What can Thermal Imaging Do For You?
November 1, 2008
Thermal imaging can unlock secrets inside the wall, ceiling, roof and floor structures of your buildings. It is a fast, easy and non-invasive way to determine and define building construction deficiencies. It will help contractors define the problems before they are apparent to the naked eye. The technology can show the extent of the most heinous of problems affecting the building envelope today-moisture intrusion. Many times it can tell you the source of water entry.
Thermal imaging can show insulation deficiencies. Locations can be delineated and the size of the deficiency defined. The technology can show the extent of water migration from plumbing leaks as well as structural deficiencies. It can pinpoint rebar and cell fill locations. It can be used to determine if lintels are poured full of concrete or if there are voids in the pour. It can be used to show fastener patterns and frequency.
HOW IT WORKSImaging of a building yields a thermal photograph which shows various surface temperatures defined in differing colors. Heat of materials within the walls, ceilings, roofs and floors is transferred to the surface. These surface temperatures are recorded with the thermal camera.
Different materials heat up and cool down at different rates. Steel heats up fast and cools down fast, so fasteners can be identified even though they’re within the wall structure. Water heats up and cools down slowly, so its presence is shown after the other materials’ heat differentials fade. Insulation blocks the transfer of heat, so insulation deficiencies become readily apparent.
Heat from the sun is absorbed by the structure and each material heats up at a different rate and cools down at a different rate. Therefore, after the sun rises or sets you can see the heat that is transferred to the surface from the different materials inside the building structure. Given the right timings, each material will show a different temperature. So the components of the walls, ceilings, roofs and floors can be identified on the thermal image.
Interpreting the images requires people with a great deal of knowledge and experience in building construction techniques as well as thermal imaging techniques. So, only qualified technicians should be used.
BENEFITS FROM THERMAL IMAGINGConstruction consultants can benefit immensely from thermal imaging. Construction deficiencies can be defined and located with no invasive investigation.
A large condominium building on the coast of Florida had water intrusion problems for more than 10 years. The condo association dealt with the developer and GC over the years. But fixes were bandages for each individual problem. EIFS was patched in spots, windows were replaced and individual roof leaks were patched.
Finally, after the general contractor declared bankruptcy, a consultant determined that the mansard roof was improperly constructed and water was entering at the wall/roof intersection.
The deficiency causing the water intrusion was corrected. But the condo association faced a multimillion dollar assessment to pay to remove the EIFS and replace it. Invasive tests in many areas showed significant EIFS degradation. All of the EIFS might have to be removed and replaced.
The consultant hired C.H Brown & Co. Inc., a contractor based in Jacksonville, Fla., that specializes in masonry, plaster and EIFS, to thermally image the walls. The company was able to define which was wet and degrading and which was dry and sound. The consultant determined that thermal imaging had saved the association $421,000 in decreased cost for EIFS replacement.
Building owners can benefit directly from using thermal imaging. Deficiencies can be located rapidly with little expense.
HOW IT HELPSA homeowner had lived in a home for five years and had constant problems with his HVAC. He had to set his thermostat as much as 8 degrees F higher at night than during the day to keep the master bedroom comfortable during the winter. During the summer, the owner had to adjust the thermostat down 8 degrees F at night to keep the bedroom livable. Thermal imaging of the walls and ceilings found that blown insulation in the attic was totally missing behind a high tray ceiling. A quick fix yielded significant utility savings.
Another homeowner had twin baby boys. One boy developed severe allergies after going home from the maternity hospital.
It was revealed that several water leaks were associated with the roof to wall flashing. Mold had formed in the wall cavities and the boy was allergic to the mold spores. The source of water intrusion was corrected and the mold abated.
A doctor purchased a million dollar condominium on the beach. Before moving into his fourth floor unit he was walking on the carpet in stocking feet. He noted a wet spot near a bay window.
Thermal imaging revealed moisture in the wall, baseboard and floor. But, even more revealing was moisture over the bay window. The imager was able to trace the water up the wall all the way to the roof of the nine story building.
The contractor was notified. He repaired the roof and parapet deficiencies and took care of the problems in the walls below.
Building contractors can benefit most from thermal imaging. Thermal imaging done before the subcontractors are paid in full can reveal deficiencies before they become problems involving big money. The subs can fix the deficiencies before they collect their final invoices.
A second imaging session after the fixes are complete can help to determine if the fix worked and the building is free of deficiencies.
Another situation was a large condominium project at the beach that had problems with moisture intrusion. Not only did imaging reveal deficiencies with the windows, it revealed water coming from the parapet cap and the roof.
Plans called for the roof membrane to be wrapped up the back side and over the top of the parapet wall. The metal parapet cap was to have been applied over the roof membrane. However someone cut the roof membrane before the cap was applied.
Wind off the ocean caused a Venturi effect over the parapet cap that resulted in a vacuum under the cap.
The water entered the parapet wall under the cap. Thermal shots revealed the water cascading down the parapet under the roof membrane and out onto the roof deck where it leaked to the units below. Moreover, water leaked behind the stucco and used the back side of the expansion and control joints as conduits to move the water throughout the walls of the building all the way to the ground floor.
Inexpensive, non-destructive thermal imaging identified the sources of the problems and helped to define the least expensive, most effective fixes.
A large development used a masonry wall as an amenity feature along the main street bordering it. A car struck the wall and knocked over an entire section of the wall; from column to column.
While trying to determine if the required cell fill was installed, thermal imaging revealed that downpours were in their proper locations in about the first eighth of the wall. However, in the remainder of the wall, downpours were only made on the columns. Dowels were revealed protruding from the footing but the cell fill was skipped.
Subcontractors benefit from thermal shots in various ways. Imaging can often be used to pinpoint the deficiency itself. It can also be used to defend against charges of shoddy building practices.
AS BELOW, SO ABOVEA large roofing contractor uses the technology to identify leak locations for repairs to older roofs. In one case, it was used to determine the source of leaks at an older warehouse that a buyer wanted but was afraid to purchase with an unlimited liability for roof repair. Imaging led to a purchase and an acceptable contract for roof repair.
A stucco contractor protects himself with thermal imaging. A seven figure lawsuit charged that moisture intrusion was degrading EIFS architectural details. Imaging showed that the EPS shapes were dry. The lawsuit was dropped.
On another occasion, an area stucco contractor wanted to determine where leaks were coming from on a large apartment project. Thermal imaging revealed that leaks were coming from poorly designed flashing at the intersection of different types of veneer siding (brick and cementious board). The stucco contractor was not responsible for this flashing and a lawsuit was dropped.
A masonry contractor laid synthetic architectural stone veneer on a church. The stone started to drop off the building walls. The GC threatened with legal action. The use of thermal imaging determined the cause of the problem and found that about one-third of the stone was delaminating from the CMU substrate.
Testing determined that the synthetic stone had a cement content that made it extremely absorbent. The stone drew the moisture out of the mortar before it could set up. The law suit was never filed and an acceptable fix was developed.
Thermal imaging is a cost effective, non-destructive way to define construction deficiencies. Since it “sees” surface temperature, not the actual hidden components of the walls, roofs or ceilings, it is not perfect. But it is a fast method that most often reveals the hidden secrets. W&C