Excessive Wet Weather Can Lead to Mold

Lucas Hamilton

The historic rain that the United States has endured in 2011 has increased moisture levels in places where moisture has never been a problem. I have heard from many people around the country who have never had water in their homes but have recently sustained water damage and are now concerned about potential mold.

As I have mentioned in a previous blog, mold needs four things to grow:  moisture (liquid water), food (typically starch or sugar), temperature between 41° and 104° and oxygen.  When water is trapped behind walls or paneling, the other elements will most likely be present and the potential for mold growth will exist. Try to clean and dry areas subjected to water within 48 hours to help prevent mold growth. After cleaning and drying, continue to be sensitive to musty odors in the affected area.

Check the exterior of homes and building regularly for accumulating ground water.  Many parts of the country have far exceeded saturation and mold can begin for form outside and find its way inside. If water is accumulating against your foundation, take measures to drain the water away from your building. Keeping things dry is the key to preventing mold growth.

There are many products available today to help protect the home or building from moisture infiltration and mold growth.  There are coating products that can be applied to dry materials to mitigate any mold growth potentials for that surface in the future. If materials are wet and can’t be cleaned or completely dried, remove them from the building and replace them with new materials which may be more mold resistant. Fiber glass doesn’t have the food needed for mold growth but often when insulation gets wet, the water which intruded into the cavity was dirty and brought food along with it. If you have wet insulation, replace it with new fiber glass.  If replacing drywall, consider selecting a board that that contains mold and moisture inhibitors.

Many people have sensitivities to mold and it can be a health concern.  Make sure that you take extra care to check for mold especially if this is the first time you are dealing with water inside your home or building. Use a mixture of common sense and caution- if it smells or looks bad assume that it is bad and take appropriate measures.

Lucas Hamilton is Manager, Building Science Applications for CertainTeed Corporation

Traditional Flashing Techniques Still Rule

Tom Silva from This Old House at CertainTeed's IBS booth

At the International Builders’ Show in Orlando, January 12 – 15, Tom Silva, general contractor for This Old House answered questions in the CertainTeed booth. One of the recurring issues that Tom discussed was flashing and the importance of proper flashing as a water barrier.  He really believes that barriers need to be constructed and maintained. 

At one point, he was talking about Fiber Cement siding and was asked what he does with the butt joints.  He said that you have to flash with physical materials and use traditional flashing techniques at all times.  He said that he flashes behind the butt joints and back caulks the boards to the flashing to prevent water from running laterally at the butt joints.

He obvious believes in traditional methods and good solid construction practices and flashing is one that is critical.  It occurs to me that we are at a low point in our cyclical knowledge process with regard to flashing. We are seeing more moisture issues because of incorrect flashing that has enabled water to penetrate. Often, we depend on newer materials to get the job done rather than using the time tested practices.  It’s funny because at one point during our discussions with Tom I mentioned SMACNA (Sheet Metal and Air Conditioning Contractors’ Association) and you could immediately tell who the seasoned builders were in the audience.  The SMACNA Manual is the sheet metal workers bible. It illustrates how to fold any piece of metal into any shape so that you don’t have to cut it. It is like origami for sheet metal. It seams that buildings constructed using the types of flashing shown in that manual have fewer moisture issues than their newer neighbors.

There are many traditional building practices that we forget and flashing is one of them. When all the failures to keep moisture out of the wall assembly point back to that simple interface between two dissimilar systems and how they should have been closed with a piece of good flashing, it becomes obvious that the basics will still work. You can’t ignore them! For example, why continuous nailing fins on a window is considered self flashing is beyond me.  You haven’t flashed anything. You have just sealed the eventual window leak into the wall.  You have not flashed and redirected to the outside. After all, it’s not the window that needs to be flashed, it’s the rough opening!

 

Lucas Hamilton

Lucas Hamilton is Manager, Building Science Applications for CertainTeed Corporation

Radon Mitigation Starts with Proper Home Foundations

Lucas Hamilton

The use of foundation drainage systems helps with water control, mold and moisture issues and Indoor Environmental Quality (IEQ) in a building. But, bear in mind that those same remedial efforts, if using the Form-A-Drain system, will also help with radon mitigation. In the same manner that these systems relieve head water pressure on the cold joint of the foundation / footer, they give migrating radon gas a path of least resistance away from the home.

Radon gas is a colorless, odorless, tasteless noble gas, occurring naturally as the decay product of uranium. Radon gas from natural sources can accumulate in buildings, especially in confined areas such as attics and basements.

Most regions of the U.S. encounter radon gas especially if they have basements or crawlspaces.  It is important to test for radon especially if the basement is part of the living area of the home.

Many homeowners are not aware they have a brewing radon problem until they put the house on the market.  It can, in some instances, be costly to install a radon mitigation system.

Leave in place Form-A-Drain systems pay for themselves not only in their benefits related to the forming of footings and moisture management but the added value of what they provide with regard to radon venting; making the use of Form-A- Drain product for all new construction projects the best ‘drainage’ solution for contractors, architects and builders.

Lucas Hamilton is Manager, Building Science Applications for CertainTeed Corporation

Not all Building Wraps are Created Equal – Technology and Common Sense Must Go Hand-in-Hand

Building wraps are now required behind all cladding by the International Residential Code. If you are building over a wood frame you must use a secondary water resistive barrier (WRB). Recent research has shown that as much as 10 percent of the wind driven rain is getting past the cladding onto the back-up layer. Intruding water must be redirected toward the exterior and not allowed to accumulate within the wall assemblies. This is the function of the water resistive barrier.

When selecting a building wrap you need to consider:

  • Install-ability – Is it tough enough to withstand exposure to the elements over a period of time?  Building wraps need to hold up to winds, not rip over staples and stay in place once installed.
  • Balanced set of physical properties – Select a material that is somewhat vapor open but not too vapor open.  There is a relatively healthy balance for a variety of cladding assemblies based on what the appropriate permeance is at that layer.  Much of the computer modeling that I have done over the years indicates a good general number for the permeance is between 10 – 20 U.S. perms for most U.S. climates.
  • Always install in accordance with the manufacturer’s recommendations –  This becomes your principle means of defense for moisture.  Moisture intrusion must stop at this line.

Building wrap needs to be installed in a shingle-like manner, so that it sheds water to the outside. It should also be installed in coordination with flashings and other accessories to ensure that any moisture that does intrude the assembly gets stopped at this layer.  It must then be redirected to the exterior and not become entrapped within the wall somewhere else.

Common sense is something that our fathers and grandfathers did far better than we do today.  Today the tendency is to rely on the silver bullet of technology to help pull us out of the fire.  The fact is, if you take these materials and install them with a great deal of common sense and construction knowledge, as older tradesmen did, then they work really well. In the best circumstances, the marriage of good technology and practical knowledge coincide and we construct durable and sustainable buildings. The correct application of a proper water resistive barrier is an example of such an installation. It’s not rocket science, it’s good building science.

 
 

Lucas Hamilton

Lucas Hamilton is Manager, Building Science Applications for CertainTeed Corporation

Tolerance for Moisture Intrusion is a Challenge in Vancouver

Lucas Hamilton

Earlier this week I traveled to Vancouver, British Columbia, Canada to present the workshop on Mold and Moisture Control in buildings at the final [Be Certain] event.  It has been fascinating to present these workshops in different Northern climates and creating simulations to address the specific challenges faced in these areas of North America.

Previously, I blogged about polyethylene in Calgary, Alberta, Canada and the challenges faced in controlling moisture because of the use of exterior insulation. In preparation for my Vancouver workshop, I re-ran the modeling for Vancouver and the results were very interesting.

Polyamide films, like MemBrain™ because it is a breathable vapor retarder can provide additional tolerance for moisture intrusion in many climates, but in extreme climates like Vancouver there is almost no way to survive water intrusion.

In such climates, the best course is to build into the design redundant drainage planes and flash, flash, flash. Expect water to pass your principle line of defense and stop it with a secondary line of defense which will evacuate the intruding moisture to the exterior environment. This would be like a window rough opening being completely wrapped prior to window installation and this rough opening flashing draining water out and onto the face of a water resistive barrier (WRB) which leads to an egress at the base of the wall system.

While there is so much we know about moisture management, there is always more to learn and our thinking must be comprehensive. If we don’t learn from the past, our attempts to build air-tight and moisture-tight buildings will leave us looking more like Wile E. Coyote grasping for the next solution. I am not comfortable with that. Thoughts?

Lucas Hamilton is Manager, Building Science Applications for CertainTeed Corporation

Is Polyethylene Creating Potential for Mold?

Lucas Hamilton

Last week, I was in Calgary, Alberta, Canada for one of CertainTeed’s Be Certain events conducting training sessions on designing for Mold and Moisture control in buildings.  In preparation for the sessions, I ran computer simulations on typical construction models in Calgary.  This gave me a better awareness of how they build as well as scientific understanding of construction practices in the province.

In extremely cold and dry climates like Calgary, which is similar to Colorado, use of exterior insulations is very common.  This practice emphasizes the use of insulation on the outside of the building.  This cuts down the thermal connectivity of the building frame to make the building more energy efficient.

The 2009 International Energy Conservation Code (IECC) mandates the use of exterior insulation in cold climates. However, when you do this with traditional materials such as rigid foam plastics, you may reduce the potential to dry a building to the outside.  If a wall gets wet normally, dry air on the outside can act as a reservoir to dry the building. When insulations like extruded polystyrenes are used on the outside of the building, while being extremely energy efficient, they may reduce this drying potential.

Some new computer modeling tools have the ability to create window leaks and other scenarios that could occur from construction defects that would place water into the wall.  In the Calgary scenarios I ran, if a window leaks and the water is not drained to the exterior surface of the water resistive barrier, it becomes trapped between two non-breathing layers – the exterior insulation and the interior traditional vapor retarder polyethylene (which they still use in Alberta.)  The wall can not dry and this creates the risk of growing mold. 

Building scientists and manufacturers have been preaching eliminating polyethylene from our buildings here in the U.S. for quite awhile, and promoting the use of smart vapor retarders as a solution to the problem.

As construction practices change to keep more energy in the building, some of the measures taken may unfortunately alter the traditional moisture balance of the assemblies and actually reduce our tolerance of intruding moisture. We must be very mindful of this as we continue to tighten our buildings while striving for improved indoor environmental quality.

We conclude our Be Certain events in Toronto and Vancouver later this month.  Stay tuned for how mold and moisture affect the building envelope in Ontario and British Columbia.

Lucas Hamilton is Manager, Building Science Applications for CertainTeed Corporation

Mold Awareness Month: The Five “D’s” to Controlling Mold

Lucas Hamilton

The U.S. Environmental Protection Agency (EPA) estimates that 50 percent of schools nationwide have issues linked to poor indoor air quality.  In many cases, this condition is linked to mold growth in buildings. Mold poses a serious health risk to individuals with respiratory health issues.

This has been a summer of record high temperatures and humidity across the country. This is a perfect storm for the propagation of mold.  As I discussed last year, mold is like a four legged stool.  Mold needs four things in order to grow:  food, water, oxygen and temperature between 41 and 104 degrees.  It is almost impossible to eliminate the potential for molds and mold spores to infiltrate an environment unless you control the elements that give mold it’s ‘legs.’

Controlling the moisture in and around a building is one of the best methods for maintaining a mold-free environment.  By following the five “D’s” you can protect against any opportunity for mold growth or infiltration:

De – Leak – Check for leaky roofs, walls, windows, foundations, facets and pipes regularly and repair them as soon as possible.

De – Bubble – Moisture trapped behind wallpaper paired with wallpaper glue is a perfect recipe for potential mold growth.

Dehumidify – Use dehumidifiers and air conditioners, especially in hot, humid climates to reduce moisture in the air.  Exhaust fans should be used in bathrooms and kitchens to remove moisture to the outside.

Dry – Clean and dry any damp furnishings within 24 to 48 hours to prevent mold growth.

De – Odor – Keep in mind, if you have had a leak, the first sign of mold may be musty or moldy odors. But do not sniff or touch mold.  If you suspect mold, contact a certified mold inspector.

Mold has a long history and a survival instinct that is almost unmatched in nature.  But let’s keep mold outside by making sure that moisture is managed in our buildings.

Lucas Hamilton is Manager, Building Science Applications for CertainTeed Corporation

Giving Back Feels More Like Getting Back

Habitat for Humanity House, Chester, PA

How often do you get the chance to help two young, deserving families build their dream homes, improve a community and learn to use a product manufactured by the company you work for? A group of us from CertainTeed and Saint-Gobain  had a special opportunity while volunteering with Habitat for Humanity in Delaware County, Pennsylvania

CertainTeed has a long history of supporting Habitat for Humanity affiliates across the country with donations and volunteers, but the Delaware County Habitat for Humanity twin home in Chester, PA is the first house covered with a brand new CertainTeed weather resistant barrier – CertaWrap™. It was great to be part of the premier installation of this product. We will also be installing CertainTeed Newtown™ vinyl siding over the next few weekends.

But the real “value-add” of this experience was:

Habitat volunteers and families

• Working alongside families who were putting in “sweat equity” in order to realize the American dream of home ownership.

• Teambuilding and relationship building with individuals across departments and making new friends.

• Helping a great organization by doing whatever was needed to be done.

For Lillian Horvitz, one of our crew, who is part of CertainTeed’s Sales Support Group, this hands-on, real life experience will help her answer questions from customers when the product is introduced in the marketplace.

But the best feeling was standing back with a group of new friends after a day of hard work and sweat and viewing the fruits of our labor. I highly recommend it!

Do you have any volunteer stories? Feel free to share them, in the comments section below.

Multi-Comfort House Competition – Global Event of a Lifetime

Philadelphia University students (left to right) David Cremer, Daniel Hitchko and Christopher Anderson

I had the wonderful experience of accompanying the winning architecture students on a trip to Innsbruck, Austria to compete in the Isover/CertainTeed Multi-Comfort House competition sponsored by Saint-Gobain as the U.S sponsor and partner with Philadelphia University.

This competition started in 2005 with nine countries participating. There were now 18 countries represented, 32 universities, 46 projects submitted and 150 participants.  In some cases, submitting universities brought their top three projects. In many universities, the Multi-Comfort House competition is incorporated into the third and fourth year architectural program.

I must admit that since this was my first experience with the International Isover/CertainTeed Multi-Comfort House finals, I was concerned that it would be more like a social event than a serious competition.  I was pleasantly surprised to find I was wrong. The level of professionalism on the part of the competition organization and the high quality of the projects presented by the students was eye-opening. 

The subject of this year’s competition was the renovation of a five-story warehouse in the Parisian quarter of Pantin. Industrial building renovation to Multi-Comfort House standard was a tough challenge, but participants had the freedom to propose any function for the building. The projects ranged from a hotel, a library, a textile factory, a museum, a shopping mall, a student residence, a vocational training center, a meeting place for young people, to name a few. All were viable and of the highest quality in terms of execution, attention to detail and compliance with Passive House standards.

It was fascinating to see the range of design from both a technical as well as a romantic/creative aspect.  The work that was presented – the concepts and elaborate ideas – was surprising.  The level of knowledge and creative solutions with regard to air-tightness in buildings, increased insulation, moisture management and zero-energy applications employed in the designs were encouraging since these are the architects, designers and engineers of tomorrow.

From the students’ perspective, what an extraordinary experience to meet with global counterparts and exchange ideas, share successes and develop professional contacts.  Two of the American students had never been to Europe; this was life changing for them.

An added benefit for the students was the opportunity to meet and hear from Professor Wolfgang Feist, the founder of the Passive House movement.  He even incorporated comments about the designs that they presented and the techniques employed by the students.

The winning designs came from Austria, Finland, Serbian and Germany, but all of participants were fantastic.  The time they have invested in broadening their knowledge and practice of sustainable design principles, will certainly pay off in their professional life.

I am looking forward to supporting next year’s competition. The finals will be held in Prague and my hope is that we can begin to reach out to other American colleges and universities to participate in this program.

Proper Roof Ventilation is Critical

Lucas Hamilton

I was in Pittsburgh recently and had the pleasure of visiting a home that was about to be reroofed again – it has been reroofed several times in the last few years.  The house was between 30 – 40 years old and originally had wood shakes which were replaced with asphalt shingles.  The roof was under ventilated to begin with but when they went to the new system it made the problem worse. Each contractor that came along tried to do different things to deal with the problem that the homeowner was encountering.

While putting away Christmas decorations a few years ago, the homeowners noticed ice forming in her attic.  Originally, they thought it was from a roof leak so they replaced the roof.  However, the next winter the ice returned. The roof leak wasn’t the cause. It was insufficient attic ventilation. The house had a great deal of moisture build up in the attic space which was causing ice to form in the winter on the underside of the roof. 

The second contractor tried to add roof ventilation but did it in a way that didn’t help the situation.  He installed a power vent up high on the roof next to the ridge vent.  They put a humidistat on the power vent to activate the vent when the humidity rose in the attic.  The problem was that when the power vent kicked on, because of its position next to the ridge vent, it was pulling air in through the ridge vent and right out through the power vent which did not correct the humidity in the attic or solve the ventilation issue.

I met with them to discuss what was happening to the roof, make recommendations and work with the roofer to correct the ventilation issue. The roofer is going to optimize the power venting and eliminate the ridge vent. This was chosen because there is a concern that with the shape of the roof, you may never get sufficient soffit intake for the ridge vent alone to be sufficient.

As a result of the moisture in the attic, mold was developing on the roof decking.  While there are many ways to remediate mold, the homeowners wanted to take the most certain route which is to remove the contaminated wood. Of course, that adds cost to the project but is the best method of remediation.

Even though the knowledge base on ventilating residential roofs has expanded tremendously over the past 50 years,  professionals can sometimes have a difficult time properly ventilating a unique or challenging roof.  The homeowners were frustrated because they received different information from each contractor.  That can happen.

It is always a good idea to research the issues and ask questions.  In buildings where the attic ventilation requirements are not straight-forward the professional needs to look at the situation  from many angles to come to the right conclusion that solves the problem.   

Lucas Hamilton is Manager, Building Science Applications at CertainTeed Corporation