these channels 22 extend towards the building interior the furthest see fig1 b between each of these vertical channels 22 a subtle v dip 20 also extends in the same direction as the channels ridges 22 see fig1 d as shown in fig1 a this type of metal panel 12 is commonly fastened to a plurality of horizontally running and vertically spaced z girts 14 each z girt 14 has an outer flange 24 see fig1 c to which using fasteners 16 the metal wall panel 12 is fastened the fasteners 16 typically are self tapping screws when it is desirable to insulate the wall a blanket of insulation 18 may be unrolled and draped down the wall panel 12 before the panel 12 is secured to the z girts 14 the blanket of insulation 18 may have a facing 19 on the inside which prevents contact with inhabitants presents a more appealing look and creates a vapor barrier the draping process may involve tacking the blanket 18 in some manner to the uppermost purlin so that it remains in an unfurled position after being unrolled and draped down the panel 12 the blanket of insulation 18 is secured between the wall panel 12 and the outer flanges 24 of the plurality of z girts 14 using the fasteners 16 see fig1 a more specifically the fasteners 16 are driven through the vertical channels 22 the blanket of insulation 18 and then into the outer flanges 24 of the z girts 14 when a fastener 16 is screwed through the inner most portion channel 22 of the wall it presses against the outer flange 24 of the corresponding z girt 14 and sandwiches a portion 26 of the blanket of insulation 18 see fig1 c this compacting of the blanket.