Roux, who made his Ireland debut during the summer tour of South Africa, will integrate fully into training this week and is available for selection. The 25-year-old South African-born lock has been out with a hip injury.
Lam said he appreciated the call made by the referee to abandon their clash with fellow strugglers Zebre as the heavens opened and the pitch flooded.
"It was the correct decision, safety is the first priority. Nobody expected the lightning and the rain and the hail and then once it went past 20 minutes, it is out of the control of both teams," he said.
"But safety has to be the first call, we all know that. So, it's a matter of refixing the game and going from there. Sometimes there are things out of your control."