Leviticus 27:15

And if he that sanctified it will redeem his house, then he shall add the fifth part of the money of thy estimation unto it, and it shall be his.

Cross-references

Leviticus 27:13 prescribes adding a fifth when redeeming an animal; same rule applies here for redeeming a house.

Leviticus 5:16 requires adding a fifth for restitution of holy things; here adding a fifth for redemption of a dedicated house. Parallel principle.

Leviticus 22:14 also adds a fifth when eating holy things unknowingly; same fifth-for-sanctuary principle.