If you have this problem, you might want to consider replacing the rotten courses of hardboard siding with more durable fiber cement siding. Fiber cement siding is available in the same look and dimensions as hardboard siding but is more resistant to water damage. Consult with a professional in your area, like Boyd Construction Co Inc in the DC area, for a free estimate.
Some helpful tips for those that would like to venture into the DIY of siding repair:
How to Remove and Replace Siding:
Boyd Construction Co
Family owned and operated in the greater Washington DC area since 1932.