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Inspection-led waterproofing for GI sheet roofs on factories, warehouses, workshops, sheds and commercial structures.
GI sheet roofs are lightweight and practical, but rainwater can enter through sheet overlaps, loose fasteners, corroded sections, damaged sealants and service penetrations. Pak Chemical Services provides professional GI Sheets Waterproofing Services in Karachi for roofs affected by leakage, rust, failed joints and deteriorated protective coatings.
Unlike RCC roofs, galvanized iron sheets expand and contract with temperature changes. We inspect the complete roof—overlaps, screws, washers, ridges, roof edges, penetrations, corrosion and previous repairs—before recommending localized repair or broader waterproofing.
Professional GI Sheets Waterproofing Services in Karachi starts by identifying where rainwater is actually entering. A visible drip may not be directly below the defect because water can travel along the underside of a sheet, purlin or overlap before appearing inside.
The objective is to treat the actual leakage source rather than patching the internal ceiling or coating unprepared metal.
GI sheet roof problems often become noticeable during rainfall or shortly afterward. Large industrial roofs can have several leakage points at the same time.
Movement, failed sealant, corrosion, poor alignment, damaged fasteners or previous repairs can open overlapping sheet edges. Overlaps should be inspected before broader coating.
Screws can loosen, washers deteriorate, holes enlarge and sealant fail as sheets move. Sound sheets may only need localized fastener treatment.
Failed paint, trapped water, corroded fasteners, exposed edges and scratches can create rust. Loose corrosion must be removed before treatment can bond properly.
Loose, corroded, poorly overlapped or movement-damaged ridge caps can admit water that travels far before dripping inside the building.
Damaged flashing, open edge joints, deteriorated sealant, movement and failed patches need detailed joint treatment rather than coating only the centre of a sheet.
Exhaust ducts, ventilation, AC lines, conduits, cable trays, pipes and skylights can leak when their sealing fails. The service itself must also be checked.
Old coatings can peel, crack, become brittle, separate from metal, wear away at joints or trap moisture. Surface compatibility and adhesion must be assessed first.
GI sheet roofing behaves differently from concrete. Metal expands and contracts with temperature changes, and its joints experience movement. Professional treatment must consider the metal substrate, sheet profile, fasteners, overlaps, ridge joints, existing paint, corrosion, drainage, penetrations and prior repairs. Rigid filling material may crack where movement continues, so the system must suit both the metal and the joint.
Factories and warehouses often have large roofs with numerous joints, fasteners, exhausts, vents, skylights, cable penetrations and ridge caps. Water entry can affect machinery, raw materials, finished goods, electrical systems, packaging, inventory, offices and production areas. For large roofs, work may be planned in sections according to access and operational requirements.
Side laps, end laps, ridge joints, screw heads, washers, flashing joints, corners and service openings are inspected and treated according to their condition. Where movement is expected, the sealing material must accommodate that movement. A rigid filler around a flexible metal joint can crack or separate, and damaged fasteners should be physically checked rather than simply covered.
Preparation may include cleaning debris, removing loose rust and unstable paint, cleaning joints, removing failed sealant, preparing exposed metal and treating previous repair areas. Severely corroded or perforated sheets may require replacement or metal repair first. A coating should never be used to hide metal that no longer provides a stable substrate.
Every treatment sequence is matched to roof condition, metal movement, corrosion and exposure.
We review sheet condition, corrosion, overlaps, ridges, fasteners, washers, flashing, edges, penetrations, coatings, repairs, holes and internal leakage areas.
Likely entry points are identified across laps, fasteners, ridges, corrosion, flashing, penetrations and failed repairs. A complete coating is not assumed automatically.
Dirt, loose rust, unstable coating, failed sealant and incompatible material are cleaned or removed to create a stable bonding surface.
Open joints, fastener holes, patch edges and suitable corroded areas are repaired. Severely damaged sheets may need replacement rather than coating alone.
Side laps, end laps, ridges, screws, washers, flashing, corners and penetrations are treated with metal-compatible material suited to expected movement.
The selected system is applied according to metal type, existing coating, surface condition, corrosion, movement, exposure, roof size and project needs.
Curing follows material, temperature, humidity, weather, thickness and coat requirements. Coverage, joints, fasteners, edges, ridges and penetrations are checked.
When sheets remain generally sound, leakage is concentrated around joints, fasteners or penetrations, corrosion is limited, and old coating can be prepared properly.
Where localized holes, unstable patches, weak fixing points or selected damaged sections must be repaired before a waterproofing system is applied.
When large holes, widespread perforation, deformation or structural weakness prevents the roof from providing a stable substrate.
Results depend on roof condition, corrosion, movement, surface preparation and system selection. No treatment is presented as permanent or lifetime protection.
Cost depends on roof area, GI sheet type, corrosion level, fasteners, open joints, ridge and flashing condition, penetrations, existing coating, previous repairs, surface preparation, local metal repair, selected system, treatment layers, access, building height and site conditions. A large maintained roof may require less repair than a smaller roof with extensive corrosion, so inspection is more reliable than a fixed square-foot rate.
Pak Chemical Services follows an inspection-led approach to GI Sheets Waterproofing Services in Karachi. We inspect the full roof, identify leakage points, check overlaps, fasteners, corrosion, ridges, flashing and penetrations, prepare the metal surface, select treatment by condition, follow curing requirements and complete a final inspection. Severely damaged sheets are not hidden beneath coating when repair or replacement is necessary.
Customers can share roof photographs, leakage videos, rusted-sheet images, fastener details, ridge areas, penetrations and previous repairs through WhatsApp for an initial discussion. Physical inspection may still be required before confirming scope and quotation.
Explore relevant PCS services or request an inspection.
Common causes include open sheet overlaps, loose fasteners, deteriorated washers, corrosion, ridge defects, damaged flashing and poorly sealed penetrations.
Some corroded sheets can be prepared and treated when the metal remains sound. Severely perforated or weakened sheets may require replacement first.
Fastener leakage can often be treated after the screw, washer, hole and surrounding sheet condition are inspected.
Yes. Suitable sheet overlaps can be prepared and sealed according to their condition and expected movement.
Not always. Localized leakage may only require selected joint and fastener treatment, while widespread deterioration may require broader treatment.
It depends on its condition and compatibility. Loose or unstable paint should normally be prepared or removed before treatment.
No. GI sheet roofs are metal systems with movement, corrosion, fasteners and sheet joints that require different assessment.
Not always. Severely weakened or perforated sheets may need metal repair or replacement.
Ridge leakage may be treated where the ridge cap and supporting sheets remain suitable for repair.
Duration depends on roof area, corrosion, joint repairs, preparation, weather, system type and curing requirements.
Cost depends on roof area, corrosion, fasteners, joints, preparation, access and the selected waterproofing system.
Yes. Inspection helps determine whether the roof needs localized repair, broader waterproofing or sheet replacement in selected areas.
Leakage can affect machinery, electrical systems, stored products, insulation and internal finishes. Treating only the visible drip point may not address the actual roof defect.
Contact Pak Chemical Services for professional GI Sheets Waterproofing Services in Karachi. Share your location, approximate roof area, photographs, leakage images or videos, corrosion details and previous repair information to request an inspection and quotation.
