What to Do If Your Siding Contractor Left Gaps at Corner Posts
Visible gaps at corner posts — where siding meets the vertical trim piece at an outside corner — are one of the more common installation shortcuts, and they’re also one of the more consequential ones, since corners see disproportionately high wind pressure during Wilson’s summer thunderstorms and a gap there is a direct water entry point rather than a purely cosmetic flaw.
See full siding repair services if you’re dealing with this issue now.
Photo by Fujiphilm on Unsplash
First Steps If You Notice This After a Recent Installation
Document the gaps with clear photos, including a scale reference (a coin or ruler in frame helps establish size), and note which corners and how many are affected. If the installation is recent and still within a workmanship warranty period, this documentation is your basis for requesting a correction under that warranty, which should cover the fix at no additional cost to you.
If the Contractor Won’t Address It
If you’re within a written workmanship warranty and the contractor is unresponsive, most warranty documents specify a process (written notice, a reasonable timeframe to respond) before you’re entitled to pursue other remedies, which might include hiring another contractor to fix it and pursuing reimbursement, depending on your specific contract terms and, if applicable, state consumer protection or licensing board avenues.
Preventing This on a New Installation
If you’re getting new siding installed and want to reduce the odds of this issue, ask to inspect the corner posts specifically once installation reaches that stage, rather than waiting for a full project walkthrough at the very end — catching a measurement or fit issue at a corner post while the crew is still on-site is far easier to correct on the spot than after they’ve moved on to the next job.
Understanding Why This Happens
Corner post gaps typically result from either measuring/cutting siding panels too short to properly seat into the corner post channel, or from rushing the final courses of a job where attention to detail sometimes drops. Neither is an acceptable excuse, but understanding the likely cause helps frame the conversation with your contractor — this is correctable installation work, not a material defect requiring a different product.
| Gap Severity | What It Suggests | Urgency |
|---|---|---|
| Hairline gap, no visible daylight through | Minor installation imprecision | Address during next planned maintenance |
| Visible gap you can see daylight or feel airflow through | Active water/air entry point | Address promptly, before the next significant storm |
| Multiple corners affected | Likely a training or rushed-installation pattern | Address all affected corners together |
Warning: Don’t accept a purely cosmetic fix (caulk smeared over the gap from outside) as a real repair. Caulk over a poorly seated panel doesn’t correct the underlying seating issue and tends to crack and fail again within a season or two, especially with the expansion and contraction cycling this climate produces. The actual fix usually means re-seating the panel properly into the corner post channel, not covering the symptom.
Getting a Second Opinion on Repair Scope
If you’re getting a different contractor to fix the original installer’s work, get their assessment of whether the issue is isolated to the visible gaps or indicates broader installation problems worth checking (nailing pattern, expansion clearance elsewhere) while they’re already addressing the corner posts specifically.
DIY vs. Professional Contractor
| Situation | DIY Feasible | Call a Contractor |
|---|---|---|
| Documenting the issue for a warranty claim | Yes | N/A |
| Re-seating a panel into a corner post properly | No | Yes |
| Assessing whether the issue extends beyond corners | No | Yes, recommended |
Common Questions
What should I do if my siding contractor left gaps at the corners?
Photograph the gaps with a date reference, then contact the contractor in writing referencing your workmanship warranty. Corner posts require more precise cutting than flat wall areas, making them a common spot for measurement errors.
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