Intro to Timber-Framed residential Building Design
Summary
TLDRThis video series explores various aspects of timber framing design for residential buildings, focusing on Australian Standard AAS 1684. It covers timber components for structures up to two stories, detailing the differences between cyclonic and non-cyclonic areas. The video explains timber grading methods, including visual and machine grading, and the importance of selecting appropriate timber grades for construction. It concludes with an overview of timber strength classifications and their application in designing timber-framed houses.
Takeaways
- 🏠 The video discusses timber framing design for residential buildings, focusing on Australian Standard AAS 1684.
- 📚 AAS 1684 is divided into four parts, addressing different aspects of timber-framed construction, including non-cyclonic loads and cyclonic areas.
- 🏗️ The standard primarily applies to Class 1 and Class 10 buildings, which include residential dwellings and non-habitable structures.
- 📏 It provides span tables for various timber members needed in a timber-framed house, considering different wind classifications and stress grades.
- 🌳 Milled timber is classified into different grades based on visual or machine grading, which helps designers select the appropriate strength for each member.
- 👀 Visual grading involves a person assessing the timber's defects, knots, grain slope, and assigning a grade based on its strength.
- 🤖 Machine grading assesses timber stiffness and assigns a color-coded grade, with the lowest stiffness value indicating the timber's strength.
- 🔍 The F-grade or MGP grade of timber must be specified by designers to ensure it meets the required strength for the application.
- 📉 Timber species vary in their F-grade values, with hardwoods generally having higher values than softwoods, though exceptions exist.
- 📊 The video includes a table illustrating the range of F values available for different timber species, with hardwoods in the shaded region.
- 🔍 Understanding the F-grade's meaning and its relation to timber strength is crucial, but the derivation process is not necessary for designers to know.
Q & A
What is the Australian standard AAS 1684 related to?
-AAS 1684 is an Australian standard related to the design of residential timber-framed construction, covering timber components in buildings up to two storeys high with specific limitations on dimensions and roof pitch.
What happens if a timber component falls outside the limits of AAS 1684?
-If a component falls outside the limits of AAS 1684, other Australian standards such as AS 1720 for tender structures or AS 4100 for steel structures might need to be referred to.
How many parts does AAS 1684 consist of, and what do they cover?
-AAS 1684 consists of four parts. The first part deals with the derivation of values used in span tables, parts two and four deal with non-cyclonic loads, and part three addresses the design of timber framing in cyclonic areas.
What types of buildings does AAS 1684 primarily deal with?
-AAS 1684 primarily deals with Class 1 and Class 10 buildings as defined in the Building Code of Australia, which includes houses and other residential dwellings, as well as non-habitable structures like sheds and carports.
How does AAS 1684 categorize wind classifications for timber framing?
-AAS 1684 has different tables for different wind classifications, which are used to design timber framing according to the wind conditions of the area.
What are the two different methods of grading milled timber in Australia?
-The two different methods of grading milled timber in Australia are visual grading and machine grading.
How is visually graded timber assessed?
-Visually graded timber is assessed by a person who examines the piece of timber for the number of knots, defects, slope of the grain, and how it has been cut, then classifies the grade of the timber accordingly.
What does the stamp on a visually graded timber indicate?
-The stamp on a visually graded timber indicates the strength of the timber according to its grade, the grading method (visual or machine), the stress grade, whether it's seasoned or unseasoned, the species, the name of the milling company, and the Australian standard used for grading.
How does machine grading assess the timber's stiffness and strength?
-Machine grading involves passing the timber through a machine that bends the timber and assesses its stiffness. The machine squirts a color of paint on the timber to indicate its stiffness, with the lowest value being the stiffness of the timber piece.
What is the significance of the F-grade or MGP grade in timber design?
-The F-grade or MGP grade indicates the strength and modulus of elasticity of the timber, which is crucial for a designer to specify the right strength for a particular application in timber framing.
Why is it important to understand the F grade of a timber piece?
-Understanding the F grade is important to ensure that the timber used has the appropriate strength for its intended application in the timber frame, but the specific derivation process of the grade is not necessary to know.
Do hardwoods always have higher F grade values than softwoods?
-Hardwoods tend to have higher F grade values than softwoods, but this is not a strict rule as there can be variations among different species.
What is the purpose of the table showing the range of F values for different timber species?
-The table provides an idea of the range of F values available for different timber species, helping to understand the relative strength of hardwoods and softwoods and to make informed choices in timber selection for construction.
Outlines
🏗️ Design and Standards of Timber Framing
This paragraph introduces the topic of timber framing design for residential buildings, focusing on the Australian Standard AAS 1684. It explains that this standard covers timber components in buildings up to two storeys high with specific dimensional limits. The standard is divided into four parts, with the first detailing the derivation of values in span tables, and parts two and four addressing non-cyclonic loads. Part three specifically deals with cyclonic areas. The standard is applicable to Class 1 and Class 10 buildings, which include residential dwellings and non-habitable structures. The paragraph also discusses the classification of timber into different stress grades based on visual or machine grading, which helps designers select the appropriate timber strength for specific applications.
🌳 Understanding Timber Grades and Species
The second paragraph delves into the concept of timber grading, emphasizing the difference in F-grade values between hardwoods and softwoods. It provides a visual representation of the range of F values available for various timber species, with hardwoods typically having higher grades. The paragraph concludes the video on timber frame construction and grading, and it previews the next video, which will explore timber framing elements in a residential house using a model of a timber-framed building.
Mindmap
Keywords
💡Timber Framing
💡Australian Standards (AAS 1684 and AS 1720)
💡Cyclonic Areas
💡Building Code of Australia
💡Timber Grades
💡Visually Graded
💡Machine Grading
💡Modulus of Elasticity
💡F Grade
💡Seasoned Timber
💡Span Tables
Highlights
The video series explores design aspects of timber framing for residential buildings, referencing Australian Standard AAS 1684.
AAS 1684 covers timber components in buildings up to two storeys with specific dimensional limits and roof pitch.
Components outside AAS 1684 scope may require reference to Australian Standard 1720 or other standards.
AAS 1684 is divided into four parts, with the first detailing the derivation of values in span tables.
Parts two and four of AAS 1684 address non-cyclonic loads, while part three focuses on cyclonic areas.
The standard primarily deals with Class 1 and Class 10 buildings as defined by the Building Code of Australia.
Different wind classifications and stress grades for seasoned and unseasoned timber are considered in AAS 1684 tables.
Milled timber is classified into various grades based on visual or machine grading methods in Australia.
Visually graded timber is assessed by a person for knots, defects, and grain slope to determine its grade.
Machine grading evaluates timber stiffness and assigns a color-coded classification based on modulus of elasticity.
Timber strength is indicated by an F-grade or MGP grade, crucial for specifying the right strength for applications.
Understanding F-grade importance for timber strength is essential, though derivation specifics are not necessary.
Hardwoods generally have higher F-grade values than softwoods, though exceptions exist.
A table is provided to illustrate the range of F values available for different timber species.
The video concludes with a teaser for the next installment, focusing on timber framing elements in a house model.
Transcripts
in this series of short videos we'll be
taking a look at some of the aspects of
the design of timber framing for a
residential building one of the
Australian standards relating to this
topic is AAS 1684 residential timber
framed construction this australian
standard deals with all of the timber
components in a timber framed building
up to two storeys high and with certain
limits on the dimensions the roof pitch
etc if a component falls outside of this
code then australian standard 1720
tender structures or a s 4100 steel or
another australian standard might need
to be referred to as 1684 comes in four
parts the first part deals with how the
values used in the span tables and the
other parts have been derived parts two
and four of a s 1684 deal with non
cyclonic loads type four is a simplified
version part three of this australian
standard deals with the design of timber
framing in cyclonic areas generally
speaking a s 1684 deals with class 1 and
class 10 buildings as defined in the
building code of Australia that is
houses and other residential dwellings
which may be brick veneer or timber
framed
weather board clad or fibro clad
buildings or non habitable structures
such as sheds and carports a s 1684 has
different tables for different wind
classifications also for different
stress grades for seasoned versus
unseasoned timber and each set of tables
includes a span table for every timber
member that you might need to design you
timber-framed house timber that is
milled is classified into different
grades so that a designer can choose the
appropriate grade or strength that is
required for a particular member in the
timber frame milled timber is graded
according to usually one of two
different methods in Australia these
being visually graded or machine great
visually graded timber is exactly that a
person will look at the piece of timber
at the number of knots at the number of
other defects in it the slope of the
grain according to how it's been cut and
assess what grade the piece of timber
should be stamped out or classified as
that grader will put a stamp on the
piece of timber like this which will
indicate the strength of the timber
according to grade the stamp on the
piece of timber will generally indicate
how that piece of timber was graded
whether visually or machine graded the
stress grade of the timber whether it's
seasoned or unseasoned the species and
also the name of the milling company it
will also generally include the
Australian standard that's been used for
the grading method machine grading is
used for some species of pine the piece
of timber is passed through a machine
which bends the timber and assesses its
stiffness as the piece of timber passes
through the Machine and the Machine
assesses the stiffness it will squirt a
color of paint on the piece of timber so
there may be several different colors
along the piece of timber indicating the
stiffness the stiffness of the timber
piece will be the lowest value that's
been squirted onto the piece of timber
the f-number on this piece of timber f/8
in the case that is that it has a safe
working stress of 8 mega Pascal's for
machine grading the value that's
determined is called the modulus of
elasticity this gives a different
number two the F grade but it's still an
indication of the strength of the timber
so this piece of timber which is mg P 10
its modulus of elasticity would be
approximately 10,000 mega Pascal's as a
designer you would need to specify the F
grade or the MGP grade of the timber
making sure that it's the right strength
for the particular application it's
important to understand what the F grade
means for a piece of timber and its
strength but it's not important to know
how it was derived different species of
timber tend to fall into different F
grades hardwoods tend to have higher F
grade values than soft woods although
that's not always the case this table
gives an idea of what range of F values
exist or are available for different
timber species the hardwoods are in the
shaded region and the bottom two are
soft woods that concludes our video on
timber frame construction and timber
grading our next video will talk about
some of the timber framing elements in a
timber framed house using a model of a
timber framed building
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