| Document and Entity Information | Feb. 23, 2021 |
| Cover [Abstract] | |
| Amendment Flag | false |
| Entity Central Index Key | 0001644440 |
| Document Type | 8-K |
| Document Period End Date | Feb. 23, 2021 |
| Entity Registrant Name | GCP Applied Technologies Inc. |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 1-37533 |
| Entity Tax Identification Number | 47-3936076 |
| Entity Address, Address Line One | 62 Whittemore Avenue |
| Entity Address, City or Town | Cambridge |
| Entity Address, State or Province | MA |
| Entity Address, Postal Zip Code | 02140 |
| City Area Code | (617) |
| Local Phone Number | 876-1400 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, $0.01 par value |
| Trading Symbol | GCP |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
