Exterior Wall Vapour Barrier

This wall assembly will dry from the vapor barrier inwards and will dry from the vapor barrier outwards.

Exterior wall vapour barrier.

Its purpose is to help prevent water vapour from reaching building walls ceilings attics crawlspaces or roofs where it can condense and cause building materials to rot or grow mould. Below grade walls and floor slabs transmit ground moisture through concrete walls or slabs. This barrier is meant to keep moisture from getting to the insulation in the walls and ceilings and it is required by building codes when insulating most houses. Vapor barriers are applied to the interior walls in climates which are predominantly cold while they are best applied to exterior wells in predominantly hot climates.

Whether or not you need a vapor retarder hinges on three main factors your climate your home and the location of the wall you re insulating. In any case the vapor barrier must point to the warm side. A vapour barrier is an important component in building construction. A vapor barrier against the concrete surface is generally recommended before wood framing or flooring materials are installed.

When a vapor barrier is on the side of a wall where the dry air is i e outside in winter or inside in summer moisture problems can occur. In hot climates any moisture that condenses on the exterior side of the vapor barrier will be drained to the exterior since the vapor barrier is also a drainage plane. It combines the superior air and water resistance vapor permeability and strength of tyvek with a vertically grooved surface to help channel water safely to the outside. Finished basements often receive a vapor barrier layer between the concrete and the floor treatment to prevent damage from heavy rains or other moisture seepage.

Above grade exterior walls with semipermeable exterior finishes like brick over oriented strand board sheathing require the placement of an additional vapor barrier on the exterior side of the. Frame wall with cavity insulation and brick or stone veneer. A vapor barrier s job is to keep water vapor in humid air from diffusing through one side of a wall and finding a cool surface inside the wall. Vapor barriers are sheets of plastic or other material placed on one side of insulation sheets.

Dupont tyvek drainwrap is a moisture barrier designed to provide enhanced drainage in areas subject to extreme wind driven rain. Building codes usually require a vapor barrier 4 mil plastic sheeting on exterior basement walls if the framing is attached to masonry or concrete surfaces or if the wood framing butts up against the outer basement walls.