Hi, all! I’m new around here, but I’ve been using the forums for reference for a while.
Anyway, I’m having a problem with my current project. I’ve got the materials all allocated to the different parts of my model, and it looks fine in “Solid” view mode:
Upload blend file to http://www.pasteall.org/blend/ and tell us the download link. Remember to pack any image textures into your blend file from the File / External Data menu or we won’t be able to see them.
Look in the outliner window. You have lots of objects hidden (greyed out eye icon) but they are still set to be renderable (camera icon). These include ‘Police box sign’ objects which give the big white boxes in your render. Clean up your scene. A messy scene is more difficult to manage and is a sign of a disorganisation. Either delete them, make them non renderable or move them to a non rendered layer.
In your screenshot you can see the effect or overlapping faces with the black bitty appearance. Go through each object and check for faces that are in the same location.