Lowe's Home Improvement

Types of Windows: Replacement Window Buying Guide

Choose the best windows for your home, using this guide to the types of replacement windows available.

Windows in a Living Room.

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 your existing windows, you typically use replacement windows unless the existing frame around the opening needs replacing.

Windows are either operable (can open) or fixed (cannot be opened). There is 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.

Window Styles

Double-Hung Window.

Consider your budget, your home's style and how you want the windows to perform. Think about the importance of ventilation, privacy, security and ease of maintenance. Decide whether you want to emphasize the windows as decorative focal points or have them serve a purely practical purpose.

Good to Know

Look for in-store guides that help you select the window styles and options that best match your home and needs.

Double-Hung Windows

Double-Hung Window.

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.

Shop for Double-Hung Windows

Single-Hung Windows

Single-Hung Window.

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.

Shop for Single-Hung Windows

Sliding Windows

Sliding Window.

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

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Accent Windows

Octagonal Accent Window.

Accent 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.

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Glass Block Windows

Glass Block Window.

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.

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Basement Hopper Windows

Basement Hopper Window.

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.

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Good to Know

Make sure you have good measurements of the rough openings for your windows. Read Measure Windows for Replacement for instructions.

Other Types of Windows

Bow and Bay Windows.

There are other common window types, often designated as windows 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, but fit together at greater angles — 30 or 45 degrees, for example — and project further from the house.

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Picture windows are fixed models designed to offer wide, unobstructed views and provide lots of light.

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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.

Shop for Casement Windows

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.

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Skylights mount in the ceiling and may be fixed or operable. During the day, they function much 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.

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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.

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Window Frame Materials

  • Vinyl is a common material for replacement windows. Vinyl windows are made from rigid, impact-resistant polyvinyl chloride (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 pre-primed on the exterior or interior surfaces. You can also buy them pre-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. 

Windows and Energy Efficiency

Cutaway of a Window.

Some windows feature two layers of glass — double-pane — or three layers — triple-plane. 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, but 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 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.

Good to Know

Windows may be labeled as ENERGY STAR® qualified for specific zones of the country. Take a look at Residential Windows, Doors and Skylights on the ENERGY STAR website 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.