Example Canopy Design and Documentation: Carports, Verandahs and Pergolas

Typically our involvement with carports, verandahs and pergolas, or more generally canopies, is the supply of structural reports or certification. Both reports and certification involve structural calculations. The difference between the report and certification is that we don’t compile the calculations into a report and issue the calculations. Instead with certification we summarise critical values from the calculations, and mention these in the discussion part of the certificate. Certification is only really appropriate for simple common place structural forms. As the structural form gets more complex, summarising becomes more cumbersome.

Site Measurement, and Sketch Proposal

Typically builders, manufacturers sales agents, or owner-builders measure up the property and produce a sketch of the proposed canopy. If the sketches provide all the necessary information to define the structure then we can certify the sketch, if not then the sketch is just considered conceptual and structural drawings are produced along with the calculations.

Drawings are produced using Acad LT, whilst calculations are a combination of hand written calculations and computer printouts (mostly from MS Excel spreadsheets produced in-house by Conrad).

Background to the Examples

Since the drawings are already digital it is relatively easy to reproduce and edit for release as examples. The calculations on the other hand have to be scanned and edited.

Scanning is a time consuming exercise, since often multiple pages are dragged through the sheet feeder, resulting in messed up pages and missing pages in the scanned document. The missing pages have to be scanned and a complete report compiled. So an exercise which could have been a 5 minute job, turns into a 2 hour job. Another option is to rehash the reports from the digital sources where available, but that would lack the hand written content of the original reports. The other problem with that approach is some of the software goes direct to the printer with no data file saved, therefore would have to rework the calculations through the software: thus basically doing the job again but printing to a pdf file rather than to paper. Such rehash also wouldn’t reflect what was approved by council.

So currently can only conveniently provide example drawings. The examples are taken from real projects which have been approved by local councils. However they do not represent the complete set of drawings required for a project. The drawings in the examples are only the additional drawings as required to specify the structural requirements not otherwise shown on the builders or owner-builders sketches. Put another way this is the additional documentation submitted after the city council requested further information and engineers calculations.

Most of the examples date back to 2005. Near the end of 2005 it seemed the councils cracked down on attached carports and verandahs, so that in one week a handful of unknown builders turned up and dumped some 50 rejected canopies on my desk. So over the following several weeks processed all these canopies and any additional ones that flowed in. Fortunately a major part of our business is producing standard designs, and therefore were able to assess structural adequacy by comparing against the standard designs and otherwise producing any additional calculations as required to cover any custom features.

Reason For Release

The examples are released so that owner-builders have an idea of what councils expect when applying for development approval, and also to illustrate what we also expect if we are requested to certify other peoples drawings.

In particular if the canopy is to be attached to a house then details of the house are required:

  1. roof shape
  2. trusses or conventional
  3. timber or steel
  4. tiled roof or sheet metal,
  5. spacing of framework
  6. location of doors, windows  and other openings
  7. hips and other roof features.
  8. location of swimming pools, fences and retaining walls is also important.

At some future date, spreadsheets, tables and standard detail drawings will be available in the webstore.

Students & Educators

The documents are also useful for educators to use in their courses. Very little documentation is perfect even if granted development approval. Also as people on both sides of the equation gain experience, their own expectations of what is acceptable also increases. So students and educators can use the documents for the following:

  1. Find drafting errors (I’ve noticed there are some)
  2. Identify deviation from national drafting standards (eg. AS1100) – (There are plenty to find, but does it matter, given most of people reading the drawings don’t know the standards? Not to mention authors of AS1684 also don’t seem to care about AS1100.)
  3. Identify ambiguities
  4. Identify lack of completeness (some drawings supplement builders drawings, and therefore not all information is presented)
  5. Do a qualitative review of structural adequacy. (eg. no cross bracing, no knee braces, are there any moment connections? Basically apply a notional load in all directions and visualise how the structure will behave.)
  6. How does the design compare against other countries. (eg. What would be different in snow country, or earthquake territory?)
  7. Produce proof-calculations to demonstrate structural adequacy. (In the main I have removed street addresses, but kept suburbs. Most are for wind class N1 or N2: so at the minimum could identify the largest wind class or wind speed for which they are suitable.)
  8. How long does it take to make an assessment and produce proof-calculations?
  9. What can be standardised and reused on multiple projects?
  10. What design tables could be produced to simplify the design and enable builders, and DIY enthusiasts to more rapidly specify something suitable for purpose?
  11. What issues complicate producing design tables and/or computer software for canopy design by sales people or customers at the point-of-sale?
  12. What simplified design tools already exist? Are the examples within the scope of these tools?
  13. Are they compliant with current codes? If no longer compliant, then in which year did they cease to be compliant?
  14. To what extent can we estimate (guess) the details of the house construction (the parts we cannot see), based on that which expect to be present, assuming the existing house construction complies with the code?

If educators would like a convenient bundle of all examples please contact me. These are just projects I could remember as having interesting issues, or represented more complete examples of common situations: they’re not the only canopies we have designed.

The Examples

  1. Example0981DrawingsR1
    Attached, Steel RHS, columns cranked under eaves.
  2. Example1004 {Not available yet}
    Free standing, Steel, curved roof (includes calcs: early attempt at using adobe acrobat to compile complete report in digital format. Proved cumbersome, it was easier to print software calc’s out, and encircle critical values with pencil, than try to do the same thing in electronic format. But since we now email most of our reports, we use Bluebeam Revu, scan the odd page of handwritten calcs and compile full report in pdf format.)
  3. Example1062DrawingsR1
    Attached, Steel building frame. Steel Canopy, Monoslope
  4. Example1722DrawingsR1
    Attached, Timber deck with balcony over.
  5. Example1736DrawingsR1
    Free standing, adjacent to swimming pool, gable
  6. Example1738DrawingsR1
    Attached, Gable canopy, gable end attached to eaves
  7. Example1741DrawingsR1
    Attached, oblique boundaries (Not believable)
  8. Example1748DrawingsR1
    Attached, gable canopy, attached to hipped roof
  9. Example1756DrawingsR1
    Attached, Gable canopy, attached to multi-slope roof (heritage style house)
  10. Example1757DrawingsR1
    Attached, Gable canopy, L-Shaped plan, attached to hipped roof
  11. Example1772DrawingsR1
    Attached, Gable canopy, T-shaped, attached to hipped roof
  12. Example1779DrawingsR1
    Attached, Gable canopy, attached to brick wall
  13. Example1780DrawingsR1
    Attached, Gable Canopy, L-Shaped plan, attached to brick wall
  14. Example1781DrawingsR1
    Attached, Gable canopy, attached to octagonal roof
  15. Example1782DrawingsR1
    Attached and Freestanding, and decking. Gable canopy with dormer(?)
  16. Example1783DrawingsR1
    Attached, canopy gable + flat
  17. Example1788DrawingsR1
    Attached, gable canopy, fitted between carport and house.
  18. Example1789DrawingsR1
    Attached, gable canopy, house plan cranked, gable end of canopy attached at crank.
  19. Example1792DrawingsR1
    Attached, gable canopies, multiple canopies fitted between existing buildings
  20. Example1798DrawingsR1
    Attached, gable canopy, partial attachment, house hipped roof
  21. Example1800DrawingsR1
    Attached, gable canopy, gable end attached. canopy stepped roof
  22. Example1802DrawingsR1
    Attached, gable canopy, various canopies around house perimeter
  23. Example1804DrawingsR1
    Free standing, Decking and canopy, adjacent to swimming pool
  24. Example1805DrawingsR1
    Free standing, gable canopy, with lattice work to side, and adjacent to fence.
  25. Example1808DrawingsR1
    Attached, gable canopy, sloping site.
  26. Example1815DrawingsR1
    Attached, gable canopy, corner cut off.
  27. Example1816DrawingsR1
    Attached, flat, trapezoid, house oblique to boundary
  28. Example1820DrawingsR1
    Attached, gable canopy, L-shaped, broken hip
  29. Example1826DrawingsR1
    Attached, gable canopy, corner notched out to fit around building
  30. Example1842DrawingsR1
    General notes only, main regarding tie-down and house strengthening
  31. Example1885DrawingsR1
    Attached, gable canopy T-shaped, posts adjacent to retaining wall, attachment to wall of 2 storey house.
  32. Example1887DrawingsR1
    Attached, gable canopy, hipped house roof. canopy roof cut at angle.
  33. Example1922DrawingsR1
    Attached, steel gable canopy, cranked posts under eaves. Detail of post attached to side of house footing.
  34. Example1934DrawingsR1
    Attached, gable canopy, steel, lintels with posts anchored to house footing beam.
  35. Example1970 {not available yet}
    Attached, tie-down assessment. {rehashed calculations}
  36. Example1981DrawingsR1
    Attached, tie-down assessment
  37. Example1982DrawingsR1
    Free standing, octagonal plan, doubly pitched roof
  38. Example2011DrawingsR1
    Attached, oblique boundary, curved roof canopy, steel.
  39. Example2163DrawingsR1
    Free standing, skillion roof, steel, industrial/commercial
  40. Example2342DrawingsR1
    Free standing, curved roof, overhanging posts.
  41. Example2347DrawingsR1
    Free standing, steel, flat, main members fabricated from circular hollow section (CHS) tubes battened together.

Revisions:

  1. [19/03/2016] Original
  2. [23/01/2019] Minor Revisions: Added Some headings, reformatted some paragraphs. Added section for students and educators.