Quick answer
To stop a leaking flat concrete roof, clean and repair the surface, seal cracks and joints, then apply a waterproof coating over the whole roof. For an exposed roof, a ready-to-use acrylic membrane such as Sikalastic-510 (primer plus 2–3 coats at about 0.5 kg/m² per coat, reinforced with Sika Fab-1 mesh at cracks and corners) is the simplest DIY fix. Where the roof will be covered with tiles or a screed, a cementitious slurry such as SikaSeal-105 or SikaTop-107 Seal goes underneath.
Common causes
- Hairline and shrinkage cracks in the roof slab or old screed
- Failed joints around parapet walls, water tanks, pipes and drains
- Water standing because the roof has too little slope or blocked drains
- Old mud/brick-tile (khaprail) layers that hold water and let it soak through
Step-by-step
- 1
Inspect and clean
Sweep the roof, remove loose plaster, moss and old flaking coatings, and clear every drain. The surface must be sound, clean and free of dust and oil.
- 2
Repair cracks and joints
Open up cracks, fill them, and seal the joints where the roof meets parapet walls, pipes and water tanks. Sika MultiSeal BT tape or a polyurethane sealant such as Sikaflex Construction works for joints and flashing.
- 3
Prime the surface
For Sikalastic-510, apply the primer coat (about 0.2 kg/m²) and let it dry as per the datasheet.
- 4
Reinforce weak spots
Embed Sika Fab-1 reinforcement mesh into the first coat at cracks, corners and wall-to-roof junctions.
- 5
Apply the waterproof coats
Apply 2–3 coats of Sikalastic-510 at about 0.5 kg/m² per coat, each coat crosswise to the last once the previous one is dry. Avoid application before rain or on a wet roof.
- 6
Cure and check
Let the system cure fully before foot traffic, then check drains and joints after the first rain.
Always follow the current Sika Pakistan product datasheet for surface preparation, temperatures and curing.
Products for this job
Sikalastic-510 PKReady-to-use acrylic membrane for exposed roofs (Raingard).From Rs. 19,580
SikaSeal-105 PKCementitious waterproofing slurry for roofs that will be tiled or screeded over.From Rs. 3,700
SikaTop-107 Seal PKTwo-component flexible slurry for roofs, terraces and wet areas under tiles.From Rs. 8,000
Sika-1 PKIntegral waterproofer mixed into roof screed and plaster mortar.From Rs. 3,299
Sika MultiSeal BTSelf-adhesive butyl tape for joints, flashing and pipe penetrations.From Rs. 1,799
Sikaflex ConstructionPolyurethane sealant for movement joints and gaps.From Rs. 4,000
Frequently asked questions
Which chemical is best for roof leakage in Pakistan?
For an exposed flat roof, an acrylic liquid membrane such as Sikalastic-510 is the most practical choice: it is ready to use, brush-applied and UV-resistant. If the roof will be tiled or screeded, a cementitious slurry such as SikaSeal-105 or SikaTop-107 Seal is applied underneath instead.
How much does roof waterproofing chemical cost in Pakistan?
It depends on the roof area and the system. Use the coverage figure on each product page (for example about 0.5 kg/m² per coat for Sikalastic-510, 2–3 coats) to work out how many packs you need; live prices are shown on every product page.
Chat leakage ka permanent ilaj kya hai?
Pehle chhat saaf karein, cracks aur joints (parapet, pipe, tanki) bharein, phir poori chhat par waterproof coating lagayein — khuli chhat ke liye Sikalastic-510 (primer + 2–3 coats, Fab-1 mesh ke sath). Tiles ke neeche SikaSeal-105 ya SikaTop-107 Seal istemal hota hai.
Can I apply roof waterproofing myself?
Yes. Sikalastic-510 is a one-component, brush-applied coating suited to DIY on a clean, dry, sound roof. For large roofs, structural cracks or active leaks through the slab, get a contractor to inspect first.
When should roof waterproofing be done?
On a dry day with no rain expected until the coating has dried, ideally before the monsoon. Do not apply on a wet roof or in extreme midday heat; check the temperature limits on the product datasheet.