CONSTRUCTION MATERIAL

Advanced Material for Construction

Name of the writer]

Advanced Material for Construction

Introduction

There have been considerable advancements in the construction technologies and material. The aim of modern construction material is to provide durable, secure, efficient and cost effective solutions to construction processes. In this paper the focus of my concern is Exterior insulation and finish system (EIFS) used for construction of a quarter of a million residences and several thousand commercial buildings in the United States, Canada, and Europe. EIFS use has been linked with moisture problems and structural rot in many buildings, necessitating value impact estimates by appraisers.

Exterior insulation and finish system (EIFS) is a generic term for an exterior cladding consisting of an insulation board, a glass fiber mesh and synthetic stucco, all structurally supported on a substrate and incorporated into an overall wall design.

Discussion

Exterior insulation and finish systems (EIFS) typically consist of polystyrene insulation boards, which are covered by a polymer-modified cementitious coating (synthetic stucco) that is reinforced with glass fiber mesh. Generally, the coating consists of two layers: a base coat and a finish coat, which is called the lamina. The insulation boards are usually adhered to exterior gypsum sheathing on a steel stud backup wall. In some systems, the insulation boards are fastened mechanically to the steel studs. Most EIFS installations have been field constructed, as opposed to panelized, and have been adhered, rather than mechanically attached, to the backup wall.

Typical EIF systems use barrier wall principles and lack any cavity or waterproofed backup. Traditional cement plaster stucco wall systems can incorporate a drainage layer through the use of asphalt-impregnated felt behind the metal lath. While this is not a clear drainage cavity, the field experience is that the felt can control water that may penetrate at cracks or joints in the stucco wall, if it directs this water onto a through-wall flashing. However, this places the metal lath and fasteners in a moist environment and invites corrosion problems.

With the barrier EIFS composite of materials, such a waterproofing layer cannot be incorporated, because it would interrupt the adhesive attachment of the insulation or plaster coats. It may be possible to incorporate a waterproofing layer if the system is mechanically attached, but such an approach has not been documented in practice. Like traditional stucco, the fasteners with mechanically attached EIF systems are in a corrosive environment and subject to premature failure.

Barrier EIF systems rely solely on the polymer-modified stucco coating and joint sealants to resist water leakage. Rain penetration through EIFS clad walls typically occurs at cracks in the lamina, at defects in the joint seals, and through unflashed window frame corners and joinery. Gypsum sheathing, if used, may degrade readily when exposed to water. Structural deterioration of the gypsum sheathing, fasteners and steel studs, and loss of attachment, become a greater concern than just discomfort of the building occupants and damage to interior finishes due to water leakage (Thomas, 2004, p. 32).

Control of cracking is important in these systems, particularly the control of cracks that occur ...