RC FLAT ROOF WATERPROOFING
RC Flat Roof Waterproofing
flat roof design is increasingly commonplace due to the minimalistic and elegant visual appeal it offers. However, without a slope inclined by more than 7 degrees, the lack of rainwater drainage becomes an issue.
Indeed, water-ponding, or the stagnation of water due to rainfall thus becomes a leading factor in the deterioration of the concrete materials in the roof. As such, a strong waterproofing membrane system installed by professionals is essential to protect against such deterioration.
Our waterproofing methodology for a RC Flat roof is a 5 coats system that comes in grey colour high quality durable flexible acrylic waterproofing system or preform Torch-On waterproofing membrane system that ensures years of protection against water leakages to your RC Flat roof while insulating against deterioration occurring due to carbonation, acid or chemical attack. Without effective waterproofing, RC Flat roofs are susceptible to spalling and corrosion of reinforced structural bars.
What To Do If My Flat Roof Is Leaking?
The first thing that you should do is to find the source of your flat roof leak. We recommend to observe the highest level of safety if you decide to go on your roof to look for the leak. Flat roofs usually would collect a lot of water, thus do dry the area and remove any debris before you attempt to conduct a flat roof leak repair. Next, you can start to check for cracks, before deciding if you would need a professional to conduct a flat roof repair for you. If you are confident, you could apply a roofing cement over the damaged area. However, if you want to go a step further above applying a patch to cover the leak, we recommend getting a professional to perform a proper RC roof waterproofing coat to damaged areas.
FAQs
What is RC flat roof waterproofing?
RC flat roof waterproofing is the process of installing a continuous waterproof membrane over a reinforced concrete (RC) flat roof to block water penetration into the slab. Without it, ponding water from Singapore’s heavy rainfall causes carbonation, concrete spalling, and rusting of reinforcement bars. Two systems are common: a 5-coat acrylic membrane in grey, or a torch-on bituminous membrane.
Why do flat concrete roofs leak in Singapore?
Flat concrete roofs leak in Singapore mainly because of poor drainage. RC flat roofs with a slope below 7 degrees hold standing water after heavy rain, and prolonged ponding breaks down the concrete surface. Water then enters through hairline cracks, expansion joints, drainage outlets, and parapet wall junctions. Once moisture reaches the rebar, corrosion accelerates and structural cracks form.
What's the best waterproofing system for a flat roof?
For RC flat roofs in Singapore, two systems perform best: a 5-coat flexible acrylic membrane in grey, or a torch-on bituminous waterproofing membrane. Acrylic is preferred for thinner builds and easier recoating; torch-on suits roofs with constant ponding because it tolerates standing water longer. Both protect against carbonation, acid attack, and chemical degradation in tropical conditions.
Liquid membrane or torch-on which is better for flat roofs?
Liquid membrane (typically 5-coat acrylic) is better for new RC flat roofs and minor recoats because it cures into a continuous flexible film, reaches all corners and upstands, and is easy to patch later. Torch-on bituminous membrane is better for older roofs with persistent ponding water, forming a thicker, more puncture-resistant layer that lasts longer under standing water.
How long does flat roof waterproofing last in Singapore?
RC flat roof waterproofing in Singapore typically lasts 10 to 15 years, with the upper end achieved on roofs that drain well. A 5-coat acrylic system averages 10 to 12 years; torch-on bituminous membranes reach 12 to 15 years if seam laps remain intact. Lifespan drops by 2 to 3 years on roofs with ponding water or blocked drainage outlets.
What happens if flat roof waterproofing fails?
When flat roof waterproofing fails, water penetrates the concrete slab, attacks the steel reinforcement bars, and triggers spalling (concrete chunks breaking off). Inside the building, you see ceiling stains, peeling paint, mould, and dripping leaks during rain. Left unchecked for 2 to 3 years, rebar corrosion requires costly concrete repair on top of waterproofing rework.