What gets checked on the final walk-through of a new window
The walk-through at the end of a window job is a short inspection, and it is where most small defects get found while they are still cheap to fix. In Riverside, CA, the same checks apply whether the unit went into a stucco bungalow near Fairmount Park or a tract house on the slopes below the Box Springs Mountains. The list below follows the order an installer works through the house, from the outside of the wall to the sash hardware, and explains what each check is meant to catch.
What does an installer look at first on the outside of a new window?
The exterior comes first because that is where water gets its chance. The installer stands back about ten feet and sights along the frame to see whether the top and sides look straight against the wall. A frame that leans out at the top or sags at one corner was not plumbed and leveled properly, and it will show up later as a sash that drags or a gap that opens in summer.
Up close, the sealant bead around the frame gets a slow look from end to end. A good bead is continuous, smooth and slightly concave, and it sticks to both the frame and the wall surface. Gaps, pinholes, places where the bead has pulled away from the stucco and places where it was smeared thin over a void are all marked for reworking. The stucco return around the window is checked for cracks at the corners, since a hairline crack there is where wind driven rain gets in.
The sill gets its own look. The outside edge should slope away from the glass so water runs off, and the weep holes in the bottom of the frame on a slider or a casement should be open and clear. A weep hole plugged with sealant is a common mistake and it turns the track into a small bathtub the first time it rains.
Which checks matter most, and what does each one show?
The table below puts the main walk-through checks in the order they are usually done. None of them needs special tools beyond a level, a tape, a flashlight and a scrap of paper.
| Check | How it is done | What it reveals |
|---|---|---|
| Plumb and level | A four foot level held on the sill and against each jamb | A frame that was shimmed unevenly, which later binds the sash |
| Gap around the frame | Tape or feeler gauge between frame and opening on all four sides | Gaps that are too tight for expansion or too wide for the sealant to bridge |
| Diagonals of the sash | Tape measured corner to corner on the sash | A racked sash, which will not seal against the weatherstripping |
| Operation | Open and close every sash several times, slowly and fast | Rough spots, hardware that catches, tracks with debris |
| Weatherstripping contact | A strip of paper slid between sash and frame with the window closed | Places where the seal does not touch, which let in air and dust |
| Glass | Look at the panes from an angle in daylight | Scratches, cloudiness, moisture between double pane layers, label placement |
| Interior sill and trim | Hand over the surface and a flashlight at a low angle | Damp spots, loose casing, nail pops, gaps at the drywall return |
How is the sash tested after the window is set?
Every sash is opened and closed more than once, because a window that feels fine on the first pass may stick on the fourth. A double hung sash should travel the full height of the frame with an even feel, stay where it is left, and tilt in for cleaning if it is a tilt model. A single hung unit should do the same with the lower sash only. A slider should roll without a grinding sound and lock firmly at the closed end. A casement or an awning window should swing out without rubbing the frame, pull in tight against the weatherstripping when the handle is turned and not drift open on its own.
The paper test is quick and tells a lot. A slip of paper goes between the closed sash and the frame at several points. If it pulls out with no resistance anywhere, the weatherstripping is not touching at that spot, and the sash needs its hinges or its latch adjusted. The test is repeated all the way around, since a sash often seals well at the latch and loses contact at a corner.
What is looked at inside the glass?
Insulated glass is two panes, sometimes three, separated by a spacer and sealed around the edge, with the space between them filled with air or with argon. The panes should be clean and clear. A film or a haze between them, or beads of moisture, means the edge seal failed, and a unit like that is not accepted at the walk-through whatever its age.
The glass also carries a label or a permanent etch that shows the coating and the ratings. A low e coating is a very thin metal layer on one surface of the glass that reflects heat, and the u factor and the solar heat gain coefficient on the sticker describe how much heat passes through. In Riverside the solar heat gain number matters on west facing walls, where late afternoon sun in summer can warm a room quickly. The installer checks that the unit on each wall is the one that was specified for that wall, since ordering mix ups usually show up at this stage.
The last glass check is for chips at the edges, which are easy to miss in bright light. A small chip can grow into a crack after a few temperature swings, so a damaged pane is replaced before the crew leaves.
Why does the inside get as much attention as the outside?
The interior is where a bad installation first announces itself. Water that has gotten past the flashing usually shows at the interior sill, at the lower corners of the casing, or as a faint stain on the wall below the window. Even on a day with no rain, a flashlight held at a low angle across the sill and jambs shows damp spots, swelling and peeling paint that would otherwise be invisible.
The trim gets tapped and pressed. Loose casing is nailed or glued back, and gaps between the casing and the drywall are caulked and painted. Where the wall is old plaster, as in some of the houses near the Mission Inn, the installer also checks that the plaster return around the window was patched flat and did not crack when the old frame came out. The floor below the window is checked for dust, sealant and glass chips, and the sash tracks are vacuumed because a pebble in a slider track will gouge the track within a few weeks.
What is explained before the crew leaves?
A proper walk-through ends with the homeowner standing at each window and operating it. The installer shows how the locks work, how to tilt a sash, where the weep holes are and why they must stay open, and how to clean the tracks. For a casement, the crank and the arm get a short explanation, since a casement forced against a stuck arm is the most common way a new unit gets damaged in the first month.
The homeowner is also shown what normal looks like. A faint bead of condensation on the inside of the glass on a cold morning is normal on any window, and a slight sound when a vinyl frame warms up in the sun is the material moving. Moisture between the panes, water on the interior sill after rain, a sash that suddenly will not close, and a draft that can be felt at the corner of the frame are not normal, and any of them is worth raising right away.
What should be kept after the job is done?
A photo of each window before the trim went back on, the glass label and the date of the work belong in one folder. If a leak ever appears, a photo taken before the casing covered the flashing is worth far more than a description.
How long does the walk-through take?
For an average house the walk-through takes a good half hour. The time goes on doing seven or eight ordinary checks at every window and writing down the defects that turn up, which is why a rushed walk-through leaves problems behind.
A window is only as good as the last twenty minutes of the job. The walk-through is how that part gets measured.