A removable barrier may help reduce water entering through an opening in some settings, but it is an active measure that depends on warning time, fit, installation, building strength, water conditions, and evacuation. FEMA’s residential retrofit guide treats dry floodproofing as a limited, building-level project that needs professional assessment; it does not make every removable panel suitable for a house. Decide whether a barrier belongs in the plan only after discussing the site and opening with a qualified local professional.
What the water-load example can—and cannot—tell you
For still freshwater, pressure increases with depth. Using water’s approximate unit weight of 62.4 pounds-force per cubic foot, a simplified triangular pressure distribution gives total horizontal force per foot of opening width:
F per foot of width = 0.5 × 62.4 × h² = 31.2 × h² pounds-force
Still-water depth h | Approximate force per foot of opening width |
|---|---|
| 1 foot | 31 pounds-force |
| 2 feet | 125 pounds-force |
| 3 feet | 281 pounds-force |
This idealized calculation describes water pressure only. It does not determine what a wall, frame, panel, seal, fastener, threshold, or foundation can resist. It omits flow velocity, waves, floating debris, leakage, water entry elsewhere, soil saturation, warning time, and installation quality. Do not use it to size anchors, choose a barrier height, or decide to stay inside.
Compare the exact product and opening
Product types vary; there is no general rating, cost, deployment time, mounting detail, or allowable leakage that applies to all barriers. Use this table to compare documentation rather than assume one system fits every doorway:
| Evidence to collect | What to verify in the exact model documents | Why it matters |
|---|---|---|
| Product identity | Model, opening range, maximum tested water depth, test method, and limitations | Marketing language or a family of products may not describe the supplied model/configuration. |
| Opening and building | Width, threshold shape, frame/support material, condition, and adjacent wall/foundation | A barrier load is transferred into the specific opening and supporting construction. |
| Performance | Test report or certification ID, leakage criterion, water conditions, duration, debris/wave exclusions | A test under static water does not establish performance in moving, debris-laden floodwater. |
| Installation | Current manufacturer manual, approved mounting detail, required installer, site measurements, permitted penetrations | Posts, seals, anchors, substrates, and clearances vary by system. Do not copy another product’s detail. |
| Use and upkeep | Deployment steps, number of people, warning time, practice, seal checks, storage, and replacement parts | A stored panel cannot help if the household cannot deploy it correctly and early enough. |
| Residual risk | Water entry at other openings, sewer or groundwater paths, overtopping, power loss, and fallback plan | A doorway closure protects only its designed opening and conditions. |
A manufacturer manual for one stop-log system, for example, specifies its own opening measurements, support surfaces, seals, and deployment procedure. That illustrates why a generic bolt size, embedment, gasket pressure, anchor substrate, sealant, or installation time should not be copied into a household checklist. Request the exact current documents and have the installation reviewed by an appropriately qualified local professional.
Flood barrier evidence record
Before requesting quotes or advice, write down:
- The opening dimensions and threshold condition, measured only if safe and without removing trim or drilling.
- What flooding is expected at the property: source, likely depth and duration, flow, debris/waves, and how much warning is typical. Use local official flood information and past records; do not invent a design level.
- Other possible water-entry routes, including nearby doors, windows, drains, and below-grade walls.
- The exact model and manual being considered, its applicable tests/certification, rated conditions, exclusions, and maintenance instructions.
- Who will assess the supporting wall/foundation, install any permanent hardware, practice deployment, and decide when to leave.
- Where household members will go and how they will get there if an alert or evacuation order occurs.
Flood safety comes first
Do not wait for a particular water depth or a fixed time trigger. Follow local emergency alerts and evacuation instructions. If ordered to leave, leave; do not delay to deploy panels or shut off services. Stay out of floodwater. FEMA advises not to touch electrical equipment if it is wet or if you are standing in water. A barrier can seal an exit, and no article can establish that a particular house or route will remain safe during a flood.
