Warning Signs
Gaps Around Windows & Doors
The short answer
Gaps opening around windows and exterior doors — or where trim and crown molding pull away from the wall — often mean the foundation has shifted, racking the framing out of square. Small seasonal gaps can be cosmetic caulk failure, but gaps that grow, appear with cracks, or leave doors and windows out of square signal foundation movement.
Gaps are the framing telling on the foundation
When a foundation shifts, it doesn’t just crack concrete — it racks the wood framing above, twisting walls subtly out of square. Rigid elements like window frames, door frames, and trim can’t follow that twist, so they separate from the surrounding structure and open gaps.
Cosmetic vs. structural gaps
Likely cosmetic:
- A thin gap where exterior caulk has aged and shrunk
- Seasonal opening/closing that tracks temperature
- An isolated gap with no other symptoms
Likely structural:
- Gaps that widen month over month
- Diagonal separation at the corners of windows and doors
- Trim or crown molding pulling away from walls/ceiling
- Gaps alongside cracks, sticking doors, or sloping floors
- Daylight visible around an exterior door
Measure it: the diagonal test
Eyeballing a gap only tells you it exists, not whether the frame behind it is actually racked. Carpenters check for square by measuring both diagonals of a frame opening, corner to corner. On a true square frame, the two diagonals are equal. Standard framing tolerance allows up to about 1/8 inch difference between them — more than that, and the frame is out of square, usually because something pulled it there.
This is a genuinely useful test because it catches movement before it’s obvious: framing can rack past that 1/8-inch tolerance well before the gap is wide enough to notice by eye, or before drywall and brick crack. If you measure a growing diagonal difference over a few months — not a one-time reading, since normal humidity swings the wood slightly too — that’s harder evidence of real movement than the gap alone, and it pairs well with sticking doors’ own “swing test” for the same racking.
What to do
Measure and date the gap (a photo with a coin for scale works). If it’s stable, caulk it and keep an eye out. If it’s growing or keeping company with other warning signs, the foundation is likely moving — get an elevation survey. On Austin’s expansive clay, gaps that open in drought and partly close after rain are a strong clue the soil is moving the foundation seasonally.
Noticing widening gaps? Talk to a vetted specialist for a free inspection.
Frequently asked questions
Are gaps around windows a foundation problem?
They can be. When the foundation moves, it twists the wall framing, and rigid windows and door frames separate from the surrounding structure — opening gaps. Minor caulk separation from age and temperature is cosmetic; gaps that widen over time or appear with cracks and out-of-square frames point to foundation movement.
Where do these gaps usually appear?
Where exterior trim meets brick, along the top of windows, at the corners of door frames, where crown molding meets the ceiling, and where countertops or cabinets meet the wall. Diagonal separation at window and door corners is an especially common foundation tell.
Can I just caulk the gaps?
Caulk hides a cosmetic gap, but if foundation movement is opening it, the gap will return as the structure keeps shifting. Caulk and monitor minor gaps; for growing ones, find out whether the foundation is moving first.
How do I measure whether a window or door frame is actually out of square?
Measure both diagonals of the frame opening, corner to corner. A square frame has equal diagonals; framing tolerance allows up to about 1/8 inch difference. More than that, and the frame is racked — usually from the foundation shifting rather than a bad original install.
Can a gap be out of square without any visible cracks yet?
Yes. Framing can rack enough to open a gap or bind a door well before drywall or brick show a visible crack — wood framing flexes more than masonry before it fails. A diagonal measurement out of tolerance is often the earliest hard evidence of movement, ahead of cosmetic cracking.