Did Dominion ships count against British treaty limits?

Were Dominion and Commonwealth ships included in Britain's Washington Treaty limits?

Yes, but Washington did not cap the total number of cruisers or smaller ships, so Dominion programs still had considerable room to grow.

Commonwealth and Dominion ships were part of the British Empire's treaty framework rather than an entirely separate allowance. The Washington Treaty restricted capital-ship and aircraft-carrier totals and set maximum characteristics for cruisers. It imposed no overall numerical ceiling on cruisers or smaller vessels. Dominion cruiser and sloop programs could therefore expand imperial strength within Washington's treaty rules.