Storm Windows USA · Installation library

Installing Aluminum Interior Storm Windows

An interior aluminum storm sits between the existing window jambs. Its perimeter seal, attachment points, and finish trim work together to create a close-fitting second layer. Fixed panels and operating sashes use different retention hardware, so start with the instructions for the configuration on your order.

MeasureInstallFinal checksShop this range

Before you begin

Use the order-specific installation drawing supplied with your window. This guide explains the workflow; your selected mounting detail controls final dimensions, fasteners, sealants, and clearances. Handle glass with support and suitable protection. Preserve any required emergency access, and have damaged or difficult-to-reach openings reviewed by a qualified installer.

Have these ready

  • Tape measure marked in 1/8 inches
  • Level, square, and suitable shims
  • Screwdriver and the specified installation fasteners
  • Compatible perimeter sealant and backer material where needed
  • Finish trim and trim fasteners, as confirmed with the order
  • Gloves, eye protection, and a safe place to set glass

Step one

Measure for the mounting method

Record the opening width at the top, middle and bottom, and height at both sidesTop widthMiddle widthBottom widthLeft heightRight heightMeasure at the surface where the frame will mount.
Opening measurements for review. Diagram is illustrative; mounting details determine the finished frame size. Record all readings, including differences.
  1. Measure between the interior jambs at the intended mounting plane. Record two or three widths and both side heights to the nearest 1/8 inch.
  2. Keep every reading and identify the smallest width and height. Do not subtract clearance yourself from the opening dimensions.
  3. For vertical operating models, measure from the top of the opening to the bottom of the existing meeting rail. This helps align the glass divisions.
  4. Check the depth and primary-window handle clearance. Where possible, allow at least 3/4 inch between assemblies for access to the original lock. Frame depth is a separate measurement.
Start your quote with width, height, quantity, and shipping ZIP. Keep opening dimensions and finished frame dimensions clearly labeled so an allowance is never applied twice.

Installation, step by step

  1. 1

    Inspect and match each unit

    Match the label to the room and opening on your window schedule. Check glass, frame, seals, and hardware before starting. Repair loose or damaged attachment surfaces first.

  2. 2

    Dry-fit the frame

    Place the unit against the existing stop. Use suitable shims to keep it square. Check primary-window lock clearance and verify that operating sashes slide freely.

  3. 3

    Use the correct attachment channel

    Secure the frame through the pre-drilled jamb holes with the specified screws. Three-track operating models use the center track; two-track operating models use the track nearest the original window. Do not overtighten or bow the frame.

  4. 4

    For a fixed panel, handle the locking bars

    Support the glass, release the retaining bars in the sequence supplied with the unit, and remove the sash if needed to install the frame. Refit the lower bar, sash, upper bar, and side bars as specified. Keep the glass supported until its retainers are fully seated.

  5. 5

    Complete the perimeter seal

    Check that the compressible seal contacts the jamb. Fill excessive gaps with the specified backer and compatible sealant. Finish the perimeter with the appropriate trim stop, without obstructing the sash or its hardware. Confirm whether trim is included with your order.

  6. 6

    Recheck access and operation

    Reinstall any removed sashes or screens. Open, close, and lock the storm and primary window. Correct rubbing by checking squareness and fastener tension. Confirm the perimeter has continuous contact.

The finished-installation check

  • Frame is square and not bowed by fasteners.
  • Glass retainers, sash latches, and screens are fully seated.
  • Primary-window locks remain accessible.
  • Perimeter seal and trim are complete.
  • Required window access and operation remain available.

If something does not fit

The sash rubs or catches

Check the frame for twist or bow. Adjust shims and fastener tension rather than forcing the sash.

There is a gap at the jamb

Check seal contact and the approved backer/sealant detail. A large or irregular gap needs review.

The trim was not in the shipment

Check the order contents before buying or fitting trim. Decorative stops and site-supplied trim may be specified separately.

Windows covered by this guide

Low-E Aluminum Fixed Interior Storm Window →Low-E Aluminum Double-Hung Interior Storm Window with Screen →Slim Low-E Aluminum Double-Hung Interior Storm Window →Low-E Aluminum Interior Seasonal Glass and Screen →Low-E Aluminum Sliding Interior Storm Window with Screen →Slim Low-E Aluminum Sliding Interior Storm Window →

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