Roof paint for mabati: how to choose it and make it last

A mabati roof takes more punishment than any other surface on a Kenyan house. It sits under the equatorial sun all day, cools fast at night, gets hammered by the long rains and collects dust in every dry spell. Paint that would last years on a wall can give up on a roof in one season if it is the wrong product or goes on the wrong way.

The good news is that most roof paint failures are avoidable. This guide covers how to pick the right paint for the roof you actually have, how to prepare the sheets, how much to buy, and the mistakes we see fundis and homeowners make most often.

First, what kind of roof do you have?

Before you buy anything, go up (safely) or look closely from a ladder and decide which of these describes your roof.

New galvanised mabati. Bright, shiny zinc surface, no rust. This is the trickiest surface to paint, because ordinary paint struggles to grip fresh galvanising.

Old bare mabati with rust. The zinc has worn off in patches and brown rust is showing, usually along the laps, around nail heads and where water sits.

Previously painted mabati. The old paint is faded, chalky or peeling in places.

Factory pre-painted sheets. Coloured sheets from the mabati maker. Many owners only repaint these once the factory coating has faded badly.

Each of these needs a slightly different start. The topcoat can be the same.

The roof paints we make, and when to use each

Colourtrend Super Roof Paint is our main recommendation for metal roofs. It is made from a blend of polyurethane and alkyd resins and is designed for resistance to abrasion, condensation and severe climatic conditions. The data sheet lists it for metal roofs and mabati in particular. It is solvent-based, dries to a gloss finish and covers approximately 15 to 16 m² per litre per coat on a smooth surface. It comes in 4 litre and 1 litre tins. See the full Super Roof Paint data sheet.

Roof Paint is our economical alkyd-based option. It gives moderate resistance to abrasion, condensation and weather, with a gloss finish, in 4 litre and 1 litre tins. It suits outbuildings, stores and budget jobs where you plan to repaint sooner. Roof Paint.

Colourtrend Acrylic Roof Paint is a pure acrylic, water-based roof coating with a matt finish, made to stand up to strong sun, heavy rain and constant heating and cooling. It comes in 4 litres. Choose it if you prefer a matt look and easy water clean-up. Acrylic Roof Paint.

Maroo Aluminium Paint (Economy range) is for exterior iron and steel, including corrugated iron roofs on houses, factories and stores. It resists heat up to 150°C, damp conditions and salt water, and dries to a leafing silver finish. It is popular on industrial and coastal roofs. Aluminium Paint.

Preparing the sheets: where roofs are won or lost

Ask any experienced roofing fundi and they will tell you the same thing: a roof paint fails because of what was under it. Paint applied over dust, damp or loose rust will lift, no matter how good the tin.

1. Clean

Wash the roof to remove dust, bird droppings, moss and loose chalky paint. Let it dry completely. On a hot day mabati dries quickly on top, but water hides in the laps and under the overlaps, so give it time.

The Super Roof Paint data sheet is clear: the surface must be clean, dry and free from oil, grease or loose material.

2. Deal with rust

On rusted areas, wire-brush or sand off all loose rust and flaking paint. For stubborn corrosion, Maroo Rust Remover chemically strips oxidation and converts remaining rust into a stable layer that is ready for coating. Follow the instructions on the tin and rinse or wipe as directed before priming.

Then spot-prime the bare steel with Red Oxide Primer, which is made for steelwork and comes in sizes from 250 ml up to 20 litres, so you only buy what you need for patches.

3. New galvanised sheets need a grip coat

Fresh galvanising is smooth and slightly greasy, and many paints will peel off it. Our Etch Primer is a two-pack primer designed for maximum adhesion on galvanised and aluminium surfaces. Mix the two parts as instructed and apply a thin, even coat before your roof paint.

[Placeholder to confirm with Maroo technical team: whether Super Roof Paint can go directly onto weathered, older galvanised sheets without etch primer, and the recommended weathering period for new sheets.]

4. Seal leaks before you paint

Roof paint is a protective coating, not a leak repair. If water is coming in at nail holes, laps or around the ridge, fix that first. Our bitumen-based Roof Sealer is made for exactly that: a tough, elastic barrier at joints and fixings. It comes in sizes from 200 ml for a few nail heads up to 20 litres for big roofs.

Applying roof paint properly

• Pick the weather. Paint on a dry day with no rain expected until the paint has had time to dry. Avoid early morning dew and late afternoon when the sheets cool and collect moisture. Do not paint wet or dusty sheets. Fading within weeks is very often caused by exactly that.
• Thin only as needed. Super Roof Paint can be thinned with white spirit depending on how you apply it. Stir well.
• Brush, roller or spray. All three work for Super Roof Paint. A brush works paint into the laps and around nails; a roller is faster on the flats.
• Two coats. Go for two even coats rather than one heavy one. Heavy coats sag in the corrugations and dry slowly.
• Respect drying times. For Super Roof Paint the data sheet gives surface dry in 3 to 5 hours, hard dry in 6 to 8 hours, and recoating after 24 hours. Weather, temperature and film thickness all affect this.

Safety: roof work kills people every year. Use proper ladders, crawl boards and a harness on steep or high roofs, and never walk on sheets between purlins. If in doubt, use a trained fundi. You can find painters through our fundi network.

How much roof paint do you need?

Work it out from the roof area, not the floor area of the house.

1. Measure the length and the slope length (eaves to ridge) of each roof face and multiply. Add up all faces.
2. Corrugated and box-profile sheets have more surface than their flat measurement. Add an allowance for the profile, because the ridges add surface area. Ask us for the figure for your sheet profile when you request a quote.
3. Multiply by the number of coats (usually two).
4. Divide by the coverage on the data sheet.

Example. A roof that measures 100 m² flat, two coats of Super Roof Paint at 15 m² per litre: 100 × 2 ÷ 15 = about 13.3 litres before the profile allowance. In practice that means at least four 4 litre tins, plus whatever the profile allowance adds. Buy everything for one colour at the same time so the colour matches across the roof.

Or let us do it: our paint calculator works out litres per product, and our team can turn it into an itemised quote.

Choosing a roof colour

Roof colour is not just looks. Darker colours absorb more of the sun's heat, and deep shades show fading sooner than lighter or mid tones. Many Kenyan homeowners go for classic maroon, green, blue or grey roofs to suit the walls below.

[Placeholder to confirm: the standard colours Super Roof Paint, Roof Paint and Acrylic Roof Paint are available in.]

Try your combination before you buy: upload a photo of your house to the room and house visualiser or browse the colour catalogue.

Common mistakes we see

1. Painting new galvanised sheets with no primer, then watching the paint peel off in sheets.
2. Painting straight over dust and dew.
3. One thick coat instead of two thin ones.
4. Painting over active rust without removing it.
5. Using roof paint to fix a leak instead of sealing the leak first.
6. Buying tins in batches weeks apart and getting a slight colour difference.

Frequently asked questions

What is the best roof paint for mabati in Kenya? For most houses we recommend Colourtrend Super Roof Paint, a polyurethane and alkyd roof paint made for metal roofs and mabati. For budget jobs, Roof Paint; for a matt water-based finish, Colourtrend Acrylic Roof Paint.

Can I paint new iron sheets straight away? New galvanised sheets need a primer that grips galvanising, such as our two-pack Etch Primer, before the roof paint.

How long before rain can I paint a roof? Paint only when the surface is dry and no rain is expected until the coat has dried. Super Roof Paint is surface dry in 3 to 5 hours under normal conditions.

How many litres of roof paint per iron sheet? Measure the sheet area, add the profile allowance, multiply by two coats and divide by the coverage (15 to 16 m² per litre per coat for Super Roof Paint on a smooth surface).

Need roof paint near you? Find a stockist or call us on +254 734 411 544.