Condensation Conundrums Webinar Association of Wall & Ceiling - - PowerPoint PPT Presentation

Association of Wall & Ceiling Industries (AWCI)

24th February 2015

Andy Russell, Proctor Group Australia

Condensation Conundrums Webinar

Disclaimer: There are a large number of factors that need to be considered in assessing and managing condensation risk. Such factors include the local climate, building use, position, thickness and type of insulation, position and integrity of vapour barriers, and the degree and location of mechanical or passive ventilation both in the roof space and the interior. The details supplied here are based upon good practice and currently available information contained in the ABCB Condensation Handbook. However Andrew Russell, Proctor Group Australia, Dynamic Composite Technologies or the Australian Institute of Architects do not accept responsibility for losses incurred resulting from the use of any details or information contained within this presentation. Any materials mentioned are generic and do not necessarily represent materials supplied by Proctor Group Australia, Dynamic Composite Technologies or any specific manufacturer. Specific advice relating to installation or appropriate use of products should be sought from the manufacturer or supplier.

Who is Proctor Group Australia?

How will future generations look back at “industry practice”

Moisture Management by climate

A – Tropical B – Temperate C – Alpine Wall type 1

Moisture Management by climate

A – Tropical B – Temperate C – Alpine Wall type 2

(Conditioned building)

Moisture Management by climate

A – Tropical B – Temperate C – Alpine Wall type 3

Moisture Management by climate

But wherever I go in Australia this is what we see?

Where are the problem likely

“But this is Australia. I’ve never seen it.”

Maybe in New Zealand but not here….

it couldn’t happen here… could it ?

it couldn’t happen here… could it ?

it couldn’t happen here… could it ?

it couldn’t happen here… could it ?

it couldn’t happen here… could it ?

it couldn’t happen here… could it ?

Mark Dewsbury (PhD), School of Architecture and Design, University of Tasmania

“But this is standard industry practice. That is what we’ve always done”

Denial

Must be the possums …. Not in Australia Did you go up there with a hose pipe.

Anger

Why hasn’t anyone told us. Not in the BCA? Kevin Rudd / tree huggers and all that energy efficiency stuff are to blame. That is what it shows in the install guide / industry handbooks.

Bloody Scotsman coming over here to tell us what we are doing wrong.

Bargaining

It is just happens in Tasmania, Darwin, New Zealand But I used that foil with holes or the foil faced blanket If I put a powered roof vent up there I’ll fix it I build to the NCC and there is nothing in there about condensation It will dry out in the summer I’ll be long gone by the time it goes wrong

Depression

Why go on? I am ruined. This is just too hard. Better put the house in the wife’s name

Acceptance

I can fix this. The solutions really aren’t that hard or expensive. If I get this right, I can make a point of difference That is all I have to do ?

• What is condensation
• What has changed
• Why more problems in buildings
• Consequences
• Insulation, pliable membranes & ventilation

WHAT IS CONDENSATION ?

Building science geeks down at the pub?

Types of condensation

• Surface condensation
• Surface condensation takes place on the

surface of a body when the temperature of the surface is less than the dew point temperature of the surrounding warm moist air.

• Interstitial condensation
• Interstitial condensation occurs as a result of

moisture diffusing through the permeable building fabric from the high vapour pressure side to the low vapour pressure side.

Where does the moisture come from?

ABCB Condensation in Buildings Handbook, 2014

Where does it end up – surface condensation

OAA Mould Control Practice Guide, Ontario Association of Architects (2003)

Where does it end up - the building envelope

Condensation can form under roofing that cools to the outdoor dew point. Night sky cooling makes condensation likely in many Australian locations. Sarking without insulation can collect condensate from under roofing and be allowed to either dry upon day break or drain to guttering where detailing allows. Condensation can form under sarking that cools to the outdoor dew point in ventilated and unventilated roof spaces Insulation to avoid condensation under sarking may need protection from wetting by roof condensate. Insulation on ceiling cuts heat loss but surface temperatures above become colder. Colder roof spaces require better control of air leakage through ceilings. Insulation in walls cuts heat loss but cavity temperatures become colder. Colder sub-floor spaces may require membrane to seal ground surfaces. Condensation can form inside impermeable wraps or panels that cool to the indoor dew point. Colder sub-floor spaces can raise relative humidity and increase moisture levels in timber framing.

WHAT HAS CHANGED AND WHY WE ARE SEEING MORE PROBLEMS ?

What has changed?

• Increased air tightness
• Increased insulation
• Reduced moisture storage capacity
• More manufactured materials

Industry / Cost Pressures A good builder problem

What has changed?

ABCB Condensation in Buildings Handbook, 2014

If we were to start all over again….?

Water tight



Air tight



Vapour Permeable



Radiant Barrier



The primary purpose of a sarking

R0.9 Insulation R0.0 P’board air films etc. R0.3 Reflective air space R0.6 = R0.9 With one reflective surface facing inwards

Need more ‘bulk’ insulation

R0.9 + R2.0 batts = R2.3 ? Insulation R2.0 P’board air films etc. R0.3 = R2.3 No still air space adjacent to reflective surface.

Vapour drive from inside to out

Vapour drive from inside to out

Just like on the inside of glazing

Preferable to have a cavity

Insulation R2.0 P’board air films etc. R0.3 Vented Cavity R0.14 = R2.44 And you get good moisture management + Drainage + Drying + Durability

The CSIRO mentioned this back in 2001

Higher levels of insulation may introduce unforeseen problems where they are incorporated into construction styles which have

previously been relatively immune to condensation.

This is because insulation, whilst it keeps some surfaces warm,

also keeps other surfaces cold.

High levels of ceiling insulation mean that roof spaces are

colder as they are not heated to the same extent from below.

Incidences of condensation within pitched roof spaces with sheet metal roofs are increasing in line with the trend to

higher levels of ceiling insulation.

How does water vapour move?

• Diffusion
• Air movement

Why does condensation occur in buildings ?

• the presence of moisture levels which are

too high;

• the presence of temperatures in the

building fabric which are too low; and

• uncontrolled flow of water vapour from a

source to a region of cold temperature (cold condensing surface).

Permeability of different building materials

110mm Med. Wgt. Brick 5.5MNs/g Glass, Steel, Aluminium Sarking >1000MNs/g 10mm FC Sheet 1.1MNs/g 10mm Plasterboard 0.6MNs/g 90mm Insulation batts 0.5MNs/g

Values from BS5250:2002

Vapour barriers, permeable sarking and beer.

Vapour diffusion and permeable materials

THE CONSEQENCES

It doesn’t always make the news....

The Consequences

• Visible and hidden fungus and mould growth
• Sick building syndrome leading to serious health

problems

• Timber decay
• Corrosion
• Loss of structural integrity
• Phantom leaks
• Saturation of insulation and loss of insulation

effectiveness

• Surface condensation problems

The ingredients for mould

Loss of insulation effectiveness

Keep insulation dry

Cammerer, J. und Achtziger,J.: Einfluß des Feuchtegehaltes auf die Wärmeleitfähigkeit von Bau- und Dämmstoffen. Bericht zu BmBau Forschungsvorhaben BI 5-800883-4, 1984.

Can one material do it all ?

Adapted from Habitat Congress Building America, Michigan, Building Science Consortium, 2006

External Moisture Management Thermal Resistance Vapour Management Air Tightness

Sarking types in relation to vapour diffusion

Vapour Barriers (vapour diffusion retarder)

• used to restrict the transmission of water

vapour Vapour Permeable (breather) membrane

• Intended to allow the transmission of

water vapour

Where are the products being sold as breathers

Drying rates for different sarking

No sarking Vapour barrier Foil with holes Vapour Permeable

Weeks Moisture Content of timber sample

CSR Building Knowledge Issues 5 (2014)

After 6 months

Vapour Permeable Membrane Foil with holes Vapour barrier

CSR Building Knowledge Issues 5 (2014)

Importance of vapour barrier integrity

WHERE TO FIND GOOD RELIABLE INFORMATION

NCC Requirements

Part F1 (volume 1) and Part 2.2 (volume 2) Damp and Waterproofing

• F01 & O2.2
• The Objective of this Part is to: (a) safeguard occupants from illness
• r injury and protect the building from damage caused by
• (i) Surface water; and
• (ii) External moisture entering the building
• (iii) the accumulation of internal moisture in a building;
• FF1.3
• A building is to be constructed to avoid the likelihood of–
• (a) the creation of unhealthy or dangerous conditions; and
• (b) damage to buildings elements, caused by dampness or

water overflow from bathrooms, laundries and the like.

The 3 objectives in a moisture strategy

Prevent building assemblies and surfaces from getting wet from the exterior Prevent building assemblies and surfaces from getting wet from the interior Should building assemblies or surfaces get wet, or start out wet, allow them to dry

Condensation Handbook – has not defused the time bomb

"Condensation in Buildings" The second edition consolidates information from the first into a more extensively illustrated and detailed form to improve the Handbook's accessibility and useability.

Volume 2: 3.12.1.1 Building fabric thermal insulation Exp. Note 3

• Artificial cooling of buildings in some climates can cause condensation to

form inside the layers of the building envelope. Such condensation can cause significant structural or cosmetic damage to the envelope before it is

• detected. Associated mould growth may also create health risks to the
• ccupants. Effective control of condensation is a complex issue. In

some locations a fully sealed vapour barrier may need to be installed on the more humid, or generally warmer, side of the insulation.

Volume 2: Fig 3.12.1.4 Explanatory Information 3

• A reflective or non-reflective building membrane should be installed with

due consideration of condensation in some climate zones and associated interaction with adjoining building materials.

Volume 2: 3.12.1.2 Roofs Explanatory Information 6

• …. in some climate zones, insulation should be installed with due

consideration of condensation and associated interaction with adjoining building materials.

There is guidance in the NCC

Figure 3.12.1.1 TOTAL R- VALUE FOR TYPICAL ROOF AND CEILING

• CONSTRUCTION. …….

reflective insulation or sarking installed on the cold side of the building envelope should be vapour permeable.

There is guidance in the NCC

Correctly placed, [a vapour barrier] will prevent water vapour from reaching the cold surface. It should always be placed on the warm side of the structure, generally on the lower side of the roof where it is kept above dew point during cold weather. In cold climates, or where greater insulation is desired, an additional vapour barrier or insulation sheet should be installed just above the ceiling.

Vapour barrier placement

AS 1562.1-1992 Design and installation of sheet roof and wall cladding Part 1: Metal

New guidance in Tasmania

• Use vapour-permeable wall

wrap (not punched sarking)

• Introduce ventilated cavities by

the use of wall battens spaces and the like for polystyrene, hardboard and cement sheet external wall claddings.

Ventilation strategies

Ridge or high level ventilation must never be installed on its own Eves ventilation should be on the longer sides

• f the roof

Eves to eves ventilation has been proven ineffective on still clear nights

Heat and moisture transport between houses and cold lofts - a combination of convection and diffusion Emannuel Essah and Chris Sanders, Glasgow Caledonian University (2006) BS5250:2002 Code of practice for control of condensation in buildings

Ventilation of the occupied space to manage moisture levels. Walls and low pitch/ skillion roofs prove very difficult. Potential for ventilation of pitched roofs

Moisture Management by climate

A – Tropical B – Temperate C – Alpine Wall type 1

(Conditioned building)

Moisture Management by climate

A – Tropical B – Temperate C – Alpine Wall type 2

Moisture Management by climate

A – Tropical B – Temperate C – Alpine Wall type 3

Climate is important

Others have been here before us

Rogers 1938 “Architects, owners and research technicians have observed, in recent years, a small but growing number of buildings in which dampness or frost has developed in walls, roofs or attic spaces. Most of these were insulated houses, a few were winter air-

• conditioned. The erroneous impression has

spread that insulation ‘draws’ water into the walls and roofs...Obviously, insulation is not at fault.”

Andy Russe ll

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Unit 8, 171-175 Ne wto n Rd, We the rill Pa rk NSW 2164 PO Bo x 7186, We the rill Pa rk DC NSW 1851 T 1800 174 900 F 02 9604 7468 M 0407 632 631 E a ndy.russe ll@ pro c to rg ro up.c o m.a u W

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