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Wind-driven rain & Environment
Flint & stone construction


Where do I purchase SureCav?

  • Directly from this web site.
  • Through Builder's Merchants.


SureCav can be delivered to site within 48/72 hours.

What is SureCav?

The SureCav Cavity Wall Spacer System is a black, injection moulded, recycled, polypropylene sheet, with raised spacer protrusions at 260 mm centres.

Measurements of each sheet:

Length: 1200mm
Width: 450mm
Depth: 50mm (SureCav50) or 25mm (SureCav25)
Sheet thickness: 2mm

How are the sheets joined together?

The sheets interlock with plastic, H-section profile joining strips at all edges. Corners are formed by folding the sheet along the bend line built into each sheet. The correct number of joiners required are included in the cost and shipped with each pack of SureCav.

Horizontal joining strip length: 900mm
Vertical joining strip length: 400mm

How do I install SureCav?

See the instructions here on the 'INSTALLATION' tab

Do you supply wall ties and wall tie clips with the system?

No. The SureCav System comprises SureCav25 and SureCav50 panels and the joining strips (and seal washers for timber-frame). It is the customer’s responsibility to supply ancillary items and ensure that best building practice is maintained.

How many joiners do I need?

On ordering, we need to know the number of sheets of SureCav you require (calculate by dividing the no. of square metres of wall area by 0.54). Sufficient horizontal and vertical joiners will be sent with the order and are included in the price of the sheets.
Please note: The 900mm joining strips are to be used for the horizontal joints. Cut a long joining strip up to a wall tie and use the off-cut to start the next section (or cut a notch in the joiner and slot it over the tie). The 400mm joining strips are designed to exactly fit the vertical joints of the SureCav panel.

Will I need seal washers, and if so how many?

Washers are recommended for fixing the SureCav panels to timber-frame buildings. The whole SureCav System can thus be fixed to the frame ahead of the masons, adding extra protection to the timber-frame. We would suggest 5 washers per panel, one in each corner pod and one in the centre. They can be purchased in bags of 50.


SureCav Limited only supply the seal washers, not the fixing screws or wall-ties. To comply with Local Authority Planning Departments and NHBC Standards (6.2: External timber Framed Walls) M10 wall ties and their fixings should be of austenitic stainless steel, comply with the BS EN 845 and be capable of accommodating anticipated differential movement.

How many sheets to a pallet?

SureCav is shipped in packs of 10 sheets.
One pallet will contain 300 sheets (30 packs) of SureCav25 or 200 sheets (20 packs) of SureCav50.

Are there any other products on the market that do the same job as SureCav?

SureCav is the only product that carries BBA certification that can successfully replace concrete backing blocks or shuttering and still maintain a moisture and mortar free cavity. Our unique patented system forms a 50mm cavity, saving time and money. SureCav25 is the only product available that allows a permitted 25mm residual cavity, approved by BBA & LABC and accepted by NHBC.

SureCav is approved by the British Board of Agrément (BBA certification No. 04/4154). View certificate 

Does the cavity need to be ventilated?

Appropriate ventilation for the cavity must be provided by air bricks or perp/weep vents, providing a minimum of 1500mm2 per linear metre, venting at DPC and lintels as normal and high level if required – see BBA certificate section 9:2. Ensure a corresponding slot, matching the vent aperture, is cut in the SureCav panel to allow full ventilation.

What insulation type is recommended with use with SureCav?

SureCav must be installed against a robust surface, so ideally, a board PIR insulation is best suited. SureCav25 will allow an extra 25mm insulation in a designed 100mm cavity, helping to achieve a possible U-Value with 75mm insulation to 0.18W/m2K. SureCav25 helps to minimise the overall wall thickness with deeper insualtion, whilst still ensuring a 25mm residual cavity.

Is SureCav compatible with Rockwool partial-fill cavity insulation?

Rockwool can be used as a suitable partial-fill cavity insulation material as long as the type of rockwool used has a robust surface. It is especially important that the surface of the insulation does not compromise the moisture protection groove on the SureCav pod. There are several products available that would be acceptable, e.g. dual density stone wool products that have a high-density outer layer and a lower-density sub-layer.

Will it protect against wind driven rain?

By building with the SureCav panels instead of a using a block leaf you are providing a barrier to protect from wind driven rain. The "wall" of plastic, formed by the SureCav panels not only provides an excellent surface for the construction of the stone wall but shields the cavity and inner leaf from water ingress. The unique shape of the SureCav pods directs any moisture to the outside leaf, thus protecting the fabric of the building... read more

Is it environmentally friendly?

SureCav is 100% recycled polypropylene. Instead of ending up as landfill or incineration material, SureCav is manufactured by injection moulding process to produce a building material that shows we care for the environment. SureCav comes out on top in reducing the Embodied CO2(ECO2) footprint in new buildings as well as being 100 times lighter than concrete blocks, making site management and movement of materials much easier... read more

Will I save money by using SureCav?

By choosing SureCav you could be saving the difference of £20.69 per square metre, compared to using a block suport wall. Also, don't forget that the time saved using SureCav results in a faster build, estimated to be 10 working days on an average four bedroom house... read more

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Can I use Surecav with SIPs panels?

Yes, SureCav still provides the best means of forming a cavity, an essential element in construction. The external leaf of stone, flint, brick or slate can then be completed with ease. Structural Insulated Panels (SIPs) offer a modern, cost-effective, environmental and energy efficient solution to building construction. A SIPs building is constructed by assembling pre-manufactured panels which are heavily insulated, often eliminating the need for additional insulation. The panels are very strong and used in external and internal walls. The ties are fixed to the outer face of the SIP panel with a stainless steel screw. The SureCav panels are fixed, as with timber-frame, by a s/s screw and seal washer through the pods (recommended 5 per panel) see seal washers above.  For more information about SIPS panels and full SIPS building systems see www.supersips.uk.com

Would the SureCav Cavity System be suitable for use with an ICF (insulated concrete former) construction such as NUDURA?

SureCav25 and SureCav50 have both been successfully used on ICF structures. The SureCav panels will provide a suitable drainage membrane, designed to keep the residual cavity it forms completely mortar and moisture-free, with the pods in the sheets preventing any moisture from crossing the cavity. Wall-ties are screwed into the special vertical sections of the ICF wall and fit between the SureCav panels each 450mm vertically, at the local designers specified centres.

Can SureCav be used with flint construction?

SureCav has been specified on many flint projects and was also featured on Grand Designs (Newbury Christmas Cottage 2013). The flint being placed directly against the SureCav sheets, with the SureCav acting as an effective backing board, protecting the cavity from moisture and mortar. Additional support for the flint can be achieved by fitting frame ties, with the SureCav seal washers through the pods, or helical ties where needed through the flat face of the SureCav panel only. Also, stainless steel EML can be set in the bed for support, cable tied to the wall ties.

Will SureCav support a natural rubble rag (limestone) stone, 125-150mm thick outer leaf?

SureCav was designed for this scenario, with standard ties at 450mm vertical SureCav board intervals. Additional frame ties can be fixed through any of the pods using the SureCav seal washers. For additional support, drill a pilot hole into the block inner leaf and fix a helical tie through any flat surface of the SureCav panel only, not through the pods.

How can we compensate for stone that is deeper than the cropped size ordered?

Assuming the cropped stone is ordered at 125mm, the preferred method is to set out at damp course with the deepest stone width (which could possibly be up to 10mm more) and then use mortar to take up any variance in gap with the narrower stone. To ensure you have a suitable base when doing the groundworks you will need to lay a concrete block flat or lay a min.150mm wide block up to damp course. This will give a suitable base on which to construct the 125mm stone walling.

Does the stonework have to be coursed, or can it be used with rubble stone walling as well?

Standard ties are installed each SureCav board coarse, 450mm vertically as normal. For random/rubble stone or flint, fix additional ties for extra support through the pods with the seal washers as required. Helical ties can be fixed through any flat surface of the SureCav sheet (not through the pods)

Can SureCav it be used with raked joints?

Raked and semi-dry coursework are acceptable and often used. Some local authorities insist on a minimum 100mm mortar bed, but is down to the structural engineer/designer to confirm with the authority.

Are there any implications to using SureCav in a radon area and is it compatible with barriers by Visqueen etc?

If SureCav is required for stonework below DPC then trim the SureCav to the tray or Radon barrier and then continue with the SureCav above, ensuring the Radon barrier is kept intact. Ensure proper ventilation to the cavity, as per BBA cert. (see BBA certificate) which requires 1500mm2 per linear metre run, achieved by air bricks/perp vents at low level, lintels and high level if needed.

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