A fluoride treatment at the dentist isn't critical but can't hurt, and carrying an umbrella when the forecast calls for rain is just a good idea.

Preventive measures can end up saving you big headaches and, potentially, lots of money down the road.

Using a windowsill pan on the rough-framed opening before a window is installed has proven to protect the surrounding interior and exterior areas from water damage. It's one step that will minimize the chance the siding someday will need to be pulled off to repair damage, or the drywall inside someday will start to reek of mold.

As building projects supervisor for the Lancaster County Career & Technology Center's Green Build Community Education Project, it's Mike Dodson's job to make sure he and the other instructors are looking for the best and most state-of-the-art materials and solutions. Research for the current Green Build Community Education Project started long before they broke ground this school year.

"We're partnered with NAHB (National Association of Home Builders) and were selected as one of six national sites for the education project," Dodson said. The NAHB sends scientists and engineers to look at each phase of the project, Dodson said, and helps LCCTC staff and students solve as many "green build" issues as possible.

Along with many other "green build" materials, applications and techniques being built into the project on Old Market Street in Mount Joy, the students have turned their hands-on textbooks to the flashing and installation of the home's windows.

The concept of all sill pans is the same: to re-direct water that makes its way past the sealed seams and edges of a window unit. Various manufacturers make prefabricated sill pans to install on the sill area before a window is set into place.

Dodson, however, feels the prefab pans are often rigid and more difficult to install.

Dodson likes the QuickPan product by Williams Building Diagnostics of Maple Grove because it's field-fabricated, inexpensive and very easy to install.

Russel Graham is sales and marketing manager at Building Diagnostic Technologies, which is owned by Williams Diagnostic Technologies. He came on board the LCCTC project to teach the students about the concept and about windowsill pan materials used as water damage protection.

THEN AND NOW

Building a house 50 years ago was a different animal than constructing one today.

With technological advances in building materials, weatherproofing, insulating and other elements of the trade, each construction step could conceivably rely on the one before to determine its success in the process.

The concept used to be much more straightforward. Houses, for the most part, were framed out of wood, insulation was placed between the studs or the house was wrapped in an insulated board, and some sort of exterior surface was applied.

Whether the house had wood or vinyl siding, stone, brick or some other type of masonry finish, the house wasn't nearly as airtight and energy efficient as the homes of today. While today's builders are striving for the most energy efficiency, zipping up a house so tightly it can't breathe presents its own host of problems, such as trapped moisture that has no place to go.

Builders and homeowners are glad they no longer have to tape up thin plastic over the windows to keep the curtains from blowing or drape a stuffed "snake" at the bottom of their doorway to keep out drafts — but they also don't want to have to deal with the newer culprit of rot and mold from trapped moisture.

New construction, additions and damage repair are all applications for the sill pan concept.

INSTALLATION

One of the most elementary concepts when dealing with water issues is that rain flows top to bottom. So all exterior parts of a house that will undoubtedly be subject to rain exposure must by installed with attention paid to overlapping, according to LCCTC student Octavio Sanchez, who has been an acting instructor to others on the job site.

"The window sill pan captures the water and directs it to the proper drainage plane, rather than allowing the water to enter the wall cavity," Graham of BDT said.

A sill pan has three components that make it successful: A back and two end dams keep water from running back into and in between any wall building material, while a front flange allows the water to run forward and away from the wall cavity.

Channeling the water this way lessens the chance of damage such as rotting, warping and mold growth.

The four materials used with the QuickPan system are a sill wedge, a 13½-inch wide flat, flexible, multilayer product made up of high-density polyethylene, a flexible flash pan made of the same material, and sealing tape.

A quick step-by-step includes placement of the sill wedge. After the house wrap is folded onto the sill and sides of the framing, Sanchez explained, the sill wedge is folded on pre-creased lines and simply stapled into place. This is the first step of creating a bevel to aim water away from the interior.

Mechanical flashing is then cut to serve as an exterior apron to the sill, running about 5 inches up the two sides of the window opening and extending 9 inches to both the right and left of the opening. A groove is cut into the flashing, so the part spanning the window opening can rest on the rough sill area.

Two 6-inch lengths of the sealing tape are applied to the bottom two corners of the opening from the outside, so the "sticky" tape lies flat on the exterior. It is slit vertically where it extends into the open space and is pushed into place on the sill as well. The sealing tape reinforces the protection in the corner of the flashing layers and serves as a backup to prevent failure in sealing prefabricated window units.

The remainder of any horizontal components being installed are considered part of the "no nail" zone, according to Dodson.

The next piece of flashing has a pre-creased back dam flap that creates a lip at the top of the slope to keep any water from running inward.

After the sill flashing is in place, mechanical flashing is used to wrap the two sides of the opening, overlapping the sill flashing by a couple inches, again creating the overlapping shingle effect.

According to Sanchez, with the correct materials and tools on hand, each window of the project house took about five minutes to flash with the sill pan system.

"For as simple and easy as it is, it's a good preventative measure," Dodson said.

E-mail: rmcroberts@lnpnews.com