It comes amid speculation that the government plans to make permanent planning reforms to convert disused office spaces into homes without planning permission.
In May 2013 ministers introduced the measure to make it easier to convert redundant, empty and under-used office space into new homes.
The policy is set to expire next May but the RLA said it believed the government will make the reform permanent.
But the RLA warned that some local authorities are preparing to use powers known as Article 4 Directions to safeguard office space in their districts.
This would mean planning permission would be required to convert such buildings to homes where they fall empty.
RLA policy director David Smith said: “Between 1996 and 2013, 83% of new homes were sold into the private rented sector, so landlords have a good record of delivering the extra housing the country needs.
“With the sector expected to account for 25% of UK households by 2025, it is vital that the planning system does not put unnecessary obstacles in the way of landlords seeking to meet this demand.
“The government’s intentions are clear and local authorities should not seek to thwart them.
“Instead, councils have an opportunity to show themselves to be willing partners in delivering the mix of homes their communities need.”