1. www.fpinnovations.ca
Design and Treatment
Specifications for Durable
Disaster Relief Housing
Paul Morris and Jieying Wang
Durability and Protection Group
FPInnovations

2. Durability Concerns for Disaster Relief Housing
• Need to maximize number of shelters pushes
down cost which leads to simplified designs with
fewer moisture management features
• May be difficult to control construction quality
• Temporary structures tend to become permanent
• Occupier improvements may increase moisture
and termite problems
– Addition of untreated wood invites decay and termites
– Addition of concrete embeds wood
– Addition of cladding or insulation hides termites

3. Durability Concerns for Disaster Relief Housing
In tropical/subtropical countries
• High humidity and rainfall promotes decay
• Warm temperatures favour termites
In extreme northern climates
• High occupancy - high interior moisture load
• High insulation can promote condensation

4. Understanding the Decay and Termite Hazard
• Scheffer index values indicate decay potential
– Derived from equation using rainfall and temperature data
• 3 main divisions in termite hazard zones
1. No termites – wood boring beetles may be a problem
2. Reticulitermes and other termite species. No Coptotermes
3. Coptotermes species present, drywood termites also likely
• Get expert advice
Beetle attack on local
hardwood in Aceh

5. Native termites in Haiti
• Subterranean termites Reticulitermes sp.
• Drywood termites Cryptotermes sp.
• Tree-dwelling termites Nastitutermes sp.

6. Coptotermes formosanus is the world’s most
economically important termite pest

7. Potential Transport of Coptotermes to Haiti etc.
• Termites can be transported via trade or aid.
Drywood termites
Formosan termites ?

8. Native termites in Indonesia
• Copotermes gestroi mainly in cities
– C. formosanus sophisticated cousin
• Coptotermes curvignathus mainly in rural areas
– C. formosanus hillbilly cousin
• Best to consider all Coptotermes as equally bad
• ~198 other species

9. Moisture Management
Design Solutions for Durability
Moisture Management
The 4Ds
• Deflection
– Divert water
• Drainage
– Let water go
• Drying
– Allow to dry
• Durability
– Durable materials
Hazleden, D.G., Morris, P.I. 1999.

10. Moisture Management
Design Solutions for Durability
Moisture Management
Vapour Control in
Northern Climates
Vapour/air
barrier on the
inside

11. Moisture Management
Design Solutions for Durability
Moisture Management
Vapour Control in
Tropical Climates
Vapour/air
barrier on the
outside

12. Design Solutions for Durability
• Pitched roof with overhangs on all sides
• Minimize penetrations in roof
• Minimize rainfall traps
• Minimize wood-soil contact
– Even if treated, this can attract termites
• Minimize penetrations through slab
– Termites enter through cracks
• Design should be congruent with local custom

13. Design Solutions for Durability
• Support posts above concrete
– Prevent wicking of water
– Facilitate inspection for termites
Ain’t
• Raised floor nobody
here but us
– Reduced flood damage chickens
– Improved ventilation
– Facilitates inspection and termite control
Chickens eating tree-
dwelling termites in Cuba

14. Integrated Termites Management : The 6Ss
Developed Countries
Suppression
Surveillance
Structural
BUG OFF
Site durability
management
Slab/foundation
Slab/foundation
Soil barrier

15. Integrated Termites Management : The 3Ss
Disaster Relief
Structural
Site
management durability
Slab/foundation
Slab/foundation

16. Integrated Termites Management : The 3Ss
Drywood
Formosan termites
termites?
Tree
dwelling
termites Structural
Site durability
management
Slab/foundation
Slab/foundation
Subterranean
termites
Slab/Foundation detailing does not stop all termites

17. Integrated Termite Management
Structure Durability
• Most of our species are not termite resistant
• Exceptions:
– Western red-cedar is non-preferred but still gets eaten
– Eastern white-cedar is non-preferred but still gets eaten
– Yellow cedar is the most termite resistant
• For most species, treatment is the only option
– Note: thermal treatment is not effective vs termites

18. Preservative Treatment Options
Not only the lumber needs to be treated
• Plywood and PSL can be pressure treated
• OSB can be treated during manufacture
• LVL very difficult to treat – avoid
• I-joists need to be made from treated material
• Glulam reacts badly to waterborne treatment
– Oil borne preservatives not appropriate for residential
– LOSP (Hi-Clear or Cu-nap) treatment not available in Canada
– Can treat lamina prior to gluing

19. Preservative Treatment Options
Must consider
• Regulations in exporting country
• Regulations in importing country
• Potential for human contact
• Building design
• Wood species
• Local decay and termite hazards

20. Preservative Treatment Options
• Many countries have their own standards
– Former British colonies may use British (European) standards
– American dependencies use AWPA standards
– French colonies may use French ( European) standards
• All should be using ISO 21887 Use Classes
– UC 1 Interior, dry
– UC2 Interior, damp
– UC3 Outdoors above ground
– UC4 Outdoors ground contact

21. Preservative Treatment Options
• Canadian species mostly impermeable heartwood
• Tough to meet foreign treatment standards
• After intensive research by FPInnovations and
UBC, Canadian standards for outdoor residential
lumber have been reduced
– No penetration requirement for 2x4 and smaller
• These specifications are fine for northern climates
• Not for tropical/subtropical regions
• Shallow penetration won’t stop termites

22. Preservative Treatment Options
• ACQ and CA Pressure Treatment
– Require incising (perforation) - 25% strength loss
– React with wood. Stop moving when pressure stops
• Borate Pressure+Diffusion Treatment
– Does not require incising
– Don’t react with wood. Keep moving when pressure stops
• New surface-applied penetrating process
– Chemistry and process provide deep penetration
• In process Zinc-borate treatment of OSB
• Surface-treatments

23. Preservative Treatment Options
• ACQ
– Copper ethanolamine – algaecide for pools and hot tubs
– Quaternary ammonium – disinfectant for surfaces and swabs
• CA
– Copper ethanolamine – algaecide for pools and hot tubs
– Azole – related compounds in dandruff shampoo/athletes foot cream

24. Preservative Treatment Options
ACQ and CA pressure treatment
• Choice of species is critical
High-density Incised White Spruce
Incised white spruce Incised Pacific Silver fir

25. Preservative Treatment Options
Termites eat through a thin shell of treatment

26. Preservative Treatment Options
Termites give up if treated shell is thick enough

27. Preservative Treatment Options
Or, if they get through, the box is strong enough

28. Preservative Treatment Options
• That is why I favour borate treatment
• Borates penetrate our wood
Red colour with reagent shows borate penetration

29. Preservative Treatment Options
Borates have a
positive perception
• Got it on your hands?
• Got it on your clothes?.
• Got it in your eyes?
• Got hungry?
• Got boron ?

30. Preservative Treatment Options
Above ground protected termite test
400mm 1000mm
m
600mm

31. Preservative Treatment Options
Performance of treated samples in Hawaii
10
9
8
AWPA termite rating
7
6
5
4
3
2
1
0
0 2 4 6 8 10
Years of exposure
hem-fir control ACZA 2% shell 3% shell
2% through 3% through 2%+DDAC CCA

32. Preservative Treatment Options
• In Hawaii almost all wood-frame homes are
100% borate treated.
• Higher loadings required for Formosan
termites than in CSA – Use AWPA standards
• Borates not for use outdoors exposed to rain
– Except under well maintained 3-coat paint finish

33. Preservative Treatment Options
New surface-applied penetrating process
• Developed for New Zealand market
• Penetrating formulation
– Various fungicides and insecticides can be added
• Dip or spray
plus kiln-
conditioning

34. Preservative Treatment Options
New surface-applied penetrating process
Treatment results on BC SPF (pine)
Red colour with reagent shows penetration

35. Preservative Treatment Options
New surface-applied penetrating process
Treatment Rating (10-0) at 2 yrs
Control (untreated) 2
Borate (sub-standard) 8
Formulation 1 9
Formulation 2 10
Formulation 3 10

36. Preservative Treatment Options
• ZB added to OSB during manufacture
• Added as a powder at the blender
• Effectively treats full cross section
• ZB is resistant to leaching
• Factory coated/sealed boards for
exterior use
• Field tested in Hawaii*
*Image courtesy of Peter Laks, Michigan Tech University

37. Preservative Treatment Options
• OSB Treated with ZB During Manufacture
Data courtesy of Peter Laks, Michigan Tech University

38. Preservative Treatment Options
Other Treatments
• What are the active ingredients?
– Vs decay
– Vs termites
• What loading is achieved?
• What penetration is achieved?
• What standards are met?
• What long term field test data are available?
– Lab testing is not good enough – small samples easily treated
• What are the warranties?

39. Preservative Treatment Specifications
• Treated wood off the shelf likely won’t perform
• Don’t accept “treatment to refusal”
• Get expert advice
• Specify standard and subsection
• Specify preservative and species
• Treatment certificates are worth
the value of the paper and the ink
• Use third party quality assurance

40. Preservative Treatment Specifications
• For Britco pre-fab homes for tsunami relief
in Indonesia we recommended to FII:
– ACQ treated plywood sheathing – no cladding supplied
– Incised ACQ treated hem-fir for outside
– Borate treated SPF for inside
protected from rain

41. Preservative Treatment Specifications
• For home kits for earthquake relief
in Haiti we recommended to SNC Lavelin:
– ACQ or CA treatment for all components because all components
were potentially exposed to soil or rain –long term
Prototype with untreated components. Photos courtesy of SNC Lavelin

42. Design plus Preservative Treatment
• Britco houses in Aceh inspected after 4 years
No evidence of insect attack. Minor instances of decay
Photo courtesy of Jim Creffield, Onwood Consulting

43. Without Preservative Treatment?
• Housing built in Aceh using untreated local
materials attacked by termites after 6 months.
– Source: representive of aid group
• Housing built in Haiti using imported material
with treated sheathing and untreated framing
– Not a good idea

44. Conclusions
• Fit design and treatment to local hazards
• Simple design solutions can improve durability
• Preservative treatment is needed vs. termites
– Deep penetration essential for termite protection
• Most Canadian species resist pressure treatment
• Diffusible/pervasive treatments are best
• Borates as effective as CCA under cover
• Tru-core process looks promising
• Specify precisely
• Quality assurance is critical

45. Any Questions