Borate as a potential wood preservative to protect building envelope components from biodegradation

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1 Borate as a potential wood preservative to protect building envelope components from biodegradation NAZMUS SAADAT, PROF. PAUL A. COOPER

2 Outline Background Durability and environmental issues About borate Experimental procedure Results to date Future work Expected outputs

Background Revised building code in BC, allowing taller(mid rise) wood buildings Introduction of Cross Laminated Timber (CLT) as structural component Unknown issues Fire performance Structural

3 Background Revised building code in BC, allowing taller(mid rise) wood buildings Introduction of Cross Laminated Timber (CLT) as structural component Unknown issues Fire performance Structural performance Joints and Connections Moisture problem Orientation of wood layers in CLT (Source: FPInnovations) Our goal is to address durability and environmental challenges for mid rise wood buildings

4 Durability and environmental issues Vulnerability of timber components in buildings to decay and mould growth Concern for areas: Difficult to access after construction Costly to repair Water source: Construction moisture from bad design and bad construction practice Trapped rain water or ice dam Idealized concept of progress of decay (Leicester 2001): Building life can be increased significantly with preservatives The moisture from leaks or condensation from plumbing, exhaust and heating

5 Trapped moisture Poor in-service maintenance Poor installation Condensation

6 Issues with common preservatives PMRA regulations for harmful components limit where and how much they can be used Must be applied by pressure treatment Higher cost Not suitable for in situ treatment A safe and environmental friendly wood preservative is necessary for residential uses

About borate Borates (BO 3 3 ) are chemical compounds which contain oxoanions of Boron (B) http://my-bankruptcy-help.com/?b=file:ax3e0-3d-balls.png in oxidation state +3.

7 About borate Borates (BO 3 3 ) are chemical compounds which contain oxoanions of Boron (B) in oxidation state +3. Examples: Boracol, Timbor/Polybor (Na 2 B 8 O 13.4H 2 O), Boron rod, etc Advantages Inexpensive Colorless and odorless Highly water soluble Proven insecticide & fungicide Safe for human health and environment

8 More advantages... Corrosion inhibitor, fire & flame retardant (at high loading) Able to diffuse into vulnerable areas even into refractory wood Easy and different treatment procedures as per requirement Can be applied as a primary treatment or applied in service. So, borate is a good system to evaluate

9 Objectives To investigate variables affecting borate movement To evaluate and develop suitable borate treatment procedures for timber components, joints and other vulnerable areas To investigate the suitability of borate preservatives for cross laminated timber (CLT)

10 Formulations 40% borate (Polybor ) in Glycerol 40% borate (Polybor ) and 10% coppermea in aqueous solution Species Eastern spruce (Picea glauca or mariana) Douglas fir (Pseudotsuga menziesii)

11 Experimental procedure Water impregnation to target moisture content Samples treated with borate preservatives and kept for a specified period Extraction by hot water ICP analysis of B (AWPA A21 00)

12 Results to date Formulations: Spruce D-fir % BAE Glycerol borate Copper borate % BAE Glycerol borate Copper borate Distance from treated surface, cm Distance from treated surface, cm Boron diffusion gradient in longitudinal direction after 7days and at 30% MC Copper borate formulation shows slight better result than glycerol borate More data required Basis: 77.2 mg of material / cm 2 surface area

13 Results to date Moisture content: Spruce D fir % BAE % MC 50% MC % BAE % MC 50% MC Distance from treated surface, cm Distance from treated surface, cm Boron diffusion gradient in longitudinal direction treated with glycerol borate and examined after 7 days Deeper boron diffusion at higher moisture content regardless of formulations and species.

14 Results to date Grain direction: Spruce 6 5 D fir 8 4 % BAE Longitudinal Radial Tangential % BAE Longitudinal Radial Tangential Distance from treated surface, cm Distance from treated surface, cm Boron diffusion gradient in different directions for samples treated with Glycerol borate and examined after 7 days (30% MC) LONGITUDINAL > RADIAL > TANGENTIAL

15 Results to date Species: MC 30% 9 8 MC 50% % BAE Spruce D fir % BAE Spruce D fir Distance from treated surface, cm Distance from treated surface, cm Comparative results for different species treated with glycerol borate in longitudinal direction and examined after 14 days Spruce shows better diffusion extent due to low density

16 Results to date Exposure to extreme condition Temp: C, R. H. : 90-95%

17 Results to date Treated & untreated parts of joints after 15 weeks(top left - Copper borate treated & right - Glycerol borate treated)

18 Results to date Comparison between glycerol borate treated(left) and copper borate treated (right)joints Top- 8 weeks, Bottom- 15weeks

19 Results to date Treatment to be evaluated: Moulded parts of the untreated joint Treated by glycerol borate and copper borate and enclosed by Tuck tape

Coefficient, cm 2 /s Quantitative measurements of

20 Future Works Estimating the diffusion coefficient for boron penetration EGNER S solution: Diffusion Coefficient, cm 2 /s Quantitative measurements of Boron distribution rate for different Variables

kept under exposure condition Borate treatment to

21 Future Works Formulation with DDAC and effectiveness test CLT panel treated with borate preservatives and kept under exposure condition Borate treatment to mouldy CLT panel to evaluate the efficacy of the preservatives

22 Expected Outputs Quantitative information on factors & variables affecting borate distribution Suitable methods for different treatment procedures Modified and cost effective borate preservative Results and recommendations for CLT

23 Acknowledgements Dr. Paul Morris and colleagues at FPInnovations NEWBuilds Network

24 Thank you!

25 Mid rise Building Project Student Workshop February 3, 2012 Assessing the Moisture Durability of Wall Assemblies for CLT Construction in Canadian Climates Robert Lepage, E.I.T. University of Waterloo

26 Agenda Determining Moisture Characteristics of Cross Laminated Timber (CLT) Panels Calibration of Hygrothermal Model Defining Durable Wall Assemblies Modelling of CLT Wall Assemblies in WUFI Concluding Results from Modelling Exercise

27 Moisture Properties of CLT Problem: Moisture performance and properties not fully understood Susceptible to rot, mould, swelling, etc Concerns about construction moisture Approach: Characterize moisture properties of CLT via laboratory tests Simulate wall assemblies with calibrated hygrothermal modelling software

28 Laboratory Experiment Water uptake test Provides absorption coefficient utilized to calculate liquid water diffusivity via suction Gravimetric drying test Provides drying rates and suggests effective liquid water diffusivity via redistribution

29 Laboratory Testing Drying Rack Setup Moisture Uptake Test

30 Laboratory Results

Hygrothermal Software WUFI Wärme und Feuchtentransport instationär Transient heat and moisture simulation software Simulation accuracy

31 Hygrothermal Software WUFI Wärme und Feuchtentransport instationär Transient heat and moisture simulation software Simulation accuracy verified by numerous full scale field studies Empirically calibrated Produced by Fraunhofer Institut Bauphysiks in Holzkirchen, Germany

32 WUFI Data Input

33 Hygrothermal Model Calibration

Durable Wall Assemblies Durability: The ability of a building, or any of its components, assemblies, or materials to perform its required function(s)

34 Durable Wall Assemblies Durability: The ability of a building, or any of its components, assemblies, or materials to perform its required function(s) in its service environment over a period of time without unforeseen cost for maintenance or repair Wall Functions Support Control Finish Distribution

35 The Perfect Wall Not a new concept Division of Building research, NRC Hutcheon, 1964 Sensitive components are protected: Ultra violet radiation Temperature variation Moisture, etc Hutcheon, 1964

36 The Perfect Wall Lstiburek, 2008

37 Wall Assemblies Schedule Cladding Exterior Insulation WRB Int. Cavity Int. V.B. Direction S N X R N P I A B Y N N R

38 Wall Assemblies Storing Cladding Drainage Cavity Vapour Permeable Exterior Insulation Vapour Permeable Membrane CLT Panel Air Space Gypsum Wall Board

39 Wall Assemblies Non-Storing cladding Vapour Impermeable Membrane CLT Panel Fibre Glass Batt Insulation Vapour Impermeable Membrane Gypsum Wall Board

40 Climates Vancouver Edmonton Winnipeg Ottawa Québec St. John

41 Metrics for Comparison MC for 4mm thick layer on outer and innermost CLT lamina

42 Modelling Results Code Vancouver Edmonton Winnipeg Ottawa Québec St. John Out In Out In Out In Out In Out In Out In SRPAN NH SRPAN RH SXIAN NH NRPAN NH SNIBY NH SNPBY NH

43 Moisture Management Previous modelling assumes ideal conditions Low starting moisture content No penetration leaks Negligible construction moisture How do wall assemblies accommodate for increased moisture loads?

Construction Moisture Results City/Code Moisture Content (%) 4mm 10mm 30mm 43mm 30mm 10mm 4mm Vancouver 58 57 57 56 49 48 47 NRPAN NH 11 13 18 21 18 14 13 SNIBY NH 49 49 49 49 48 21 16 Environment 14

44 Construction Moisture Results City/Code Moisture Content (%) 4mm 10mm 30mm 43mm 30mm 10mm 4mm Vancouver NRPAN NH SNIBY NH Environment Ottawa NRPAN NH SNIBY NH Environment St. John NRPAN NH SNIBY NH Environment After 3 years of simulation

45 Observations CLT panels have capacity to be durable Due to thermal properties, large moisture storage capacity, and vapour flow resistance Vapour impermeable membranes increase moisture risks Specifically on the exterior and with no insulation Vapour permeable membranes, especially coupled with outboard insulation, allow for drying

46 Conclusions For durability: Exterior insulated Vapour permeable membranes only Failing this: Restrict construction moisture levels (<14%MC) Eliminate leaks from penetrations, details, etc

47 Field Study of Hygrothermal Performance of Cross Laminated Timber Wall Assemblies with Builtin Moisture Ruth McClung MASc. Building Science Candidate Department of Architectural Science Ryerson University Supervisors: Dr. Hua Ge, Ryerson University Dr. John Straube, University of Waterloo

48 Problem Moisture performance and properties are not fully understood Susceptible to the same moisture problems as wood (rot, mould, swelling, etc) Construction moisture may pose an issue

Field Testing Layout CLT samples wetted on

to monitor moisture content, temperature, and

hg1 4 wall configurations, with 4 CLT wood

49 Field Testing Layout CLT samples wetted on both faces by immersion in water Instrumented to monitor moisture content, temperature, and relative humidity within the wall assemblies hg1 4 wall configurations, with 4 CLT wood species will be tested Wetted panels installed in field testing facility and monitored for at least one year Waterloo BEGhut Test Facility

50 Slide 3 hg1 change "will be" to "being tested" hua ge, 01/02/2012

51 Planned Field Testing Layout BEGHut Layout Entrance Foyer 8 N Slab on Grade C L 510 Ø column on 1200 x 1200 footing Heating/ C Cooling L Data 11 acquisition 24 electrical system 12 service panel computer Each quadrant is symmetric with the centre lines Ply clad corner 140/140 P.T. post 140 batt insulation CLT Test Wall Location

52 Field Testing Layout CLT Panel Species Type A: European B: Black Spruce A1 Int Dry B1 A2 A3 A4 B2 Int Dry B3 B4 5: Stud Wall 5 All panels wetted on both sides except as indicated C: Western SPF D: Hem fir/ E: Eastern SPF C1 D1 C2 Int Dry E2 C3 D3 Int Dry C4 Ext Dry E4 6: Dry European SPF CLT Panel A6 Wall Assembly Type 1: Low 2: High 3: Medium 4: Low Int ⅜ Gypsum Interior Minimum 3½ Air Space Materials Poly Sheet Blueskin Blueskin VP Exterior 3 Roxul RockBoard 3 Plastifab EPS Materials ½ Fiber Cement Board Built-in Moisture Experiment Stud Wall Materials ¾ Vented Cavity CLT Wall Materials ½ Gypsum + Poly Sheet 2x6 16 centres 5½ Roxul ComfortBatt Tyvek ¾ Vented Cavity ½ Fiber Cement Board Same as 2: High Dry/Heat Flux Experiment

53 Field Testing Layout Wall Configurations: 1. Low Permeability 3 Roxul RockBoard Blueskin Nothing 2. High Permeability 3 Roxul RockBoard BlueskinVP Nothing 3. Medium Permeability 3 Plastifab EPS BlueskinVP Nothing 4. Low Interior Permeability 3 Plastifab EPS BlueskinVP Poly sheet

variability in drying behaviour between samples of

54 Sensor Layout Panels 1A to 4D With most panels drying freely to the interior, an estimate of the variability in drying behaviour between samples of the same wood species may be obtained. Typical Sensor Layout

55 Test Wall Construction Soaking of CLT panels in pool Interior Sensor Leads Panel Installation

56 Test Wall Construction CLT test wall with insulation, strapping and clading. Interior of wall before drywall installation After installation of water resistive barriers

57 Preliminary Results Freely Drying to Interior Relatively Uniform Behaviour

58 Preliminary Results Low Interior Permeance Many Panels still above 26% MC, risk of decay initiation

59 Preliminary Results High Exterior Permeance Panels dry quickly, react quickly to outdoor RH

60 Preliminary Results Medium Exterior Permeance Panel Surface RH is high, some risk of mould between insulation and VR WRB

61 Preliminary Results Medium Exterior Permeance Panel Surface RH is high, causing some panels to increase in MC

62 Preliminary Results Low Exterior Permeance MC remains high, and likely close to 100% RH on surface

63 Moisture Content Profiles Low Exterior Permeance Drying towards interior

64 Moisture Content Profiles High Exterior Permeance Rapid drying across panel

65 Moisture Content Profiles Medium Exterior Permeance Some drying towards interior

66 Moisture Content Profiles Low Interior Permeance Drying to Exterior

67 Preliminary Conclusions Wetted panels dried very quickly during construction under typical Southern Ontario Summer conditions. The drying may be slower under cooler and more humid conditions, such as in the rainy winter conditions in Vancouver, causing higher initial MC High permeance envelope materials can effectively promote drying of CLT panels Impact of assemblies with medium permeance, including the use of EPS, should be further investigated before any firm recommendations can be made. Low permeance materials should not be used Prolong the time period required for wetted panels to dry to a safe level CLT panel itself is a good vapour retarder, and any additional vapour barrier should not be used in a CLT assembly. Wood species does not appear to have a significant effect on the drying behaviour of the CLT panels.

68 Next Steps Continue data collection and analysis Compare collected data to WUFI simulations made using material properties developed in labratory testing Potentially examines core samples of CLT panels at the end of winter. hg2

69 Slide 21 hg2 "..made using material properties" may try "...compare collected data to WUFI simulations using material propoerties derived from laboratory testing" hua ge, 01/02/2012

70 Key outputs and potential impact of research Refined understanding of assembly level moisture characteristics Guidelines for CLT wall assembly design and construction procedures Calibration of computer hygrothermal simulation models Facilitate market penetration

Acknowledgments Thanks to NSERC for funding this research project as a part of the NEWBuildS strategic research network FPInnovations, Nordic Engineered Wood, and

71 Acknowledgments Thanks to NSERC for funding this research project as a part of the NEWBuildS strategic research network FPInnovations, Nordic Engineered Wood, and Henry for building materials Robert Lepage, Emily Vance, and Sam Siassi for their generous donations of time, effort, and knowledge in commissioning the test wall.

Developing Durable CLT Building Enclosure Assemblies

Developing Durable CLT Building Enclosure Assemblies Dr John Straube, P.Eng. University of Waterloo Faculty of Engineering / Architecture Co Investigators: Dr Hua Ge Ruth McClung / Robert Lepage Durable