Archive for the ‘Moisture & Mold’ Category

Home drainage

February 10, 2010

If someone were to come up to me on the street and ask me, “Hey Matt, what do you consider to be the top five problems with homes?”, I would definitely have to include drainage as one of those five.  However, drainage problems have many causes.  Some are due to improper control of the roof drainage, while others are due to improper sloping of the ground around the home. The thing is the severity of these kinds of problems are highly under-rated by most homeowners.  In many cases, fixing drainage problems could stop or severely reduce water intrusion through foundation cracks.  For those with concrete block or stone foundations, fixing these problems could reduce moisture intrusion through the blocks, which is a chronic problem with most block and stone foundations.

Well, I just happened to have an e-letter arrive in my inbox this week with a link to a very nicely illustrated and explained article about site drainage.  I believe it explains a lot and could be very useful to those who have drainage problems, and even those who think they don’t.  Here it is:   http://www.greenbuildingadvisor.com/green-basics/water-management.

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The lowly window well

January 1, 2010

Let me start out right away by saying that I am NOT a fan of windows in basement foundations, UNLESS the basement was intended in the original design as living space.  Windows in the latter case are usually larger and in many cases intended to be alternate escape routes during emergencies.  These windows are also usually insulated glass and of a better quality.

Windows in the former case are usually relatively small and are usually single-pane and relatively cheap.  I guess they are supposed to offer some light into the basement and, since many can be opened, are apparently intended archaically to provide basement ventilation.  They don’t, particularly in the modern home.  I am especially not in favor of basement of cheaper basement windows because they are a security hazard.  As cheap as most are, they could be easily compromised and allow a route for an unwanted to enter the home.  If you think someone could not get int through the window, think again.

So, what does that discussion have to do with window wells?  Pretty much every time I perform an inspection on a home with below-grade cheaper basement windows, I find water stains on the foundation wall beneath the windows, indicating that water has leaked through the windows.  In these cases, water in the window well has gotten deep enough to partially submerge the window and then enter the basement around or through the window.  If this problem happens often enough, windows with steel frames will rust through and windows with wood frames will rot.

Let me step back and talk about the basic construction of a PROPERLY installed window well.  Window wells provide a space around the window to let in light and provide adequate room to maintain the window.  (Most require periodic painting, window replacement and possibly caulk.)   Most of the current window wells are a plastic or galvanized metal, and form a semi-circular space around the window.  However, I have also seen window wells constructed from stone, concrete block and wood.  Most window wells are 18″ to 24″ deep.

Manufactured window wells are supposed to be fastened to the foundation wall and should be caulked to prevent water intrusion through the gap between the well and foundation wall.  The well wall should be above the grade at least three to four inches; but it also has be extend several inches below the window opening the foundation.  Note that I did not say the window frame; I meant below the concrete edge of the opening.  If stone or other materials that cannot be fastened to the foundation are used, I believe that landscape fabric with a layer of gravel should be installed over the outside joint between the well wall and foundation to prevent soil entering into the well through the gap.  Just this past week, I witnessed a case where soil had extensively eroded into the window well through the gap between the well wall and foundation, partially plugging up the drain opening.  Heaven only knows how much soil entered into the drain line.

Each well should have a drain, which is usually three or four inch PVC pipe, although I have also seen corrugated, non-perforated drain pipe used.  The drain line should have a screen or strainer to keep larger debris out of the line where it could eventually clog the line, particularly leaves and grass clippings.  The top of the drain should be two inches or, even better, more below the window opening in the foundation, again not the window frame.  Pea gravel should cover the floor of the well to prevent soil erosion and mud constantly splashing up on the windows and foundation.  BTW, NO other drain lines should be run into the window well from elsewhere, ESPECIALLY downspout drain lines.  (I would not have mentioned it if I had not seen it myself.

Now, what about that drainage?  Where should it go?  In many cases, the window well drain line is run to the footing drain.  I do not favor the window wells draining to the footing drain because debris from the window well could eventually plug up parts of the footing drain line, and that drain line is extremely important in many cases for preventing water intrusion into the basement.  I first wrote that they could be tied into the downspout drain lines.  After thinking about that arrangement, I decided that was not a good idea.  If the downspout drain line plugged up, water could backflow into the window wells if their inlets were lower than the downspout drain line inlets.  The best arrangement would be to run a separate drain line for the window well drains.  This line could be tied into the downspout drain line if the tie-in were far enough below the window well drain line inlets to prevent backflow into the window wells.

I emphasized that the opening to the window well drain line should be inches below the opening in the foundation rather than the window sill.  The reason is that in many cases, water leaks into the basement around the window frame, particularly beneath it.  I have seen cases where the window frame has had the dickens caulked out of it on the inside, and just as well seen my share of leaks despite the caulk.  What the homeowner usually does not realize is that on the outside, water has gotten into the gap between the foundation and the window frame.  Over time, this water rusts metal frames and rots wood frames.  Furthermore, gaps in materials form what we call a capillary gap which tends to hold the water in place even after the water in the window well has drained away.

One way to prevent, or at least slow down, water intruding through basement windows is to install glass block windows.  These are basically mortared in place and provide about as much water intrusion prevention as concrete block.  More importantly, glass block windows are more secure than most single-pane basement windows.  If you still want a window vent, they are available for glass block windows.  You can even provide an opening for a dryer vent, just be sure to put it higher in the window to prevent water entering through it should the window well flood.  A word of caution, though, glass block windows CANNOT be installed if the window is an escape route.  Those escape windows are required by building codes.  I am talking about replacing the cheapy, single-pane windows.

Before I leave this subject, let’s talk maintenance.  I have seen my share of wells nearly filled with leaves, grass clippings and trash.  I have also seen small pastures in them; that is, a lot of vegetation.  Creatures also have a bad habit of getting trapped in the wells—usually frogs or turtles, but the latest edition to the cats who run my house was also apparently born, and abandoned, in one of mine.  My point is that window wells need probably as much maintenance as gutters.  They have to be kept clean to prevent debris and vegetation clogging the drainage system.  You should keep them clean if for no other reason to be able to periodically check your windows.  One final note, if I have not convinced you to change to glass block windows, make sure that plantings around the foundation do not block view of the wells.  Should an intruder choose that route into the home, at least make it possible for someone to see him/her.  While your at it, maybe you should check the lock on the basement door.

Plants as indoor air cleaners

December 9, 2009

Here we go again.  WebMD reported this week that HortScience had an article in August about research on using house plants to remove indoor air pollution.  Interestingly, the article did not report anything about been there, done that.  Well, not me personally.  But, a few years ago, NASA was doing similar research.  At that time, a bunch of people were proposing that plants could be used to clean indoor air.

The research seems to be clear.  Yes, some plants appear to be able to remove some indoor pollutants.  The truth is in the practicality.  Usually, these studies are designed using injection of an initial concentration of a chemical inside an airtight container that contains the plant.  The chemical’s concentrations are then monitored over time to determine how well the plant removes the compound.  The first possible problem with this kind of research is that some of the compound could be lost to surfaces inside the container.  If this research is like most of this kind of research, such losses are not included in the study details.  Another problem is that, over time, chemicals can also break down, depending on the environment and the chemical.  Again, study details don’t usually describe how this loss is accounted for.  And a final detail about the study methodology is sometimes overlooked, and that is loss of chemical to the study.  Each time a sample is removed, the chemical concentration inside the container decreases.

Those facts were about the practicality of the study design.  Reality is probably the least practical aspect of the study results.  We don’t usually have only one chemical floating around in the air.  Does that mean if a whole bunch of plants would be needed if they each have their own chemical they like to dine on?   Realistically, chemicals are not put into the environment in one squirt and then left to decline over time.  Some chemicals are emitted into the air over time, such as those from building materials.  Even more complicating is the fact that chemical concentrations can vary over time because the emissions from materials vary over time, depending on a range of environmental factors.  I have collected this kind of sample data myself, as have many other researchers.  The changes in chemicals floating around a building are pretty amazing to study, actually.

In our buildings, air is constantly being exchanged–moving in and out.  No building is airtight like the containers used for most plant studies.  Air coming in also can carry chemicals into a space and air leaving can taken them out, which is also another reason why chemicals and their concentrations can vary dramatically over time.  Changes in the rate that air enters and leaves a space can be controlled by factors inside and outside the building.  Wind direction and speed, house design, sun and many other factors can influence air movement inside a home.  Operation of the air handler, people movement, heat sources, interior design and many other factors can influence air movement inside a home.  As vapors, chemicals are also influenced by the Ideal Gas Laws, in particular the part about partial pressures which says that vapor pressure of any one chemical in one area will equilibriate with vapor pressure of the same chemical in an adjoining space if the chemical can move between them.  So, chemicals at a higher concentration inside compared to outside a building will eventually equilibriate with concentrations in the outside air.

Materials inside a building also absorb and re-emit chemicals.  Ever smell cigarette odor on non-smoker who has been in a smokey bar?  The fixed things in buildings, the things of which the building is constructed, as well as the solid materials floating around in the air and the other things moving through the building, such as people, pets and their related materials, all absorb and re-emit chemicals.  The researchers call things that absorb sinks and the things that emit sources.  A dynamic exchange is going on between these things all the time.  Further, something that is a sink at this time can become a source when a chemicals concentration changes.  So, what is a plant to do?  Then again, how many plants should a person have when the emission rates could be constantly changing?

But, let’s dig into that question a little more.  How many plants would be needed.  Past research has shown that plants absorb a definable, but minute amount.  Such research predicted that a small forest would be needed to make a significant dent in the chemical concentrations.  Again, we are talking about static chemical concentrations, whereas most buildings have dynamic concentrations.  That brings me to another subject that seems to often overlooked.

Past “Plants Eat Chemical Compounds” researchers also took a lot of criticism for one major overlooked factor.  Plants grow in soil.  Soil contains–dare I say that M word–yes, mold!  In fact, many plants have a symbiotic relationship with certain molds to help them absorb nutrients.  But, many molds themselves emit chemicals into the air.  So, a person has to ask, is it practical to use plants to absorb one chemical when the soil in which they grow could be emitting a whole bunch of other ones?  Probably not.

NASA had a good reason to research whether plants absorbed chemicals or not.  NASA was interested in using plants on spaceships making long journeys where plants might be used for food and to help control the air quality inside the ship.  Currently, NASA uses chemical filters to control chemicals emitted into their ships.  On a long journey, those filters could become saturated, and in some cases then start re-emitting chemicals back into the air.  Having something that absorbs and holds the chemicals would be nice.  Having something that absorbs those chemicals and then turns them into a product that the spaceship residents can use would be great.  Now, given we are kind of like astronauts flying along on this great ship Mother Earth, we still have enough air to take care of plants, chemicals and us.  The amount of air around us is currently adequate to support a recycling system that maintains a reasonably (although I admit debatably) healthy air quality.  Other systems inside out buildings do a better job than plants.

For solid materials floating around in our building air, particle filters do a very good job–as long as air is moving from the building through the filter.  For gaseous materials, chemical absorption filters can work well; but in most cases, they are impractical for many buildings.  More effective, though, is dilution where outside air is brought indoors to reduce chemical concentrations.  And that is where I am going to leave things for right now.  I promise to cover more about control of gaseous chemicals in a future blog.  Suffice to end this blog this way:  use plants to make you feel good mentally; but use dilution or filters to make you breathe well.

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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