I am looking to add plywood flooring in my attic for storage page. There is a lot of space, very large areas. From what I've been reading, it looks to be ill-advised to add flooring if the roof was constructed with trusses instead of rafters (one such site). I have no idea what these are. Would someone be able to explain what these are and if my home has it.
Here's an overview:
Other pictures are here.
Also I am aware that I would need to extend the floor joists keep the insulation intact.
This is "Ridge board and rafters":
These are roof Trusses:
From your pictures, you clearly have ridge boards with rafters coming off of them.
The reason trusses shouldn't hold the weight of flooring or heavy boxes is because they are typically made from relatively small boards (2x4's in some cases) and the bottom board is already carrying a significant roof load because of the design of the angled elements.
The roof itself doesn't matter. It is the boards on the bottom (truss chords) or ceiling joists that will carry the weight of whatever you are storing.
If it is a few boxes of christmas ornaments that is one thing, but if you try to store your bowling ball collection up there and build a weight room then you will be in trouble.
Any normal floor is built on joists that span a distance between vertical supports and have to be sized for that span. Check the span tables here.
You will notice the absence of 2x4's on the span tables. Your ceiling joists, or the boards that will become the floor joists of this bonus room, are most likely 2x4's which means they would have to be reinforced to be used as a floor.
Good luck with your project!
