The FHA appraisal validity period is 120 days.
The 120 day validity period for an appraisal may be extended for 30 days at the option of the mortgagee if :
(1) the mortgagee approved the borrower or HUD issued the Firm Commitment before the expiration of the original appraisal; or
(2) the borrower signed a valid sales contract prior to the expiration date of the appraisal.
An appraisal update must be performed before the initial appraisal, with no extension, has expired. Where the initial appraisal is subsequently updated, the updated appraisal is valid for a period of 240 days after the effective date of the initial appraisal report that is being updated.
For additional information see Handbook 4000.1 II.A.1.a.i.(A)(1)(b) available at https://www.hud.gov/program_offices/administration/hudclips/handbooks/hsgh