The boards said that it had “concluded that they are not capable of delivering the quality of opportunity or level of sustainable margins that we require”.
Both will be closed by the end of 2015 and the company will book a pre-tax loss of £2.6m on the closure.
Outstanding contractual obligations will be assumed by an expanded TClarke South West out of offices in Plymouth and St Austell.
The closure of Cardiff and Bristol will leave TClarke with 14 offices across the UK. The Cardiff problems were attributed to “specific contract challenges”.
Overall, however, TClarke as seen a steady improvement in its core markets, it said in a trading update. The order book as at 30th September was worth £320m, which is 15% higher than 12 months earlier, and increasingly the work in hand is predicted to generate a better profit than work taken on during the downturn.
“The underlying performance of the group for the year continues to be in line with the board's expectations,” the company said.