Pricing windows when you are buying a project
The most expensive habit on a whole-house job is comparing unit prices. Around half of what you pay is labor, disposal, wrap, flashing and finish, and that half is where two bids on the same house separate. A $700 window installed badly in an eighty-year-old opening will leak before a $500 window installed well.
The fix is to make every bidder price the same scope opening by opening, then compare totals. If one bid is $6,000 lower, find the line that explains it. Nine times out of ten it is insert versus full-frame, exterior capping, or disposal quietly left to you.
A useful test at the kitchen table: ask what share of the contract is labor. Anyone who has run crews answers in a couple of seconds and lands somewhere near half. A long pause means the number came off a price sheet and the installation is going to whoever is free that week.
Guessing the opening count from memory
The ones that hide
Homeowners commonly undercount by two or three. Basement hoppers, the stairwell landing, the attached garage, a bathroom obscure unit, transoms and sidelights at the front door. At $800 an opening, three missed windows is $2,400 arriving after you believed the budget was settled.
The ones that count twice
A wide kitchen or dinette window is often two or three sashes joined inside a single frame, and it is quoted, built and installed as two or three. The same goes for a bedroom pair that looks like one unit from the driveway. Count frames and sashes separately, and put the tally in writing before the first appointment rather than during it.
The count is also what unlocks the volume price. A company quoting sixteen openings prices differently than one quoting the twelve you remembered, so an undercount costs twice: once in missed windows and once in a per-opening rate you never qualified for.
Reading the price on a contract that is mostly not price
The rot clause and the change-order rule
You want a stated repair rate, a requirement that changes be approved in writing before the work happens, and a cap or an estimate range so a bad day does not become an open account. Ask what the crew does if a header is compromised, since that is a framing repair rather than a window repair.
The warranty nobody reads until year seven
Separate the glass warranty, the frame warranty and the labor warranty, because they are almost never the same length. Ask whether the coverage transfers if you sell, whether a service call carries a fee, and who you actually call, the manufacturer or the installer. Glass seal coverage is the term that matters most in this climate, because a failed seal is the most common defect and the fog usually does not show up until year eight or ten.
What these add up to on one Prestwick house
Take the sixteen-opening house. Three missed openings, $2,400. Four rotten sills with no agreed rate, $1,200 to $2,600. Triple pane specified on all four walls instead of the two that needed it, $1,600. A same-day discount that steered the job to the wrong crew, unpriced until the second winter. The window itself never changed in any of that.
None of these mistakes is exotic. They are what happens when a five-figure project is priced in a single evening at a kitchen table. Three appointments spread across two weeks, and an opening list you wrote yourself, prevent most of them.
Assuming the wood behind the trim is sound
Nobody knows what is under the exterior trim until it comes off, and on a whole house you will find something at three or four openings. The mistake is not the rot, it is signing a contract with no stated rate for it. A written per-hour or per-opening repair rate turns a surprise into a line item. No rate turns it into a negotiation while your wall is open.
The tells before you start: soft wood at the sill corners, blistered paint on the siding directly below a window, and interior stains at the bottom of the casing. Two of those at the same opening and you are looking at full-frame there whatever the rest of the house gets.
There is a second cost hiding in pre-1978 houses. Federal rules on lead-safe work practices apply once painted surfaces are disturbed, and the containment, cleanup and verification add crew time at every single opening. It belongs on the bid as a line rather than as an upsell, and a bidder who has never mentioned it while standing in an eighty-year-old house has told you how they work.
Letting a discount expiration set the calendar
Whole-house numbers are big enough that a percentage sounds like real money, which is exactly why the same-day version exists. A price that is genuine on Tuesday is still genuine on Friday. The version that expires when the salesperson reaches the driveway is a pricing tactic, not a saving.
There is a real seasonal effect worth using instead. Crews around Prestwick are busiest from late spring through fall, and midwinter is when schedules open up. Winter installation is routine, one opening at a time with under an hour of exposure each, and it is when a company with a gap in the calendar will sharpen a number honestly.
Ask for the price with a shorter presentation, too. A four-hour in-home appointment is a cost the company carries and prices into every job it sells, and a homeowner who has already built an opening list and chosen a method does not need the flip chart or the sample corner cut in half.
Budgeting around a credit or rebate you have not confirmed
Federal energy credits for windows have changed more than once in recent years, and eligibility attaches to specific performance ratings and to the year the work is completed. Utility programs in Indiana more often fund insulation, air sealing and HVAC equipment than windows. None of that is a reason to skip checking, but all of it is a reason to keep the money out of the budget.
Treat any credit or rebate as funds that may arrive after the job rather than a discount on it, confirm what applies for the tax year in which the work finishes, and have a tax professional look at your situation. A project sized around a credit that turns out not to apply is the most avoidable overrun on this list.
Buying one window for all four walls
Sun walls and shade walls
In central Indiana the west and south elevations take the heat and the driven rain, while the north wall takes the January wind. A glass package chosen for the south side is not what you want on the north side. Most suppliers will spec by elevation at no extra cost if asked. Almost none offer.
Grid patterns fall into the same trap. A house that reads correctly with divided lights across the front often looks wrong with the same grids on a rear addition, and grids run $25 to $75 an opening on every window that gets them. Sixteen openings of decoration you did not want is a real line on the invoice.
Bedrooms, basements and the code you cannot spec around
Escape and rescue requirements apply to bedroom windows and to any basement room used for sleeping. A unit that is perfectly fine in a hallway can be non-compliant in a bedroom because the operable area is too small once the new frame takes up space. Identify those openings before the order, not when twelve units are on a truck.