Your own measurements and photos are for describing the project, not for ordering it. A good record tells an estimator how many openings there are, roughly how large they are, what each one looks like inside and out, and what problems you have seen. The dimensions a window is actually ordered to are taken and verified by a professional for the specific product and installation method, and the written proposal should say who is responsible for them.
This guide shows how to keep a record that is useful at that handoff without implying it is more precise than it is.
Why rough notes are not order dimensions
A window can be described by several different sizes: the visible glass, the sash, the existing frame, the opening in the wall, and the size of the replacement unit that will fit into it. Which one matters depends on whether the old frame stays (an insert) or comes out (full-frame), and on the product’s own sizing and installation requirements. The insert-versus-full-frame guide explains how those methods differ.
That is why there is no single rule for converting a homeowner’s tape reading into an order size, and this guide does not offer one. Any deduction or clearance depends on the product, the opening and the installation method, and belongs to the person who measures for the order. Label every number you record as preliminary. Here, “rough” means preliminary notes, not a verified measurement of the structural rough opening. Pella’s initial measurement guidance also distinguishes preliminary size estimates from professional measurements and inspection before manufacture. This is an educational reference, not a statement of which products our installation partner supplies.
Inventory units as well as openings
Count window units and openings separately. One opening may contain several units: a combination of a picture window and two casements may contain three units in one framed opening. Record what you can identify and ask the installer to confirm how the assembly and opening are counted. The online estimator and the project planner both ask for units, because that is how the published benchmark is priced.
| Record | What it means | Why it matters |
|---|---|---|
| Opening | An opening in the wall; confirm the framing arrangement with the installer | Scope, trim and installation are planned per opening |
| Unit | One manufactured window within an opening | Products and budget benchmarks are counted per unit |
| Configuration | How units are arranged and which ones operate | Changes the product order and the price |
Give each opening an identifier you will use everywhere, such as “LR-1 living room front” or “BR2-S bedroom two south.” Put the same identifier on photos, notes and every proposal so answers can be matched to the right window.
Record rough dimensions safely
Measure only what you can reach from the floor inside the house, without removing anything. Do not remove trim, pry at stops, disturb old paint or climb a ladder to take a measurement. In a home built before 1978, EPA guidance treats disturbance of painted surfaces as a lead-safety question, so leave that to a professional who will handle it appropriately. EPA contractor RRP guidance.
For each opening, a useful preliminary note includes:
- What you measured, stated in words. For example, “inside edge of interior trim, left to right.” A number without its reference points cannot be interpreted.
- Width and height, rounded to what you actually read. Write “about 36 in” rather than inventing precision.
- How many units and which ones open.
- Anything unusual. Out-of-square appearance, arched tops, mulled units or trim you want to keep.
- The word “preliminary.” So nobody mistakes the note for a verified order size later.
If you cannot reach or measure an opening safely, write “not measured” and let the photos carry the information. An estimator can work from a clear photo and a count; an invented number is worse than none.
Take a photo set for every opening
Photos help the estimator arrive prepared. Take them from indoors and from safe ground-level positions outside. You do not need to open anything up.
- Full interior view of the opening, straight on, with trim visible.
- Full exterior view from the ground, showing surrounding siding or brick and trim.
- Close views of any problem, such as fogged glass, stains, soft-looking wood, failed hardware or gaps.
- Any label or etching on the glass or frame that may identify the manufacturer.
- Access conditions, such as shrubs, a deck, a second-story location or furniture that will need to move.
- Context shots of adjacent windows you want the new units to match.
Name each file with the opening identifier. The project planner keeps text notes only; it does not store or upload photos. Keep the photos in your own files and share them yourself with the professional you choose.
Hypothetical example of an opening record
The record below is invented to show the format. It is not a real house, a measurement instruction or an order specification.
| Field | Example entry |
|---|---|
| Identifier | BR2-S (bedroom two, south wall) |
| Units in opening | 1, operable |
| Current style | Double-hung, appears original |
| Preliminary size note | About 34 in wide by 58 in tall, measured inside the interior trim; preliminary, not verified |
| Observed problem | Lower sash will not stay open; no visible water staining |
| Home built | Before 1978; painted trim not disturbed |
| Goal | Easier operation; keep existing interior trim if suitable |
| Room requirement | Bedroom; confirm emergency-opening function with installer and authority |
| Photos | BR2-S-interior, BR2-S-exterior, BR2-S-sash-detail |
| Open questions | Is the balance repairable? If replaced, insert or full-frame? Who verifies order dimensions? |
Notice that the example records a problem that may be repairable. A good record helps you avoid buying a window you do not need, which is covered in the repair-or-replace guide.
Hand the record to a professional for verification
At the visit, walk through each opening using the identifiers. Ask the estimator to confirm or correct your notes, and to state in writing:
- Which dimensions will be used for the order and who takes them.
- Who is responsible if a delivered unit does not fit.
- The installation method for each opening.
- Any condition they could not verify without removing material.
Before you approve an order, the final window schedule should list every opening with its verified size, configuration and product. Compare it with your record, and ask about any difference rather than assuming it was intended. The order and installation checklist covers that final review.
Keep your record in the project planner, which lets you download a brief or save a file to resume later. For how documentation fits into the full purchase, read the complete buying guide.