Not by the Hair of MY Chinny Chin Chin!

The third little pig met a man with a load of bricks, and said, "Please, man, give me those bricks to build a house with." So the man gave him the bricks, and he built his house with them.
The wolf came, as he did to the other little pigs, and said, "Little pig, little pig, let me come in."
"No, not by the hair of my chinny chin chin."
"Then I'll huff, and I'll puff, and I'll blow your house in."
Well, he huffed, and he puffed, and he huffed and he puffed, and he puffed and huffed; but he could not get the house down.

The story of The Three Little Pigs is an English folk tale first written in the 18th century, but it is thought that the story and the lessons are much older. In the category of “Lessons Learned,” realizing that stronger materials make a stronger house is an important one to have on the list. On the Outer Banks, the material used to keep the house from being huffed and puffed away is not brick but fiber-cement board, and it is not only the quality of the siding but also the quality of the installation that keeps the wind outside. Our house is being beautifully “dressed up” by Lewis Babb, who owns a company called Exterior Specialists.

Before the siding is attached, the house must be wrapped and “weathered in”. The product choices for both the house wrap and the siding came by working through a series of causes and effects as each decision’s consequences affected the next. One early decision with impact on the siding processes was the choice of a dense closed-cell polyurethane foam insulation that is sprayed on the exterior walls inside the house. The foam expands, filling any open spaces to provide a continuous, protective air barrier that eliminates air leakage, a primary cause of energy waste. It forms a virtually airtight thermal, sound, and condensation barrier. Since the exterior walls are eight inches thick, there will be 2 ½ inches of spray foam with the remaining space being filled with fiberglass batts. It would be cost prohibitive (and not very smart) to fill the cavity with foam with no appreciable gain in the quality of insulation. Using the polyurethane foam prevents water and water vapor from getting through the sheathing into the house, which means that any water absorbed by the sheathing would be essentially trapped. Wet sheathing = rot and mildew = an unwelcome and far reaching problem. The question became how to either assure that the sheathing could dry when it became wet or to prevent the sheathing from ever getting wet. After looking at the more traditional house wraps, like Tyvek and tar paper, Vince decided to use an impermeable application and chose Grace Perma-Barrier wall wrap to keep the sheathing dry. This Grace product is a self-adhesive, rubberized, asphalt/polyethylene waterproofing membrane that is applied directly to the sheathing. Correct installation includes a specific amount of overlap and “rubbing” the material to provide secure adhesion, and the butyl rubber adhesive literally melts into the house. With this product on the outside and the foam on the inside, the exterior sheathing is sandwiched between two impermeable substances. That sounds ideal, except that there must be a way to assure good air quality and for moist air that accumulates inside the house (people breathing, doors opening, washing machines, etc.) to get out. The answer to this problem is an ERV (Energy Recovery Ventilator) that is a part of the whole-house HVAC system. The ERV recaptures heat from the air stream and replaces it with fresh, cooler air through the use of an air-to-air heat exchanger. (More on that later!) Applying the Perma-Barrier was problematic because it was something different to the crew, and it required a lot of time and patience to put it on smoothly and to go back and literally rub the entire house for good adhesion. That’s a lot more work than just nailing up tar paper! Grace makes another house wrap product that literally sprays on like paint, but that would have been even harder to apply correctly in our windy environment.

Years ago, when beach houses were not used in the winter, the issues of mold and rot were almost non-existent. Since there was little or no insulation in a house, anything that got wet would be open to the air and simply dry out. Over the last fifty or so years there have been a lot of changes in how houses everywhere have been made more comfortable. At first there was just sheathing and siding (primarily wood or brick), and then there was sheathing and tar paper and siding, and now there is sheathing, house wrap or tar paper, siding, and insulation in the interior part of the house envelope. Insulation solved the problem of keeping the interior of the house more protected from the weather, but it caused the secondary issue of not allowing the sheathing to dry by reducing the air flow through the wall. Moisture and reduced air flow causes mold and rotting, and that’s the “circle” of dominos to work through.

One solution came in the 1960’s, when the National Building Council of Canada began to address problems associated with the deterioration of sheathing and siding. It had been noted that the air inside various structures was becoming increasingly humid, which indicated high water absorption. It was determined that the increasing water absorption was caused by advancing deterioration of the sheathing, which was then transferred into the house. A process was developed to create a physical separation between the siding and the sheathing, called a pressure-equalized rain screen wall. The concept is to deflect water absorption into the sheathing by tackling the forces that drive water into the building shell. By neutralizing these forces, rain screens can withstand extreme environments. The rain screen wall is created by the use of vented or porous exterior cladding, an air cavity of a few inches, and a drainage layer on a rigid, water-resistance and airtight support wall. Rain screens effectively "drain the rain" by controlling powerful building wetting forces-gravity, capillary action, and wind pressure differences.

Here’s how it works: The exterior cladding deters surface raindrop momentum. It is typically porous with several air bypasses. An airspace separates the cladding from the support wall. The airspace decouples most of the cladding from the support wall, thereby reducing splash and capillary moisture transfer. Protected openings (e.g., vents, or weep holes) positioned at the top and bottom of the wall promote convective airflow, allowing moisture to quickly drain or evaporate from the air cavity. The exterior face of the support wall is protected with a drainage layer to further protect against any moisture that bypasses both cladding and air cavity. The wall air tightness (i.e., sealed assembly) buffers the remaining differential air pressure force. A “pressure-equalized” rain screen wall means that the pressure between the siding and the sheathing becomes equal to the outside pressure. The velocity component of the wind has been removed, preventing the wind from forcing water into the house. Since the siding and the sheathing are no longer in intimate contact with each other, the siding essentially absorbs the momentum of the wind. (That’s why face-nailing the siding with stainless-steel ring shank nails is so important!) Water that penetrates the siding freely drains down the membrane-wrapped sheathing, and any water that doesn’t drain evaporates. Cor-a-vent siding vents have been added to help promote air movement along the rain wall and to prevent various critters from colonizing behind the siding. Additionally, stainless steel drip edges were installed along the bottom of the siding to take the draining water away from the house and prevent the soaking of the foundation.

Our siding of choice is Hardi-plank. Fiber-cement board was chosen because it meets the requirements of a tough coastal area, and Hardi-Plank was chosen because it has a resume that backs up its qualifications. It has passed Miami-Dade testing for wind gusts of 150 mph and is rated to withstand both large small missile impact with tested design pressures of +53 and -53 (pushing and pulling). Hardi-plank also has FEMA approval for use in flood prone areas and is fire resistant. Those qualities provide a lot of assurance from James Hardie Corporation, but a key piece is making sure that the siding is installed according to the specifications for hurricane zones. That requires a siding installation crew that is patient and attentive to detail. We also specified that type 316 stainless steel fasteners be used, because no siding can do its job if the fasteners fail. Hardi-plank also comes pre-painted using a process called Color-Plus Technology. This application is particularly good for use oceanfront, because the paint is applied in a controlled environment before the siding is exposed to moist salt air or sand, and it has a 15 year warranty. In a cost comparison, the pre-painted product adds a small percentage of cost over the unpainted siding and is a big savings over having the house painted after installation. Louis has also made sure that the end cuts are painted before the boards are put on the house to prevent moisture from wicking through those vulnerable spots. Since the recommendation for hurricane zones is that the siding be face nailed, that also means that the nail heads have to be painted individually… one of the less desirable aspects of pre-painted siding. For this house, the trade-off was appropriate, and the siding will always have that first controlled paint application to protect it.

At the moment, Lewis and crew are close to finishing up their piece of the job, and each step brings us a little closer to seeing the exterior or the house as we planned it. Years ago, when we were up at the lot planting grass, I would take Vince’s arm and say, “Let’s pretend that we really do have a house here and that we have had a wonderful walk on the beach together. We would take the steps up from the beach onto our walkover and head into the kitchen for a cup of coffee or sit on the deck with a glass of wine.” And now, that vision is almost a reality!