French Phrase
Si besoin, scelle les fenêtres et les portes.
Meaning
Literally, “If needed, seal the windows and the doors.” The phrase is a concise instruction that tells the listener to close or block any openings when a situation calls for it, such as a security drill, a storm, or a fire‑safety protocol.
When to use
Use this sentence in written or spoken instructions where you want to give a conditional command—e.g., in a safety manual, a building‑maintenance checklist, or when directing someone during an emergency drill.
✦Grammar Breakdown
Sibesoin,scellelesfenêtresetlesportes.
Si besoin
A fixed expression meaning “if needed/if necessary”. It omits the verb être (si besoin est) and is used to introduce a conditional instruction.
scelle (imperative)
Imperative form of the verb sceller for the second‑person singular (tu). It gives a direct command without the subject pronoun.
les fenêtres / les portes
Both nouns are plural feminine; the definite article les agrees with the plural and signals the specific windows and doors being referred to.
et (conjunction)
Simple coordinating conjunction that links two noun phrases of the same grammatical type.
🗨In Conversation
Le vent se lève et la tempête approche.
The wind is picking up and the storm is approaching.
Si besoin, scelle les fenêtres et les portes.
If needed, seal the windows and doors.
✕Common Mistakes
Si besoin de, scelle les fenêtres et les portes.
The expression is “si besoin” without the preposition de; adding “de” makes it ungrammatical.
Si besoin, scellez les fenêtres et les portes.
Use “scelle” for informal singular (tu). “Scellez” is correct for formal or plural, but would change the register of the sentence.
Si besoin, scelle les fenêtre et les portes.
Both nouns are plural; the article must agree in number.
↔Alternatives
Si nécessaire, scelle les fenêtres et les portes.
If necessary, seal the windows and doors.
En cas de besoin, scelle les fenêtres et les portes.
In case of need, seal the windows and doors.
Si besoin, ferme les fenêtres et les portes à clé.
If needed, lock the windows and doors.
Cultural Tip
In French, the informal imperative (tu) drops the subject pronoun, which can sound abrupt if you’re not familiar with the listener. In a professional or formal setting you would use the plural/formal imperative scellez. Also, “sceller” is a slightly formal verb; everyday speakers might say “ferme à clé” or “barricade”. The expression “si besoin” is common in written instructions and adds a polite, conditional tone.