Polyurethane (PU) expanding foam provides a fast solution for sealing, bonding, and insulating in construction projects. Its ability to expand and fill irregular voids makes it useful for tasks ranging from window installation to soundproofing.
Contractors across Kenya use our PU foam solutions to achieve airtight and durable results.
What is PU Expanding Foam?
PU expanding foam is a one-component chemical seal that expands significantly when released from its canister.
It relies on atmospheric moisture to cure into a semi-rigid and closed-cell structure. This expansion allows the material to penetrate deep into gaps that standard caulk or construction adhesives cannot reach.
Once cured, the foam becomes water-resistant and can be cut, sanded, or painted. It serves three main functions on a job site. It insulates against heat and sound transfer. It acts as a strong adhesive for mounting lightweight structures. It seals voids to prevent air, dust, and pest infiltration.
We offer different grades depending on the specific project requirements. The Dingli A6618 (B2 Grade) includes flame-retardant properties which commercial buildings often require for safety compliance.
For standard residential filling, the A6615 (B3 Grade) offers consistent expansion and high bond strength to concrete, wood, and metal surfaces.
Sealing and Fixing Window & Door Frames
Improperly fitted frames allow dust, drafts, and noise to enter a building. PU foam provides both a mechanical fix and an insulation barrier in a single step. Most contractors use wedges to hold the timber or aluminium frame in place before applying the foam to the gap between the frame and the concrete.
You must moisten the masonry surface with water before application. This moisture helps the foam cure faster and creates a stronger bond to the concrete.
The foam expands to fill every irregularity in the rough opening. Once it hardens, it holds the frame securely without warping it. You should then trim the excess material and apply a weatherproof silicone sealant over the external edge to protect the foam from UV damage.
Filling Gaps, Cracks, and Voids in Walls
Masonry work often leaves irregular holes around pipe penetrations, utility lines, or electrical boxes. Leaving these spaces open invites pests and compromises internal air quality. Expanding foam fills these deep cavities completely.
It expands to match the exact shape of the void which rigid filler materials cannot do.
This capability creates an airtight seal that blocks insects and dust effectively. It is also useful for closing large non-structural cracks in plaster before repainting.
You can inject the foam deep into the crevice to bond the masonry together. For heavy-duty bonding of metal fixtures near these repairs, you might consider our Construction PUR adhesive.
Insulating Pipes and Electrical Conduits
Loose pipes inside walls often rattle or vibrate when water flows through them. Encasing these pipes in PU foam stabilizes them and reduces plumbing noise. It also provides excellent thermal insulation.
Cold water pipes in roof spaces can suffer from condensation during Nairobi’s colder months. A layer of foam prevents this sweating and protects ceiling panels from potential water damage.
Electrical conduits also benefit from this insulation. Sealing the point where conduits pass from the exterior to the interior prevents warm air from escaping. This is particularly useful where PVC-U pipes enter the building foundation, as it seals the entry point against groundwater dampness.
Soundproofing and Noise Reduction
Noise transfers easily through small air gaps around doors and thin partition walls. PU foam creates an effective acoustic seal because of its dense closed-cell structure. It stops air movement which carries sound waves from one room to another.
Applying foam around the perimeter of internal door frames significantly reduces noise transmission between offices or bedrooms.
You can also use it to fill the hollow spaces inside door jambs or behind drywall in washrooms to dampen vibration.
This application is valuable in multi-story residential buildings where plumbing noise or neighbor activity travels through shared walls.
The foam absorbs these vibrations and deadens the sound before it reaches the living space.
Sealing Roof Structures and Minor Leaks
Small openings in roof structures often lead to leaks during heavy rain or allow wind to lift roofing sheets. PU foam adheres strongly to common roofing materials including corrugated iron, clay tiles, and stone.
You can use it to seal gaps around ventilation pipes or where the roof meets the wall plate to prevent draft entry.
It also serves as a bonding agent for loose ridge tiles. The foam expands into the underside of the tile and locks it to the mortar or timber below.
You must paint over any foam exposed to direct sunlight on the roof. UV rays degrade the yellow foam over time and turn it brittle if you leave it unprotected.
Best Practices for Applying PU Foam
Getting a clean and strong result requires specific preparation. You must wear protective gloves and eyewear because uncured foam is extremely difficult to remove from skin and clothes.
Shake the canister vigorously for at least one minute before use to mix the propellant and the pre-polymer.
Always spray water on the surface before applying the foam. This moisture is necessary for the chemical reaction that cures the foam. It also prevents large air pockets from forming inside the bead.
Hold the can upside down with the valve facing the floor to ensure the gas pushes the foam out effectively. Fill gaps only about 50 percent full. The material will continue to expand and fill the remaining space as it cures.
Choosing the Right Dingli PU Foam for Your Project
Selecting the correct grade of foam depends on the specific safety requirements of your building. We supply two primary grades to cover residential and commercial needs.
Dingli A6618 (B2 Grade)Â is our fire-retardant option. Building codes often require this grade for commercial spaces, public buildings, or areas with higher fire risks like kitchens and electrical ducts.
It creates a seal that resists combustion for a specified period, adding a layer of safety to the structure.
Dingli A6615 (B3 Grade)Â is the standard general-purpose foam. It is ideal for residential window installation, gap filling, and landscaping.
It offers the same bonding strength and insulation properties as the B2 grade but without the specialized fire-retardant additives. This makes it a cost-effective choice for standard home repairs and construction tasks.
Frequently Asked Questions
Can I paint over PU foam?
Yes. Once the foam has fully cured (usually after 24 hours), you can trim the excess with a sharp knife and sand it down.
It accepts both water-based and oil-based paints, which is essential for protecting it from sunlight.
How long does it take to cure?
The foam forms a non-sticky skin within 10 to 15 minutes. It can be cut after about one hour depending on the humidity. Full curing takes approximately 24 hours.
Do not disturb the bond before this time has passed.
Is PU foam waterproof?
Cured polyurethane foam is water-resistant. It creates a watertight seal against rain and dampness. However, it is not designed to be permanently submerged underwater.
Expert Take on PU Foam Use in Kenya
Polyurethane foam offers a reliable solution for sealing, bonding, and insulating across Kenyan construction sites.
Using it correctly improves the energy efficiency and structural integrity of windows, doors, and walls. You need to assess whether your project requires the safety rating of B2 foam or the standard efficiency of B3 foam.
Contact the Dingli Kenya team today to get the Technical Data Sheet (TDS) for our foams or to place a wholesale order for your hardware store or construction site.
