welcome back to the channel and in today's video we're gonna go through a set of
structural drawings i have to admit that i had a lot of trouble trying to figure out
how to read structural drawings when i first started working in the industry so if you are
a carpenter apprentice draftee builder young engineer architect and even if you don't work
in the industry but you are you might be building your house this video will help you to understand
how correctly follow the structural engineers instructions which is pretty much what structural
drawings are they are set of instructions given by the engineer and it's essential that you get
it right because that's the skeleton of your house and you don't want to get that wrong all right so
let's get into it these drawings are a courtesy of esc structural engineers on the gold coast
on our first page is the general notes so general notes are common to any set of drawings and the
notes are usually organized to help you understand how the building is put together so if i read here
structural still i can expect seeing still members in this project if i read concrete or timber
framing that means i will see these materials throughout the project we start from the top left
corner we've got a couple of general notes about the drawings and the contractor responsibilities
we also have the design loads that the structural engineer considered to design the house
so if you're a builder and you need to include items that are outside of the scope of work of
the structural engineer like trusses windows or any proprietary structure you can pass on
this information to the manufacturer and they will design this item according to these loads
down here is the foundation notes this item is super important because it is where you will
find the soil report number name of the company which performed the soil investigation and the
site classification the foundations is the base of your house and you want to make sure the footings
are founded into adequate material because once it's done to rectify any foundation problem
is extremely difficult and it's the builder's responsibility to make reference to the soil
report and its recommendations so basically you should go through every note on this page and
make sure you understand everything you read and if in doubt ask your engineer also on the
title block it says he issued for construction so i expect this to be the final drawings if it says
issued for tender or preliminary you should not be building off this set of plans so to summarize by
going over the structural notes what i've learned is that this building is made of a bunch of
different materials like concrete steel and timber as well as that the structural engineer wants me
to follow the instructions and specifications shown on this page moving to the next page
plans tend to go in sequence from bottom to top so our first plan should be the fling and slab plan
when it comes to slab on ground we have two main systems used in australia
first one is a rough slab and the second one which is what we've got here is a waffle pod slab which
is built on top of a flat ground and this waffle pod slab consists of an edge beam that goes all
around the house and a series of narrow internal beams which is represented by these dashed lines
by the way a dashed line means that the element is not visible in that plane okay so for instance bp
ones are concrete board piers and they are under the beams that's why we use dashed lines same for
the grid of beams which are located under the slab plane what else i can see here is that under every
load bearing wall i have a larger beam and the same applies to point loads and how do i know what
this symbols represent so it should be all in the bottom of this page so here this symbol denotes
load point and lbw denotes internal load bearing wall the slab should be 85 millimeters thick
25 mpa concrete with a layer of top mesh here you have information about reinforcement and
cover of beams and slab this letter x denotes trimmer bars to all negative corners for
crack control so if we zoom in on the planes you will find this letter x in every re-entrant corner
of the slab they will prevent cracks to appear i can also see some of the pods have this hatch
let's see what that is so the notes locally reduce pad level or part high to maintain slab thickness
in set down areas refer typical sections and details so let's have a look at this detail
so basically we have a step to an outdoor area and we need to reduce the part high to maintain
slab thickness we also have some sc1s pf1 sf1 sc1 the node steel column and if you want to
know the size of this column you should refer to the framing plan pf1 is a pad footing and
sizing reinforcement can be found on the footing schedule sf1 is a strip footing on the top corner
there is a note saying that all footings should be founded into sandy clay with minimum 100 kpa
allowable bearing capacity so my understanding is that we will not achieve 100 kpa at ground level
and this is the reason the engineers specified board piers to support the slab next page should
be the details for the footing and slab blends so let's zoom in in a typical waffle pot slab section
this narrow beam is called ribs and it has 1 and 12 rebar central represented by this circle
this was dashed line on the plants because it's underneath the slab as you can see here
on this side we have a brick veneer wall
which consists of a brick and a timber wall separated by a gap so if i go back to the plants
you can see these walls here so brick on the outside and chamber on the inside and
where i don't have anything it means there is a door or window or any sort of opening
going back to the detail this edge being is 300 wide by 310 deep with three l11 tm at the bottom
so tm is strange mesh with three longitudinal bars of 11 millimeters and then we have a typical
slab which is 85 millimeters thick reinforced with sl82 mesh at the top which is this dashed
line here let's jump to the first floor framing plan and try to figure things out together here
looking at this corner we have three timber posts we have a steel beam a deck beam deck joists
and a couple of steel columns we do have some symbols here that i don't know what they denote
therefore i need to look for the legend right so we have a hashtag this letter c
and we also have this sc1 in brackets so looking down here c1 denotes column posts above above only
therefore i know that this three poles are above only okay so they're sitting on the steel beam
c1 in brackets denotes column or posts under only okay so this sc1 is under these two being
therefore supporting the steel beam okay easy and then the c denotes continuous
so this column here is continuous from the ground floor to the roof okay cool and the
hashtag denotes floor beam to be within the plane of the joists okay so we know that
the beam and the joists are in the same level so the deck joists run in plane with the steel beam
we've got fj3 fj3 is 360 ijoys at 450 centers
floor joists and they run from top to bottom of the page being supported by these walls and lingus
so fg3 starts from here to here and then fj2 goes from here to here
this hatch denotes wet area set down which could be which could be a bathroom for example
that's why we have a different size of joists in this section so fj2 is a 300 ijoys which is
60 millimeters shallower than fj3 therefore it creates a 60 millimeters step to the bathroom
so note that in this section here the engineer
rotated the joist so fj 3 runs from side to side of the page and it's been supported by
this wall here on this side and on the other side by this nib wall this linto and this being
this b3 continuous spans from this wall lands
on this two column under picks up this other b3 and then lands on sb2 which is a steel beam
sb2 is supported on this side by steel column let's do column under while on the other side is
being supported by a still linto notice that i've got hashtag hashtag and sl1 doesn't have a hashtag
so i'll quickly show you some details so you can understand this better so b3
b3 connects to b3 they both have the hashtag symbol which means they are in the same plane
the still lintel didn't have a hashtag symbol and that means the steel beam will land
on top of the steel into they're not in the same plane if they were in the same plane
the detail would look like something like this
so let's pan around a little bit we have a set of stairs here there's a void here another void here
there's a wing beam next to the void to deal with the lateral forces there's this little
symbol here which denotes load point on no load bearing wall so this being three is landing on
this known load bearing wall therefore the builder needs to provide extra studs under this point load
okay in this section we have some roof beams and trusses so this tells me that the roof
the floor framing the floor framing finish here and the lower roof framing started here
let's jump to the roof framing plane now i'm going to have a look at the member schedule first
so we have lentils roof beams trusses hip trusses gear trusses and truncated gear trusses there
are no size for the trusses because they're designed and installed by a truss manufacturer
however the engineer will still do a layout with the trusses location so we can identify the load
paths and design roof beams and link tools and there's a note on the top of the page saying beams
lintos and tie downs design has been based on the trouser layout shown truss layout to be confirmed
by truss manufacturer prior to construction and that's because if the truss layout change
the load path may also change and the structural elements may have to be revealed and redesigned so
i've got lintels here lintos lintos are beams that go inside of the wall and span openings
where windows and doors are installed so have lintels at all openings in the external walls
truncated girded truss are usually located 2.4 meters away from the external wall i'm seeing that
we've got a couple of roof beams those three three timber poles starting from the first floor now
are in brackets because they are under the roof framing and the way you read this framing plan is
pretty much the same way you read the floor framing plan so i'm not gonna spend much time
here so next page is the framing details this page is gonna be organized in a way that the builder
can understand how the framing is put together so for example on the framing plane we have b3 to b3
and b3 is a 360 lvl therefore if i go back to the framing details page
we should have a detail on how to connect a 360 chamber beam to another 360 chamber beam
let's find another example on the framing plan so we've got b3 is connecting to sb2
b3 as we know is a 360 timber and sb2 is a 300 pfc so going back to the framing details
if i'm if i'm a builder i know that i have to weld a 10 millimeter plate to the pfc
and bolt that to the timber beam with four m12 volts and that's how you read any other detail
on this page you go to the framing plan and you find the connection on the framing details page
next is the ground floor bracing and tie down plan which is where the structural engineer will
specify the required amount and length of plywood bracings and tie down rods so plywood bracings are
sheets nailed to the stud walls to resist the wind force and the tie-down rods as the name suggests
are steel rods that hold down the structure against wind uplift so let's start from the notes
all external and internal load-bearing walls require m12 1800 tied down so in other words
the builder will have to identify all load bearing walls and install m12 rods spaced
at 1800 millimeters at the bottom of the page we have some forces in kilonewtons and what this mean
is that the engineer calculated that for this specific house the wind loading might get as
high as 71.4 kilonewtons in this direction and 56 kilonewtons in the other direction and the sum of
the capacity of all bracings is the provided force in kilonewtons and obviously needs to be greater
than the required so if we look at the plan we have 600 millimeters long steel truss which could
be a power truss or net brace i'll show you how it looks like here so this is a power truss detail
we have roof straps and we also have the ply bracings so p2 1200 is a 1200 millimeters long
ply bracing and p1 600 is a 600 millimeters long ply brace i'll show you the difference
between p1 and p2 shortly so first floor bracing and tie down is the same thing and then we have
the bracing details page which is where we're going to find the difference between p1 and p2
so p1 offers a 6.4 kilonewtons per meter bracing capacity and it requires m12 rods at each end
while p2 offers a 6 kilo newtons per meter bracing capacity for a minimum 900 millimeters length it
doesn't require rods but it requires m12 bolts at each end and at 1200 maximum and also the space
the spacing between nails to the top and bottom plates are reduced to 50 millimeters instead of
150 we do have these other two methods here but they're not used much from my experience
next page shows us how to connect these bracing walls to the floor and roof diaphragm and also
the power truss as i showed before and finally on the last sheet you will find specifications on
how to frame the stud walls including size size of studs top blades bottom blades noggings and
also a couple of notes about the tie down window seal or lintel trimmers and that's pretty much how
you read structural drawings hope this video was helpful to you if you have any questions
just drop a comment below and i will see you in the next video