Posts Tagged ‘mold’

Want Proof That Termites Are (Misplaced) Evil?

April 15, 2011

I recently had a structural inspection that showed (once again) how much damage a gang of termites can do to a home. This damage was located in the rim joists and sole plates of a home with brick veneer. However, these termites had incentive to invade the wood due to the rim joists and sole plates being apparently exposed to excess water coming from behind the brick veneer.

Some background is needed before getting into the termite business. The sole plates are the boards that sit atop the foundation, upon which the first floor joists rest. Rim joists, also known as band joists, are the boards that box in the floor joists. The ends of all floor joists resting on the sole plate but up against rim joists. Rim joists also help stabilize the joists and help keep them from angling or twisting.

In a properly designed brick veneer wall, a gap is supposed to be installed between the brick veneer and the exterior wall sheathing. The exterior sheathing is the material that covers the outside face of the wall framing. Sheathing can be boards (in older construction), or plywood or oriented strand board (OSB) panels, although in some construction Styrofoam panels may be installed between the plywood or OSB panels. The gap between the exterior sheathing and brick veneer is supposed to serve as a drainage plain to provide water that gets past the brick veneer a drainage path to the base of the wall. And, believe me; water can get past the brick veneer, particularly if the brick is especially porous. Drainage holes (in combination with flashing) in the brick veneer just above the foundation in the brick veneer are supposed to provide a path for water to flow out of the drainage plain. Brick veneer installed on concrete block construction, more commonly used for commercial construction, is also supposed to have a drainage plain with weep holes.

Full brick exterior walls, such as those on many old buildings in Cincinnati, do not need weep holes because the water supposedly travels fully through the brick into the interior wall surface or back out to the exterior surface. Another brick construction that was usually not built with drainage holes was concrete block on a concrete foundation with brick veneer installed in front of the block. Unlike the previously described brick veneer/concrete block wall, the first floor framing in this construction was built on the block and the upper floor framing was built above that. The brick veneer in this construction extended from the concrete foundation and up the exterior wall. This last construction, as used for a crawlspace construction, is the subject of this blog post.

Let’s start with a photo of the foundation construction from inside the crawlspace, shown below:


This photo shows the concrete foundation with the concrete block above it. On the exterior side of the foundation, the soil level would be to the top of the first row of concrete block above the foundation. Now, take note of the dark streaks on the facing concrete foundation. Those streaks are due to water drainage through openings in the block mortar. The question is from where is that water coming. For sure, water can migrate from the soil through the block. But, the darkened block in the area in the corner area and along the foundation to the left that extends the full height of the block hints at another source—the drainage gap behind the brick veneer. Darkening of the block indicates that they are water-saturated. Further support for the drainage gap being a water source is evident from the darkened sole plate wood sitting on top of the darkened concrete block.

Let’s take a closer look at part of the area along the facing foundation. Note the copper water pipe in the photo above. This pipe is the same as the one shown to the left in the photo below. In this photo, the darkened woods of the sole plate and rim joist above the water-saturated concrete block is visible. However, also visible are darkened areas in the subfloor boards on top of the joists. The material that looks like resin or droplets is water droplets on the wood surfaces. The pattern of the water stains on the subfloor indicates that the water source is the exterior wall, and more particularly the drainage gap behind the brick veneer. Areas like these were found all along the exterior walls of this crawlspace foundation.


So, what do these findings have to do with termites—as it turns out, a lot. Termites are one of Nature’s maintenance creatures. They reduce wood back into a form that is useful to plants, microflora and soil. The trouble is that they cannot distinguish between the dead wood of a tree in the forest and the lumber we use in our buildings. The subterranean termites we have in the Cincinnati area also require water to live. In fact, they build mud and frass tubes in areas where they would be exposed to air to conserve water and will carry water from the soil into the tubes to keep them damp enough. In the photo below, the dark streaks on the foundation are the remains of such tubes between the ground and the sole plate. Note that the distance between the ground and the sole plate in the photo is about 5 feet. Termites can be very determined to find a food source.


If termites can find wet wood, their job gets much easier because they do not have to bring as much (if any) water up from the ground. So, in the case of this home, they found it in the wet sole plate and rim joist woods. And once they set up their work area in them, they went to town. The following photos show some of the visible damage. Note in all of these photos that the wood is darkened due to water exposure.




I want to emphasize the words “some of the visible damage.” The exact extent of the damage generally would only be known when the damaged wood is removed and inspected. An ice pick or awl can be used to probe the wood and somewhat determine the extent of damage. If the damage is on the other side of solid wood, though, this method would not find it. Also, termites form multiple tunnels in the wood, which means that unless the wood has been greatly degraded by the tunnels, as in the photos, a lot of probing would be needed to fully determine the damage. More sophisticated and expensive methods to determine the extent of damage exist, such as injecting chilled or heated air into the termite tunnels in the wood and viewing the wood using a thermal camera. In theory, the air would follow the tunnels and provide a temperature difference within the wood that is visible to the camera. The common method, however, is using a probe.

The damaged wood in this home will need to be removed, which will be expensive due to where it is located. The repair will also not be as ideal as new construction. Even worse, as wood is removed, more damaged wood that is not readily visible might be found, making the project much more expensive.

But, a question still exists as to why the sole plate and rim joist wood is getting wet when the wood is at least 16 inches above outside grade. Additionally, the drainage plain behind the brick should extend below the wood to the concrete foundation level. I believe that a couple of possibilities exist. The brick might not have a proper drainage plain, in that the brick veneer is right up against the exterior sheathing. I hope not because that likely means the exterior sheathing and upper floor framing could have moisture and/or termite damage. Another possibility is that the rim joists and/or sill plates block the drainage plain. Then again, water from the upper drainage plain may be filling up the concrete block and/or the gap between the brick and block to the level of the wood. Overall, though, the fact that the subfloor appears to be getting wet indicates that a drainage plain issue is present. When the wood is replaced, the real water source might be evident.

What are the morals of this story? Here are a few:

  • Damp crawlspaces or basements can be an invitation for termites to move in.
  • Properly designed and installed drainage plains behind exterior finishes, whether brick veneer or siding, can help prevent expensive repairs.
  • A great amount of water can penetrate through brick.
  • Trick observation—the crawlspace floor was muddy apparently due to water flowing into it. Since no vapor barrier was present, water from the wet soil can evaporate and enter the home where it can cause mold growth in those dark and quiescent locations where mold likes to hang. Then again, even a vapor barrier might not help if too much water is getting into the crawlspace.

Unfortunately, like most projects of this kind, I will not know the outcome due to the nature of these kinds of projects. Be assured that if I hear anything, you will be the first to know.

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Home weather barriers, vinyl siding and Hamilton County Ohio

July 29, 2010

In inspecting a home under construction, I recently ran into an issue dealing with a weather-resistant barrier.  This barrier is one that protects exterior wall materials from weather exposure, particularly water.  So, the best place to begin this discussion is by defining what a weather-resistant barrier is.  The American Vinyl Siding Institute states the following on their website:

What Is a Weather Resistant Barrier System? It is a system that includes water shedding materials and water diversion materials. Weather resistant barrier systems commonly consist of a combination of exterior cladding, flashed wall openings and penetrations, weather resistant barrier material, and sheathing. Effective weather resistant barrier systems will shed the water initially, control moisture flow by capillary and diffusion action, and minimize absorption into the wall structure. The level of weather resistance required is determined by the applicable building code and structure.

The 2007 Ohio Building Code, which basically is taken from the 2006 International Building Code, defines a water barrier, which is basically one of the major purposes of a weather resistant barrier, as:

WATER-RESISTIVE BARRIER. A material behind an exterior wall covering that is intended to resist liquid water that has penetrated behind the exterior covering from further intruding into the exterior wall assembly.

This code further details a weather-resistant barrier as:

1403.1 General. The provisions of this section shall apply to exterior walls, wall coverings and components thereof.

1403.2 Weather protection. Exterior walls shall provide the building with a weather-resistant exterior wall envelope. The exterior wall envelope shall include flashing, as described in Section 1405.3. The exterior wall envelope shall be designed and constructed in such a manner as to prevent the accumulation of water within the wall assembly by providing a water-resistive barrier behind the exterior veneer, as described in Section 1404.2, and a means for draining water that enters the assembly to the exterior. Protection against condensation in the exterior wall assembly shall be provided in accordance with the International Energy Conservation Code.

1404.2 Water-resistive barrier. A minimum of one layer of No.15 asphalt felt, complying with ASTM D 226 for Type 1 felt or other approved materials, shall be attached to the studs or sheathing, with flashing as described in Section 1405.3, in such a manner as to provide a continuous water-resistive barrier behind the exterior wall veneer.

1404.1 General. Materials used for the construction of exterior walls shall comply with the provisions of this section. Materials not prescribed herein shall be permitted, provided that any such alternative has been approved.

1404.2 Water-resistive barrier. A minimum of one layer of No.15 asphalt felt, complying with ASTM D 226 for Type 1 felt or other approved materials, shall be attached to the studs or sheathing, with flashing as described in Section 1405.3, in such a manner as to provide a continuous water-resistive barrier behind the exterior wall veneer.

Section 1405.2 Weather protection. Exterior walls shall provide weather protection for the building. The materials of the minimum nominal thickness specified in Table 1405.2 shall be acceptable as approved weather coverings.

In looking at the home under construction for the first time, I noted that a weather-resistant barrier was not installed on the home.   Most people will recognize a weather-resistant barrier as the usually white paper-like wrap, most commonly with the name Tyvek printed on it in large letters.  Other similar wrap or other materials are also used.  That is where the problems began.

In inquiring about the lack of weather-resistant barrier, I asked for the drawings.  In reviewing the drawings, I noted that no weather-resistant barrier was specified.  When I inquired about why none had been installed, the builder informed me that the Hamilton County, Ohio Building Department did not require it.  Apparently, the building department believes that vinyl siding, which was being installed on this home, was an adequate weather-resistive barrier.

I decided to investigate further on the ultimate authority.  On the internet, I found that the Vinyl Siding Institute states in its Vinyl Siding Installation Manual (http://www.abtco.com/kp_abtco/docs/ABTCO_Vinyl_General_Installation_Instructions_.pdf):

Weather Resistant Barrier

Vinyl siding has always been designed as an exterior cladding, not a weather resistant barrier.  Vinyl siding is designed to allow the material underneath it to breathe; therefore, it is not a watertight covering. Because of its design and application, it provides a supplemental rain screen that enhances the weather resistant barrier system by reducing the amount of water that reaches the underlying weather resistant barrier.

What Is a Weather Resistant Barrier System? It is a system that includes water shedding materials and water diversion materials. Weather resistant barrier systems commonly consist of a combination of exterior cladding, flashed wall openings and penetrations, weather resistant barrier material, and sheathing. Effective weather resistant barrier systems will shed the water initially, control moisture flow by capillary and diffusion action, and minimize absorption into the wall structure. The level of weather resistance required is determined by the applicable building code and structure.

Best Practice: To achieve designed performance, vinyl siding must be installed over a weather resistant barrier system that includes 1) a continuous weather resistant material and 2) properly integrated flashing around all penetrations and where vinyl siding interfaces with other building products such as brick, stone, or stucco. Refer to the manufacturer’s installation manual for specific product applications and recommendations. Whichever product(s) you decide to use as part of a weather resistant barrier system, be certain the materials meet the applicable code by contacting the manufacturer of the weather resistant barrier material(s). Always consult the applicable building code for minimum weather barrier requirements in your area. Keep in mind that additional measures may provide better protection against water intrusion than the minimum requirements of the building code.

The Vinyl Siding Institute clearly states that vinyl siding is not an acceptable weather or water resistant barrier.  Since vinyl siding is not considered to be a weather or water resistant barrier, installing vinyl siding without a proper weather-resistant barrier cannot meet the requirements of the building codes for Hamilton County, as taken from the Ohio Building Code and the International Building Code and cannot be considered as proper building practices.  Furthermore, The Vinyl Siding Institute states that vinyl siding needs to be installed over a weather-resistant barrier, and basically describes the properties of a material such as Tyvek, although it is not the only weather-resistant barrier available.  This Institute further states that proper flashing is required for the siding.

So, am I making much ado about nothing.  I hope not.  Water, especially from wind driven rain can get behind any siding material, but more so vinyl siding.  This water then can reach the underlying wood materials.  The problem areas might not be behind where the water reaches the underlying materials, they usually are where that water flows after landing on the materials.  Water that gets behind the siding will flow down the face of the sheathing to points where it can pool, such as above windows and doors and at the base of walls.  At these points, it can enter into the wall cavity itself if those areas are not properly flashed.  It can also enter through gaps between the sheathing.

Once inside a wall, the water can be absorbed by the insulation.  Insulation holds water really well–nearly as well as a sponge.  If enough water is present, mold will grow because mold spores and their food sources are endemic.  Mold can further cause wood rot.  Other moisture-related damage can also occur, particularly to materials made from oriented strand board (OSB), a very common building material and one that has a bad habit of delaminating when exposed to enough moisture.  Do you think that repairing these materials can be expensive?  You betcha it can, particularly if structural members are involved.

What is the bottom line here?  If you have the abilities to review the construction drawings, do so very carefully and inspect closely for a proper weather-resistant barrier.  If you don’t have this expertise or ability, then hire someone who does, such as a capable architect or engineer.  And remember this point, drawings are best reviewed BEFORE construction begins.  My clients learned that lesson at a cost of $1800, and even then, the weather-resistant barrier was not ideal because the windows and doors were not properly flashed according to the manufacturer’s recommendations.

Is air sampling for mold a necessity?

February 22, 2010

I lost a home inspection job for this weekend and I believe I know why.  The job involved not just the routine inspection but also had a suspected mold problem.  Although I would have liked the income, I am more concerned that the potential client decided on another inspector because he was convinced that air sampling for a potential mold problem was needed.  The client said that possible mold was present and described construction that could create moisture conditions conducive to mold growth.  But, I told the client that usually air sampling for mold is not needed because no matter what, if you see mold, you clean it up.  If you find moisture problems that could lead to mold growth, even if no visible mold growth is present, you attempt to eliminate them.  A skilled inspector should be able to recognize both without the need for air sampling.

The truth is that no where is there a requirement for air sampling.  In fact, air sampling is usually not recommended.  The main reason is that the complexities of mold and sampling for mold usually creates more confusion than explanation.  The results are usually confusing, and many times do not mean anything.  Over the years, I have found that nearly every time I have collected air samples–and a lot of other types of mold samples other than clearance samples–the results create confusion and misinterpretation.  When I have been an expert consultant in legal cases, I most often do not have trouble discrediting others mold sampling results.  And the truth is to get any kind of statistical accuracy upon which to make significant conclusions, many more samples are needed rather than the two or three most so-called “mold experts” collect.

Over the years, I have found that when so-called experts do not really understand what they are doing, they rely religiously on protocols they learned in their two or three day mold courses.  Those courses teach them how to conduct sampling, but usually do not dig very deep into the logic behind the sampling.  In most cases, the limitations of the sampling are not explained.  Further, I suspect that even when the limitation are explained, most attendees at these classes do not really grasp those limitations because they do not have the background to understand them.  I know my background and all of the various bits of expertise, special training  and experience I have needed to understand those limitations, and it took over 25 years to get it.  So, I suspect highly that a person coming from a non-science background with less than a week’s training probably does not understand them.

The thing is air sampling for mold is a tool, just like many other tools needed to investigate such problems.  In fact, I can think of nearly 20 different types of sampling used to investigate mold problems.  In fact, many various air sampling methods exist besides the usual Air-O-Cell cassette usually used by so-called “mold experts” and I know of at least three air samplers that collect samples similarly to the Air-O-Cell.   I have found that many of the other sampling methods even provide more useful information than any air samples.  With air samples, you HAVE TO understand how air travels throughout an area to determine the validity of the sample and whether it provides information about a risk.

But, the most important tools that an investigator takes into an area is his/her visual acuity and knowledge.  I specifically stated visual acuity because the inspector needs to have an eye for detail.  I have been on many inspections with clients where I have pointed out possible mold or signs of moisture problems that the client did not even see.  The stuff between the ears can only be gotten one way and that is through long hours of learning, knowing the right people and a lot of hard work.  No one is going to stuff that expertise into someone’s head in a couple of days.

So, when it comes right down to it, I lost an job opportunity because someone else was much better at selling a likely unneeded service than I was at convincing the client that the service was NOT needed.  At the same time, the client had a part in my loss and  I don’t mean by just selecting the other person.  No, the client also came into the picture with beliefs–things read or heard.  In fact, I could hear doubt in the client’s voice when I said that I rarely take air samples.   When I get these calls, I try to educate the client.  Sometimes, I succeed and sometimes I don’t.  My only request to anyone reading this is that you listen and learn to ask the right questions.  I also recommend that you also dig deeper into the expertise of the person offering you advice.  It could save you a lot of money in the long run.

It's not a mold problem-It's a moisture problem

November 8, 2009

This is the first post to my blog and I have been thinking about what would be a good first post.  I have been thinking that it should be related to mold, because it is a subject I know well and which has a lot of confusion surrounding it.  Yesterday, I attended one of those “conferences” where the “presentations” are basically sales pitches for the presenter’s much more expensive trainings seminars.

One of these guys, who claimed to be a “mold expert” because he was certified for taking the EPA Mold Course, claimed that he could reduce any foreclosed property’s sales price by taking a mold test.  Yes, he was right that a person could pretty much find mold in any house and develop an expensive remediation plan for it.  Even if the house is squeaky clean, if it has been around a couple of years, all the person collecting an air sample has to do is set the thermostat’s fan switch to ON and whack the duct leading to the area.  That will generate a good amount of material for the sample.

Now, by passing this information I do not want to say that I am recommending that people collect samples this way.  What I am trying to say is that a lot of ignorance exists around mold sampling, what the sample results mean and whether a mold problem exists.  And, that last point is where I want to begin.

When does a mold problem exist in a building?  Straight out, a mold problem exists only when the mold growth is or potentially can be a health hazard to the people occupying the building.  These are the cases that require immediate and sometimes drastic remediation, which can be expensive.  In most cases, mold is a nuisance to people and not a true health hazard, although some would argue that nuisances are health problems.  But, that may be a subject for a future blog post.

Mold growth in a building is always a symptom–of a moisture problem.  Mold contaminants are pretty much common in all buildings.  However, mold growth is not.  For mold to grow, adequate moisture must be present.  A person cannot get rid of the mold growth without first understanding and getting rid of the moisture problem.  Cleaning up the mold problem without resolving the moisture problem will end up with more mold growth.  The exception is those cases where the moisture problem was an unusual event, such as a flood.

To bring this blog post to an end and keep under my self-imposed 500 word limit, I want the reader to take away this point:  the problem is not a mold problem; it is a moisture problem.  To bring it around to my original point about the banks, if the bank personnel were a little wiser about this point, they would not be so easily duped by a mold problem report, which could save them thousands of dollars.


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