Speaker of the House of Representatives Tony Smith and Senate President Scott Ryan released a joint statement on Friday outlining their decision.

"While recognising that the wearing of masks is not mandatory in the ACT, at the specific request of the acting chief medical officer and out of an abundance of caution, in the public common areas of Australian Parliament House everyone is recommended to wear a mask at all times," the statement said.

"As an additional precaution the wearing of masks is encouraged in the presence of others, especially where physical distancing is not possible, and by those at increased risk of COVID-19."

"This measure is in addition to the range of control measures to manage the risk of COVID-19 exposure to senators, members and building occupants that have already been put in place."

The statement outlines the proper use and disposal of face masks, and tells visitors to dispose of masks in designated bins.

This advice is in addition to a different joint statement by the Speaker and Senate President released on August 17.

That statement urged parliamentarians to avoid socialising in groups and to limit visiting hospitality and retail centres in the ACT.

Parliament House will be closed to the public from August 24 to September 3.