Sika Boom
A single-component polyurethane fixing foam that expands to seal, insulate and anchor gaps around frames, pipe entries and service penetrations in one pass.
What is it?
A one-component, moisture-cured polyurethane expanding foam supplied in an aerosol can, used to fill, fix and insulate connection joints and gaps on site.
Where is it used?
Around window and door frames, pipe and cable penetrations, air-conditioning ducts, roller-blind housings and any irregular gap needing sealing against draught, cold and noise.
Why use it?
It expands to fill awkward voids, cures to a stable semi-rigid closed-cell foam, and delivers thermal plus acoustic insulation without mixing, primers or heavy tools.
How is it applied?
Shake the can, fit the nozzle, pre-dampen the substrate, then dispense in layers in any position; the foam expands, skins in minutes and is trimmable to shape.
About Sika Boom
Sika Boom is Sika’s multi-position polyurethane fixing foam, built for the everyday sealing and fixing jobs that come up on almost every building site. It ships as a ready-to-use aerosol can charged with a one-component PU pre-polymer; the moment the bead leaves the nozzle it reacts with airborne and substrate moisture, expands to several times its dispensed volume and sets into a light-yellow, semi-rigid closed-cell foam. There is nothing to weigh out or mix, no primer to apply, and the can can be held in any orientation, so overhead frame heads and sideways pipe collars are handled as easily as a floor-level gap. For a distributor’s customer base of window fabricators, MEP contractors and finishing crews, that translates into a fast, forgiving product that closes the messy interface between building elements.
The technical insight
The foam works on moisture-triggered polyurethane chemistry. The isocyanate-terminated pre-polymer in the can stays liquid under the propellant pressure; once released, it reacts with water vapour, which both crosslinks the polymer and generates carbon dioxide. That gas is what drives the expansion, inflating the resin into a cellular structure while the crosslinking locks the cell walls in place. This is why moisture control matters so much on site: pre-dampening the substrate gives the reaction the water it needs to cure fully and evenly, and prevents the delayed secondary expansion that occurs when a dry, under-cured core keeps reacting later. The cured cells are largely closed, which is what gives Sika Boom its low thermal conductivity of around 0.04 W/mK and its useful sound-damping, while the modest density of roughly 20 kg/m³ keeps the set foam light and easy to trim back flush.
Where it is used
- Sealing and insulating the perimeter gap around window and door frames
- Filling and fixing pipe entries and cable penetrations through walls and slabs
- Sealing around air-conditioning ducts and HVAC service openings
- Filling roller-blind and shutter box housings for draught and noise control
- Bedding and temporarily fixing frames and fittings until permanent fixings take load
- Draught-proofing and acoustic gap filling between building elements
- Closing irregular voids and construction gaps that are awkward for board or mortar
Key advantages
- One-component and ready to use, with no mixing, weighing or primer required
- Multi-position dispensing lets you foam overhead, sideways or downward from any can angle
- High expansion rate fills large or irregular voids from a compact can
- Fast set, tack-free in about 9 minutes and trimmable in roughly 23 minutes
- Cures to a semi-rigid closed-cell foam with low thermal conductivity for insulation
- Effective sound damping across the sealed gap
- HFC-free formulation and a TÜV-certified gold-valve variant
- Trims, saws and plasters cleanly once cured, so it disappears into the finish
Limitations & considerations
- Not resistant to UV light, so exposed foam must be trimmed and over-coated or covered
- Needs moisture to cure properly; a dry substrate with no pre-dampening risks under-cure and post-expansion
- Does not bond to polyethylene, polypropylene, PTFE/Teflon, silicone or oily and greasy surfaces
- Hollow sections must not be filled completely, as continuing expansion can distort or bow frames
- Can and ambient temperatures must be within range and within about 10 degrees C of each other for reliable foam quality
- Opened cans have a short working life and must be used within about four weeks
Selection & best practice
Shake the can hard for at least 20 seconds and repeat after any long pause. Make sure the substrate is clean, sound and free of dust, oil and loose material, then mist it with clean water before and, on deep joints, between layers. Screw the nozzle on firmly before pressing the trigger, and regulate the bead by how hard you squeeze. Fill deep or wide joints in several thin passes rather than one heavy shot, allowing each layer to expand and skin over, and never fill a hollow section right up because the foam keeps growing as it cures. Keep temporary fixings and packers on any frame until the foam is fully cured at around 12 hours, then cut back flush and protect the exposed face from sunlight. Keep the can and the working area between roughly +18 and +25 degrees C for the best expansion and cure, and clean fresh residue immediately with a PU cleaner since cured foam only comes off mechanically.
Specifications
| Chemical base | 1-component polyurethane (moisture-cured), HFC-free |
| Colour | Light yellow |
| Density | ~20 kg/m3 |
| Compressive strength | ~0.05 N/mm2 at 10% deformation (ISO 844) |
| Thermal conductivity | ~0.04 W/mK (EN 12667) |
| Tack-free / cutting time | ~9 min tack-free; ~23 min to trim a 20 mm bead |
| Full cure | ~12 hours |
| Service temperature | -40 °C to +80 °C |
| Yield | ~37 L (750 ml), ~24 L (500 ml), ~12 L (250 ml) free expansion |
Industry use cases
Windows & Facade
Fabricators seal and pack the perimeter gap around UPVC and aluminium window and door frames, insulating against draught and noise while holding the frame until anchors are set.
MEP & HVAC
Services contractors close the annular gaps at pipe, conduit and duct penetrations through walls and slabs, restoring the thermal and acoustic line at each opening.
Residential fit-out
Finishing crews fill roller-blind boxes, shutter housings and irregular gaps behind joinery for a draught-free, quieter interior that trims flush to the finish.
Commercial & retail
Site teams handle the many small penetration and frame gaps in offices and showrooms quickly from a single can, in any position, without cordoning off wet-mix areas.
Renovation & repair
Refurbishment crews re-seal around replacement frames and re-routed services in existing buildings where clean, low-tool, moisture-cured filling suits occupied conditions.
Frequently asked questions
Is Sika Boom a gun-grade or a straw-applied foam?
How much foam does one can give?
Why do I have to wet the surface first?
Can the cured foam be left exposed outdoors?
What surfaces will it not stick to?
How soon can I trim and finish over it?
How we position Sika Boom
Within Sika’s own range, Sika Boom is the go-to multi-position can foam for general frame and penetration sealing; step up to the gun-applied, higher-yield Sika Boom gun-grade variant for high-volume window and door installation, and reach for a Sika elastic PU joint sealant such as Sikaflex where the joint stays visible or must accommodate movement rather than simply be filled. It is a sealing-and-fixing foam, not a structural leak-stopper: for actively leaking cracks and construction joints under water pressure the right tool is an injection resin like Fosroc Nitofill PU 11R, which we also stock. Space Arc supplies Sika Boom alongside complementary joint-treatment and sealant lines from Fosroc, Dr. Fixit and other brands, so specifiers can standardise on one supplier across the whole gap-sealing scope in Delhi NCR and Pan-India.
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