Climate group Insulate Britain is staging its 10th day of protests in the past three weeks.
The organisation said around 30 of its activists have blocked roundabouts at Junction 3 of the M4 near Heathrow Airport, west London, and Junction 1 of the M1 at Brent Cross, north London.
Drivers stuck in long queues of traffic beeped their horns in frustration.
Insulate Britain said the demonstrators include eight people released from police custody on Thursday after blocking the M25 at Junction 30 in Essex, and others who were arrested earlier this week.
It has pledged to continue its actions until the Government makes “a meaningful statement indicating that they will insulate all of Britain’s 29 million leaky homes by 2030”.
The group said in a statement: “It’s incomprehensible that the Government is continuing to delay action on home insulation when we urgently need to cut our carbon emissions, eliminate fuel poverty and help hard-working families with their rising energy bills.
“Added to which industry is crying out for the Government to show some leadership and get behind a national retrofitting strategy. Come on Boris: get on with the job.”
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