

Luxury house with a two-car garage and beautiful landscaping on a sunny day. Home exterior.

For building envelopes, chronic condensation on interior drywall surfaces can cause unsightly staining by trapping dust or smoke particulates in these areas. Chronic condensation on organic building components is also conducive to mold growth. Condensation often goes unnoticed until building occupants notice stains associated with the aforementioned conditions. Fortunately, a thermal imager can be used to detect condensation problems before they become serious.

To utilize a thermal imager to detect potential condensation sites, identify the dew point temperature for the room or areas that you are inspecting. Set your imager’s isotherm function to appear at, and for several degrees below, the dew point temperature. As you inspect high emittance building surfaces from the interior of the building, note any components that cause the isotherm to appear. These areas should then be further investigated for cause and appropriate action taken.

When using an isotherm, be sure to practice proper measurement techniques giving particular consideration to viewing angle, spot measurement size and emissivity settings.


What’s the unit of measure for water vapor through a barrier?

Perms (and what a sweet one that is!)

While the hairdo may not be as influential as it used to be, vapor barriers – justifiably – are getting more and more attention.


Controlling humidity is arguably the most important – and potentially controllable – aspect of Building Science.  Air conditioning itself was created when Carrier devised a way to lower the humidity in his library.  The cooler air resulting started a revolution. (Thank God!)  Aside from comfort, the damage from not controlling humidity in your home can be disastrous.

Maybe you’ve never heard the term vapor barrier, but you’ve certainly seen new builds with “Tyvek” printed all over the outside – or maybe the inside. . .  It all depends on where you live.  In more humid climates you’ll see the vapor barrier on the outside.  While dryer climates have them on the inside trying to keep the warmth and moisture in.

Vapor Barriers ALWAYS keep the Moisture, or humidity, always flows from areas with more humidity to those with less.  If you keep it out, the air in your home can be uncomfortable dry.  If you trap it in – you might create a breeding ground for molds and mildew.  Ever leave water in an ice chest for too long?  On a home’s scale, these effects can have health and construction consequences.

I.E.  The rate at which water vapor flows through a barrier (like Tyvek) is measured in Perms!

No-Clog Clothes Dryer Duct Booster® Conforms to the New DEDPV Safety Standard

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Improves Drying Times, Prevents Lint Build-up, Dust and Fire Hazard Potential.

The level of safety and performance of residential clothes dryers has been raised thanks to the Model LB2 Dryer Duct Booster® available from Tjernlund Products, Inc. This unique booster fan offers a 5-year No-Clog guarantee, the potential of reducing clothes drying time up to 60 percent to save energy, while incorporating features allowing it to be Listed to the updated DEDPV, Dryer Exhaust Duct Power Ventilator supplement to UL#705. The latest IRC restricts use of dryer booster fans to those tested to the DEDPV supplement. The TjernlundModel LB2 is Listed for use on both gas and electric clothes dryers.

Adding dryer booster fans in clothes dryer ducts has increased substantially with the placement of laundry rooms not adjacent to outside walls. Duct runs often exceed the maximum duct length that the dryer is rated for – typically 25 feet and two elbows. TheModel LB2 Dryer Duct Booster® is rated for duct lengths up to 150 feet! It can reduce drying times and energy consumption up to 60 percent.

The Model LB2 Dryer Duct Booster® fan attaches easily to four-inch rigid duct and plugs into an electrical outlet. A display panel mounted near the dryer confirms system status and operation. It communicates via a factory-connected low voltage cable to an on-duct boosterboard booster fan control. The control monitors pressure and temperature within the duct to operate the booster fan in sync with the dryer and to stop booster fan operation if duct temperature exceeds 165˚F or signal if the duct becomes blocked. A rotating mounting bracket allows the Model LB2 to be installed vertically or horizontally. Rubber vibration mounts isolate the fan ensuring quiet operation.


Beyond the DEDPV compliant control system, the heart of the Model LB2’s effectiveness is its exclusive No-Clog lint handling blower design to eliminate regular cleaning of lint from the housing and blower wheel. This feature assures consistent booster fan performance with minimum maintenance.
The Model LB2 Dryer Duct Booster® is available through industrial, HVAC distributors and online. For additional information contact us today!

Your Monthly Maintenance Minute


Easy Home Fixes in the Summer

When it gets warm, it’s tempting to ditch any housework for the beach or the golf course. Hard as it may be, consider suppressing that urge for a few weekends, because some fairly easy work can improve the state of your home, give it an appearance makeover, and even save you some money.

Keep Your Cool With a Fan

There’s an easy trick to keeping cooler and saving money, and it’s as close as your ceiling fan. Switch the ceiling fan’s blades so the leading edge is higher as the fan turns, so you can feel the breeze from the fan as it rotates. This simple action will push cool air down, enabling you to set the air-conditioning lower and save money on energy.

Clean Your Dryer Vent

Without some maintenance, your dryer could cause a house fire. The U.S. Fire Administration reports nearly 16,000 dryer fires occur annually, which happen largely because dryers’ vents get clogged with lint and dust.

Thankfully, you can avoid any unnecessary dryer-caused danger with a few simple steps. First, you’ll need a vent-cleaning brush kit, which can clean your dryer vent tubing more thoroughly than a vacuum cleaner can. Begin by cleaning the dryer’s lint trap housing with a smaller brush to remove as much lint and dust as possible. Then disconnect the dryer duct from the dryer and the wall for a thorough cleaning. Also use a brush to clean the vent on the outside of the house to keep both ends clean and free of lint.

A dryer fire is just the sort of thing you’ll want to be sure you’re covered for. Check out Allstate’s property insurance for information on making a smart protection decision.

Keeping Your Property-and Family-Safe

While you’re making sure your house is in order, you’ll want to ensure your backyard is safe, too. Our Keep Your Backyard Safe and Hazard-Free article can help you make sure your kids can play in the backyard without worries of potential danger.

And our Make Summer Activities Safer article can help your entire family have a busy, fun, and safe summer. And if you have a swimming pool, our Swimming Pool Safety Tips article will help you keep things safe.

Clean Your Gutters

Water and debris can accumulate in your gutters over the fall and winter, which can lead to water damage in your house. And you don’t want that. So get a ladder that can reach your gutters, but be sure not to overextend yourself. If the gutter is too high, you might want to call in an expert to do the job.

If you’re doing the work yourself, don’t lean the ladder against the gutter or near electrical wires. Scoop out the gutter’s wet leaves and debris, and wet down caked-on dirt so you can scoop out the mud with a trowel.

Also, use a garden hose to flush the gutters after you’ve cleaned them. This will get the gutters clean, and it will also let you know if you have leaks. Then use the hose to wash out your downspouts to make sure they’re not clogged. But be gentle-downspouts aren’t meant to withstand the same water pressure as a house drain.

Some experts recommend covering your gutters with a wire mesh guard to keep debris out. And remember: Never hang onto a gutter for support. It’s built to hold water and some leaves, not your weight.

Keep Your Deck Healthy

Your deck provides a great place to hang out in the summer, but it needs a little TLC to stay in good shape. Visually inspect the boards to look for curling, cracked, or rotting wood. If you see a board that’s damaged, remove it and replace it with a board that you’ve cut to fit the same space.

Go underneath your deck to make sure the support structure is in good shape, and keep an eye out for cracked boards and missing screws or nails. If you see signs of insects or unwanted animals, such as spider webs or chewed boards, call a pest-control expert to take care of the problem.

Lastly, if your deck is sealed or stained, some experts say you should refinish it annually. Start by power washing the deck, then letting it thoroughly dry. Remove the finish or seal with a remover/stripper, and let it dry again.

With a sander and medium-grit sandpaper, lightly sand the deck, then remove all of the dust before continuing. Before you apply your finish, do a small test area to make sure you’ve got the right color. If you do, apply the finish with the wood’s grain and don’t stop in the middle-that can cause uneven coloring and streaks.

Two things to remember: make sure you’re wearing a mask to prevent inhaling dust and fumes, and don’t do any of this work if it’s going to rain.

Spruce Up Your Paint Job

When your house looks good, it makes your entire property look better. So every summer, rent a power washer and use a mild detergent to clean your house’s exterior. With just a little work (that’s actually pretty fun), you can get rid of dirt, dust, bird droppings, tree sap, and more. And it provides a good opportunity for you to inspect your house and make sure everything is still in good order.

Infrared Imaging and Mold Detection

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As concerns regarding indoor air quality increase, there is increasing concern with respect to mold. Used properly, a thermal imager can help identify areas of potential mold growth.

Mold is a ubiquitous single cell organism that tends to favor moist environments. Of the thousand species of mold found worldwide, many are harmless; however, certain species are toxic. Others can cause chronic health problems in humans.

Luxury house with a two-car garage and beautiful landscaping on a sunny day. Home exterior.

While thermal imagers cannot detect mold directly, they can often detect evidence of the latent moisture often associated with mold presence. When using a thermal imager to detect latent moisture, keep the following in mind:

  • Evidence of moisture can only be detected if a temperature differential exists across the surface of the material being inspected.
  • Frequently, a delta T can be created by actively heating or cooling a structure or by relying on solar loading of the subject areas.
  • Subject building components should be imaged from both indoor and outdoor aspects under the correct weather conditions.
  • Suspected moisture presence must be confirmed by independent means.
  • A negative finding for latent moisture does not guarantee that mold is not present.

Since moisture presence is not positive proof of mold presence, further laboratory tests will be required to confirm mold within any moist areas detected.

Tortoise and the Hare



Everyone has heard the fabled race between the in which the tortoise beats the hare. One of the morals of the story is that a steady pace may be more fruitful than erratic bursts of speed.

Thermographers who perform infrared inspections should keep in mind that a slow and steady pace can lead to victory. Working at an even pace can help to prevent overlooking the subtle temperature variations that often indicate serious problems. Purchasers of thermographic services should bear in mind that the best value is not in the fastest inspection time, but rather in the thoroughness and accuracy of the inspection.

When it comes to your next infrared inspection, beware of the hare. Inspections that are praised more for their swiftness today may be cursed in the future for their costly oversights.

Why GFCI Devices Appear Warm

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When performing an infrared inspection of an electrical panel you may notice that the phenolic bodies of Ground Fault Circuit Interrupters appear warm. This same condition may also be observed on self-contained GFCI receptacles. This condition is usually due to the construction of the device itself.

In order to monitor the amount of current flowing through the supply and neutral conductors of a circuit, GFCI devices have small transformers built into them. These transformers can cause the body of the GFCI to run several degrees warmer than ambient temperature. Depending upon the settings of your thermal imager, these device may show a marked contrast to their surroundings.


When inspecting GFCI devices, compare the thermal patterns of these devices to other similar devices under similar load. When inspecting GFCI breakers, be sure to inspect the load side connection at the GFCI device as well as the neutral bus bar connection for the subject breaker.

Infrared inspection of electrical distribution systems is one of the many topics covered in the Level I Infraspection Institute Certified Infrared Thermographer® training course.

Mitigating Risk Through Communication

“To effectively communicate, we must realize that we are all different in the way we perceive the world and use this understanding as a guide to our communication with others.”

– Tony Robbins, American motivational speaker and writer in Unlimited Power: The New Science of Personal Achievement

The words you say and how you say them can have a profound impact on the message you give your clients and your business partners. According to William Chandler, Owner of Property 360 in Florida, communication is paramount to an inspector’s success.

“Communication, reporting—that’s where the rubber meets the road,” Chandler said. “You can be an excellent inspector, but if you’re not competent in verbal and written communication, you’ll struggle to grow your business, or you’ll find yourself on the wrong end of a claim.”

In a technical field like home inspecting, it’s important that you communicate clearly and effectively. Only through strong communication can you both mitigate risk and satisfy clients…..(read more)

Spring is the Time for IR Inspections of Roofs

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With the onset of warmer weather, the harshness of winter is but a fading memory for most. Left undetected, the damage caused by winter’s fury is a reality that can lead to premature roof failure. Fortunately, an infrared inspection of your roof can detect evidence of problems before they get out of hand.


Performed under the proper conditions with the right equipment, an infrared inspection can detect evidence of latent moisture within the roofing system often before leaks become evident in the building.


The best candidates for infrared inspection are flat or low slope roofs where the insulation is located between the roof deck and the membrane, and the insulation is in direct contact with the underside of the membrane. Applicable constructions are roofs with either smooth or gravel-surfaced, built-up or single-ply membranes. If gravel is present, it should be less than ½” in diameter and less than 1″ thick.


For smooth-surfaced roofs, a short wave (2-5.6 µ) imager will provide more accurate results especially if the roof is painted with a reflective coating. All infrared data should be verified by a qualified roofing professional via core sampling or invasive moisture meter readings.

A Quick Tip from Bayou State Inspections, James Yaeger ( LHI #10025)

The Crafty Way to Outwit Window Drafts

Homeowners are always looking for ways to save energy while making our homes more comfortable. One of the easiest ways of doing this is to improve insulation in the attic. The attic is relatively easy to access. Often, it’s also the source of major energy losses, because warm air rises.

On many cold, sunny days it would be great to air out your home without feeling a nasty cold draft from an open window. In fact, it may be essential to air out the house when you have just fried some bacon and the kitchen exhaust fan can’t remove the odor. But if you open the window, you get a cold draft that only seems to spread the bacon smell throughout your home. You can avoid this fate if you understand the basic science of wind hitting your home.

The side toward the wind will be under positive pressure as air tries to push in. The downwind side will experience suction, and air will tend to move out of the window. So, to easily and comfortably ventilate your home, open a window on the downwind side. Air will move out of the open window as it leaks into the side of your home facing the wind. If you open a window on the windy side, too, air will flow in and out more quickly. If you also open a window on the second story, the effect will even be greater as a chimney effect causes warm air to rise.