There are three principal layers; 1  External intercostal muscles aid in quiet and forced inhalation. They originate on ribs 1-11 and have their insertion on ribs 2-12. 2  Internal intercostal muscles aid in forced expiration (quiet expiration is a passive process).
Costs. A professional concrete contractor will typically charge $2-$4 per square foot for a simple stain application, including the sealer. A stain application with patterning and sawed lines will typically cost between $4 and $10 per square foot.
The cost to apply average concrete staining depends upon the area and condition of the surface, the type of stain, special preparation needs, and the labor rate. In the following table the Labor Cost figure is what the able and prepared DIY persons should expect to save by performing the corresponding tasks. Concrete staining: 500 sq.ft.