Supplemental Flood Insurance: Do You Need It on Top of Your Existing Policy?

"Supplemental" and "excess" flood insurance often describe the same basic idea — additional coverage layered on top of a primary flood policy — but the terms get used inconsistently across the industry. If you've searched for supplemental flood insurance, here's how to think about it and how to tell whether you actually need it.

Supplemental vs. Excess: Is There a Real Difference?

In most everyday usage, no — "supplemental flood insurance" and "excess flood insurance" both refer to additional coverage purchased on top of a primary flood policy (NFIP or private) once that policy's limit is reached. Some carriers use one term consistently in their own product naming; others use them interchangeably. Sterling uses the term Excess Flood for its product offering

What matters more than the label is the function: does your current flood coverage's limit actually match your property's rebuild cost? If not, you have a gap — regardless of which word you use to describe the fix.

How to Tell If You Need It

Ask three questions:

1. What's my primary flood policy's coverage limit? (Check your policy declarations page.)
2. What would it actually cost to rebuild my home or business today? (Not market value — rebuild cost.)
3. Is there a gap between those two numbers?

If your rebuild cost is higher than your primary limit, that gap is uninsured unless you add supplemental/excess coverage. This is especially common for:

• NFIP policyholders whose homes are worth more than the $250,000 building limit
• Commercial property owners above NFIP's $500,000 commercial cap
• Anyone whose home has appreciated or been renovated since their flood policy was first written, without a corresponding coverage review

What Supplemental Coverage Typically Includes

Mirroring the excess flood structure covered elsewhere on this site, supplemental coverage generally extends:

• Building/structure coverage above the primary limit
• Contents coverage above the primary limit

A Common Mistake: Assuming Your Policy Auto-Adjusts

Flood policy limits don't automatically increase as home values or rebuilding costs rise. If you bought your policy years ago and haven't reviewed it since, there's a real chance your coverage hasn't kept pace — even if you haven't made any changes to the property itself. This is one of the most common ways homeowners end up underinsured without realizing it until a claim.

How to Add Supplemental Coverage

In most cases, this doesn't mean replacing your existing policy — it means adding a second policy that sits on top of it. Your current primary carrier doesn't need to change; the supplemental/excess layer is typically written by a different carrier that specializes in that coverage. Sterling can offer primary and excess coverage. While we do offer primary coverage, it is not a requirement to have primary coverage with Sterling for a Supplemental/Excess policy.

Frequently Asked Questions

Do I need to switch flood insurance carriers to add supplemental coverage?

No — supplemental/excess coverage is generally added as a separate policy on top of your existing primary policy, not a replacement for it.

How often should I review my flood coverage limits?

At minimum, whenever you renovate, refinance, or notice a significant change in local rebuild costs — and ideally at every renewal.

Is supplemental flood insurance the same product as excess flood insurance from Sterling?

Yes – Sterling uses the term Excess flood

Get a Quote

Not sure if your current flood policy would actually cover a full rebuild? Get a coverage review and supplemental flood insurance quote from Sterling Flood.