Render depth seperately

I currently have a lighting system which renders all lights to a render texture, and then renders the world (inc. unity's built in depths and normals). The problem is, the lighting rendering requires the depths and normals for its calculations. Currently the result is all lighting is using the normals and depths from the previous frame.

What I would like, is to have all depths and normals rendered, then the lighting to happen, and then all the rest of the rendering to occur.

I would also rather not have to go and put two materials on all of my renderers.

Thanks