The heaviest and lightest woods.
The Guinness Book of World Records lists the South African black ironwood (Olea laurifolia) as the heaviest wood with a specific gravity of 1.49
, and the tropical American balsawood tree (Ochroma pyramidale) is one of the world’s softest and lightest woods with a specific gravity of only 0.19.
Archaeologists have unexpectedly uncovered London’s oldest timber structure, which predates Stonehenge by about 500 years.
Wood species.
Timber framing.
What is the difference between log, timber framing, and post & beam?
Log: round and squared off, stocked horizontally, creating walls.
Timber framing: (specialized version of post & beam) that is built like furniture, using mortise and tenon joinery held in place with wooden pegs.
Post & beam: upright posts supporting horizontal beams.
*Timber post & beam: post and beam structures made of heavy timber, fastened with metal bracket.
What are the benefits of timber framing?
Aesthetic: The feel of a timber frame building is one of warmth, strength and security. The quality of the woodworking is apparent; reminding occupant of the care and craftsmanship that went into the construction of the house.
Open floor plan: Since there are typically no interior load bearing walls, the floor plan can be very open, and can be changed as the needs of the occupants change.
Longevity: Timber frames are structurally very sound buildings which will last hundreds of years. And unlike log homes, there are no maintenance or settling problems to worry about.
Energy efficiency: Timber frames are usually completely enclosed in an envelope of insulated panels. These panels are more energy efficient than conventional framing and insulation methods, preventing air leaks so that heating and cooling costs are lower.
Defects in Lumber.
Defects due to conversion
Occurs during the process of converting timber into commercial form;
- chip mark: this defect is indicated by the marks or signs placed by chips on the finished surface of timber
- diagonal grain: improper sawing of timber
- torn grain: when a small depression is made on the finished surface due to falling of some tool
- wane: presence of original rounded surface on the finished surface
Defects due to fungi
When,
- the timber moisture content is above 25%
- the environment is warm enough
- there is lots of air
the fungi will attack the timber.
Fungi timber defects:
- blue stain
- brown rot
- dry rot
- heart rot
- sap stain
- wet rot
- white rot
Defects due to insects
- beetles
- marine borers (barnea similis)
- termites
- carpenter ants
Defects due to natural forces
- abnormal growth
- rupture of tissues
Defects due to seasoning
One of the cause for splinters and slivers.
Engineered Lumber.
4. Glue-lam Beams
Size: Created from 2×4 or 2×6 stock by gluing the faces together to create beams such as 4×12 or 6×16. By gluing multiple, common sized pieces of lumber together, they act as one larger piece of lumber - thus eliminating the need to harvest larger, older trees for the same size beam.
5. Manufactured Trusses
Function: Used in home construction as a pre-fabricated replacement for roof rafters and ceiling joists (stick-framing).
Engineered Lumber.
3. Finger-Jointed Lumber
Size: Solid dimensional lumber lengths typically are limited to lengths of 22 to 24 feet (6.7 to 7.3 meter), but can be made longer by the technique of finger-jointing lumber by using small solid pieces, usually 18 to 24 inches (45.7 to 60.9 centimeter) long, and joining them together using finger joints and glue to produce lengths that can be up to 36 feet (10.9 meter) long in 2×6 size.
Finger-jointing also is predominant in precut wall studs. It is also an affordable alternative for non-structural hardwood that will be painted (staining would leave the finger-joints visible).
Woods Of Net by Tezuka Architects.
