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

Leaving a Slab Edge Un-insulated is like Leaving a Window Open

Climate zones

Improving the energy efficiency of a structure’s building envelop doesn’t end with the walls, windows and attic.  The foundation of a home whether a basement, crawl space or slab on grade needs to be insulated as well.

The International Energy Conservation Code (IECC) requires slab edge insulation and 36 states have adopted this IECC standard. The IECC code requires R-10 at the slab edge.  The requirement runs from the Canadian border (and Alaska) south, covering Climate Zones 4 and above. In California Title 24 mandates insulated edges for radiant slabs even if in Zones 1, 2, and 3, which predominate in the state.

As we have seen over the past 20 years, there has been a move to improve energy efficiency in all parts of the building envelop.  This is evidenced by the move to 2 x 6 wall construction to increase the amount of insulation in walls, the recommendation for increased amounts of attic insulation, and increased use of energy efficient windows.

Slabs have a stem wall that is similar to a foundation wall but without a basement. 60% of heat loss from the foundation occurs in the top eight inches of the un-insulated stem wall/slab edge; insulating these eight inches results in a tremendous amount of energy savings.

If your home is built on an un-insulated slab, the first 10 feet of floor from the slab edge will conduct cold because concrete has little R value (it takes 10 feet of concrete to achieve an R-10 insulation value).  Considering the overall footprint of an average home is approximately 25’ x 50’ there is a significant amount of first floor area that will remain chilled.  In fact, a properly insulated slab edge is estimated to save at least $200 a year in energy costs in addition to increasing comfort in the living space. 

There are products designed to insulate the slab edge for both current and new construction. For retrofit applications EnergyFlash® protects insulation that can be adhered to the slab edge and provides a durable decorative finish.  For new construction, EnergyEdge® forms and insulates the slab at the same time.  It provides the required R-10 value for slab on grade construction and is a great product for the contractor because once done pouring the slab no return trip to the job site is required to strip forms; also eliminated is the disposal of old wooden forms.  The builder benefits by eliminating the additional cost to insulate the slab after the pour.  

EnergyEdge saves time, money and energy. 

Moisture Management Remains Key Issue Across America

Lucas Hamilton

Lucas Hamilton

I recently spent some time in the St. Louis area and New York conducting workshops and trainings on moisture management. To my surprise the interest level in this topic remains sky high. The design community as well as contractors still have extreme need for knowledge around moisture management and design options to control this problem.

I guess because I have been dealing with the moisture and mold issues for so many years I feel that just about everyone knows how to protect against it but the truth is there are mold remediation cases from New York to California and it continues to plague the construction industry. But there are solutions to this age old problem – proper wall assembly design and product selection.

Following a training one my co-workers gave there were an hour’s worth of questions about moisture and mold issues. Questions such as:

• What is best assembly to prevent moisture?
• Higher insulation systems vs regular insulation systems?
• What about changes to the building codes regarding vapor retarders?

In a previous blog we did address the conditions that need to exist for mold to grow and we continue to develop solutions around this very critical issue.

We are in the solutions business and have crafted solutions and created balanced systems with products that can help to minimize moisture build up in wall assemblies and continue to conduct presentations and trainings to assist in the understanding of the best practices in resolving moisture issues in construction.

We will continue our efforts to help people build more robust assemblies and welcome the opportunity to respond to questions.

We need to fight the fight because this effects construction costs. The point is if you build it right to begin with you can solve half the problems that result in moisture and mold damage.

Lucas Hamilton is Manager, Building Science Applications at CertainTeed Corporation.

Creative Developers Dabble in Material Science

The Villages

The Villages

I recently visited The Villages and The Villages Construction Division in Florida.  They are lifestyle developers, creating a complete community including homes, recreation, and town centers.  The Villages is located north of Orlando and the community stretches 11 miles with 58 different neighborhoods or “villages”, dozens of golf courses and two old fashioned “downtown” areas.

One goal of their business model is to build quality homes as efficiently as possible. But they are in a climate with occasional summer showers. This can create a challenge as a developer can’t, typically, build wet houses and get away with it when moisture gets trapped. The Villages, however, meets the challenge and is succeeding against their unique environmental situation.

The homes are constructed with techniques ranging from stick-built wood frame to concrete masonry unit (CMU) to cast-in-place concrete. The CMU structures and cast-in-place structures have a cementitious finishing system on the exterior. People familiar with the chemistry of concrete know that new concrete is very alkaline.  On the scale of acid to base, basic materials are alkaline and they actually burn like acids do. The scale ranges from zero to 14.  At seven, a product is neutral and is safe.  If material registers too low it’s acidic and if it’s too high it’s too alkaline.  Either creates its own unique challenges.

If anyone has tried to paint fresh concrete they know what alkalinity does to coatings; it actually burns them up.  For The Villages to construct the quality product they do, they need to dry-in the structures as quickly as possible.  As a result, they have worked with paint and coatings manufacturers to develop special primers that can be put on green concrete or mortar without burning the paint and thereby preventing failure within the year.  To meet the needs of their unique climate and construction schedule, this developer has sought out manufacturers who can work with them.

In order to succeed, The Villages went to science to create a solution and based on my observation, they have an exceptional product. And they are on track to sell over 2,000 homes again this year. 

In this economic climate, that is extraordinary.

Lucas Hamilton

Lucas Hamilton

Lucas Hamilton is Manager, Building Science Applications at CertainTeed Corporation. 








The Durability Challenge of Energy Retrofits

Stan Gatland

Stan Gatland

As a member of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE),  I participate in technical committees that deal with building performance from a heat, air, and moisture perspective. One committee explores best practices for building envelope design. The committee focuses on how to manage heat, air, and moisture flow through assemblies. 

At a recent forum, members discussed concern that in the rush to create air-tight building envelopes with high levels of energy efficiency, the long-term impact on durability due to these changes may be overlooked.  Energy efficient, air-tight buildings have a greater potential to accumulate moisture and have less energy to dry out.

The Department of Energy is poised to support the energy efficiency retrofit of existing homes by improving air tightness and adding thermal insulation.  This time, hopefully, the history of the 1980s and 1990s does will not repeat itself regarding the durability issues related to energy efficiency retrofits.  Moisture related damage typically takes seven to 10 years after the retrofit of an existing home or construction of a new energy efficient home if measures are not taken to address moisture.

DOE recognizes the need to control interior humidity levels, as well as address combustion safety.  If adjustments are not made to control humidity levels and circulate fresh air it could cause other problems like excess moisture which could result in mold.

Another concern is combustion safety. By making an assembly more air-tight, you have less air available for combustion events. For example, hot water heaters and furnaces that once relied on a building’s air leakage to supply enough air to the combustion process may backdraft if enough air is not available in a well sealed home.   Direct ventilation may now be required to compensate for the retrofit.   

DOE is recommending that energy retrofit contractors address moisture management issues and combustion safety by following guidelines outlined in ASHRAE Standard 62.2 as a way to insure proper indoor air quality for residential buildings and increase the durability of assemblies.

Americans have traditionally had access to inexpensive energy but that is changing. We do need to address retrofitting older buildings, but it is crucial to not create other problems while doing so.

Stan Gatland is Manager, Building Science Technologies for CertainTeed Corporation