Due diligence
Flooding and overland flow path checks
This stage investigates mapped and observed flood hazards, flood-prone areas, flood plains, overland flow paths, site levels, access, finished-floor implications, insurance concerns, and the effect on buildable area. This page shows what a beginner residential developer in Auckland should check, who to ask, what evidence to save, and where to verify before committing money or instructions.
How to execute this stage
Micro-stage control plan
Work through each applicable step in order. A hold point means pause the dependent decision or work until the stated evidence and authorised review are complete.
01Current mapped hazardsLevel 2 · Due diligence
TaskCheckHold pointEvidenceRecordNext actionSimple explanation
Current mapped hazards
Technical context
Test this point against GeoMaps hazard layers, the current feasibility version and written input from Civil engineer. Separate verified facts, professional opinion and assumptions.
Why it matters: This check can change yield, consent pathway, acquisition terms, funding, cost, programme or exit strategy. It must be resolved before the developer relies on whether specialist modelling or advice is needed.
Prerequisites
- GeoMaps hazard layers is current and its source/date are recorded.
- The project objective, feasibility version and decision deadline are clear.
- Civil engineer has a focused brief where professional confirmation is required.
Checks
- Does GeoMaps hazard layers directly support the conclusion?
- Which information is verified, assumed, missing, superseded or contradictory?
- Has the feasibility, programme, risk register and decision register been updated?
Evidence to save
- GeoMaps hazard layers
- Written Civil engineer response or a recorded reason it is not required
- Dated feasibility/risk/decision update
Hold point
Do not waive a condition, instruct design/work, commit funding, lodge, purchase, settle or represent the conclusion as confirmed until the authorised decision-maker has the required evidence and advice.
Stop or escalate when
- The source is missing, old, inconsistent or outside the reviewer's scope.
- The check changes yield, approval pathway, funding, legal rights, tax, safety or a material cost/programme assumption.
- A deadline is approaching and the responsible professional has not confirmed the position.
Documents and records
- GeoMaps hazard layers
- Site assessment checklist
- Civil engineer brief
- Current feasibility, risk register and decision register
- Cost effect
- Record changes to land value, consultant/council cost, construction/civil cost, finance, holding cost, contingency and exit value before whether specialist modelling or advice is needed.
- Programme effect
- Record the decision deadline, dependencies, information lead time and effect on acquisition, consent, procurement, construction, sales or settlement milestones.
Next action
Observed flow routes and low points
Applicability: Confirm whether this check applies to the actual site, ownership, strategy, consent pathway, infrastructure and delivery model; record a reason when not applicable.
Use current site-specific documents and appropriately appointed professional advice. BuildPath does not make the development decision for you.
02Observed flow routes and low pointsLevel 2 · Due diligence
TaskCheckHold pointEvidenceRecordNext actionSimple explanation
Observed flow routes and low points
Technical context
Test this point against LIM, the current feasibility version and written input from Planner. Separate verified facts, professional opinion and assumptions.
Why it matters: This check can change yield, consent pathway, acquisition terms, funding, cost, programme or exit strategy. It must be resolved before the developer relies on platform and access strategy.
Prerequisites
- LIM is current and its source/date are recorded.
- The project objective, feasibility version and decision deadline are clear.
- Planner has a focused brief where professional confirmation is required.
Checks
- Does LIM directly support the conclusion?
- Which information is verified, assumed, missing, superseded or contradictory?
- Has the feasibility, programme, risk register and decision register been updated?
Evidence to save
- LIM
- Written Planner response or a recorded reason it is not required
- Dated feasibility/risk/decision update
Hold point
Do not waive a condition, instruct design/work, commit funding, lodge, purchase, settle or represent the conclusion as confirmed until the authorised decision-maker has the required evidence and advice.
Stop or escalate when
- The source is missing, old, inconsistent or outside the reviewer's scope.
- The check changes yield, approval pathway, funding, legal rights, tax, safety or a material cost/programme assumption.
- A deadline is approaching and the responsible professional has not confirmed the position.
Documents and records
- LIM
- Site assessment checklist
- Civil engineer brief
- Current feasibility, risk register and decision register
- Cost effect
- Record changes to land value, consultant/council cost, construction/civil cost, finance, holding cost, contingency and exit value before platform and access strategy.
- Programme effect
- Record the decision deadline, dependencies, information lead time and effect on acquisition, consent, procurement, construction, sales or settlement milestones.
Next action
Proposed platforms and access
Applicability: Confirm whether this check applies to the actual site, ownership, strategy, consent pathway, infrastructure and delivery model; record a reason when not applicable.
Use current site-specific documents and appropriately appointed professional advice. BuildPath does not make the development decision for you.
03Proposed platforms and accessLevel 2 · Due diligence
TaskCheckHold pointEvidenceRecordNext actionSimple explanation
Proposed platforms and access
Technical context
Test this point against Topographical survey, the current feasibility version and written input from Surveyor. Separate verified facts, professional opinion and assumptions.
Why it matters: This check can change yield, consent pathway, acquisition terms, funding, cost, programme or exit strategy. It must be resolved before the developer relies on yield change.
Prerequisites
- Topographical survey is current and its source/date are recorded.
- The project objective, feasibility version and decision deadline are clear.
- Surveyor has a focused brief where professional confirmation is required.
Checks
- Does Topographical survey directly support the conclusion?
- Which information is verified, assumed, missing, superseded or contradictory?
- Has the feasibility, programme, risk register and decision register been updated?
Evidence to save
- Topographical survey
- Written Surveyor response or a recorded reason it is not required
- Dated feasibility/risk/decision update
Hold point
Do not waive a condition, instruct design/work, commit funding, lodge, purchase, settle or represent the conclusion as confirmed until the authorised decision-maker has the required evidence and advice.
Stop or escalate when
- The source is missing, old, inconsistent or outside the reviewer's scope.
- The check changes yield, approval pathway, funding, legal rights, tax, safety or a material cost/programme assumption.
- A deadline is approaching and the responsible professional has not confirmed the position.
Documents and records
- Topographical survey
- Site assessment checklist
- Civil engineer brief
- Current feasibility, risk register and decision register
- Cost effect
- Record changes to land value, consultant/council cost, construction/civil cost, finance, holding cost, contingency and exit value before yield change.
- Programme effect
- Record the decision deadline, dependencies, information lead time and effect on acquisition, consent, procurement, construction, sales or settlement milestones.
Next action
Upstream and downstream context
Applicability: Confirm whether this check applies to the actual site, ownership, strategy, consent pathway, infrastructure and delivery model; record a reason when not applicable.
Use current site-specific documents and appropriately appointed professional advice. BuildPath does not make the development decision for you.
04Upstream and downstream contextLevel 2 · Due diligence
TaskCheckHold pointEvidenceRecordNext actionSimple explanation
Upstream and downstream context
Technical context
Test this point against Flood assessment where required, the current feasibility version and written input from Architect. Separate verified facts, professional opinion and assumptions.
Why it matters: This check can change yield, consent pathway, acquisition terms, funding, cost, programme or exit strategy. It must be resolved before the developer relies on cost allowance.
Prerequisites
- Flood assessment where required is current and its source/date are recorded.
- The project objective, feasibility version and decision deadline are clear.
- Architect has a focused brief where professional confirmation is required.
Checks
- Does Flood assessment where required directly support the conclusion?
- Which information is verified, assumed, missing, superseded or contradictory?
- Has the feasibility, programme, risk register and decision register been updated?
Evidence to save
- Flood assessment where required
- Written Architect response or a recorded reason it is not required
- Dated feasibility/risk/decision update
Hold point
Do not waive a condition, instruct design/work, commit funding, lodge, purchase, settle or represent the conclusion as confirmed until the authorised decision-maker has the required evidence and advice.
Stop or escalate when
- The source is missing, old, inconsistent or outside the reviewer's scope.
- The check changes yield, approval pathway, funding, legal rights, tax, safety or a material cost/programme assumption.
- A deadline is approaching and the responsible professional has not confirmed the position.
Documents and records
- Flood assessment where required
- Site assessment checklist
- Civil engineer brief
- Current feasibility, risk register and decision register
- Cost effect
- Record changes to land value, consultant/council cost, construction/civil cost, finance, holding cost, contingency and exit value before cost allowance.
- Programme effect
- Record the decision deadline, dependencies, information lead time and effect on acquisition, consent, procurement, construction, sales or settlement milestones.
Next action
Potential displacement or obstruction
Applicability: Confirm whether this check applies to the actual site, ownership, strategy, consent pathway, infrastructure and delivery model; record a reason when not applicable.
Use current site-specific documents and appropriately appointed professional advice. BuildPath does not make the development decision for you.
05Potential displacement or obstructionLevel 2 · Due diligence
TaskCheckHold pointEvidenceRecordNext actionSimple explanation
Potential displacement or obstruction
Technical context
Test this point against Civil report, the current feasibility version and written input from Geotechnical engineer where relevant. Separate verified facts, professional opinion and assumptions.
Why it matters: This check can change yield, consent pathway, acquisition terms, funding, cost, programme or exit strategy. It must be resolved before the developer relies on whether the site remains acceptable.
Prerequisites
- Civil report is current and its source/date are recorded.
- The project objective, feasibility version and decision deadline are clear.
- Geotechnical engineer where relevant has a focused brief where professional confirmation is required.
Checks
- Does Civil report directly support the conclusion?
- Which information is verified, assumed, missing, superseded or contradictory?
- Has the feasibility, programme, risk register and decision register been updated?
Evidence to save
- Civil report
- Written Geotechnical engineer where relevant response or a recorded reason it is not required
- Dated feasibility/risk/decision update
Hold point
Do not waive a condition, instruct design/work, commit funding, lodge, purchase, settle or represent the conclusion as confirmed until the authorised decision-maker has the required evidence and advice.
Stop or escalate when
- The source is missing, old, inconsistent or outside the reviewer's scope.
- The check changes yield, approval pathway, funding, legal rights, tax, safety or a material cost/programme assumption.
- A deadline is approaching and the responsible professional has not confirmed the position.
Documents and records
- Civil report
- Site assessment checklist
- Civil engineer brief
- Current feasibility, risk register and decision register
- Cost effect
- Record changes to land value, consultant/council cost, construction/civil cost, finance, holding cost, contingency and exit value before whether the site remains acceptable.
- Programme effect
- Record the decision deadline, dependencies, information lead time and effect on acquisition, consent, procurement, construction, sales or settlement milestones.
Next action
Design and consent implications
Applicability: Confirm whether this check applies to the actual site, ownership, strategy, consent pathway, infrastructure and delivery model; record a reason when not applicable.
Use current site-specific documents and appropriately appointed professional advice. BuildPath does not make the development decision for you.
06Design and consent implicationsLevel 2 · Due diligence
TaskCheckHold pointEvidenceRecordNext actionSimple explanation
Design and consent implications
Technical context
Test this point against Planning memo, the current feasibility version and written input from Insurer or broker. Separate verified facts, professional opinion and assumptions.
Why it matters: This check can change yield, consent pathway, acquisition terms, funding, cost, programme or exit strategy. It must be resolved before the developer relies on whether specialist modelling or advice is needed.
Prerequisites
- Planning memo is current and its source/date are recorded.
- The project objective, feasibility version and decision deadline are clear.
- Insurer or broker has a focused brief where professional confirmation is required.
Checks
- Does Planning memo directly support the conclusion?
- Which information is verified, assumed, missing, superseded or contradictory?
- Has the feasibility, programme, risk register and decision register been updated?
Evidence to save
- Planning memo
- Written Insurer or broker response or a recorded reason it is not required
- Dated feasibility/risk/decision update
Hold point
Do not waive a condition, instruct design/work, commit funding, lodge, purchase, settle or represent the conclusion as confirmed until the authorised decision-maker has the required evidence and advice.
Stop or escalate when
- The source is missing, old, inconsistent or outside the reviewer's scope.
- The check changes yield, approval pathway, funding, legal rights, tax, safety or a material cost/programme assumption.
- A deadline is approaching and the responsible professional has not confirmed the position.
Documents and records
- Planning memo
- Site assessment checklist
- Civil engineer brief
- Current feasibility, risk register and decision register
- Cost effect
- Record changes to land value, consultant/council cost, construction/civil cost, finance, holding cost, contingency and exit value before whether specialist modelling or advice is needed.
- Programme effect
- Record the decision deadline, dependencies, information lead time and effect on acquisition, consent, procurement, construction, sales or settlement milestones.
Next action
Insurance and lender questions
Applicability: Confirm whether this check applies to the actual site, ownership, strategy, consent pathway, infrastructure and delivery model; record a reason when not applicable.
Use current site-specific documents and appropriately appointed professional advice. BuildPath does not make the development decision for you.
07Insurance and lender questionsLevel 2 · Due diligence
TaskCheckHold pointEvidenceRecordNext actionSimple explanation
Insurance and lender questions
Technical context
Test this point against Concept plan, the current feasibility version and written input from Auckland Council. Separate verified facts, professional opinion and assumptions.
Why it matters: This check can change yield, consent pathway, acquisition terms, funding, cost, programme or exit strategy. It must be resolved before the developer relies on platform and access strategy.
Prerequisites
- Concept plan is current and its source/date are recorded.
- The project objective, feasibility version and decision deadline are clear.
- Auckland Council has a focused brief where professional confirmation is required.
Checks
- Does Concept plan directly support the conclusion?
- Which information is verified, assumed, missing, superseded or contradictory?
- Has the feasibility, programme, risk register and decision register been updated?
Evidence to save
- Concept plan
- Written Auckland Council response or a recorded reason it is not required
- Dated feasibility/risk/decision update
Hold point
Do not waive a condition, instruct design/work, commit funding, lodge, purchase, settle or represent the conclusion as confirmed until the authorised decision-maker has the required evidence and advice.
Stop or escalate when
- The source is missing, old, inconsistent or outside the reviewer's scope.
- The check changes yield, approval pathway, funding, legal rights, tax, safety or a material cost/programme assumption.
- A deadline is approaching and the responsible professional has not confirmed the position.
Documents and records
- Concept plan
- Site assessment checklist
- Civil engineer brief
- Current feasibility, risk register and decision register
- Cost effect
- Record changes to land value, consultant/council cost, construction/civil cost, finance, holding cost, contingency and exit value before platform and access strategy.
- Programme effect
- Record the decision deadline, dependencies, information lead time and effect on acquisition, consent, procurement, construction, sales or settlement milestones.
Next action
Make and record the stage decision: Platform and access strategy. Then open the next applicable development stage.
Applicability: Confirm whether this check applies to the actual site, ownership, strategy, consent pathway, infrastructure and delivery model; record a reason when not applicable.
Use current site-specific documents and appropriately appointed professional advice. BuildPath does not make the development decision for you.
Developer go / no-go control
Decision gates before the next commitment
A gate records whether evidence supports a commercial decision. It does not replace advice or predict an authority, lender, purchaser or market outcome.
Before the next material commitment
Decision: Proceed, pause, obtain evidence, or escalate
Minimum evidence
- • Current source documents and professional responses
- • Versioned feasibility, risk and programme update
- • Named owner and deadline for every unresolved dependency
Update before deciding
- • Cost and contingency
- • Time and holding/finance effect
- • Yield, value, consent and exit effect
Stop / escalate when
- • A material conclusion is still an assumption
- • Sources conflict or are out of date
- • The authorised decision-maker cannot see the downside consequence
What this stage means
- Flooding and overland flow path checks is the part of the project where the developer turns an idea into a checked decision, not a guess.
- The stage should connect market demand, planning rules, legal constraints, design, cost, funding, time, risk, and exit strategy.
- For Auckland residential development, the answer is site-specific. The same idea can be low risk on one site and unworkable on the next because of zoning, overlays, title interests, services, slope, flooding, neighbours, or finance.
Why this stage matters
- Early mistakes become expensive because land, design, consultants, holding costs, consent fees, and finance costs continue even when the project is paused.
- The developer needs written evidence for lenders, consultants, lawyers, valuers, builders, purchasers, and future dispute protection.
- This stage usually needs verification from Auckland Council GeoMaps, Auckland Council LIM report, Auckland Unitary Plan, Relevant professional advice before the developer treats the conclusion as reliable.
Step-by-step guide
- 1Define the decision needed at the end of this stage and the date it is needed by.
- 2Gather the stage documents: GeoMaps hazard layers, LIM, Topographical survey, Flood assessment where required, and the remaining stage records.
- 3Read the documents once for understanding, then again to list unknowns, risks, contradictions, missing evidence, and professional questions.
- 4Ask the responsible professionals to confirm the critical points: Civil engineer, Planner, Surveyor, Architect.
- 5Update the feasibility, programme, risk register, and decision register with source references and dates.
- 6Decide whether to proceed, pause, redesign, renegotiate, add conditions, seek more advice, or abandon the option.
- 7Save the evidence in a dated folder and write a short stage closeout note explaining what was decided and why.
What the developer must do
- Write down the development objective for flooding and overland flow path checks in one clear paragraph: build-to-sell, build-to-rent, retain one dwelling, subdivide, renovate, or staged development.
- Open the current feasibility, programme, decision register, risk register, and due diligence folder before making new commitments.
- Collect the documents needed for this stage: GeoMaps hazard layers, LIM, Topographical survey, Flood assessment where required, Civil report, Planning memo, Concept plan, Site and neighbourhood photos.
- Send focused questions to the right people: Civil engineer, Planner, Surveyor, Architect, Geotechnical engineer where relevant, Insurer or broker, Auckland Council.
- Record assumptions separately from verified facts so the feasibility does not look more certain than it really is.
- Update cost, time, consent, finance, and sales assumptions immediately after receiving new information.
- Escalate anything that changes yield, sale price, cost, timing, consent pathway, title, funding, or settlement risk.
Verification
Source / where to check
Use current official information and the controlled documents for the actual project.
Use GeoMaps as an early desktop check for property layers, contours, flooding/overland flow information, services context, and council spatial information. Confirm critical matters with professionals and council.
Use the LIM to check council-held information relevant to the land. Treat it as one due diligence document, not a substitute for title, survey, planning, engineering, legal, or finance advice.
Check the operative plan, maps, zones, precincts, overlays, activity status, development controls, subdivision rules, and assessment criteria for the specific site.
Planner, surveyor, architect, engineer, quantity surveyor, lawyer, accountant, lender, valuer, real estate agent, and other project specialists must confirm site-specific decisions.
Project-specific consented documents and professional advice override generic guidance.
Common mistakes
- Treating an agent comment, generic online rule, or old document as verified site-specific advice.
- Forgetting to update the feasibility after design, consent, finance, or market information changes.
- Not allowing enough contingency, professional fees, council fees, finance costs, holding costs, and time risk.
- Failing to keep written records of who confirmed what and when.
- Using flooding and overland flow path checks to push ahead even when the red flags show the project should pause.
Common risks
- Yield reduces after proper planning, engineering, title, or infrastructure review.
- Costs increase after QS, builder, civil, geotechnical, demolition, asbestos, or consent information is received.
- Programme moves out because consultant inputs, council RFIs, neighbour issues, finance, title, or construction sequencing take longer than assumed.
- Funding or sales assumptions change before the project reaches settlement.
- The developer relies on unverified information and loses negotiating power or misses a due diligence deadline.
Common costs
- Professional fees for planner, architect/designer, surveyor, engineer, QS, lawyer, accountant, valuer, and lender reports.
- Council fees, consent fees, development contribution estimates, engineering approvals, infrastructure checks, and inspection/monitoring costs where relevant.
- Design revisions, reports, investigations, demolition/asbestos work, service location, geotechnical testing, and valuation updates.
- Holding costs such as interest, rates, insurance, utilities, temporary maintenance, and security.
- Contingency for unverified conditions until the relevant professional confirms them.
Quotes and fee proposals to obtain
- Obtain written fee proposals or quotations from the relevant stage professionals: Civil engineer, Planner, Surveyor, Architect, Geotechnical engineer where relevant, Insurer or broker, Auckland Council.
- Issue the same current documents and a clear scope to each party so prices, exclusions, assumptions, deliverables, lead times, and programme can be compared.
- Identify council, authority, investigation, testing, design, construction, monitoring, and close-out charges that may sit outside a consultant or contractor quote.
- Record every provisional sum, estimate, exclusion, expiry date, dependency, and unverified allowance in the Quote Register and feasibility.
- Do not approve an appointment or purchase order until scope ownership, evidence required, payment terms, variation process, insurance or competency checks, and completion deliverables are understood.
Common delays
- Waiting for property file, LIM, title instruments, survey information, consultant reports, or council responses.
- Design changes caused by planning controls, infrastructure constraints, engineering findings, budget pressure, or market feedback.
- Lender, valuer, lawyer, or purchaser conditions not being satisfied on time.
- Council RFI responses needing more consultant work than expected.
- Construction or subdivision closeout documents not matching settlement or sales deadlines.
Common consultant questions
- For Flooding and overland flow path checks, what are the three highest risks that could change cost, time, yield, or approval pathway?
- Which parts of your advice are confirmed, which are assumptions, and which require another professional to confirm?
- What documents did you rely on, and are any documents missing, outdated, superseded, or inconsistent?
- What decision does the developer need to make now, and what should wait until more information is available?
- What wording should go into the decision register, consultant meeting minutes, or lender/client update?
Red flags
- A professional says the issue is outside their scope and no one else has been asked to confirm it.
- The feasibility only works if optimistic sale prices, low construction costs, fast consent, low interest, and no delays all happen together.
- A title, planning, flooding, geotechnical, access, service, or covenant issue may prevent the intended yield.
- A seller, agent, builder, or consultant pressures the developer to waive due diligence before core checks are complete.
- The project file has no written evidence for a major decision.
When to stop and get professional advice
- Stop and get professional advice when title, easements, covenants, unit title, cross lease, or subdivision matters affect the proposal.
- Stop and get professional advice when zoning, overlays, activity status, notification, infrastructure capacity, flooding, geotechnical, contamination, or heritage could affect yield.
- Stop and get professional advice when GST, income tax, entity structure, lending, guarantees, or sale contract terms affect the decision.
- Stop and get professional advice when the developer is about to sign, waive a condition, lodge consent, start work, approve a variation, accept practical completion, or settle.
Decisions that must be made
- Whether specialist modelling or advice is needed
- Platform and access strategy
- Yield change
- Cost allowance
- Whether the site remains acceptable
Evidence to save
- Dated source documents and consultant advice.
- Feasibility version showing the assumptions used at the time of decision.
- Risk register and decision register entries.
- Meeting notes, emails, marked-up plans, calculations, photos, and council/lender/consultant responses.
- Clear note of who approved the next step and any conditions attached to that approval.
Beginner-friendly example
A mapped flow path crosses the preferred driveway, so the developer pauses the concept and obtains civil and planning advice before pricing the site.
Use this in my project
Turn flooding and overland flow path checks into controlled action
Open the relevant workspace register, create the project-specific record, link the controlling documents and preserve evidence. The guide does not automatically approve or verify the action.