SHAPES OF WINDOWS
Many homes have only the basic types of windows - meaning square and boring. Updated windows can make a nondescript home into one that shines with curb appeal. But you need to know what is available (and what it’s called) when talking to your window professional. Here are some terms you should know.
This type of window cannot be opened. It is usually inexpensive and suitable for higher windows that won’t be opened anyway.
One of the most common windows and a great window for a period home. The window consists of two sashes that move up and down. Only half of the window can be open at one time.
Another common window, casement windows are hinged vertically to swing in and out like a door and operated with a crank.
Awning windows are similar to casement windows but are hinged horizontally.
Jalousie windows are horizontally placed narrow strips of glass, lowered by crank. Out of favor today, they were very popular in the mid-century.
Sliding windows move on top and bottom tracks. They are very common and can be inexpensive.
A paladian window consists of group of three windows with an arch over the center. These windows have become very popular in the last decade. They provide visual interest and drama to a home.
Picture windows are especially popular in ranch-style homes. They are large fixed windows flanked by 2 casements or double-hung windows.
Clerestory windows were especially popular in Craftsman homes. They consist of a strip of small horizontal panes set high on a wall.
ELLIPTICAL OR ARCHED
Elliptical or arched windows often placed above double hung or fixed windows in today’s new homes.
A bay window is a window space projecting outward from the main walls of a building and forming a bay in a room, either square or polygonal in plan.
TYPES OF FRAMES AND SASHES
Window frames and sashes can be manufactured from a variety of materials – aluminum, fiberglass, vinyl (PVC), wood, or a combination of these materials -, which has implications in the thermal efficiency, durability, environmental impact and costs of the windows.
Aluminum windows are durable and offer low maintenance and low costs. But they aren't efficient in cold climates. Only aluminum frames with thermal breaks (that is, with their external and internal frames separated by a good insulating material) can rate high, and constitute a good option in moderate climates.
Fiberglass frames and sashes are very energy efficient, and offer good structural strength, high durability and minimal or no maintenance costs. Hollow sections of the frame and sash can be filled with foam insulation to increase the energy efficiency of the window.
Extruded vinyl frames (PVC) are good or even excellent in terms of energy efficiency, and demand low or no maintenance costs; vinyl frames can also be filled with foam insulation to provide a better energy efficiency. Thermally welded corners also improve the performance of vinyl frames and sashes, preventing air and water leakage.
Solid wood frames have a good insulating value, and a good structural strength. The disadvantage? The impact of the weather on them… and their possible short durability and high maintenance costs. High performing wood frames and sashes demand factory-applied cladding and finishes, and well-sealed corners and gaskets. They tend to be expensive.
Some window frames and sashes combine two or more materials (aluminum, fiberglass, wood…) in order to get the best features of each material. But a composite nature doesn’t necessarily mean high-efficiency. The final performance depends on multiple manufacturing details.
SELECTING FRAMES AND SASHES
When choosing window (or skylights or patio doors...) frames and sashes, you may check or inquire about:
- Tight-fitting sealed joints (they prevent air and water leakage)
- In the case of aluminum (and other materials requiring thermal breaks), ensure that the exterior and interior surfaces of the frame are separated by an adequate insulating material.
- In the case of large windows (skylights and patio doors) requiring additional reinforcement, inquire about the impact of the reinforcement material on the thermal performance
- the sealing methods used involving the interface between the glass unit and the sash (to prevent water from entering)
- insulated frames: the hollow sections of the frame and sash should be filled with foam insulation to increase the energy efficiency of the window.
- warm edge spaces: they are particularly important to reduce thermal bridging at the edges of the window