Properties of Paulownia Timber
1. Weight - Paulownia is a very light timber. At a dry density of around 280 kg/m³ Paulownia
is lighter than most common timbers. Density comparisons are Western Red Cedar
(340), Meranti (580), Pine (500), Teak (750), Robinia (750).
Contactform
2. Strength - With a modulus of elasticity (stiffness) of 5.6 GPa and a
modulus of rupture (bending strength) of 28 MPa, Paulownia is not classified as
a structural timber in its natural state. However because of its light weight, Paulownia
has a high strength to weight ratio, an important feature in the various uses
of the timber.
3. Deformation & Warping - The shrinkage co-efficient of Paulownia
is very low compared to most timbers being 0.094 radially, 0.268 tangentially
and 0.362 in volume giving the dried timber a high level of dimensional
stability.
4. Hardness - The Janka hardness rating for Paulownia is low at 1.3 kN.
Western Red Cedar is rated at 1.5 and Meranti 2.6. While modern treatments can
substantially harden up a finished surface, Paulownia is not suitable for
flooring or areas where physical damage is likely.
5. Durability - The in-ground durability rating for Paulownia is 4 and
the timber should not be used for that purpose. Paulownia used for other
external uses out of ground has a similar durability to western red cedar and
should be treated with at least two coats of a water repellent sealant.
6. Resistance to Decay - Paulownia is highly resistant to insect attack
and rot. Research carried out by Queensland Forestry Research Institute in
Australia indicates the timber to be unattractive to termites. Rot showing on
neglected timber tends to be surface deep only.
7. Thermal Insulation - With one of the lowest thermal conductivities
for wood of just 0.07 Kcal/m/hr/Cdeg, Paulownia has an excellent heat
insulation capability being one of the best heat insulating timbers and far
superior to brick, concrete or steel.
8. Fire Resistance - With an auto ignition temperature of around 400 deg
C (most hardwoods around 220 deg C) Paulownia is reported to have a flame
spreading rate considerably below most building codes.
9. Finishing - The sap of Paulownia is not gum or resinous based, thus
the application of finishing products with various solvents as carriers does
not risk any interaction with the timber, contributing to the very good
finishing properties of Paulownia products. The timber readily takes stains,
estapols and paints with excellent finished surfaces.
10. Workability - A major feature of Paulownia timber is its ease of
working. All aspects of carpentry such as machining, nailing, screwing, gluing,
sanding, sawing and handling are very user friendly with no splinters, cracking
or splitting and excellent take-up of glues and finishes.
