EIFSFACTS.ORG
The Real Facts About EIFS
- About Moisture Probes -
Ah, the dreaded moisture probe. EIFS homeowners fear it like a child fears the doctor's needle. But just as the doctor's needle is necessary to insure health, the moisture probe is necessary to assess the health of the sheathing that lies below the EIFS of a home.
There are two kinds of moisture meters in current use. One is a surface meter that is non-intrusive. That is, it makes no penetration through the cladding (EIFS) of the home. The other is a moisture probe. This is an intrusive device in that it is inserted through the cladding.
Image 1: A Surface-Scanning Meter
Image 2: A Moisture Meter with Attached Probes
A surface scanning meter uses electromagnetic principles to measure the moisture content of the sheathing behind the EIFS. The principles are much like used in a metal detector. Once it is properly calibrated for the type of sheathing that is present (a vital step) it is passed over the surface of the cladding and the meter indicates the relative moisture content of the sheathing below.
A moisture probe is basically a device that meaures the electrical resistance of a material. The probe has two pointed, metal prongs that are inserted through the EIFS and into the sheathing. These prongs look much like the prongs on meat thermometers. The moisture content of the sheathing is then determined by reading the meter. Just as important as enabling the inspector to read the moisture content of the sheathing, the moisture probe enables an experienced inspector to feel the condition of the sheathing it is being inserted into. Once the probe is withdrawn the holes, typically referred to as a "snake-bite" are filled with sealant.
Image 3: Probes Inserted Through EIFS
Image 4: Reading the Moisture Level
Image 5: Typical "Snake Bite"
Image 5: Once Sealed Properly, the "Snake-Bite" Can be Hard to Find
An experienced and qualified inspector will use both types of meters during an inspection. Why? Quite simply, a surface-scanning meter cannot indicate areas of damage that are dry at the time of inspection. If it has been a while since it has rained, an area of intrusion may have dried out. If an area of the sheathing has rotted and the moisture-intrusion has subsequently been halted the area will eventually become dry-rot. The experienced inspector will be able to feel the difference by the way the probe feels as it is inserted into the sheathing. If the inspector suspects dry rot s/he will usually pull out a small sample of the sheathing (basically a biopsy) with a small tool.
There are currently several inspectors around the country who capitalize on the fear of the moisture probe. http://www.allstucco.com, for example. We contacted the owner, Scott Zaeske, in October of 1998 with several questions, including how he can find areas of dry rot with a surface scanner. He replied that he was "not interested" in answering our questions.
Remember, beware of any inspector who claims to be able to do a thorough moisture intrusion inspection without invasive probing. The experts are unanimous in their agreement that invasive probing is required to accurately assess the health of the sheathing under the EIFS. Surface scanning cannot find areas of dry-rot. Ask any inspector who does not use a moisture probe how he intends to find any areas of dry-rot.
You would not go to a cancer specialist and say "tell me if I have cancer, but you can't use any needles".
