Integrated Waterproofing and Root Barrier Method for Extensive Green Roofs

More than a static template

Unlike a downloadable Word or PDF template, this method statement is an AI-assisted editable starting point connected directly to a matching Inspection and Test Plan. Every section is structured, project-adaptable, and ready to export.

AI-assisted drafting — Customize every section with AI for your specific project scope.
Linked ITP — A matching inspection and test plan is generated alongside the method statement.
Multiple export formats — Download as a formatted PDF or editable Excel spreadsheet.
Editable starting point, not a final document — Review, verify, and adjust all content against your project requirements before use.

Static template vs. Quollnet workflow

Feature	Static template	Quollnet
Project-specific content	Manual fill-in required	AI-assisted customization
Linked ITP	Separate document, no link	Matching ITP included
Export formats	Usually PDF only	PDF and Excel
Structured sections	Free-form layout	13 standardized sections
Saved to your account	Local file only	Cloud-saved, reusable
Content accuracy	You verify everything	AI-assisted, you still verify
Cost	Often free but time-intensive	Free to customize and download

What you can customize

When you save this method statement to your account, every section becomes editable. The following 13 sections are included:

Scope — Defines the activity and its boundaries.
References — Standards, specifications, and drawings.
Responsibilities — Roles and accountabilities.
Resources — Labour, plant, and equipment summary.
Materials — Materials and compliance requirements.
Equipment — Tools and equipment details.
Prerequisites — Hold points and pre-conditions.
Method sequence — Step-by-step construction sequence.
Safety controls — HSE risk controls and PPE.
Environmental controls — Environmental mitigation measures.
QA/QC — Quality inspection and test requirements.
ITP — Inspection and Test Plan table (has its own page).
Attachments — Referenced drawings and documentation.

Why this method statement is used

This method statement is used to define and communicate the approved procedure for carrying out method statement: integrated waterproofing and root barrier system for extensive green roofs on site. It ensures the work is planned in advance, the correct resources and controls are in place, and all personnel understand responsibilities, sequence, quality requirements, and safety controls before work begins. It aligns site execution with the documented scope and acceptance expectations.

Who uses this method statement

This method statement is used by contractors, site supervisors, project engineers, QA/QC engineers, HSE officers, consultants, and client representatives. It serves as a shared reference for planning, execution, supervision, inspection, and approval of the activity on site.

When it is prepared and submitted

The method statement is prepared before the work activity starts and submitted as part of the pre-construction documentation package for review and approval.

Who reviews or approves it

The method statement is usually submitted to the client representative, consultant, resident engineer, or project management consultant for review and approval before the work commences.

Important approval note

This method statement is an AI-assisted editable starting point, not a pre-approved document. Before use on any project, all content must be reviewed and approved by the relevant parties (superintendent, principal contractor, or client representative) in accordance with your contract and project quality plan.

For example: if your specification requires a departure from a referenced standard, that departure must be documented and approved separately — this method statement will not capture that automatically. Always verify against your applicable drawings, specifications, and regulatory requirements.

Method statement content

Scope

Work Summary

Supply and installation of integrated waterproofing and root barrier system for extensive green roofs on flat/low-slope roofs, including:
1) Substrate preparation and priming
2) Application of waterproofing membrane (single-ply or cold-applied liquid per approved submittal)
3) 100% non-destructive electronic leak detection (ELD) prior to overburden
4) Root barrier installation
5) Drainage/water-retention layer installation with inspection boxes at outlets
6) Filter geotextile placement
Excludes structural works, thermal insulation, growing medium and vegetation installation unless specifically included by contract.

Objectives

Achieve a watertight membrane with zero defects, resistant to root penetration, with controlled drainage/retention and filtration consistent with an extensive green roof configuration.

Key Performance Targets

No membrane breaches detected by ELD across 100% of tested area.
Root barrier materials meeting EN 13948/FLL root resistance with continuous integrity.
Drainage/water retention and filter layers continuous without blocking outlets and with specified overlaps.

Extents

All horizontal field areas, upstands, parapets, penetrations, terminations, outlets, and transitions within the designated green roof zones on .

References

Document Type	Reference / Number	Notes
Standard	BS 6229:2018
Standard	EN 13956 / EN 13491 (plastic & rubber sheets, underground)	For PVC/TPO/EPDM single-ply [Verify per product].
Standard	ASTM D4434 (PVC), ASTM D6878 (TPO)
Standard	ASTM D6162/D6164; EN 13707	Use only if contract specifies modified bitumen; avoid hot works where practicable.
Standard	ASTM D7877 (Guide), ASTM D8231 (Low-Voltage Vector Mapping Practice)	Third-party ELD specialist to test 100% of membrane prior to overburden.
Standard	EN 13948; FLL Green Roof Guidelines (latest)
Standard	EN 13252; ASTM D4491 (permittivity), ASTM D4632 (grab), ASTM D4751 (AOS)
Standard	ISO 9001; ISO 14001	Contractor certification [Verify per project].
Project Docs	& Approved Submittals	Prevail over generic guidance where conflicts arise.

Responsibilities

Role	Responsibility	Name / Party
Project Manager	Project Manager	Main Contractor
Site Engineer	Site/Section Engineer	Main Contractor
QA/QC	QA/QC Engineer	Main Contractor
HSE Manager	HSE Manager	Main Contractor
Subcontractor Supervisor	Roofing Subcontractor Supervisor	Roofing Subcontractor
ELD Specialist	ELD Specialist (Third-Party)	Specialist Vendor
Manufacturer Rep	Manufacturer's Technical Representative	Manufacturer
Storekeeper	Storekeeper	Main Contractor

Resources

Resource Type	Description	Quantity
Labor	Membrane applicators/welders or liquid-applied installers (3–8 persons typical). [Verify]	1 crew
Third-Party	Certified ELD technician(s) and assistant (2 persons).	1 team
Staff	Full-time for high-risk activities (edges, lifting, hot works).	As allocated

Materials

Material	Specification / Grade	Quantity
Membrane	T ≥ 1.2 mm [Verify]	As per BOQ [Verify]
Primer/Adhesive	Per manufacturer	As required [Verify]
Root barrier sheet	T ≥ 1.0 mm typical [Verify]	As per BOQ [Verify]
Protection fleece	≥300 g/m² [Verify]	As per BOQ [Verify]
Drainage board	Height 20–40 mm typical [Verify]	As per BOQ [Verify]
Geotextile	150–200 g/m² typical [Verify]	As per BOQ [Verify]
Accessories	Per detail	As required

Equipment

Equipment	Quantity	Inspection Required
Hot air welder	1 set/crew	Yes
Mixers/sprayer	As required	Yes
ELD LVVMA kit	1 set	Yes
Meters	Set	Yes
Lifting/Access	As required	Yes
Hand tools	Sets	Yes

Prerequisites

Approvals and Submittals

Approved method statement, ITP, roofing system submittals, shop drawings, and details by Consultant.
Manufacturer’s technical approval for substrate and details; installer credentials confirmed.

Permits and Plans

Work at Height permit; Hot Works permit only if torch or heat tools beyond hot-air welding are used. [Verify per project HSE plan and local regulations]
Lifting plan and permits for rooftop deliveries; exclusion zones established.

Substrate and Design Conditions

Substrate clean, dry, smooth, free of laitance, sharp edges, standing water, contaminants.
Moisture limits: Concrete moisture ≤ 5% CM method or as required by membrane manufacturer. [Verify]
Ambient/application conditions within manufacturer limits: generally +5°C to +35°C, wind < 9 m/s (20 mph) for adhered sheets; no precipitation during application. [Verify]
Falls to drains achieved: finished falls ≥ 1:80; formed falls typically 1:40. [Verify per project]
Upstands/penetrations complete; minimum upstand height typically ≥ 150 mm above finished green roof surface. [Verify per BS 6229 / project]
Roof outlets installed, protected, and temporarily screened to prevent debris ingress; water-test internal drainage prior to membrane.

Materials & Equipment Readiness

Materials inspected for damage; batch numbers logged; within shelf-life.
ELD specialist scheduled; equipment calibrated; test grid/area plan agreed.
Sample panels/mock-ups completed where required and approved.

Interface Coordination

Confirm sequence with insulation, parapet capping, MEP penetrations, and lightning protection.
Protection and access routes planned (walk boards) to prevent membrane puncture.

Briefings

Task-specific risk assessment communicated; toolbox talk on ELD water use and slip hazards; fall protection briefing.

Method Sequence

Step	Activity	Description	Responsibility	Inspection / Hold Point
1	Setting Out & Pre-Start Checks	Confirm extents, details, and drainage points; verify permits and weather window; cordon roof edges and establish access routes.	Site Engineer / HSE	Checklist review
2	Substrate Preparation	Sweep/vacuum; remove protrusions; rectify surface defects; check dryness and falls; prime if required by system.	Roofing Supervisor	Surface inspection
3	Primer Application (if applicable)	Apply primer at coverage rate per TDS using roller/spray; allow to tack-off/cure.	Roofing Crew	Wet film check
4	Waterproofing Membrane – Field Area	Install single-ply sheets (mechanically fastened or adhered) or cold-applied liquid per approved system; weld seams using calibrated hot-air welder or apply liquid to specified DFT.	Roofing Crew	Continuous supervision
5	Details: Upstands, Corners, Penetrations	Form/extrude corners; install preformed boots or liquid flashing; maintain continuous waterproofing and terminations.	Roofing Crew	Detail inspection
6	Terminations & Outlets	Fit termination bars, sealant, clamping rings; ensure outlet strainers and inspection boxes compatible with layers.	Roofing Crew	Functional/visual
7	Protection of Membrane	Place protection fleece in traffic routes; deploy walk boards; restrict loads/point impacts.	Roofing Supervisor	Daily check
8	Electronic Leak Detection (ELD) – Pre-Test Setup	Coordinate with ELD specialist; verify electrical continuity (grounding) and wetting plan; isolate penetrations as needed.	ELD Specialist / QA	Pre-test briefing
9	ELD – Testing	Perform low-voltage vector mapping across 100% of field and details; mark defects; record coordinates.	ELD Specialist	Third-party test
10	Membrane Repairs & Retest	Repair indicated defects per system; allow cure (if liquid); retest repaired zones until pass.	Roofing Crew / ELD Specialist	Witness retest
11	Root Barrier Installation	Lay root barrier loose-laid over membrane (or as system); overlap seams ≥ 100 mm; weld/tape as specified; upstands turned per detail without puncturing membrane.	Roofing Crew	Visual/continuity
12	Drainage/Water-Retention Layer	Install boards/mats per flow direction to outlets; interlock/connect; cut neatly around outlets; install inspection boxes; ensure no folds bridging outlets.	Roofing Crew	Functional
13	Filter Geotextile	Place nonwoven geotextile over drainage layer; overlaps ≥ 150 mm (≥ 300 mm at corners/irregularities); upturn at edges to prevent fines migration.	Roofing Crew	Visual
14	Final Inspection & Protection	Walk-through with QA/Consultant; record as-builts; place temporary protection until growing medium placement.	QA/QC / Consultant	Joint inspection

Safety Controls

Task-Specific Hazards and Controls

Hazard: Fall from height at roof edges/openings
Consequence: Serious injury/fatality
Engineering/Procedural Control: Install guardrails/edge protection; demarcation 2 m from edge; use certified lifelines and harnesses for work within 2 m; cover/guard roof openings.
Required PPE: Full-body harness with double lanyard/ SRL, hi-vis, helmet with chinstrap, gloves, safety boots.
Collective Measure: Temporary guardrails, toe boards, safety nets where feasible.
Inspection/Permit: Work at Height permit; daily inspection of edge protection and anchor points by competent person.
Hazard: Manual handling of rolls/boards and wind uplift during handling
Consequence: Musculoskeletal injury; dropped objects
Control: Team lifts; mechanical hoisting; limit sheet sizes in high wind; store pallets ≥2 m from edges; secure materials.
PPE: Gloves with grip, safety boots.
Collective: Exclusion zones below lifts; tag lines.
Inspection/Permit: Lifting plan; pre-use checks of hoists/cranes; LOLER/ASME certificates.
Hazard: Slip hazard from wetting during ELD
Consequence: Slips/falls; damage to membrane
Control: Use controlled wetting; squeegee standing water; designate wet-test zones; non-slip footwear.
PPE: Slip-resistant boots.
Collective: Barricade test area; signage.
Inspection/Permit: HSE supervisor to brief and monitor ELD activity.
Hazard: Electrical exposure from ELD equipment (low voltage)
Consequence: Minor shock, trip hazards from leads
Control: Only trained ELD technicians; GFCI/RCD protection; cable management; low-voltage equipment per ASTM practice.
PPE: Insulated gloves as required, dry gloves.
Collective: Keep public/other trades out of area.
Inspection/Permit: Equipment calibration records; PAT/testing tags where applicable.
Hazard: Membrane puncture by trafficking/tools
Consequence: Future leakage, costly rework
Control: Lay protection fleece and walk boards; tool control; no sharp debris; prohibit wheeled plant without load spreaders.
PPE: Knee pads, gloves.
Collective: Defined access routes.
Inspection/Permit: Supervisor daily walkdowns.
Hazard: Hot works (only if torching specified)
Consequence: Fire, burns
Control: Prefer cold-applied systems; if unavoidable, hot works permit; fire watch 60 min post-works; extinguishers and thermal camera checks.
PPE: Flame-resistant gloves, long sleeves, eye protection.
Collective: Fire blankets/guards.
Inspection/Permit: Hot Works Permit; gas hose/regulator checks; [Verify per project HSE plan and local regulations].
Hazard: Chemical exposure from primers/adhesives/cleaners
Consequence: Dermal/respiratory irritation, VOC exposure
Control: Use low-VOC where possible; apply in well-ventilated conditions; follow SDS; avoid ignition sources.
PPE: Nitrile gloves, safety glasses, half-mask respirator with organic vapor cartridges if required.
Collective: Spill kits and ventilation fans where enclosed.
Inspection/Permit: SDS on site; COSHH assessments; fit testing records.
Hazard: Cutting operations (knives, shears)
Consequence: Lacerations; punctures to membrane
Control: Use hook blades; cut on cutting boards; blade control & disposal boxes.
PPE: Cut-resistant gloves.
Collective: Tool tethering near edges.
Inspection/Permit: Supervisor checks; toolbox talks.
Hazard: Weather (rain, heat, high wind)
Consequence: Slips, poor adhesion, wind damage
Control: Stop works outside manufacturer limits; secure loose materials; provide shade/water for heat.
PPE: Weather-appropriate PPE, sunscreen.
Collective: Weather monitoring.
Inspection/Permit: Daily weather log; stop-work authority.
Hazard: Working around roof drains and parapets
Consequence: Falls into openings; water ingress
Control: Guard drains; temporary strainers; limit water testing volumes.
PPE: Standard PPE
Collective: Barriers around openings.
Inspection/Permit: Daily inspection records.

Environmental Controls

Environmental Risk Controls

Runoff and Drain Protection
Risk: Primer/adhesive spills, silt, and fines entering drainage
Control: Temporary strainers on outlets; spill kits; use absorbent booms; prohibit washout to drains; controlled water use during ELD.
Inspection: Daily check of outlets; record any spills and remedial actions.
Waste Management
Risk: Mixed waste and offcuts
Control: Segregate polymers, metals, cardboard; store in labeled containers; recycle HDPE/PP where facilities exist.
Inspection: Weekly waste audit; maintain waste transfer notes.
VOC and Odor
Risk: Air emissions from solvents/primers
Control: Low-VOC products where feasible; keep lids closed; avoid application above recommended temperatures.
Monitoring: HSE to verify SDS and ventilation measures.
Noise and Vibration
Risk: Nuisance to occupants
Control: Limit noisy activities to permitted hours; maintain equipment; use low-noise tools.
Monitoring: Complaint log; dB spot checks if required.
Material Storage
Risk: Sun/heat degrading materials; leaks
Control: Store under cover on pallets; secondary containment for liquids; prevent wind blow-off.
Inspection: Daily storage check, inventory log.
Resource Efficiency
Risk: Excess material use
Control: Apply primers/adhesives to TDS coverage; optimize sheet layout to minimize offcuts.
Monitoring: Track usage vs BOQ.
Compliance
Note: All environmental controls to align with project Environmental Management Plan and local regulations. [Verify per project HSE plan and local regulations]

QA/QC

Quality Objectives

Watertight membrane with zero ELD-detected breaches.
Verified root resistance of barrier layer; correct overlaps and continuity of drainage and filter layers.

Inspections & Test Frequencies

Substrate acceptance: 100% area visual plus moisture readings (grid every ~50 m²) [Verify].
Trial seam welds: At start of each shift/change in settings; retain samples.
Seam probing: 100% of welded seams.
Liquid-applied DFT: Minimum 1 measurement per 25 m² per coat; additional at details [Verify].
Outlets: Water pour test at each outlet (≤ 5 L to avoid ponding).
ELD: 100% coverage by third-party prior to overburden; retest repaired areas.
Root barrier seams: 100% visual; random peel check where welded [Verify].
Geotextile overlaps: Check every 10 m and at corners/changes.

Acceptance Criteria (typical – verify per project)

Membrane seams continuous with required overlap (≥ 75 mm) and fusion; liquid membrane total DFT ≥ manufacturer minimum.
No punctures, fish-mouths, wrinkles, or blisters.
ELD final report: Pass with zero active leaks.
Root barrier: Pass EN 13948/FLL certification; overlaps ≥ 100 mm; sealed per system.
Drainage/retention: Continuous path; outlets accessible with inspection boxes installed.
Filter fabric: Overlaps ≥ 150 mm (≥ 300 mm at corners/irregular), no tears; upturns at edges.

Documentation

ITP checklists, calibration certificates (welders/ELD/meters), material COCs/SDS, batch logs, photos, as-builts, NCRs and corrective actions, final ELD pass report, manufacturer site visit/warranty pre-approval.

Nonconformance & Corrective Action

Stop works on detection of leaks/damage; raise NCR; repair per manufacturer detail; retest (including ELD) until pass; update as-builts.

Handover

Submit O&M manuals including membrane and root barrier warranties, ELD final report, maintenance recommendations (traffic control, inspection of outlets, periodic green roof maintenance per FLL).

Attachments

Approved shop drawings and detail sheets (upstands, penetrations, outlets, parapets)
Product Technical Data Sheets (TDS) and Safety Data Sheets (SDS) for membrane, primers/adhesives, root barrier, drainage, and geotextile
Certificates of Compliance (COC) and EN 13948/FLL test certificates for root-resistant components
ELD specialist credentials, equipment calibration certificates, and test method statement
Welding equipment calibration/verification records; sample trial weld coupons (where applicable)
Lifting plan, Work at Height plan, and relevant permits (Hot Works if applicable)
Risk Assessment & Method Statement (RAMS) specific to this activity
Substrate acceptance forms, inspection checklists, and photographic records
Nonconformance Reports (if any) and closure documentation
Manufacturer’s site visit reports and warranty pre-approval letter
O&M maintenance guidance for green roof interfaces (outlet cleaning, inspection frequency)

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ITP preview

The first inspection activities from the linked ITP for Method Statement: Integrated Waterproofing and Root Barrier System for Extensive Green Roofs:

Activity	Inspection / Test	Acceptance Criteria	Responsibility	Record
Pre-works review & approvals	Check approvals, permits	Method/ITP, submittals approved; permits in place.	PM / QA/QC	Approval records, permits
Substrate acceptance	Moisture meter (CM); falls check	Clean, dry; moisture ≤ 5% CM [Verify]; falls achieved; outlets functional.	Site Engineer / QA/QC	Substrate acceptance form, photos
Primer application (if used)	WFT gauge; cure time	Coverage and cure per TDS; no contamination.	Roofing Supervisor / QA	Primer log

Showing 3 of 13 inspection activities. View full ITP →

Related Inspection and Test Plan

An Inspection and Test Plan (ITP) is available for Method Statement: Integrated Waterproofing and Root Barrier System for Extensive Green Roofs. The ITP defines the inspection activities, acceptance criteria, hold and witness points, responsible parties, and records required to verify the work described in this method statement.

View the Method Statement: Integrated Waterproofing and Root Barrier System for Extensive Green Roofs ITP →

Frequently asked questions

Single-ply PVC/TPO membranes to EN 13956 and ASTM D4434/D6878, or approved cold-applied liquid systems. Torch-applied bitumen only if specified.

After waterproofing is complete and before any overburden. All defects must be repaired and retested until a pass report is issued.

Products must pass EN 13948 or FLL root resistance tests and be installed with sealed overlaps per manufacturer instructions.

Minimum 150 mm, increased to 300 mm at corners or irregular transitions. Verify per project specifications.

Install temporary strainers, maintain access via inspection boxes, and perform limited-volume pour tests to confirm free discharge.