In photoshop does anyone know how to or can you take a Blueprint of a house and select say the roof and then use a fill to fill in different photos of roofing. But it would need to be held to scale. I would love to know if and how this is possible
You will first need to create a pattern with the texture of your choice. Look also in the preset patterns libraries, as there is a brick one, and others that might fit your needs.
The next step will be to select the areas you want to fill, using the different selection tools, "Jump" them on their own layer by using the CTRL+J (PC) or Command+J (mac) shortcut, so that you can then apply a texture using for instance a pattern overlay layer style (so that it can be scaled)
About the scale, is the blueprint a 2D or a 3D projection? There are 3D tools for the latter.