| Building | Year Completed | Builder | Style | Location | Image |
| Rideau Cottage | 1905 | David Ewart - 1905 rear addition | Georgian Revival | Ottawa, Ontario | |
| Connaught Building | 1913 | David Ewart | Tudor-Gothic | Ottawa, Ontario | |
| Victoria Memorial Building | 1912 | David Ewart | Baronial style | Ottawa, Ontario | |
| Canadian Mint | 1908 | David Ewart | Tudor-Gothic | Ottawa, Ontario | |
| Mappin Wing of Rideau Hall | 1913 | David Ewart | Baronial style | Ottawa, Ontario | |
| Customs Examining Warehouse, Sinclair Centre | 1911-1913 | David Ewart | Scottish Baronial architecture | Vancouver, BC | |
| Moose Jaw City Hall | 1914 | David Ewart | Edwardian Classical | Moose Jaw, Saskatchewan | |
| Strathcona Public Building | 1913 | David Ewart | Baronial style | Edmonton, Alberta | |
Post Office Building, Sinclair Centre | 1905-1910 | David Ewart | Edwardian Baroque architecture | Vancouver, British Columbia | |
| Prince Edward Building | 1906 | David Ewart | Baronial style | Regina, Saskatchewan | |
| Bowmanville Post Office | | David Ewart | Baronial style | Bowmanville, Ontario | |
| Humboldt Post Office | 1911 | David Ewart | Baronial style | Humboldt, Saskatchewan | |
| Royal Military College of Canada Fort Lasalle Dormitory Building R33 | 1912 | David Ewart | Baronial style | Kingston, Ontario honours René-Robert Cavelier, Sieur de La Salle. The limestone carvings are of a crown, the initials GR, 'Dormitory', and 'RMC 1912'. | |
| Royal Military College of Canada Building 9 Rideout Row | 1908 | David Ewart | Baronial style | Kingston, Ontario
- after renovations known as Rideout Square;
- recognized Federal Heritage Building 1994
| |
| Royal Military College of Canada Building 9a Rideout Row | 1908 | David Ewart | Baronial style | Kingston, Ontario after renovations known as Rideout Square;recognized Federal Heritage Building 1994 | |
| Royal Military College of Canada Gymnasium, Old Building R25 | 1903 | David Ewart | Baronial style | Kingston, Ontario recognized Federal Heritage Building 1989 | |
| Royal Military College of Canada Headquarters, Former RMC Riding Establishment, Building R5 | 1908 | David Ewart | Baronial style | Kingston, Ontario recognized Federal Heritage Building 1994 | |
| Royal Military College of Canada Panet House, Building R27 | 1903 | David Ewart | Baronial style | Kingston, Ontario recognized Federal Heritage Building 1994 honours Lt Col. Charles-Eugène Panet | |
| Royal Military College of Canada Tailor Shop, former Gun Shed, Building R24 | 1914 | David Ewart | Baronial style | Kingston, Ontario recognized Federal Heritage Building 1994 | |
| Dominion Observatory, Carling Avenue | 1902 | David Ewart | Baronial style | Central Experimental Farm, Ottawa, Ontario | |
| Chief Astronomer's Residence | 1909 | David Ewart | Baronial style | Central Experimental Farm, Ottawa, Ontario | |
| Geodetic Survey Building | 1914 | David Ewart | Baronial style | Central Experimental Farm, Ottawa, Ontario | |
As federal architect he oversaw the design and construction of several buildings at the