Attack of the Dew Point!

Over the years we have seen a lot of window installations gone wrong. I remember a house where after only four years dangerous mold developed on the inside walls. When the builder opened the drywall, the studs were black! What had happened?  

The holes in the wall where water can penetrate into a house are typically the windows and doors. Even if water somehow manages to seep behind the roof flashing or enters the floor system through a badly installed balcony floor, in the end the water will always make it into the building through the window and door openings. Because we have a long track record of successfully installing hurricane rated windows and doors, we have been called to many failed installations to share our expertise. Here is what we found in the majority of cases:  

Windows (other than Henselstone) are sitting on metal sill pans. The sides and the top are typically connected to the membrane of the house (house wrap, tar paper stucco wrap) but on the bottom there is a gap with a few weep holes often caulked. The thought is that if water leaks through the typical American double hung or crank casement window, this sill pan can save the day because the water will drain out of instead of into the wall. So, let's look at this train of thought in detail: A builder buys substandard fenestration product which he expects to fail. The buying decision is almost always based on price. Then he custom-makes copper sill pans and installs them. The labor and material cost of these sill pans are lumped into the framing cost, making the windows look like a good deal, when in reality they are not. Since the windows were cheap and the expectation is that they will fail, no pressure is put on the manufacturer to improve his technology (like make a window that does not fail!).

Although sill manufacturers, stucco manufacturers, architects and engineers specify flashing pans to be on a slope, in reality they rarely ever are. Imagine setting a window on this pan. The slope will now point into the house instead of away from it.

Although sill manufacturers, stucco manufacturers, architects and engineers specify flashing pans to be on a slope, in reality they rarely ever are. Imagine setting a window on this pan. The slope will now point into the house instead of away from it.

The craziness continues. The metal sill is now an energy bridge between the outside and the inside climate of the house. Let's take a typical day in beautiful Charleston, SC. The outside is hot and humid, the inside cool and dry (air conditioning). The house wrap does its job. The house is tight. But wait, the sill pans. Here the energy conducting metal connects the outside with the inside climate and, guess what? Yes, it rains right in the middle of the wall. No problem, I have been told many times, the water will run out. True to a degree, if the weep holes are not clogged or caulked and the pan is actually on a slope (which it typically is not). Add to that the fact that the typical American window is not prefinished. The moisture does not drain out but is absorbed into the raw wood window frame. Ever wondered why on a nice hot day your double hung window sticks? Yup, the frames have swollen with the moisture, squeezing the sashes. Not only do they not operate well, the aluminum cladding (which does not expand with the wood frames) delaminates. Now rainwater can even enter into the miter gaps. Then, within a few years the sills rot out. The window has failed and yes, now you need your sill pan to prevent the worst. 

Note how these instructions from a major EFIS manufacturer say nothing about weep holes, slope, spacers to window frame or material of the sill pan.

Note how these instructions from a major EFIS manufacturer say nothing about weep holes, slope, spacers to window frame or material of the sill pan.

There are some real solutions to this issue: 1) Buy a window that will not leak. Yes, they exist! Check the design pressure ratings (which include a water resistance rating). A good window should have a design pressure rating of 60 psf or higher. Watch out for manufacturers who advertise a design pressure rating but exclude water penetration. 2) Check the construction of the window. A good window has interior and exterior seals with a drainage system in between. Metal cladding should be a separate, extruded profile, spaced from the wood (because of condensation), and welded in the miters (not glued). Miters in wood frames and sashes should be joined, not nailed or stapled. The product should be completely factory prefinished. 3) Avoid the use of sill pans. Your window installation should keep interior and exterior climates as separated as a regular wall does. If you have to use pans, use non-metal products. Insure that the pan is on a slope. Some products in the market place already have a built in slope. Keep the window frame from the pan with non metallic spacers. Seal the end dam to the window and keep the opening to the exterior properly drained. 4) Design you water proofing. Water does not only run downward. If you do not have a fenestration partner who knows his construction engineering, consult with a specialist on proper water proofing. Make that consultant take responsibility (i.e. issue a warranty for his design). Make sure you and your sub contractors are using the right materials. Tar paper is different from Tyvek. Stucco is different from shingles and brick. Use proper flashing and sealant materials. If you switch one piece of your water proofing design, others might have to be changed as well. Caulk is never a primary waterproofing material!!! 

Custom? Try This!

Custom-manufacturing in the window and door industry is quite a different animal from other industries. First, most window and door products are manufactured in large, automated, industrial facilities. Custom work has to be designed into the automation and flexibility of the factory. Then comes the distribution. Custom manufacturing by definition means longer lead times. Standard sizes allow manufacturers to produce for inventory, distribute the product into regional warehouses, and, when an order comes, be able to bring the product quickly to the customer. The distribution costs are lower, at least if the inventory resembles somewhat the market needs in the future. Forecasting that is more an art than a science. If forecasting is inaccurate, shifting inventories between distribution points and pushing overstocked items on the customer increase costs and lower customer satisfaction.

In Germany, custom manufacturing of windows and doors has been a necessity, not a choice for several reasons. Unlike the United States, where standardization of features and sizes has provided opportunities for making the same product over and over, in Germany, standardization has been difficult. Most construction revolves around renovation not new construction. Because of the age of buildings and the historical nature of many of them, openings and requirements are different for almost every project. Recognizing this, German manufacturers designed factories around the requirement of customization. Fully automated, walking through one of these window companies in Germany feels like an automotive factory: cars of the same platform move along assembly lines, some convertible, everyone in a different color, different engine sizes, and features specified by individual customers. Only that the variation possibilities of windows are even higher than those of cars. Thousands of hardware options, indefinite sizing, hundreds of glass options, thousands of color options, and other features the customer could specify. All that German manufacturers have managed to integrate into industrial production, while costs and delivery times resemble those of manufacturers producing standard products.

The trend in the window and door industry in the United States is moving towards the European system: Designers require custom products to expand their possibilities and competitiveness. The legal environment adds to the variability of products based on requirements for energy efficiency, wind resistance, and security. Standard product manufacturers see their offering expand continuously, undoing the cost advantage of manufacturing standard units. It will not be long until a manufacturer here in the United States will take the European manufacturing example and open a factory that will change the U.S. window and door industry profoundly. While maintaining competitive pricing, customers will be able to procure custom-made products without extended delivery times. Until then, the most experienced importers of European products will lead the market, at least the portion that likes custom products. 

Tripe Insulated Glass - A Fad?

Not too long ago Henselstone attended a podium discussion with three representatives of the largest window and door manufacturers in the United States (which will remain unnamed) in front of a group of architects. The topic was energy efficiency and sustainability. The discussion turned into a three against one melee since our company was the only one promoting triple insulated glazing. "Nothing but a fad," commented one. "Unstable and bound to fail because the glass is so thick," piped in another. "Insulated glass is efficient enough, insulating the rest of the structure is far more important," was supposed to be the knock out blow against triple insulated glazing. Our representative remained quiet until they were done. Then he raised a cut-out sample of a 3 1/4" sash profile with a 1 1/2" triple insulated glass in it.

The glass had an R-rating of 11 (industry average is R3). The sash and frame had an R-rating of 6. Put together in a standard size window (3 feet by 5 feet) the units achieved an R-rating of 8. Counter intuitive to most, the larger the glass area the more efficient the window or door becomes. Consternation in the audience. Self satisfied smiles on stage. Then a question from the audience... It was all over for the big three after that.

Why do American manufacturers continue to spend more money on lobbying against energy regulations than on product development to create an R8, R10 or better window? Because American manufacturers are stuck with 1 3/4" thick sashes. They cannot accommodate 1 1/2 inch glass because their sashes can't support it. The only other option is to use a different gas in between the glass panes that would allow the glass to be as efficient but thinner. This gas (Krypton), however is very expensive. They could not compete against a European window with thicker sashes.

Here you have it! Sorry, we made our competitors angry. They are just the foot soldiers of an industry that has been milking products for cash that they developed 25 years ago. Meanwhile, the rest of the world spent a lot of money and resources on truly energy efficient products. Triple insulated glazing has not only become the standard in most European countries, it has proven to be a stable, reliable product with low failure rates, and easy manufacturability. Agreed, selling some weatherstripping to a homeowner 25 years ago would have increased the energy efficiency of his or her home by 100%. However, today buildings are generally much more efficient and tight. Better insulation materials, improved construction processes, and highly efficient HVAC systems have all taken a modern building to new heights when it comes to energy efficiency.

Why not deal with the last bastion of inefficiency? Over 60% of energy loss occurs through windows and doors. So, dear architects, builders, and homeowners. Don't be snowed by arguments supporting ancient technology. Your customers deserve better and will demand better. Energy efficient construction raises the attractiveness of a project, reduces the long term cost of ownership, and increases the resale value. Those are facts. Would that not be worth 10% more for your window and door package?

Join the Evolution!

Join the Evolution!

Security does not have to be ugly

Thinking security most people have visions of steel doors, thick glass, locking systems that are hard to operate, and limited color choices. This does not have to be the case. Security features come in specific categories: Frame and wall connections, hardware, glass and fillings. Within these categories the level of security you want to achieve can be defined.

Bullet resistance requires steel frames and sashes. The steel can be sandwiched in wood. It is possible to have a beautifully finished mahogany door that is resistant to. small arms fire. Thinner steel sandwiched in wood provides security for most other applications, such as saws, drills, wedges, sledgehammers and such. Often forgotten but most important are the wall connections of your security windows and doors. Lag bolts from the frame to the wall have to be strong and firmly established in distances determined by the envisioned level of security. If the walls are 2 by 4 wood frames or brittle brick, the door security does not matter. A determined attacker will be able to break the door or window out of the wall.

Hardware is crucial. Security units require hardened steel hinges, strike plates, and multiple locks. The hinge pins have to be secured so that they can only be removed once the door or window is open. Ideally, locking points should include the corners of the door or window. The should not just slide in place but have mushroom heads that cannot be pried out of the receptacles.

Finally, glass and fillings. There are lots of options for glass. Security levels are determined by the thickness of glass, its hardness, and the laminates in between panes. The higher the impact resistance, the stronger the laminations. Most people would not be able to tell security glass from any other, unless they would have to lift it. However, laminated, tempered glass alone will not provide security. The glass (or wood panels sandwiched with steel) have to be glued to the frame of the windows or doors. That will make sure that, even if the glass has been broken, it cannot be removed from the unit. The downside of security glass glued into the frames is that, once broken, the whole sash has to be replaced. Even our installers will have a very rough time cutting security glass out of sashes.

There you have it: Have a beautiful hardwood door and large windows with the finishes you like while you can feel safe in your home.

Hurricane Testing Revealed

Hurricane Andrew hit the coast of South Florida in the early morning hours of August 24, 1992. The category 5 storm with wind speeds in excess of 150 mph caused billions of dollars of damages. Experts who analyzed the destruction decided quickly that the building codes on Florida were out dated and a lot of damage could have been avoided. Dade County administrators were the first to look into strengthening building codes. The first thing that was need was a realistic simulation of what happens when a hurricane moves through a building. Hence the "Dade County Test." Of course Dade County was not the first entity to look into this. Scientists in Australia had developed testing standards for all kinds of building materials in a simulated lab environment. 

Today, both the Dade County test and the ASTM test (part of the International building code that adapted the Australian test specifications) are accepted in most locations along the U.S. coastline.  All windows and doors have to pass a design pressure test that measures air infiltrationwater resistance, and structural integrity at certain pressures, positive and negative (DP rating). For wind zones up to 120 mph a DP rating of 50 pounds per square foot is usually required, 60 psf for wind zones up to 130 mph, 65 psf for wind zones up to 140 mph, 80 for wind zones up to 150 mph and 100 for larger than 150 mph. While in the beginning small missile impact tests were conducted with small steel balls to imitate flying gravel from flat roofs, most modern hurricane tests are either conducted with a 4.5 lbs (Missile C) or a 9 lbs (Missile D and E) piece of lumber. Depending on wind zone certification the missile is shot at a certain speed into three specimen either in one, two, or three impact points. The missile cannot penetrate. After the impact, the three specimen are cycled 9,000 times at varying positive and negative pressures (suction and pressure as exists in a hurricane) up to 1.5 times the 
Design Pressure rating. The glass cannot come out of the frames or show any openings larger than 2 inches. Henselstone's standard Design Pressure rating for all windows and doors is 65 psf positive and negative. All impact rated products pass the large missile impact test for wind zones up to 140 mph (missile D). 

The results are measurable. Since 1992 more and more municipalities and counties have mandated hurricane tested building materials and a conforming construction process. In 2005 Hurricane Wilma allowed for a first time to make scientific comparisons. This storm hit southern Florida from the west, an area of Florida not as densely populated as the east. However, surveys of neighborhoods showed a significant reduction in damage to buildings in residential neighborhoods that had been built under the new building codes.  These findings for the first time confirmed that the theoretical environment where building materials are subjected to impact, pressure and suction do relate to better performance in the field.