Everbuild 450 Builders Silicone is a premium low modulus, neutral cure silicone sealant that bonds to virtually all surfaces, porous and non-porous. Ideal for expansion joints, door frames, window frames and general construction pointing. Conforms to ISO 11600 F 25LM.
Price
QTY
£3.49£4.19
£3.49£4.19
£3.49£4.19
£3.49£4.19
£3.49£4.19
£3.49£4.19
£3.49£4.19
Everbuild 450 Builders Silicone is a low modulus, neutral cure silicone sealant built for the kind of general construction work where you need something that performs without drama. Whether you’re sealing around window and door frames, finishing expansion joints or pointing perimeters on a new build, this is the sealant most fixers reach for first. The everbuild 450 builders silicone sticks to virtually all substrates, which genuinely covers a lot of ground on a busy site.
Low modulus matters more than people give it credit for. Unlike high modulus silicones, which stay rigid when cured, a lo-mod product remains flexible and moves with the joint. That’s important in construction where thermal expansion, settlement and general building movement are facts of life. Stick a rigid sealant in an expansion joint and it’ll crack or pull away. A lo-mod neutral cure sealant like this one is designed specifically to flex rather than fail.
Neutral cure also means no acetic acid off-gassing during cure. That matters when you’re sealing around natural stone, metals, or sensitive finishes where an acetoxy-cure silicone would cause staining or corrosion. This one won’t. It cures quietly and cleanly, which is part of why it’s trusted on such a wide range of substrates.
Where Everbuild 450 Builders Silicone Gets Used
The 450 is predominantly associated with UPVC glazing and window frame installation, but it earns its place far beyond that. Construction expansion joints, curtain walling perimeters, cladding details, conservatory frames, door surrounds and general external pointing all fall within its territory. It’s also used internally where a clean, durable flexible seal is needed around frames and architraves.
Colour Options and Site Practicality
Available in white, clear, grey, black, buff, brown and oak, there’s a colour to suit most frame finishes without the need for overpainting. That saves a step on site and helps achieve a clean finish on exposed details. The 300ml cartridge fits standard sealant guns, so no special kit is needed. Conforms to ISO 11600 class F 25LM, confirming its suitability for facade and glazing applications where performance standards are specified.
Pro Tip: When gunning into deep expansion joints, back-fill with a backer rod first to control joint depth and prevent three-sided adhesion, which will restrict movement and cause the sealant to fail prematurely.
The Everbuild 450 is a staple on residential and commercial construction sites. It's most commonly used for perimeter sealing of UPVC window and door frames, both on new builds and replacement installations. Glazing contractors use it for weather-tight seals around double glazed units and curtain walling systems. Beyond glazing, it's suitable for construction expansion joints in facades, cladding interfaces, conservatory joints and general perimeter pointing wherever a flexible, weather-resistant seal is needed. It bonds to UPVC, glass, timber, aluminium, brick, concrete and most coated or painted surfaces without the need for a primer in most situations.
Best For
UPVC window and door frame sealing
Construction expansion joints
Perimeter pointing on facades
Glazing and curtain walling
Conservatory frame joints
General external construction sealing
Compatible Surfaces
UPVC
Glass
Timber
Aluminium
Brick and masonry
Concrete
Most painted and coated surfaces
Key Properties
Low modulus (flexible when cured)
Neutral cure, non-corrosive
Adheres to porous and non-porous substrates
ISO 11600 Class F 25LM certified
Available in 7 colours
300ml standard cartridge
Suitable for interior and exterior use
Not suitable for: Not recommended for aquariums or continuous water immersion without checking specific grade suitability. Not intended as a structural or load-bearing sealant.
Surface preparation makes the difference with any silicone. Clean both surfaces thoroughly, removing old sealant, grease, dust and any loose material. Dry surfaces cure more reliably and adhere better. For most common substrates, no primer is required, but on highly porous or problem surfaces it's worth checking the Everbuild technical guidance.
Cut the cartridge nozzle at a 45-degree angle to suit the joint width, fit it to a standard sealant gun, and apply in a steady, continuous bead. Tool the joint immediately while the sealant is still wet, using a damp finger or a profile tool to compress and shape the bead. Clean up any excess with a damp cloth before it skins.
Remove all old sealant, dirt, grease and loose material from both joint faces
Ensure surfaces are clean and dry before application
For deep joints, install a backer rod to control sealant depth
Cut the nozzle at 45 degrees to match the joint width
Load the cartridge into a standard sealant gun
Apply a continuous, even bead in a single pass where possible
Tool the joint immediately with a damp finger or profile tool to achieve a neat finish
Remove excess sealant with a damp cloth before it begins to skin
Allow to cure fully before exposing to water or heavy weather
What is the difference between low modulus and high modulus silicone?
Low modulus silicone remains flexible after curing and can move with the joint, making it suitable for expansion joints and building movement. High modulus silicone cures harder and is less forgiving of movement. For window frames and construction joints where thermal expansion is a factor, low modulus is the correct choice.
Is Everbuild 450 suitable for use on natural stone?
Yes. Because it is a neutral cure silicone, it does not release acetic acid during curing, so it won't stain or damage sensitive surfaces like natural stone, marble or polished metals. Acetoxy-cure silicones can cause staining on these materials, which is why neutral cure is specified for such substrates.
What does ISO 11600 Class F 25LM mean?
ISO 11600 is the international standard for sealants used in building construction. Class F means it is rated for facade applications. 25 refers to the movement accommodation factor, meaning it can handle plus or minus 25% joint movement. LM stands for low modulus. This classification confirms the product meets defined performance requirements for glazing and facade sealing.
Everbuild 450 is a one-part, neutral cure, low modulus silicone sealant that cures on exposure to atmospheric moisture. The neutral cure chemistry avoids the corrosive by-products associated with acetoxy silicones, making it compatible with a broader range of materials including metals and natural stone. Conforms to ISO 11600 Class F 25LM, confirming its classification as a low modulus facade sealant with 25% movement accommodation. Available in a 300ml cartridge for use with standard sealant guns.
Size
300ml
Cure Type
Neutral cure (moisture curing)
Modulus
Low modulus
ISO Standard
ISO 11600 Class F 25LM
Movement Accommodation
25%
Product Type
UPVC Glazing / Builders Silicone
Available Colours
Black, Brown, Buff, Clear, Grey, Oak, White
Application
Interior and exterior
Size
300ml
Box Quantity
1
Colour
Black, Brown, Buff, Clear, Grey, White, Oak
Product Type
UPVC Glazing Silicone
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