The beginning of a chapter is always accompanied by decorations, especially the first letter. then it continues relatively boring: it is just small text, about 42 lines per page, with few illustrations. There is a three-sided frame; the thickest being on the outside, which is used for annotations and explanations. This format is uninterruptedly used. De l’Orme used a typical font for the times.
The illustrations are not used frequently but I suggest on average on can say there is an illustration every three pages. It is a technical book so the images are detailed drawings of junctions, 3D-drawings of roof constructions or perspective views. The images’ purpose is the demonstration of the building manner so there is no emphasis on sunlight or the feeling of a building.
The images are mostly full-page in size. They are put in with care and supporting their importance Philibert de l’Orme printed them big. He refused to number or label the drawings (maybe it was not usual at the time…?), though some are supported by a small explanation.
visually speaking the text is not very appealing, for there are not even paragraphs os it looks a bit monotonous. The illustrations are used so little so they seem even more interesting, also because of their size.
The rules of composition, mentioned earlier on, do not apply to the rather long introduction of the book. Some of the text is composed like the rest of the book but there are parts that look like a poem, judging from their format, and some parts are written in italics.
The book is divided in two books which are composed the same way, just concerning other subjects: the first one materials the second one techniques (of what I have understood). So in the book the whole composition repeats once.