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2.1 AIR/WEATHER/MOISTURE/THERMAL/VAPOUR/TERMITE BARRIERS - Coggle Diagram
2.1 AIR/WEATHER/MOISTURE/THERMAL/VAPOUR/TERMITE BARRIERS
1) AIR BARRIERS (AB)
In cold climates Air Barriers (AB) are
designed to reduce the outward migration of moisture-laden air through the envelope structure and to reduce the inward migration of cold air.
Air Barriers is the most important component in the building envelope for preventing condensation in insulation cavaties.
OTHER BENEFITS OF AIR BARRIERS
Reduce wind-driven rain prevention
Reduce heating loads in the winter
Allows for healthy indoor humidity
Reduces cooling loads in the summer.
Reduces outside noise penetration
Increase occupant comfort.
4 TECHNIQUES TO ACHIEVE A CONTINUOUS AIR BARRIER (2 INTERIOR+ 2 EXTERIOR)
Sealed PolyEthylene Approach (SPA)
Airtight Drywall Approach (ADA)
Uses drywall in combination with sealants, gaskets, framing members and other rigid materials.
Exterior Insulation Approach (EIA)
Uses Rigid Foam insulation boards
House Wrap Approach (HWA)
Uses flexible sheathing membrane
If an Air Barrier (AB) is also a Vapour Barrier, then it must be kept on the WARM SIDE of the assembly.
Exterior applied Air Barrier advantages:
Lower labour and material costs
Can be tested for Airtightness before drywall is completed.
2 Classic types of Air barrier (AB) Materials:
SHEET MEMBRANE: More
appropriate for one and two storey buildings in wind shaded locations.
RIGID PANEL:
Best used in thee or four storey buildings
2 INTERIOR MEMBRANE AIR BARRIERS:
Sealed PolyEthylene Approach (SPA)
PolyEthylene:
Most common Air Barrier material.
Primary
advantage is that it provides both air and vapour barriers**
. I
f it is designed as an Air barrier system then it must be continuous and sealed**
throughout the building envelope.
If it is solely
designed as a vapour barrier, then it needs to be continuous but does NOT NEED TO BE SEALED
Airtight Drywall Approach (ADA)
An alternative to the PolyEthylene method. This approach uses rigid materials, usually drywall as components of an air barrier system.
Advantages:
Not easily damaged during construction
Stands up to high wind
Accessible from the interior
2 EXTERIOR AIR BARRIER SYSTEMS (HWA and EIA)
Flexible exterior membrane composed of a House Wrap.
The membrane must be systematically sealed at all joints. With such a system, a Vapour barrier must be used on the WARM SIDE (inside) of insulation.
Rigid Exterior Insulation System:
Rigid insulation is applied as an exterior sheathing and sealed at all joints and penetrations.
In the case of vapour permeable exterior barriers, Vapour barriers must be loacted on the INSIDE of the assembly
Insulated Concrete Foaming Systems
Insulated Concrete Form (ICF)
A good Air Barrier provided the details at penetrations and junctions with other materials are made airtight
2) VAPOUR BARRIERS (VB)
Vapour Barrier is a membrane,
material or coating that slows the diffusion of interior water vapour into insulated exterior assemblies such as walls, ceilings and exposed floors which helps prevent condensation of water vapour on cold surfaces.
PolyEthylene, Aluminum Foil and certain kinds of paint can be used as vapour barriers
AIR BARRIERS (AB): Need to be CONTINUOUS AND SEALED
VAPOUR BARRIERS (VB): ONLY NEEDS TO BE CONTINUOUS
In residential construction, PolyEthylene is often used as both AB and VB
Depending on the vapour permeance of the interior AB, ALKYD paints or Vapour retarding drywall sealers, PolyEthylene, or Foil-backing on drywall can be used as the VB.
VB must have a water vapour permeance NO GREATER than 60ng/(Pa. s . m(squared)2)
3) WEATHER BARRIER
Also called SHEATHING MATERIALS or SHEATHING BARRIERS
Protects the components of exterior walls from the effects of wind, rain, snow and sun
2 TYPES OF WEATHER BARRIERS
BUILDING PAPERS (TAR PAPER):
Should be installed horizontally and lapped to ensure shedding of water towards the exterior/.
PROPERTY HOUSE WRAPS (
Dominant Choice
):
Will perform best as weather barrier, if they are sealed at all joints and penetrations with a compatible, durable tape.
4) THERMAL BARRIERS
2 WAYS HEAT IS LOST FROM A BUILDING
As a result of air leakage ( CONVENTION). This can be significantly reduced by means of an effective Air Barrier.
CONDUCTION heat loss via walls, ceilings, and floors separating heated spaces from unheated--->
Sufficient thermal insulation will reduce this kind of conduction heat loss.
5) BASEMENT MOISTURE BARRIERS AND FOUNDATION DAMP PROOFING
Moisture can move from the ground through the foundation wall and slab by DIFFUSION, as well as CAPILLARY ACTION.
TO AVOID THIS, DAMP PROOFING is required on the exterior foundation walls located below grade. The application of BITUMEN coating can prevent water in the soil from penetrating the concrete walls.
A drained bed of crushed rocks or clean gravel base with no fine particles beneath a slab will provide a capillary break
that prevents the ground water from passing through the slab.
DAMP PROOFING is also required below-grade portion of interior foundation walls where wood framing or BATT Insulation is in contact with the concrete. A MOISTURE BARRIER acting as a DAMP PROOFING is usually provided on the INTERIOR of the foundation wall, using Building Paper or House Wrap.
6) TERMITE BARRIERS
Termites are present in the southernmost region of Canada.