So What Is Fenestration, Anyways?

Okay, if you speak to contractors, especially those who specialize in installing windows and doors, you’ll probably hear the word “fenestration” come up sooner or later. You might see it mentioned in documents like the Florida Building Code (FBC) or other legal standards related to construction.

So, what is fenestration? What does the word mean and why do so many contractors throw it around?

Defining Fenestration

The word fenestration has three technical definitions, as noted by Merriam-Webster. The first is “the arrangement, proportioning, and design of windows and doors in a building.” This is the definition typically used by contractors in the construction industry. 

The second definition per the dictionary is “an opening in a surface (such as a wall or membrane).” This definition is also common in construction circles and among window and door installation companies like Karoly. However, the ‘membrane’ part also makes it relevant to the medical industry or natural studies.

The third definition is not relevant to windows and doors, as it is concerned with a surgical ear operation, making it a verb rather than a noun: “The operation of cutting an opening in the bony labyrinth between the inner ear and tympanum to replace natural fenestrae that are not functional.”

Most of the time, when the term is used by workers in the window and door replacement/installation industry, it’s basically being used as a fancy way of saying “windows and/or doors.” In fact, the Building and Science Education website clearly states “Fenestration (i.e. windows and skylights)” when talking about the term.

An easy way to remember the link between fenestration and windows/doors is to think of the term “defenestration,” which often pops up in court dramas or cop shows when the charges involve someone getting thrown through a window.

Types of Fenestration

Fenestration can be broken into three distinct categories: 

• Windows. Openings in the wall, typically set some distance from the floor based on local building code ordinances, meant to provide a clear, unobstructed view to the outdoors. Not generally used for egress, but may be designed to allow it in an emergency.
• Doors. Openings in the wall of the structure that are intended to allow occupants to pass through with minimal obstruction when the door is open. May be opaque or clear depending on the door type.
• Skylights. Openings in the roof of a structure that allow light to enter, hence the name ‘skylight.’ Often made of similar materials to windows and generally not meant to bear weight beyond that of the glass and the frame of the skylight itself.

Since we don’t deal in skylights, we’ll focus on the two forms of fenestration we specialize in: windows and doors.

Types of Fenestration: Windows

Windows can be broken down into distinct types of fenestration, such as:

1. Single-Hung Windows. One of the most common types of window, single hung windows have two sashes, one fixed and one that can move up and down to open or close. 
2. Double-Hung Windows. From the outside, these windows look almost exactly the same as single-hung windows. However, both sashes on these windows can move, making the more flexible fenestration option for homeowners. Also, when both sashes have pivot mechanisms, that makes them easier to clean from the inside of the home, since you can tilt both sashes inwards to get at both sides of the glass.
3. Sliding Windows. Rather than moving up and down on counterbalance mechanisms, these windows slide side to side on built-in rollers. That makes these windows ideal for larger fenestration openings in the home, as heavier sashes are easier to slide than lift.
4. Picture Windows. These are fixed windows that do not open or close like the other window types. These windows often have minimal frames to obstruct your view and enhanced rigidity since they aren’t meant to open or close. Window openings that touch the floor often get filled with picture windows.
5. Bay Windows. Bay windows are actually a composite of multiple pieces of fenestration. They project out from the sides of the home and typically have 3-4 windows built into them to let in light from multiple angles, increasing the amount of natural light your home gets. 
6. Casement Windows. These windows have sashes that swing horizontally out and away from the window frame on a hinge and armature mechanism. This moves the sash more completely out of the opening to allow more air flow into the home. However, these windows can still shut tight to keep out inclement weather. Often good for small-to-midsize window openings in rooms where you want greater airflow.
7. Awning Windows. These windows are similar to casements, but swing open vertically. This lets in breezes easily while blocking light rainfall, since the window sash is angled to cover the opening like an umbrella.

Some might add another category of ‘structural windows’ or ‘architectural windows’ to this list for non-operable fixed windows meant to fill in small gaps or arched window openings, but such windows could also fall under the ‘picture windows’ category.

Furthermore, windows can be subdivided based on construction standards, such as impact or non-impact. Impact windows are built to withstand heavy hits from flying debris without breaking and letting in wind, water, and pests. Non-impact windows, meanwhile, are not built for impact resistance and will break much more easily when exposed to strong winds and flying objects.

They can have frames made from wood, vinyl, or metal, each material having its own unique advantages and disadvantages over the others.

Types of Fenestration: Doors

You might think that doors are simple. However, there are a lot of different types of doors to choose from and that’s before even accounting for things like sidelights that can be used to fill in gaps in larger doorway openings. The two major types of doors are sliding glass doors and entry doors.

Sliding glass doors all use rollers on tracks to slide a large glass pane from side to side to let users open and close the door opening. Entry doors typically have hinges that let them swing open and closed and are usually the main entryway for the home from the street. 

• Bi-Parting Sliding Glass Doors. These sliding glass doors open and close from the center of the doorway rather than either end. Styles may vary. For example, some bi-parting doors may have a central post, basically creating two separate sliding doors, while others may simply have one door overlap the other when shut.
• Patio Sliding Glass Doors. This is the ‘standard’ type of sliding glass door that most people picture when they hear the term. These doors typically have two or more panels that slide from the edge of the door frame to the other side.
• Pocket Sliding Doors. These sliding doors have an extended track that runs along the wall of the door opening, allowing the glass panes to slide beyond the edge of the opening to create a wider gap. In the past, exterior pocket doors actually slid into the wall, but this is not currently up to FBC guidelines.
• Single Entry Doors. The basic type of door found at the front of homes throughout Florida. These consist of a single door on hinges that opens and closes securely. Often has strong anti-intrusion features to prevent forced entry into the home, as the front door is often the easiest for a would-be intruder to reach.
• Double Entry Doors. In larger front door openings, homeowners can install double doors, which consist of two separate doors that join in the center of the doorway when shut. Like with bi-parting sliders, double door styles may vary. Some double doors create two separate doors that lock into a central pillar, while others have the two doors secure to one another. Often more difficult to install than single entry doors, requiring more care and expertise.
• Panel Doors. A subcategory of entry doors that have grooved ‘panels’ built into them. Very commonly used. Some manufacturers can customize these doors by cutting out the panels and replacing them with glass panes to let in more light or provide visibility from the house to the outside.
• French Doors. Doors that feature large panes of glass (similar to sliding glass doors) to let in more light and provide visibility to the outside, but with a distinct style that incorporates more inspiration from the Renaissance era. Available both as on-rail sliding doors and as double doors that swing open and closed. 

Residential entry doors are typically made from wood or fiberglass. In Florida, fiberglass is typically the best option, as it provides plenty of durability to resist strong impacts and is more resistant to corrosion and rot than wood fibers.

Fenestration Terms to Know

When looking at fenestration, whether it’s windows or doors, there are a few important terms to understand. Here are a few that were highlighted by Energy.gov:

• U-Factor. A measure of how quickly thermal energy can pass through a window or door (i.e., how effective it is at insulating your home). The lower the number, the less energy passes through the door. Typically measured on a scale from 0.2 to 1.2.
• Solar Heat Gain Coefficient (SHGC). A measure how how much thermal energy passes through fenestration in the form of solar radiation on a scale from 0 (none) to 1 (the most possible). The higher the number, the easier it is for solar radiation to warm the home. 
• Air Leakage. A measurement of how much air can flow through fenestration when there’s a pressure difference between the inside and outside, expressed in cubic feet per minute per square foot of frame area (cfm/ft²). The larger the number, the more air can get into or out of the structure.
• Visible Transmittance (VT). How much visible light can make it through a piece of fenestration on a scale from 0 (no light) to 1 (perfect clarity). The higher the number, the more light gets through the window (or door) glass.
• Light-to-Solar Gain (LSG). A measurement that takes the SHGC of a window or door and compares it to the VT rate to create a gauge of how effectively the glass blocks solar heat compared to its clarity. The higher the number, the more effective a piece of glass is at blocking solar radiation while letting light in. This is not always a metric that is presented on a fenestration product’s labeling.

Many of the above terms (U-factor, SHGC, air leakage) have a direct impact on the energy efficiency of a window or door product, so it’s important to know these terms so you can identify fenestration that will ensure you can maximize your energy savings.

Need Help Finding the Best Fenestration for Your Home?

Karoly Windows & Doors is here to help! We have 25+ years of experience installing fenestration for homeowners throughout the Tampa Bay area.

All of our installations are handled by 100% in-house technicians—never an outsourced contractor or third party company. Why? Because, that lets us ensure that every installation we perform is handled purely in accordance with our high standards.

Our installation technicians are all trained and experienced so you can get the best installation quality for your new windows and doors, every time.

Get the best fenestration installation experience in Tampa Bay! Reach out to Karoly Windows today to get started.