Restoration Guide: Windows and Doors - Storm Windows

Editor's Note: This is article 5 of 12 in Chapter 4: The Windows and Doors Guide of Old House Web Restoration Guide. This guide was developed and edited for old homes from original materials in the U.S. Housing and Urban Development Rehab Guide.

Section 1--Overview

Adding storm windows cuts down on drafts, increases the thermal performance of single-pane windows, protects a home from severe weather, and reduces noise. They are a relatively inexpensive investment when undertaking a home renovation project to improve energy efficiency. This section of the restoration guide covers selection and installation of storm windows, repair or replacement of screen material, and installation of sun screens. Consider storm windows if your old house is in a climate subject to severe weather.

Section 2--Selecting Storm Windows

Aluminum storm windows are strong and have a narrow profile, and their conducive properties for transmitting cold are not a concern if they're used with wood windows, which provide thermal protection. Conventional storm windows aren't recommended for vinyl prime units because the air between the units rises and can cause expansion and contraction of the frames. Storm windows are often a good choice for steel windows because the storm units provide needed thermal protection.

Consider all of the following elements to evaluate storm window performance:

• Frame design and material
• Assembly
• Installation
• Weatherstripping

You should be able to get rating information from any American Architectural Manufacturers Association (AAMA) certified manufacturers or National Fenestration Rating Council (NFRC) program participants.

2.1: Interior Storm Windows

These fixed windows are attached to the frame of the primary window unit and are designed for easy removal. You can find them in custom-fit or do-it-yourself kits. Acrylic glazing is popular because it's lightweight and tough. Fixed units are less expensive than operable storm windows and suitable for windows of all types without altering the appearance of your old house from the outside--a key consideration in many home renovations.

The downside? These types of storm windows might promote condensation on the primary window unit, and the acrylic products can discolor over time.

2.2: Exterior Storm Windows

These storm units are more expensive than interior storm windows because they are moveable and stay on year round. They provide a cost-effective solution to improving energy efficiency and help protect against weather damage. But they alter your home's exterior appearance, and because of the humidity and temperature between units, these storm windows can damage vinyl or wood window frames.

2.3: Screen Materials

Different types of screening materials are available for storm windows. Aluminum screening is strong, but it's also vulnerable to dents or corrosion. Fiberglass screening won't dent, but it can stretch and later sag. Some types of fiberglass screening can reduce heat gain in warm climates, but with the gain in energy efficiency you lose some natural daylight and ventilation. This type of screen works best on east and west sides of a structure where the sun is low and can't be blocked by awnings or overhangs.

Copper, bronze, or stainless steel screening are good alternatives in coastal areas because they resist corrosion better than aluminum. Don't combine these screens with aluminum windows, or a corrosive reaction can occur.

2.4: Sun Shade Installation

Exterior sun shades block the sun, although they might trap hot air between the window and the screen. Sun shades can pay for themselves by reducing air conditioning costs in hot climates, but they interfere with views and daylight, and they require regular maintenance.

Section 3--Installation and Repair

Storm windows slide vertically or horizontally, or they come as fixed units, which can be removed in spring. You can install storm windows on the inside or outside, and general seasonal maintenace may be required.

Replacing the screen material is an inexpensive, easy repair, but take care to check the compatibility of the new material with the window frame. Fiberglass screening material is easier to handle and install than aluminum, but it might stretch over time.