How to read residential structural drawings

Summary

This educational video offers a comprehensive guide on interpreting structural drawings, essential for industry professionals and homeowners alike. The host explains the importance of understanding these blueprints as they form the 'skeleton' of a building. Key elements such as general notes, foundation details, slab plans, and framing plans are discussed, with an emphasis on following the engineer's instructions precisely. The video demystifies symbols, materials, and specific structural elements, ensuring viewers can correctly implement the structural engineer's design to avoid costly mistakes.

Takeaways

• 🏗️ The video is aimed at helping various professionals, including carpenters, apprentices, builders, and engineers, understand structural drawings, which are crucial as they form the 'skeleton' of a building.
• 📝 General notes in structural drawings are essential for understanding the building's assembly and should be thoroughly reviewed for any special instructions or considerations.
• 📐 The foundation notes are particularly important as they include soil report details and site classifications, which are vital for proper footing design to avoid future rectification difficulties.
• 📊 Design loads mentioned in the drawings represent the forces considered by the engineer for the building's design, and additional items like trusses or windows should be designed according to these loads.
• 🏡 The video uses a waffle pod slab as an example, explaining its components like edge beams, internal beams, and the significance of dashed lines indicating non-visible elements in the plane.
• 🔍 Symbols and annotations on the drawings, such as load points and internal load-bearing walls, are key to understanding structural elements and their relationships.
• 🛠️ The video explains the importance of reinforcement and cover for beams and slabs, including the use of trimmer bars for crack control in re-entrant corners.
• 🔄 The framing plan details how different structural elements like timber posts, steel beams, and columns are connected, emphasizing the need to refer to legends and details for proper construction.
• 🏠 The first floor framing plan is used to illustrate the arrangement and connection of various structural components, including the significance of symbols indicating continuous or under-only elements.
• 🌪️ Bracing and tie-down plans are crucial for wind resistance, with the video detailing the types of bracing, their capacities, and how they are installed to ensure structural stability.
• 📝 The final sheet of drawings includes specifications for framing stud walls and additional notes on tie-downs, window seals, and lintel trimmers, which are important for the building's integrity and safety.

Q & A

What is the primary purpose of structural drawings?

Structural drawings are a set of instructions given by an engineer, essential for understanding how to correctly follow the structural engineer's instructions, as they form the skeleton of a building.

Why are general notes important in a set of structural drawings?

General notes are important because they help in understanding how the building is put together and provide information about the materials used and the responsibilities of the contractor.

What should a builder do if they need to include items outside the scope of the structural engineer's work?

A builder should pass on this information to the manufacturer, who will then design the item according to the design loads specified by the structural engineer.

Why are foundation notes considered super important in structural drawings?

Foundation notes are super important because they provide information about the soil report, the company that performed the soil investigation, and the site classification, which are crucial for ensuring the footings are founded into adequate material.

What does the term 'waffle pod slab' refer to in the context of structural drawings?

A waffle pod slab refers to a type of slab-on-ground system used in Australia, which consists of an edge beam around the house and a series of narrow internal beams represented by dashed lines.

What does a dashed line in structural drawings represent?

A dashed line in structural drawings represents an element that is not visible in that plane, such as concrete board piers under the beams or a grid of beams located under the slab plane.

What is the significance of the 'X' symbol found in the slab reinforcement details?

The 'X' symbol denotes trimmer bars to all negative corners for crack control, which helps prevent cracks from appearing in the re-entrant corners of the slab.

What is the role of a 'lintel' in structural framing?

A lintel is a beam that spans openings in a wall where windows and doors are installed, providing support for the structure above these openings.

Why is it important for a builder to understand the truss layout in roof framing?

It is important because if the truss layout changes, the load path may also change, which could require the structural elements to be revealed and redesigned.

What is the purpose of plywood bracings and tie-down rods in a building's structural design?

Plywood bracings and tie-down rods are used to resist wind forces and uplift. Bracings are sheets nailed to stud walls, while tie-down rods are steel rods that secure the structure against wind uplift.

How can a builder identify the required connections and details for framing from the structural drawings?

A builder can identify the required connections and details by referring to the framing plan for the specific members and then finding the corresponding detail on the framing details page.

Outlines

00:00

🏗️ Introduction to Structural Drawings

This paragraph introduces the video's focus on understanding structural drawings, essential for professionals in the construction industry such as carpenters, apprentices, draftees, builders, and engineers. It emphasizes the importance of these drawings as instructions from the engineer, which form the skeleton of a building. The speaker mentions that the drawings are provided by ESC Structural Engineers and starts with general notes, which are common to any set of drawings and help in understanding the assembly of the building. The paragraph also touches on the significance of the foundation notes, the soil report, and the builder's responsibility to reference the soil report for proper footings.

05:02

📐 Understanding Slab and Footing Details

The second paragraph delves into the specifics of slab-on-ground systems, particularly the waffle pod slab, which includes an edge beam and internal beams represented by dashed lines, indicating visibility in the plane. The speaker explains the use of symbols for load points and internal load-bearing walls (LBW), the slab's thickness and material specifications, and reinforcement details. It also discusses the importance of maintaining slab thickness in set-down areas and the role of various footings and structural elements like steel columns and beams in supporting the slab.

10:08

🔍 Analyzing First Floor Framing and Roof Framing

This paragraph examines the first floor framing plan, identifying various structural elements such as timber posts, steel beams, deck beams, joists, and steel columns. It explains the use of symbols to denote different types of columns and beams, and how to interpret their placement and support. The speaker also discusses the importance of understanding the load paths and the connection between different structural elements. The roof framing plan is introduced, including the member schedule for roof beams, trusses, and the note on the truss layout confirmation by the manufacturer before construction.

15:14

🛠️ Framing Details and Bracing Requirements

The final paragraph covers the framing details, explaining how to connect different types of beams and the importance of understanding the framing plan to execute the construction properly. It also discusses the ground floor and first floor bracing and tie-down plans, which specify the amount and length of plywood bracings and tie-down rods needed to resist wind forces. The speaker explains the difference between various bracing types, the forces they can withstand, and how they are connected to the floor and roof diaphragm. The paragraph concludes with specifications for framing stud walls and notes on tie-downs, window seals, and lintel trimmers.

Keywords

💡Structural Drawings

Structural drawings are technical documents that detail the structural components of a building and how they are to be constructed. They are essential for understanding the skeleton of a building and ensuring that it is built according to the structural engineer's specifications. In the video, the host explains how to read these drawings, emphasizing their importance in the construction process.

💡General Notes

General notes in structural drawings provide important information common to the entire set of drawings. They guide the reader on how the building is assembled and what materials to expect throughout the project. In the script, the host mentions reading general notes to understand the presence of still members and materials like concrete or timber framing.

💡Foundation Notes

Foundation notes are critical in structural drawings as they provide details about the soil report, the company that performed the soil investigation, and the site classification. These notes are vital for ensuring that the footings are built on adequate material, as correcting foundation issues after construction is extremely difficult. The script highlights the importance of the builder referencing the soil report and its recommendations.

💡Waffle Pod Slab

A waffle pod slab is a type of slab-on-ground system used in construction, consisting of an edge beam around the house and a series of narrow internal beams. In the video script, the host describes this system and explains how it is represented on the drawings with dashed lines, indicating elements not visible in that plane.

💡Reinforcement

Reinforcement in construction refers to the steel bars or meshes used to strengthen concrete structures. In the context of the video, the host discusses the reinforcement of the slab with a specific mesh and the use of trimmer bars for crack control in the corners of the slab.

💡Footing Schedule

A footing schedule is a part of structural drawings that provides details about the size and reinforcement of footings. It is crucial for the design and construction of the building's foundation. The script mentions that the host looks at the footing schedule to understand the details of pad footings and strip footings.

💡First Floor Framing Plan

The first floor framing plan is a specific type of structural drawing that illustrates the layout and details of the first floor's structural components. In the video, the host uses this plan to understand the arrangement of timber posts, steel beams, and other elements that make up the first floor's structure.

💡Load Path

Load path refers to the route through which forces are transferred from the roof or floors to the foundation of a building. The host explains that the truss layout affects the load path and that structural elements may need to be adjusted if the truss layout changes.

💡Lintel

A lintel is a horizontal structural element that spans over an opening such as a door or window. In the script, the host describes lintels as beams that go inside the wall and are crucial for supporting the structure above openings.

💡Bracing and Tie-Down

Bracing and tie-down systems are structural elements designed to resist wind forces and uplift. Plywood bracings are nailed to stud walls, while tie-down rods are steel rods that secure the structure. The host explains the different types of bracings, their capacities, and how they are installed according to the engineer's specifications.

💡Stud Walls

Stud walls are constructed from vertical wooden studs that form the framework for walls in many types of buildings. The script mentions the specifications for framing stud walls, including the size of studs, top plates, bottom plates, and noggings, which are all essential components of a stud wall.

Highlights

Introduction to structural drawings as essential instructions for building construction.

Explanation of the importance of understanding structural drawings for the safety and integrity of a building.

Overview of general notes in structural drawings that provide crucial information about the building's assembly.

Importance of design loads in structural engineering and their impact on building components.

Foundation notes' significance in ensuring the building's base is established on adequate materials.

Clarification on the responsibility of builders to refer to soil reports and their recommendations.

Identification of materials used in the building through the structural notes.

Introduction to the fling and slab plan as the starting point for structural plans.

Description of the waffle pod slab system and its components in Australian construction.

Explanation of symbols and their meanings in structural drawings, such as load points and load-bearing walls.

Details on slab thickness, concrete strength, and reinforcement requirements.

Importance of trimmer bars for crack control in structural slabs.

Understanding of footing and slab blends through typical sections and details.

Identification of different types of beams and their roles in supporting the building structure.

Explanation of symbols and legends used in structural framing plans.

Analysis of the first floor framing plan to understand connections between various structural elements.

Importance of understanding the load paths in roof framing and the role of trusses.

Details on how to connect structural elements as per the framing details page.

Explanation of bracing and tie-down plans for wind resistance in structural design.

Specifications for framing stud walls and additional notes on construction details.

Transcripts

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