If two corners have shifted in two axis, the face may not fill it with a single face. You would need to make up valid triangles. Look at these screenshots of one section of your roof, and how I drew in lines to make it work:
Many houses are typically made from rectangular shapes, even if they overlap.
This makes construction - including adding a roof - relatively uncomplicated.
Your current form is not like that, so adding a series of simple pitched roofs is all but impossible, even with the hips/valleys/gables etc needed.
I think you ought to redraw the plan form - making it more logical - and then revisit the roof.
When you have a suitable plan form then adding a pitched roof is relatively straightforward…
With a little work you get this…
It might not be exactly as you want - e.g. the front roof’s ridge is higher than the main roof’s ridge etc…
Perhaps there are different pitches ?
That explains a couple of odd elements how ever the roof pitches are rather unorthodox. the back roof pitch is a 10/12. The other pitches on the front view are close but not the same. One is a 5.5/12 the other 5.625/12.
as other have said the geometry you have form is what is keeping the faces from forming. There is a small offset in one wall that makes me wonder if it was intentional or a modeling error.
I opened your model in SU 2017 make and it’s dims are in feet/inches. Are you working in metric?
I don’t know about the walls and the pitch of the roof, but the floor plan should be sound. I got the measurements of the exterior walls from a survey that was recently performed on the property. I think I had the pitch of the eaves above the garage off, but it might be better now. I’m still having tons of problems with the roof, though.https://we.tl/t-g23ldejkZR
Forget about it being a roof, you just need to remember that all geometry in SU is made of planar faces which are formed when the relevant edges create a closed loop that is all on the same plane. So you need to draw in the appropriate edges to allow the faces to form. Triangles are always planar but a square or rectangle isn’t automatically planar, but a diagonal will generally close both faces.
So you need to work through your model making edges that will form faces.
Have you looked at the various videos and other advice about how to use Sketchup? If not, you should. You will soon get into an even bigger muddle if you just launch in.
For starters, you don’t seem to be using grouping. That will almost certainly start to create issues if they haven’t already. How you group is up to you but it would be logical in this case to separate out the walls and roof.
You have a dark band running around the eaves of the roof. My guess is that it’s meant to represent the eaves. In most cases, an eave overhangs the wall below but you have made it coplanar with the walls.
Do you have any photos of the house so that we can see what you are trying to reproduce?