Building Paper

Definition

Building paper is a water-repellent paper used to shed incidental moisture that may penetrate exterior finishes of exterior wall construction. It is thick paper used to insulate a building before the siding or cladding is installed and is occasionally used in flooring between double floors.

Purpose

Building paper acts as a moisture barrier, preventing water infiltration that could damage structural components and insulation. It helps maintain the integrity of the building envelope by providing an additional layer of protection against weather elements. In flooring, it can reduce sound transmission and add a layer of insulation.

Examples of Use

1. Wall Construction: Building paper is installed under exterior siding or cladding to prevent moisture from penetrating the wall assembly.
2. Roofing: Used under shingles or other roofing materials to provide a secondary moisture barrier.
3. Flooring: Placed between subfloor layers to reduce noise and improve insulation.

Related Terms

• House Wrap: A modern alternative to building paper, made from synthetic materials that provide a similar moisture barrier function.
• Vapor Barrier: A material used to prevent moisture from passing through walls, floors, and ceilings.
• Sheathing: Boards or panels that are attached to the exterior studding or rafters of a building, forming the substrate for roofing or siding.

Notes

Proper installation of building paper is essential to ensure its effectiveness as a moisture barrier. It should be overlapped and sealed correctly to prevent water ingress.