Decide Insert or Full-Frame Before Measuring

Insert replacement typically leaves the existing primary frame in place and installs a new window within it. Full-frame replacement removes more of the existing assembly and may expose the rough opening.

These methods use different reference points. An insert unit must fit the sound, prepared opening remaining inside the old frame. A full-frame system relates to the larger structural opening and the planned flashing and finishing details.

If rot, movement, failed flashing or an unsuitable existing frame is discovered, an insert plan may no longer be appropriate. Review Suburban Wholesale’s Gentek Signature Elite product information and confirm the intended frame system before finalizing the dimensions.

The Measurements That Matter

A Reliable Field-Measuring Sequence

1. Number every opening. Use a floor plan or elevation so each measurement remains connected to the correct room and wall.
2. Photograph the complete opening. Include interior, exterior, sill, head, jambs and nearby obstacles.
3. Identify the existing assembly. Record material, window style, frame type, storm windows, stops and visible deterioration.
4. Define the removal scope. Decide what materials will remain before choosing the surfaces from which to measure.
5. Measure each width and height in three locations. Do not assume the opening is parallel or uniform.
6. Check diagonals and frame condition. Determine whether the opening is reasonably square and whether movement or settlement is present.
7. Measure depth. Note stops, blind clearances, jamb extensions, stool projection and exterior returns.
8. Inspect the sill. Record slope, level differences, drainage conditions and damaged material.
9. Evaluate code-related conditions. Identify sleeping rooms, safety-glazing locations and other regulated openings.
10. Recheck before submitting the order. Compare the field sheet, photographs, quote and final order line by line.

Use the Smallest Opening Measurement Carefully

Contractors commonly begin order-size calculations with the smallest measured width and height because the new frame must pass through the tightest portion of the intended opening. That is a useful principle, but it is not the complete order calculation.

The installer must still provide the manufacturer-required space for positioning, shimming, insulation, sealing and normal frame movement. The correct allowance depends on the product and installation.

An extremely narrow point may also indicate a problem that should be corrected rather than built into the new window size. Ordering around a badly bowed jamb can unnecessarily reduce glass area and preserve a defective opening.

Square, Level and Plumb Are Different Conditions

A rectangular opening can have equal diagonals and still be out of level. It can be level at the sill while one jamb leans. These conditions affect sash alignment, locking, weatherstripping contact and drainage.

• Square describes the relationship among the corners.
• Level describes a horizontal surface relative to gravity.
• Plumb describes a vertical surface relative to gravity.

Record all three conditions. Do not order an undersized window merely to avoid planning how the opening will be corrected and supported.

Inspect Before Assuming the Existing Frame Can Stay

Insert replacement depends on a suitable existing frame. The visible surfaces may look acceptable while concealed sill or jamb areas contain decay.

Probe suspicious areas where appropriate, look for staining and identify loose joints, soft wood, failed sealant, insect damage and evidence of repeated water entry. If the condition cannot be determined during the initial visit, the contract should explain how concealed damage and scope changes will be handled.

New vinyl and trim should not be used to conceal active deterioration. If the receiving structure is unsound, change the installation plan before ordering the windows.

Measuring Window Groups and Mulled Units

Twins, triples and larger combinations require more information than the total opening width. Record each intended unit, mull arrangement, operating direction, structural divisions and interior and exterior sightlines.

Do not assume an existing center mull can be removed. It may be structural or may separate individual rough openings. Larger factory or field combinations may also require reinforcement, performance upgrades or engineering review.

Gentek notes that larger Signature Elite units or windows ordered to meet specific design-pressure or performance-grade ratings may require particular reinforcements or performance options. Confirm those requirements during quoting—not after the windows reach the jobsite.

Do Not Lose Egress While Replacing a Bedroom Window

Emergency escape and rescue requirements can apply to sleeping rooms and other locations governed by the adopted code. The required opening is based on the new window’s actual clear opening when operated—not the rough-opening dimensions, glass size or overall frame size.

An insert window reduces the available opening because its frame sits inside the existing frame. A replacement that appears nearly identical from across the room can have a smaller net clear opening.

Code editions, local amendments and existing-building provisions vary. The International Residential Code includes provisions addressing existing emergency escape and rescue openings, but the contractor must verify what the authority having jurisdiction has adopted for the specific project.

Do not promise code compliance from nominal dimensions. Obtain the manufacturer’s net-clear-opening data for the exact style and size and confirm the applicable local requirement before ordering.

Check Safety-Glazing Requirements

Window location can trigger safety-glazing requirements. Examples may include certain glass near doors, walking surfaces, tubs, showers, stairs or other hazardous locations defined by the adopted code.

Do not determine tempered-glass requirements from size alone. Record the distance from the glazing to relevant doors, floors, bathing areas, stairs and landings. Verify the current locally adopted code and Gentek availability.

Tempered or laminated glazing can affect price, lead time, labeling, glass-breakage coverage and the available insulated-glass configuration. Identify it before the homeowner signs the final order.

What “United Inches” Means—and What It Does Not Mean

United inches generally refers to the window width plus height. Manufacturers and suppliers may use this total when organizing price brackets, size limitations, shipping rules or available options.

Two windows can have the same united-inch total while having completely different proportions. A 36-by-60-inch window and a 48-by-48-inch window each total 96 united inches, but their structural, operating and manufacturing considerations are not identical.

United inches are not a measurement shortcut, rough-opening allowance or proof that a unit falls within Gentek’s allowable width and height. Check individual dimensions and configuration limits.

Measurements Alone Do Not Complete the Order

A perfectly measured window can still arrive wrong if the configuration is incomplete. Each line item should identify:

• Width and height in the required order
• Window style and series
• Quantity and opening number
• Operating direction viewed from the specified side
• Interior and exterior colors
• Glass package and safety glazing
• Grid pattern, profile and color
• Screen type
• Exterior casing or brickmould
• Sill and frame options
• Mull configuration and reinforcement
• Required performance grade or design pressure

Use Suburban Wholesale’s professional quoting service to review project details before committing a custom order.

Common Ordering Mistakes

Popular Homeowner Questions

AAMA Gold Label Certification and Custom Sizes

FGIA’s AAMA Gold Label Certification Program provides third-party verification for qualifying labeled products under applicable air-leakage, water-penetration and structural-performance requirements.

Certification should not be assumed for every size, operator type, mull arrangement or field modification. Larger units may require reinforcement or performance options, and some configurations may fall outside tested or authorized limits.

Verify the exact ordered product and preserve its label. The AAMA Gold Label Certification Program explains that a product is considered certified when the manufacturer applies the proper certification label.

InstallationMasters Starts With Site Inspection

FGIA describes InstallationMasters as a training and certification program for replacement and new-construction installers. Its scope runs from initial site inspection through installation, cleaning and maintenance.

That starting point matters. Measurement is not an isolated sales activity; it is part of installation planning. The person determining the order size needs to understand how the opening will be prepared, supported, flashed, insulated and finished.

Learn more through the FGIA InstallationMasters program . Manufacturer instructions take precedence, and an installer should only be advertised as certified when their current credential has been verified.

Final Order Review Checklist

1. Every opening has a unique number and photographs.
2. Insert or full-frame scope has been selected.
3. Width, height, diagonals and depth have been recorded.
4. The existing frame and sill are suitable for the planned method.
5. The manufacturer-required order-size calculation has been used.
6. Window style, handing and vent location are correct.
7. Glass, grids, colors, screens and exterior trim are specified.
8. Egress and safety-glazing requirements have been evaluated.
9. Size and performance limitations have been confirmed.
10. The supplier acknowledgment matches the field sheet and contract.
11. The responsible person has approved the complete order in writing.
12. The customer has approved design selections without being asked to accept measurement responsibility.