Archive for September, 2010

Minimizing Asphalt Shingle Buckling

September 30, 2010

We seem to have an organization for everything out there nowadays.  Well, engineered woods are no different.  One of these is a trade association that is concerned with products that pretty much all modern homes have.  Those products are oriented strand board (OSB) and plywood.  This organization is also concerned with glu-lam beams and other manufactured wood products.  Its name is APA-The Engineered Wood Association. APA at one time stood for the American Plywood Association, there forerunner of the current association.

One of the things that APA does is research in engineered wood products, and they share that research with building professionals and tradespeople.  People not in these trades can also access the APA publications on-line, although in most cases, the publications really are oriented toward professionals and tradespeople.  This past week, APA posted a new document on its website that is useful to the general public who are having roof work done or a home built.  That publication, in PDF format, is “Builder Tips:  How to minimize buckling of asphalt shingles“.  If you want to download this document, you will probably have to register, which is not such an issue because the APA uses that information to keep you informed of new and changed publications.  At least, I have found that to be a benefit.

I recommend that you stop by the APA website and get this document.  It is a good and easy read.  While you are there, you might also want to pick up, “Builder Tips:  Minimize nail pops”.  Nail pops result from nails working their way upward out of the wood deck due to a number of causes.  You can usually spot a nail pop as a tented part of a shingle as shown in the photo below:

Nail Pop Under a Shingle.

In future posts, I will discuss various aspects of roof issues.  I promise pictures.

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Humidification and Virus

September 29, 2010

The Environmental Health Journal published an article this past month titled, “Modeling the airborne survival of influenza virus in a residential setting: the impacts of home humidification“.  The results of the research taken from the article are, “The presence of a portable humidifier with an output of 0.16 kg water per hour in the bedroom resulted in an increase in median sleeping hours AH/RH levels of 11 to 19% compared to periods without a humidifier present. The associated percent decrease in influenza virus survival was 17.5 – 31.6%. Distribution of water vapor through a residence was estimated to yield 3 to 12% increases in AH/RH and 7.8-13.9% reductions in influenza virus survival.”

What the article states that a slight rise in relative humidity in the room caused a slight drop in the influenza viruses in the air.  I have a couple of criticisms about the article, though.  The authors derived this conclusion based on limited data using modeling instead of actual sampling of the virus.  The lack of data does not really show how the trend would go for humidity versus virus concentrations.  Without data from actual virus, the question also exists whether the model is realistic or whether the results are repeatable.  I cannot really fault them because sampling for viruses is difficult at its least, particularly infectious viruses and research is expensive.

But, I am still concerned about whether the risks of a humidification system are worth the beneficial effect on virus.  Other studies have shown that hygiene–hand washing and avoiding sick people–are quite effective in preventing or minimizing virus-related illnesses.  Flu shots are also effective in preventing flu for which the sera are developed.  I can personally attest to that fact.  I also tend to believe that flu shots, even past ones, may help minimize the effects of other virus.

I will confess, though, that I am not a big fan of some humidification systems, particularly central humidification systems.  I have observed too many issues with them from basic design to maintenance-related issues.  In future blogs, I am going to go into more detail about humidification systems and their pros and cons, as I see them.  I even got off on that tangent writing about those issues for this blog.  I decided to reign in this post to stick with the topic of humidity and virus.

What can be drawn from this and other research.  I believe that humidity levels could have an effect on virus levels in the air.  I have known for a long time that when those sloppy wet infectious particles that are sneezed into the air, or fomites as the medical gang call them, they have a better chance of drying in low-humidity air.  Drying of the particles means that they become smaller and lighter, which in turn means that they can stay afloat in the air longer.  They can also be breathed deeper into the respiratory system where they can more easily set up shop.  The weird thing is that some virus actually survive better in the dried out state.   (Here are a couple of examples of research pointing to that conclusion:  “Dry air might boost flu transmission” and “Flu Mystery Solved? Why It Flourishes in Winter“.)  Elevated humidity is a good thing.  My dispute is with the way to humidify, and that will be the subject of other posts.

Take note: ALL new manufactured home installations in Ohio MUST be inspected

September 23, 2010

I am a certified inspector for the Ohio Manufactured Home Commission (OMHC).  About every month, the Commission meets to discuss issues that arrive relative to the installation requirements for manufactured homes.  At the meeting this month, the Commission discussed the fact that a large number of manufactured home owners are still unaware that manufactured home inspections have been required since September 2007.  Therefore, I thought that this would be a good subject to blog about.

Prior to initiation of the OMHC, the Department of Housing and Urban Development (HUD), powered by the manufactured home industry, developed rules to serve as a model code for all of the states.  The law that passed also dictated that all states would have to initiate a program for inspecting all new installations (sets) of manufactured homes.  At the least, the states had to use the HUD model code as a minimum code for each state.  Ohio adopted a slightly stricter version of the HUD model code, and at times various revisions to the Ohio code are made.

The basic fact is that the Ohio code requires all new installations of manufactured homes undergo inspections.  “New installations” does not mean installations of just new manufactured homes.  It means all manufactured homes, whether they are installed on private property or in manufactured home parks or whether they are brand new or years old.  Even if you are relocating the home from one manufactured home park to another, you must have its installation inspected.  Even if you are relocating a home from private land to a manufactured home park or vice versa, you must have it inspected.

Installations currently require three inspections: footing, electrical safety and final installation.  The footing inspection may not be needed if approval is given to an existing footing that is being reused.  Furthermore, all installations must receive a permit prior to any work beginning.  For information on the permits, the permit application forms and the steps you need to go through in the installation process, refer to this location: http://www.omhc.ohio.gov/Consumers/tabid/59/Default.aspx.  The permit is issued by the same certified OMHC inspectors that perform the inspections.  Local building departments and some Ohio Department of Health agencies perform manufactured home inspections as well as Third Party Agencies, such as my firm, Criterium-Cincinnati Engineers.  You can find a list of Third Party Agency  inspectors by county at this location:  http://www.omhc.ohio.gov/CallforInspections/tabid/57/Default.aspx.   Note that you can be fined if you begin work without obtaining a proper permit.

The rules require that installers licensed by the OMHC perform both the footing and installation work.  Most installers have unlicensed assistants helping them.  In these cases, the licensed installer must be on-site 80% of the time supervising the work.  Installers may also obtain the permit and line up the inspection agency.

After a home passes its inspections, the inspector will place a seal inside the electrical panel.  Note that this seal is only for that home’s installation on the site for which the seal was issued.  If the home is moved to another location, it will need to undergo the permitting and inspection process again and receive a new seal for the new location.

Several other important points need to be understood:

  • If a home was installed  after September 2007, it must still be inspected and meet the existing rules.
  • Homeowners may do their own installations; however, if a homeowner chooses to do the work, he or she is required to do all of the work him or herself, including obtaining a permit.  We highly recommend that homeowners not do their own installations because we have had nothing but bad experiences when they do.  In pretty much all cases, the homeowner is taking on much more work than they realize and likely does not have the proper equipment to do a complete installation.  Homeowner who are thinking about doing the work themselves should review the rules to which the home’s installation must adhere at this location:  http://www.omhc.ohio.gov/LawsandRules/tabid/66/Default.aspx (if you looked, yep, every one of ’em).  Whereas, most installers have had a number of years of experience.  They are also required to be trained and pass a qualifying test prior to obtaining a license.  We therefore recommend that homeowners have licensed installers do the installation.
  • We recommend that the homeowner have the installer obtain the proper permits.  If the installer obtains the permit, he or she is responsible for completing the work.  If the homeowner obtains the permit, he or she is responsible.  If additional work is needed for the home to pass inspection, having the installer responsible for the permit gives the homeowner leverage to assure the work gets done.
  • On the other hand, we recommend that the homeowner select the inspection agency.  Some installers have a “comfortable” relationship with some inspectors and, let’s just say, the homeowner might not be getting the inspection they should.
  • Permits are for 180 days only, which should be adequate time for the installation to occur.  An extension can be given; but, if one is needed, then something is definitely wrong.
  • The homeowner is not supposed to occupy the home until it receives a passing final inspection and is sealed.  The inspector can issue a temporary occupancy permit if he or she finds that the issues that need to be resolved for the home to pass inspection are not serious.  However, the temporary permit, as the name implies, means that the home must eventually pass inspection.
  • Most electrical companies will not connect the electric service to a home until after it passes the electrical safety inspection.  The problem has been that some homeowners have gotten the electrical service connected and then not completed the installation so that it passes inspection.  The Commission is currently working to close this loophole.  Inspectors are also going to get more aggressive at assuring that the installation is satisfactorily completed.

I have heard all of the excuses about why manufactured homes should not be inspected and complaints about the inspection requirements.  But, after performing nearly 600 manufactured home FHA inspections, I understand the requirements for every part of the rules.  The inspections are not intended to simply aggravate the homeowner.  They are there to assure that the home is installed safely and to help preserve the homeowner’s investment.  With proper installation, a manufactured home can last for many years.  I see no reason why a properly installed and cared for home cannot increase in value over time.

The warning bears repeating again, again and again

September 19, 2010

The warning bears repeating again, again and again.

The on-line version of the Chicago Sun Times carried this story today:

Infant drowns in water pail

http://www.suntimes.com/news/metro/2725352,CST-NWS-baby19.article

In a previous post (https://criteriumincincinnati.wordpress.com/2009/12/02/a-sobering-reminder/), I discussed another infant drowning in a sump pump pit.  Granted, a drowning in a sump pump pit is a pretty rare event, especially since sump pits usually have lids that are supposed to be used with them.  In the case of the infant in the Sun Times article, the culprit is a common water pail.

But, water pails are not the only potential downing locations.  Every adult who is responsible for watching kids should know about the drowning potential of bathtubs, sinks or other bathing facilities.  What about toilets?  As I stated in the previous post and will repeat here, infants and toddlers can drown in only a few inches of water.  Exasperating the drowning potential is the fact that infants and toddlers are head-heavy.  If they fall into a container of water head-first, they likely will not be able to get out of the container, whatever it is.

Containers are not the only potential drowning places.  Fountains, pools, ponds, streams–any body of water should be off-limits to infants and toddlers.  If they are mobile, they are not the steadiest people on their feet.  On visits to Fountain Square in Cincinnati, I have watched many parents let their young ones walk on the lip of the various parts of the fountains.  I have to wonder what are those parents thinking.  What would happen if they looked away for a short time or could not make it to the fountain in enough time.

Apparently, the City of Cincinnati thought about this issue because the main fountain now has a low fence installed along the inside lip of the large fountain.  My son thinks it is because of other reasons, such as adults using the pool for other means.  Even still, maybe Cincinnati helped resolve another potential issue at the same time.

If you are a child’s caretaker, don’t just react.  Anticipate if you can what the child is going to do.  And take stories like the one in the Sun Times as a warning and be educated.

Water that foundation

September 18, 2010

Well, I don’t mean literally.  Actually, I mean that sometimes homeowners need to water the soil around the foundation.  Here in the Cincinnati area, as with many other areas, we experienced a very wet spring.  Then, Mom Nature, apparently fearing that she might mess up the averages, pretty much completely shut off the valve.  We are now nearly 6 inches below average on rain–and our clayey soil is rock-hard dry.

One of the characteristics of clay soil is that it shrinks significantly when it dries.  You might have noticed such shrinkage in the gap that has opened between your foundation and the soil.  Keeping the soil evenly moist around the foundation helps prevent or even prevent shrinkage.  However, when watering the soil, don’t just water a narrow band of soil.  I normally recommend watering a band of about 6 feet.  Now, 6 feet is not a magical width; I just mean to water a wide enough band.  If you water too narrow a band or soil, the surrounding ground will suck up the water rapidly, essentially countering your good intentions.  You should also not spray water directly on the foundation, which is never a good practice.

How much to water depends on the soil composition, type and conditions.  Checking the soil using the old finger probe similar to the way you would check the soil in a planted pot is possible.  You just push your finger into the soil to a depth of about an inch and, if the soil feels damp to your finger, it is probably wet enough.  Then again, not being able to push your finger into the soil probably also tells you that the soil is too dry.  You can also use the simple plant moisture meters available in many stores for use on potted house plants.  If you want to get real sophisticated, soil moisture sensors that actuate an irrigation system are also available.  You can find these by Googling “irrigation soil moisture sensors”.  Creative homeowners who don’t want or can’t have an irrigation system installed around their foundations should be able to make up a system using soaker hose, the moisture sensor and control system and an irrigation valve.

So, what is the big deal about the soil being too dry around the foundation.  (Truth is, maybe I should not even be telling you this preventive measure because in the past, we have had a lot of jobs from homeowners because of this issue.  But, that is not our way.)  First and foremost, the foundation can settle and develop cracks and some of these cracks can be severe.  The most common reason for cracks is that the foundation settles unevenly, which is a particular problem with the type of foundation that everyone wants nowadays–the walk-out basement.  Heck, I like ’em too, even though I don’t have one.  With these types of foundations, the soil may be dry to the same depth all around the foundation; but the soil around one part of the foundation may be dry to below the depth of the footing while the soil around another part of the foundation is not.  Dry soil shrinks; so some of the soil around the foundation shrinks while it doesn’t around the other parts.  This condition results in part of the foundation moving while part of it doesn’t.  And that difference in movement can result in cracks.

Besides walk-out basement foundations, stair-step and concrete block foundations (both of which may also be a walk-out basement foundations) are especially prone to developing cracks under uneven soil drying conditions.  Another susceptible foundation construction, which is VERY common, is the crawlspace, stem wall or porch foundation that is poured continuous with, but which is much shallower than, a basement foundation.   The same logic can be used to explain why cracks could develop.  The shallower foundation settles while the basement foundation doesn’t.  Basement foundations that are not walk-out types, stem wall and crawlspace foundations aren’t totally immune from developing cracks either.  The conditions dictate the development.

Slab on grade foundations are also susceptible to developing cracks in the slab, depending on the slab construction.  In the case of these slabs, the soil around the outer edges of the slab could dry while the soil farther under the slab dries slower.  In this case, the soil around the perimeter of the slab shrinks while the soil farther under the slab doesn’t.  The perimeter of the slab settles, while the parts farther under the slab do not.  In this case, the slab might develop cracks as well as heave.

The second reason is that what does down might need to come back up.  Just as clayey soils shrink when they dry, they re-expand when they moisten.  If the foundation settles due to dry, shrinking soil, the foundation might not move back the same way when the soil moistens and re-expands.  In moving back with the expanding soil, the differences in the amount of movement around the foundation could occur, creating stresses that cause cracks.  The soil also might have shifted and exerts pressure on the foundation differently than before.  Soil that shrinks may not re-expand as much as it shrank because the spaces between the soil particles are squeezed reduced as it shrinks.  When the soil re-expands, the spaces between the soil particles might not be the same as before, causing stresses that create cracks.

A third reason for keeping the soil around the foundation evenly moist is one I hinted at earlier in this post.  The gap between the soil and the foundation becomes a water channel when it finally rains.  This issue is a problem mainly for basement foundations.  Don’t let anyone kid you, nearly all foundations are porous to a varying degrees, even those with some exterior water barrier coatings.  Water running down the foundation wall is absorbed by the foundation materials and transferred to the inside of the foundation.  If the foundation happens to have a crack in the right place, the water will have an open path through the foundation wall.

Water that isn’t absorbed by the foundation materials or doesn’t flow through cracks can cause issues around the foundation by eroding soil around the foundation.  In most areas, building codes now require that homes have a foundation drainage system.  Those systems work to capture a great deal of water around the foundation IF they are installed properly.  On the other hand, water has a mind of its own and seeks the path of least resistance.  Therefore, the water might choose to flow under the foundation and not into the foundation drainage system.  If enough of it travels through one area, soil erosion can occur, causing the whole uneven foundation support thing, which can case cracks, and/or worse shifting, of the foundation.

A final, not so directly an issue, is loss of vegetation around the foundation.  In particular for homes built on hillsides, loss of vegetation could result in loss of soil erosion control.  With soil erosion could come soil sliding.  Cracks in dry soil could also open channels to deeper soil layers that are not as well bound together as the upper layers, resulting in slides.

A couple of other things should also be kept in mind.  The foundation may not the only thing that has moved when it settled.  Everything sitting on the foundation might have also moved.  Foundation movement might be imperceptible but still be enough to cause cracks in other interior and exterior building materials. Further, movement is greater higher up in the building, which means that cracks might be found in upper floor materials without be found in lower floor materials.

Another thing to keep in mind is that movement creates stresses in the foundation and other building materials.  Those stresses might not cause cracks right away.  Those stresses could still be present only to cause cracks later on, such as when another condition creates additional stresses—the old straw-camelback syndrome.

I have thrown a lot at you in this post—and without pictures.  (Over time, I promise more pictures.)  The issues can be complex.  Still, they do not mean you need a structural engineer to look at every crack.  If you have doubts, then hire an engineer to check things out and hopefully provide assurance.  On the other hand, you might try keeping the soil around the foundation evenly moist and avoid having the need for an engineer.

5 Things that have changed in building design to cause today’s issues

September 16, 2010

I received a link to an excellent article by someone whose writing I follow.  His name is Dr. Joe Lstiburek and he is to me THE authority on building moisture issues.  His article is titled, “5 Things”, and the link to it is:  http://www.buildingscience.com/documents/insights/bsi-039-five-things/files/BSI-039_Five_Fundamental_Changes.pdf.

Those 5 things that Dr. Lstiburek lists as changes that have occurred to buildings to cause today’s moisture issues are:

  1. Increased thermal resistance.
  2. A change in the permeability of the linings that we put on the inside and outside of building enclosures.
  3. Water and mold sensitivity of building materials.
  4. The ability of the building enclosure to store and redistribute moisture.
  5. Complex three dimensional airflow networks that inadvertently couple the building enclosureto the breathing zone of the occupied space via the mechanical system.

Let me see if  I can translate from the engineer-ese.

  1. Thermal resistance is the ability of a material to transfer heat, similar to the way a wire conducts electricity.  A higher thermal resistance material, such as fiberglass, slows heat transfer.  Dr. Lstiburek says that with reduced thermal transfer, building materials do not dry as rapidly in newer buildings as older ones.
  2. Permeability is a measure of how easily moisture can move through a material.  Over the years, the exterior wall materials have become less permeable.  The result is that moisture that gets into walls cannot get out and moisture inside the home cannot get out of the home the way it used to.
  3. Dr. Lstiburek uses the term sensitive in his list of  Things, but then uses a better term later in his article–resistant.  Basically, the materials being used in today’s buildings are not as resistant to mold growth as those in older homes.
  4. Dr. Lstiburek states that older building materials were able to absorb and not be harmed by moisture than newer materials.  We still have buildings with lath and plaster walls that are over 100 years old because they could take moisture exposure.  The same moisture exposure would have demolished drywall in one exposure to the same moisture quantity as the older homes.
  5. In the older homes, the building exterior was usually more solid than now and it acted as an air barrier.  Nowadays, the exterior is not as resistant to airflow as back then.  The stud and joist cavities serve as runs for wiring, plumbing and supply and return airflow.  Every time a hole is made in a stud or joist, a new airflow path is created.  Then, we open holes in walls for electrical outlets, which are air paths.  So, the newer buildings are holier than the older ones–and not in a good way.

Dr. Lstiburek provides recommendations for resolving these issues in the latter part of his article, and you can read those as well as I.  So, check out the article and if I have not adequately translated the terminology in an understandable way, send in your comments and I will do better.  BTW, if you want other excellent articles on building construction, visit the Building Science website at http://www.buildingscience.com/.

Some more links I believe are useful

September 15, 2010

The following article, 10 Things Your Plumber Won’t Tell You, came in an e-letter I received today:

http://www.smartmoney.com/spending/rip-offs/10-things-your-plumber-wont-tell-you-18259/?cid=sm_pfspend_rss&mod=smartmoney

I recommend that you also check out the other 10 Things articles  that Smart Money has posted on-line at:

http://www.smartmoney.com/spending/rip-offs/

BTW, one of those articles are about home inspectors, on which I hope to comment in the near future.  That is one article, with which I don’t totally agree–at least for my firm.

A picture is worth a thousand words

September 13, 2010

A picture may be worth a thousand words; but a picture is also much better than a human memory.  As related to my business, I am referring to whenever a homeowner has work done on their home.  Time and again, I have had homeowners tell me about former work that was done to the home or its surrounding grounds.  Shortly after my questions begin, their memory of exactly what was done stops.

Now, I don’t blame the homeowner for not remembering.  In many cases, he or she trust that whoever is doing the work will do it well and right.  (Well, not always and that is a subject for another blog post.)  In other cases, the homeowner did not exactly understand what was being done and did not pay much attention to what a contractor is doing.  In still other cases, the homeowner may have been very observant of the work, but seen it through different eyes than I would as an engineer.  The result is the same–pretty shaky details.

I will give an example.  A home has trouble with water running out from under a sidewalk and curb and onto an asphalt parking area.  Water running onto asphalt is never a good thing because the water degrades the asphalt and shortens its life.  I was told a drain line was installed.  The problem was that the homeowner did not remember whether it was a drain was only for the gutters or whether the line had holes to also drain the soil.  The difference is important because it could either be the source of the problem if done one way or be a solution for the problem if done another way.  Furthermore, the homeowner could not remember exactly where the line was run relative to everything else.

With the age of digital photos and the prevalence and price of decent cameras, photos are cheap and can be made readily.  You can also take a bunch of photos and they will all have date codes.  And folks, please, please, please don’t use the camera phones to take the photos unless that is the only camera left on Earth.  Camera phones do not have the resolution of the digital cameras or the features, such as image stabilization.  I also recommend that you take photos with the highest resolution camera you can get.  I normally use a 12 megapixel camera.  The reason is that the more megapixels a camera has, the more a person can zoom into the picture to pick out fine details.  I have had to use this feature on many occasions  when trying to dig out details.  I also recommend that you take all photos with the flash on rather than with the camera set to automatic because the flash can highlight some details, even on sunny days.

So, how often should you take photos during the work?  At the least, I recommend photos of before work has begun and when demolition is done or when the dirt is removed depending on which is applicable.  Other times to take photos depends on the work progress.  Maybe the best recommendation would be at the end of every work day because work can progress rapidly.  Any time the contractor states that a change in plans has occurred would be another.  If in doubt, call us and we might be able to provide ideas.

And, what should you take pictures of?  I think one person said it best.  Paint the area with pictures.  In other words, take enough photos to show a complete picture.  Whichever way you have to look to see the work that was done, take a picture.  Be generous.  But, also be sure to review the picture in the camera view screen to be sure the shot is acceptable.  To do so effectively, you may need to go into your camera’s menu functions and change the time the image stays on the screen.

Once you have those photos, do not just put them on your computer or leave them stored in your camera.  I have learned over the years that hard drives are not the most reliable things.  I have also learned, through others thankfully, that laptops  can be stolen very easily.  Cameras also seem to sprout legs and walk.  I recommend that you store the photos on a dedicated SD card, thumb drive, CD or DVD.  In addition, I recommend storing them online through one of the many storage areas because I can tell you from personal experience, it works.  I personally use Mozy and like the service–but you may find others acceptable.  Flickr is a freebie for a certain amount of storage.  Most on-line storage services are quite reasonable for not only photos, but also for the other important documents on your computer.

Again, Criterium-Cincinnati Engineers provides service.  Although we like to earn money, nearly as much as the guys who like to receive money from us for their services.  That does not mean we charge callers for every phone inquiry.  We don’t and we don’t do the hard sell.  Call and discuss what is going on with one of our engineers.  We will be glad to help.


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