Planning drawings, construction drawings and shop drawings: what does your shed project actually need?

A set of drawings prepared for planning approval is not automatically suitable for pricing, construction or steel fabrication. Each stage answers a different set of questions, and moving ahead with the wrong documentation can leave critical decisions to the builder on site.

For pig and poultry sheds, that gap matters. Equipment layouts, fan walls, pad levels, steel frames, precast panels and slab details all need to line up. A drawing set that is clear enough for council may still be missing the information a builder, engineer or fabricator needs to commit to a price or start work.

The main drawing sets

Most shed projects move through four practical levels of documentation.

The names can vary from project to project, but the distinction is important: each set has a different job.

Planning drawings are for approvals

Planning drawings explain the proposal at a site and building-envelope level. They help show where sheds sit, how traffic moves, how the project relates to boundaries and what the development generally looks like.

They are not meant to resolve every construction decision. A planning set might show the size and position of a poultry shed, but it may not include final fan-frame details, slab thickenings, steel member sizes, precast panel fixings or equipment penetrations. Those decisions usually depend on later coordination with the equipment supplier, structural engineer and builder.

That is normal. The problem starts when a planning set is treated as if it is ready for tender, construction or fabrication.

Design development closes the coordination gap

Design development is where the shed becomes buildable in principle. The key question changes from “can this project be approved here?” to “how do the building, equipment, structure and site works fit together?”

For intensive livestock sheds, this stage often coordinates:

• Fan walls, cooling pads, inlets, shutters and service doors.
• Feed lines, silos, augers, drinker lines and internal equipment zones.
• Portal frames, end framing, bracing, girts and purlins.
• Slab falls, setdowns, spoon drains, aprons and traffic areas.
• Precast panel heights, joints, rebates and cast-in items.
• Repeated shed variants across a multi-shed site.

Good design-development documentation reduces surprises before the expensive documentation begins. It is also the stage where repeated variants should be named and locked down, so the construction and shop drawing effort is based on the real number of design problems rather than the total shed count.

Construction drawings are for the site

Construction drawings turn the coordinated design into instructions a builder can use. They should be dimensioned, referenced and detailed enough that the site team is not guessing about levels, openings, junctions or sequencing.

For a pig or poultry shed, construction drawings commonly include general arrangement plans, elevations, sections, slab and footing details, wall setouts, roof setouts, door and opening schedules, equipment coordination notes and references to engineering drawings.

They still are not the same as shop drawings. A construction drawing might show a portal frame grid and a typical connection reference. The steel fabricator still needs fabrication drawings that break that frame into members, plates, holes, welds, marks and assembly logic.

Shop drawings are for fabrication

Shop drawings are the manufacturing layer. They translate the approved construction intent and engineering requirements into information a workshop can use to cut, drill, weld, cast, mark, pack and install components.

Steel shop drawings usually deal with individual members, connection plates, cleats, bolt groups, purlin and girt supports, bracing connections and assembly marks. Precast shop drawings deal with panel dimensions, reinforcement, cast-in ferrules or plates, lifting points, rebates, penetrations and panel numbering.

This level of detail should not be improvised from a planning set. If the construction information is incomplete, the fabricator is forced to make design assumptions. That creates risk for everyone: the owner, builder, engineer, supplier and fabricator.

What goes wrong with the wrong drawing set

Using the wrong level of documentation usually looks cheaper at first. It rarely stays that way.

Common problems include:

• Builders pricing different assumptions because the tender set is not detailed enough.
• Equipment openings being framed twice: once in the building design, then again after supplier coordination catches up.
• Fan walls, pads or service doors clashing with bracing, columns or precast joints.
• Slab setdowns and falls being decided too late for clean detailing.
• Fabricators adding conservative allowances because shop information is missing.
• Site crews resolving details in the field that should have been coordinated on drawings.

None of these issues are mysterious. They are documentation-stage problems. The fix is not more drawings for the sake of it; it is issuing the right drawings to the right people at the right time.

The practical rule

Ask what decision the drawing set is meant to support.

If the decision is planning approval, planning drawings may be enough. If the decision is equipment coordination, the project needs design-development drawings. If the decision is construction, the builder needs a coordinated construction set. If the decision is fabrication, the workshop needs shop drawings.

One drawing set cannot replace all the others because the audience changes at each stage. Council needs to understand the proposal. The builder needs to build it. The fabricator needs to manufacture it. A good documentation process respects those differences instead of hiding them.