Concrete & Structural Defects
Magnesite Flooring Deterioration
Magnesite flooring deterioration occurs when moisture activates the magnesium chloride salts within the screed, causing softening, delamination, surface breakdown and accelerated corrosion of the underlying steel deck or concrete reinforcement.
Common Signs
- Soft, powdery or friable surface
- Surface delamination and flaking
- Rust staining through flooring
- Moisture-related swelling or softening
- Cracking and surface breakdown
- Loose or hollow areas underfoot
Common Causes
- Moisture activating magnesium chloride salts
- Failed waterproofing below or around flooring
- Inadequate surface sealing
- Drainage or plumbing failure
- Age-related deterioration
- Corrosion of steel deck substrate below
Risk of Neglect
- Ongoing moisture damage to the structural substrate.
- Accelerated corrosion of reinforcement or steel deck.
- Structural deterioration if left untreated.
- Damage to finishes and fixtures above flooring.
- Increasing scope and cost of removal over time.
- Health and safety concerns from deteriorated surfaces.
- Moisture transmission affecting lower floor tenancies.
Inspection Requirements
- Assess magnesite condition across the floor — firmness, delamination, cracking and surface breakdown.
- Identify moisture source and confirm waterproofing condition below and around the flooring.
- Use a moisture meter to measure moisture levels in the magnesite and substrate.
- Break out locally to inspect the structural slab, steel deck or reinforcement below.
- Assess extent and severity of corrosion to embedded reinforcement or steel substrate.
- Confirm extent of magnesite removal required before proceeding.
- Document affected areas with photos and mapping prior to any works.
Start Inspection Checklist
Create a project inspection record, add defect locations, upload photos, and save notes for scope writing.
Typical Repair Methodology
Magnesite removal and reinstatement must be planned carefully. The moisture source must be resolved before repair. Final scope and substrate treatment to be confirmed by the project engineer.
- 01.Identify and address the moisture source before commencing any removal or repair.
- 02.Isolate affected areas and establish containment to manage dust and debris from removal.
- 03.Remove deteriorated magnesite flooring by mechanical means — grinding, scarifying or jackhammering as appropriate.
- 04.Take care during removal not to damage the structural slab, steel deck or waterproofing substrate below.
- 05.Clean all magnesite residue from the substrate surface after removal.
- 06.Expose and assess the structural substrate fully once magnesite is removed.
- 07.Treat corroded reinforcement or steel deck substrate as directed by the engineer.
- 08.Apply concrete repairs to the slab substrate where required before waterproofing.
- 09.Install an approved waterproofing or moisture barrier system to the prepared substrate.
- 10.Allow waterproofing to fully cure and complete any required testing before overcoating.
- 11.Install new approved flooring system compatible with the substrate and building use.
- 12.Ensure adequate curing and protection of the new flooring system during construction.
- 13.Record QA photos, product details, batch numbers, test results and completed hold points.
Related Repair Systems
- Moisture suppression primers
- Self-levelling underlayments
- Floor patching compounds
- Floor grinding and preparation
Open Repair Systems →