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Window Replacement Buying Guide

An image of a woman opening a kitchen window.

Updated June 29, 2020

Marc M.

By Marc M.

Use this guide to learn about the types of replacement windows available and the best ones to choose for your home.

Window Basics

You can find windows designated for new construction and replacement. A window for new construction has a nailing fin — a rim that allows you to secure it in the rough opening of a wall. A replacement window doesn’t have a nailing fin. It’s secured in an existing window frame with fasteners that run through the window assembly, making it easier to install. When updating existing windows, you typically use windows that are designated for home window replacement unless the existing frame around the opening needs to be replaced. Before buying replacement windows, make sure you have good measurements of the existing rough openings. Read Measure Windows for Replacement for instructions. 

Windows are either operable (they can be opened) or fixed (they can’t be opened). There’s at least one sash — a sheet of glass and a framework of vertical stiles and horizontal rails — in a window. A pane is a single sheet of glass framed in a window. Glazing can refer to either the glass in a window or the process of securing the glass into the framework. The window frame consists of the head, jamb, side jamb and sill.

Anatomy of a Window

A diagram showing parts of a window.

Single Hung or Double Hung Vinyl Window

  1. Head jamb
  2. Grilles between the glass (GBG)
  3. Glazing/glass
  4. Sash
  5. Side jamb 
  6. Stile
  7. Rail
  8. Sill

Window Types

Each type of window has specific features and characteristics. In addition to appearance (from inside and outside), consider their function, whether or not you want to open them and the amount of light they should let in. Also think about how you’ll clean and maintain them.

Double Hung Windows

Double hung windows offer a classic look. They have operable upper and lower sashes. Lowering the top sash and raising the lower sash can allow warmer air near the ceiling to move out through the top, while cooler air can flow in through the bottom. Many double hung windows have sashes that tilt inward, allowing you to clean the exterior surfaces from inside your home. This feature is particularly valuable if the windows are on a second story.

Single Hung Windows

Single hung windows look similar to double hung models, but only the lower sash is operable. As with double hung windows, some models allow you to pivot the sash inward to clean the exterior.

Sliding Windows

Sliding windows have one or more panels that move horizontally along upper and lower tracks, allowing you to easily open up half of the window for ventilation.

Picture Windows

Picture Windows are available in a standard rectangular design or shapes that offer more visual variety, such as an octagon. These windows are usually fixed and don’t allow ventilation. Picture windows are fixed models designed to offer wide, unobstructed views and provide lots of light.

Glass Block Windows

Glass block windows are constructed from individual blocks sealed together with mortar. The thick, break-resistant glass provides privacy but still allows light into your home. Glass block windows are fixed, but some have a built-in vent you can tilt open. Other models — designed for use in a laundry room — include an outlet for a dryer vent hose.

Basement Hopper Windows

Basement hopper windows are hinged on the bottom and open from the top. They can provide airflow for a basement and are typically placed low on an exterior wall.

Other Types of Windows

An image of a wood-finish double-hung window that's hinged opened for cleaning.

There are other common window types often designated for new construction. 

Projection windows extend out from the house. A bow window is an assembly of three or more individual units positioned at slight angles — 10 degrees, for example — giving the appearance of a gentle outward arc. Bay windows are similar to bow windows but fit together at greater angles — 30 or 45 degrees, for example — and project further from the house. 

Casement windows are hinged on one end and pivot out for ventilation at the other end. They’re easy to open and provide good air flow. 

Awning windows have a top-hinged sash that tilts out from the bottom. The design of an awning window helps keep rain out when the window is open. 

Skylights mount in the ceiling and may be fixed or operable. During the day, they function like overhead light fixtures. Larger, traditional skylights need a direct connection between the ceiling and roof for installation. Smaller tubular skylights include a reflective tube that channels natural light through an attic space and to a diffuser in the ceiling, illuminating small spaces, such as hallways or bathrooms. Their size allows them to work with any roof-support type without cutting and reinforcing joists.

Storm windows reduce the flow of air into the home, providing an economical way to increase the energy efficiency of single-pane windows. The space between the storm window and the existing window acts as added insulation.

Window Frame Materials

A closeup cross section of a window frame and lock.

The frame material of a window affects factors such as heat transfer, durability and maintenance. 

  • Vinyl is a common material for replacement windows. Vinyl windows are made from rigid, impact-resistant polyvinylchloride (PVC), with hollow chambers inside to help them resist heat transfer and condensation. Vinyl windows don’t require painting or finishing, and the material doesn’t fade or rot.
  • Aluminum windows can be an economical option for replacement windows. They’re durable, light and relatively easy to handle. Aluminum windows are corrosion-resistant and require little maintenance.
  • Wood is popular, particularly for the interior parts of a window. It’s available on new-construction windows. Wood doesn’t conduct as much heat or cold as other materials and doesn’t allow as much condensation. Wood windows often come unfinished, but you can save work by purchasing them already primed on the exterior or interior surfaces. You can also buy them already painted in a few standard colors.
  • Clad-wood windows offer the benefits of wood on the inside but are covered on the exterior with a tough, low-maintenance jacket of aluminum. The cladding makes the exterior durable and prevents rot. Clad-wood windows are available for new construction. 
  • Fiberglass windows are durable and waterproof. They won’t crack, bend, warp, rust, rot, corrode or peel, and they’re long lasting and easy to care for. The lower heat conductivity and lower thermal expansion mean the frames won’t expand and contract as much as other materials.

Windows and Energy Efficiency

An image of a white double-hung window that is hinged opened for cleaning.

Some windows feature two layers of glass (double pane) or three layers (triple pane). Air or argon gas, which has better insulating properties, is sealed between the panes as an insulator. If the unit is properly constructed, condensation shouldn’t occur between the panes. A drying agent, called a desiccant, may be used between the panes as added protection from condensation. 

Low-emissivity (Low-E) glass has a coating that allows light in but blocks out much of the heat that contacts it. A Low-E coating can help keep your home cool on a hot day by reducing the exterior heat entering your home. On a cold day, it can keep most of the interior heat from escaping through the glass. Low-E glass also reduces the amount of ultraviolet (UV) light entering the home, helping protect carpets, upholstery and furniture from fading. 

The U-value or U-factor of the window indicates the rate at which heat flows through the window and frame, and measures overall energy efficiency. A lower U-value means the window will insulate better.

Solar heat gain coefficient (SHGC) is a specification that indicates how much solar energy passes through the window. A higher number means the window allows a higher percentage of solar heat to pass through. If you live in the South, you may want to consider windows with lower SHGC ratings to block heat in the summer and reduce cooling costs. In the North, you may want to look for windows with higher ratings to allow the sun to aid in warming your home. 

Windows may be labeled as ENERGY STAR® certified for specific zones of the country. Take a look at Residential Windows, Doors and Skylights to learn the benefits of these windows. 

Other Window Features and Options

Tempered glass is a type of safety glazing. The glass crumbles when broken rather than shattering like standard (annealed) window glass. 

The sound transmission class (STC) rating of a window indicates how well it reduces noise from outside. A higher number means less sound is transmitted through the window. 

Double-strength glass is thicker and resists breakage better than single-strength glass. 

Rough-opening dimensions indicate the size opening the window will fit. The actual dimensions of the window are slightly smaller than the rough measurements to allow for installation materials.

Grids or grilles are available with some windows to simulate the look of a window made up of multiple, smaller panes of glass. The grid may be mounted on the window surface or encased between panes of glass.

Window Cleaning Tips

There are many ideas about what formula works best for cleaning windows. A simple mixture of a gallon of water with either a teaspoon of baby shampoo or 1-1/2 cups of vinegar is an effective recipe for general cleaning. 

Follow these simple steps to keep your windows clean and streak free. For more tips, visit our guide How to Clean Windows

  • Rinse the window surface from top to bottom with clean water. 
  • Clean with one of the mixtures listed above and a sponge. Apply uniform pressure horizontally, then vertically. 
  • Don’t allow solutions to collect or puddle on vinyl surfaces and quickly rinse, dry and run down. 
  • Rinse thoroughly using clean water without allowing any solution to dry on the glass. 
  • Wipe the window, frame and sill with a lint-free, dry cloth.

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