For the bars at the window, we use 'line'. For the bars in the middle, let us curve the bottom edges into a semi-circle. For better results, you can draw a cylinder and model the bars from it.
For the bars on the sides, let us curl them inwards to seal them. It will be easier to model these bars by using a cylinder.
Now let us create the frame and the iron pieces that hold the bars.
After we have done this, instead of using 'loft', let us choose the 'enable in render' and 'enable in viewport' options from our 'line' properties.
And let us also choose 'rectangular' and adjust the thickness of the bars. Then let us group them and copy them onto other windows
When drawing the windows, let us draw a box and let us select two opposite surfaces (both front and back), then by using 'inset' let us create a 'face' towards the inside. Let us delete the 'faces' already on the inside and with the help of 'bridge', let us connect them with the opposite side and let us not forget to add 'chafer' to the sides. I do not see the need to add more details to the windows.
After having created the glass for our window, let us then copy them to their places.
When drawing the ledges on the roof, let us first draw the outline and then with 'extrude', let us stretch them outwards.
You can also out the ledges in the middle of the roof.