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4.5mm Windstopper Extreme Cembrit 1200x3000mm (3.6m²)

4.5mm Windstopper Extreme Cembrit 1200x3000mm (3.6m²)
4.5mm Windstopper Extreme Cembrit 1200x3000mm (3.6m²)
4.5mm Windstopper Extreme Cembrit 1200x3000mm (3.6m²)
4.5mm Windstopper Extreme Cembrit 1200x3000mm (3.6m²)
4.5mm Windstopper Extreme Cembrit 1200x3000mm (3.6m²)
4.5mm Windstopper Extreme Cembrit 1200x3000mm (3.6m²)
4.5mm Windstopper Extreme Cembrit 1200x3000mm (3.6m²)
4.5mm Windstopper Extreme Cembrit 1200x3000mm (3.6m²)
4.5mm Windstopper Extreme Cembrit 1200x3000mm (3.6m²)
  • 4.5mm Cembrit Windstopper Extreme External Sheathing Board
  • 4.5mm x 1200mm x 3000mm (3.60m²) - 15 Year Cembrit Warranty
  • Cembrit Extreme features a windproof membrane for exterior walls
  • Windstopper is powerfully resistant towards both rot and fungal growth
  • Extreme Board function as a temporary façade protection for up to 12 months
Estimated delivery:
In Stock
£ 114.76
Ex VAT: £ 95.63
  • Brand: Cembrit
  • Model: Windstopper Extreme 3m
  • Weight: 27.72kg
  • Dimensions: 3,000mm x 1,200mm x 4.50mm
  • SKU: 4.5mm Extreme
  • Product code: P1-2699
  • MPN: Windstopper Extreme 3m

Options available

Cembrit 4.5mm Windstopper Extreme (1200mm x 3000mm) is a special type of fibre-cement weather resistant breathable external sheathing board with A2 fire protection class that features a windproof membrane for exterior walls.

Windstopper Extreme by Cembrit is a non-combustible, vapour permeable cement based building board that has a very low vapour transmission resistance, enabling moisture from inside the building to pass through.

The board consists of grey cement and limestone filler, reinforced with a specially selected fibre material that can absorb and release moisture without affecting the durability, strength or performance of the board.

Cembrit Windstopper Extreme is available in two thicknesses 4.5mm and 9mm, the boards can be scored and snapped making them an ideal choice for rapid and dust-free installation.

Both thicknesses provide good acoustic insulation properties, when installed according to Cembrit installation instructions, Cembrit Windstopper Extreme will function as a temporary facade for up to 12 months.

Windstopper Extreme can accept insulation being placed against the board on the warm side of the building, whilst acting as a fire break against any blaze in the ventilation cavity behind the rainscreen.

This special Cembrit panel has been designed for use as a sheathing board in rainscreen facade cladding application and is BBA Approved (no. 21/5885). 

As part of a non-load bearing vertical building element Windstopper Extreme 9mm will provide up to 90/90 minutes of fire resistance when exposed to fire from one side.

This board consists of natural materials and variations may occur in the product colour or other characteristics from board to board.

Cembrit Windstopper Extreme has been tested in accordance to BS EN 1364-1:2015 (BS 476-22:1987).




Thickness: 4.5mm

Width: 1200mm 

Length: 3000mm

Board Coverage: 2.88m2

Density: 1450kg/m3

Surface Front Face: natural rough surface

Surface Back Face: natural rough surface

Durability (Life Expectancy - Minimum): 15 years

Fire Reaction: Class A2-s1,d0, Non-combustible


Cembrit Windstopper Extreme External Sheathing Board Features:

 · Non-combustible

 · Highly durable.

 · Breathable.

 · Only 4.5mm thick!

 · A2 fire protection class.

 · Fibre-cement based.

 · Moisture and mould resistant.

 · Can be used as a wind barrier.

 · Vapour permeable board.

 · Natural rough surface.

 · Windproof membrane for exterior walls.

 · Sustainable solution.

 · Resistant to harshest weather and climate conditions.

 · 15 Year Cembrit Warranty.

 · Can be used as temporary facade protection for up to 6 months.

 · Resistant towards both rot and fungal growth.


4.5mm Cembrit Windstopper Extreme External Sheathing Board Installation Guidelines:

 · The boards are fixed to the wall frame with screws or clout nails spaced 200mm along all edges and 300mm elsewhere.

 · The distance between screws or nails and the board edges shall be minimum 15mm, and distance to the corners minimum 70mm.

 · The screw or nail heads shall be level with the board surface.

 · The diameter of clout nail heads shall be minimum 8mm.

 · If other types of nails with smaller heads are applied the nails shall be covered by a tape in the same way as for joints between boards.

 · Connections to foundations, window and door openings, roof and wind barrier penetrations shall follow the principles shown in relevant Building Research Design Guides.

 · When used as sheathing and wind barrier in floors over crawl space foundations Cembrit Windstopper boards are fixed with screws spaced 200mm along all edges.

 · The distance between screws and the board edges shall be minimum 15mm, and distance to the corners minimum 70mm.

 · Penetrations of the wind barrier layer in structures with a classified fire resistance shall have a documented fire resistance performance which do not reduce the fire resistance performance of the boards.

 · All joints between boards shall be sealed with Cembrit Windstopper Tape.

 · The board surface shall be dry and free from dust before the tape is applied.

 · Minimum effective width shall be 50mm.

 · At tape joints the overlap shall be minimum 25mm.

 · The boards shall be stored on a level support in a dry place.

 · If stored outside the boards shall be protected from moisture, dirt and mechanical strain by a ventilated tarpaulin.


You can order free Cembrit Windstopper Extreme External Sheathing Board samples here.


*Further information may be found in our Downloads section.

Fairly easy access to all PDF files.

Datasheet ǀ Declaration of Performance - DoP ǀ BBA Certificate ǀ Installation Guide ǀ Certificates ǀ Brochure ǀ SPEC Sheet

Board covarage 3.24 m2
Density 1400kg/m3
Length 3000mm
Material Fibre-cement based
Profile Extreme External Sheathing Board
Size 4.5mm x 1200mm x 3000mm
Temperature resistance max. 105°C
Thermal Conductivity 0.32W/mK
Thickness 4.5mm
Water Vapour Resistivity 0.3 sd1
Weight/m2 7.70kg
Width 1200mm 
Bending Strength 16.9 MPa
Fire Classification Rating K1 10 & K2 10
Fire Reaction A2-s1, d0
Coverage 3.60m2 per board
Finish Natural rough surface
pH Value 9 pH
Durability Minimum 15 years
Sound insulation reduction 29Rw (dB)
Applications External Cladding Façade Sheathing Board
Fixing method Screws and Nails
Features Fire Resistant Sheathing Board
Manufacturer Cembrit® Windstopper Extreme

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We deliver insulation materials to Mainland UK only. Deliveries to Highlands, Northern Ireland, Isle of Wight etc.. might be possible at additional cost.
We offer free delivery on most of the orders above £300 (excluding VAT) (except special products - shipping cost via courier - products marked ''Request A Quote'')

Delivery of some insulation materials might be extended due to the current situation (Covid-19, stock shortages, allocations).
If you need materials quickly please contact us - we will do our best to help you source materials needed.

We do not deliver on weekends and bank holidays. Sometimes we can deliver on Saturdays - please check with us before placing the order.
If you need any further information please contact us tel. 02081910776

We can help to calculate price per m2 or linear meter (one meter in length) cost, please just contact us via phone 02081910776, email or live chat. Alternatively, you can work it out yourself quickly and easily: to get cost per meter square please divide price shown in orange area by ''Required area (m2)'' Example price of £28.80 divided by board coverage 2.88m2 = cost of £10.00 per m2.


No matter whether you choose a local installer or a national company, there’s a few tips to help you find the right installer for your home insulation improvements, such as asking for recommendations and making sure that they’re part of a certification scheme. This makes sure that they have the right skills and standards of workmanship to carry out the installation, and you can be sure that they know exactly what they are doing.


1. Thermal inspection picture in portfolio

It’s worth seeing a installer’s previous work. There’s no harm asking if you can see any properties nearby that they’ve installed insulation in. Best way would be to see Infrared Thermal Imaging Inspections. Thermal cameras spot small, but key changes in temperature in different areas of a house, identifying problematic areas that the human eye never could and some that a visual inspection could only hypothesize.

2. Reviews

Along with checking recommendations and previous work, finding reviews online can often be a great way to find out if they provide a good service or not. However, it’s best not to solely rely on reviews you may find or review websites, as there’s no controlling who writes them.

3. Compare prices

Comparing prices will also ensure companies can’t take advantage of you and give you a fair price. 

4. Word of Mouth

The best way to find a great insulation installer is through recommendations. Make sure you ask friends and family. They will most likely give you their honest opinion and can tell you from first hand experience.


Whether you require a wall, cladding, external wall, loft or floor insulation fitted, you can find and hire your local insulation installers from popular UK web pages. A simple internet search will return thousands of potential installers near your area.



We are the stockist of construction materials and related products for both trade and DIY from most recognizable brands in the UK like Cordek, RCM, Promat, Rockwool, Isover, Celotex, Xtratherm, Ursa, Low-E, Cedral, Kingspan, Dufaylite, British Gypsum, K-rend, Ecotherm, Iko enertherm, Kay-Metzeler, Terrawool to allow you to complete your insulation job on time at competitive prices and the highest standards.


Whether you are a large company or a DIYer, if you need a large amount of insulation materials, we can offer quantity discounts at the best prices. Please contact us and our friendly customer service will try to find the best and cheapest solutions for you. We value your time and we will try to deliver the products as soon as possible at a reasonable price to your construction site or house. The UK's leading insulation supplier near you and your needs. Price List available upon request.
4.5mm Windstopper Extreme Cembrit 1200x3000mm (3.6m²)
4.5mm Windstopper Extreme Cembrit 1200x3000mm (3.6m²)
£ 114.76