PU Expansion Foam in Nairobi | Wisdo Merchants

PU Expansion Foam for Filling and Sealing Gaps

Every building has gaps: around new door and window frames, where pipes pass through walls, and between blocks and roofing. Left open, they let in dust, rain, insects and noise, and they let heat or cool air escape. Filling them with mortar is slow and messy. PU expansion foam does the job in minutes. At Wisdo Merchants, we supply it to builders, fundis, plumbers, AC installers and maintenance teams across Nairobi and Kenya.

PU expansion foam is a one-component polyurethane foam in an aerosol can. It comes out as a sticky paste, then grows to fill the gap and cures by reacting with moisture in the air. As a result, it fills uneven cavities completely, sticks firmly to most building materials and forms a light, insulating seal.

Features and Benefits of PU Expansion Foam

• Expands to fill any shape. It swells into irregular gaps that are hard to fill with mortar or sealant.
• Strong bond. It sticks to concrete, brick, block, wood, metal, plaster and most plastics.
• Insulates and soundproofs. The cured foam blocks draughts, reduces heat transfer and dampens noise.
• Fast and clean. It cures quickly, with far less mess than wet mortar.
• Easy to finish. Once cured, it can be cut flush, then plastered, sealed or painted.

For contractors, this means faster finishing and neater results. Meanwhile, building owners get a sealed, better-insulated building.

Technical Specifications

Applications of PU Expansion Foam and How to Use It

• Fixing and sealing door and window frames
• Filling gaps around pipes and cables passing through walls
• Sealing AC pipe holes through external walls
• Filling cavities between blocks, roofing and walls
• Insulating around water tanks, pipes and cold room openings

Fitting a Window Frame

Picture a fundi fitting a new aluminium window into a block wall. First, they clean dust out of the gap and lightly mist the surfaces with water, which helps the foam cure. Next, they shake the can well for 60 seconds. After that, they fill the gap only about halfway, working from the bottom up, because the foam keeps expanding. Finally, they let it cure fully, trim the excess with a knife and finish with plaster or sealant.

When to Choose Fire Rated Foam

Standard expansion foam is ideal for everyday gap filling. However, for gaps where fire resistance matters, such as service penetrations in corridors and kitchens, choose our flame-retardant, self-extinguishing version instead. For bonding cold room panels, use our sandwich panel adhesive set.

Safety and Handling

• Wear gloves and safety glasses. Uncured foam sticks firmly to skin and is hard to remove.
• Ventilate the area. Avoid breathing the vapour while applying and curing.
• Keep away from flames and heat. The can is pressurised and contains flammable propellant.
• Don’t overfill. Too much foam can push frames out of shape as it expands.
• Protect cured foam from sunlight. UV light breaks down exposed foam, so cover it with paint, plaster or sealant.
• Store cans upright and cool, below 45 °C, and never puncture or burn them.

Frequently Asked Questions

How much does PU expansion foam expand?

It expands to several times its wet volume. That’s why you should fill gaps only about halfway.

How long does it take to dry?

It’s usually touch-dry within minutes and can be cut after a few hours. Cure time depends on temperature, humidity and gap size, so follow the times printed on the can.

Is it waterproof?

Cured foam resists water, but exposed foam degrades in sunlight. Seal or paint it on outdoor joints.

Is it fire resistant?

Standard foam is not fire rated. For better fire performance, choose our flame-retardant version.

Do you deliver outside Nairobi?

We offer same-day delivery once your order is confirmed, subject to stock availability. Call or email our sales team to confirm stock and arrange delivery to your site.

Order PU Expansion Foam from Wisdo Merchants

Seal gaps fast and finish jobs neatly. Our PU expansion foam fills, bonds and insulates in one easy step. Furthermore, you can browse our sealants and adhesives for your other building needs.

Visit us: Dar es Salaam Road, Off Enterprise Road, Industrial Area, Nairobi
Call: +254 795 938305
Email: sales@wisdomerchants.com