Open the faucet or fixture connected to the frozen drain. For example, if the kitchen sink drain is frozen, turn on the cold water tap slightly.
Before you start applying heat, confirm that the drain is indeed frozen and not just clogged with debris. how to thaw frozen drain pipes
Use expanding foam or caulk to close holes where cold air enters your crawlspace. ✅ Summary of Thawing Solutions Open the faucet or fixture connected to the frozen drain