Attachment member for insulation panel

An insulation panel comprising:

• a foam insulating layer comprising a front face, a rear face, a first end edge, and a second end edge that define a body of the foam insulating layer;
• and
• an attachment member comprising:
• a main portion having a forward edge and a rear edge;
• a nailing hem extending transversely from the rear edge of the main portion in an upper direction, the nailing hem having a base and an apex, the base including an arched portion extending in a forward direction;
• and
• at least one lower leg extending transversely from the main portion in a lower direction at a point between the forward edge and the rear edge;
• wherein the at least one lower leg of the attachment member extends into the body of the foam insulating layer along the first end edge, the attachment member and the first end edge cooperating to be complementary in shape with the second end edge such that adjacent panels can engage each other.