2.5 Fastening EPS / XPS / Graphex board - to solid filled masonry

There must be no horizontal surfaces which will be subject to water ponding; a minimum slope of 5 degrees is required (for metal caps only, 10 degrees for liquid membranes). Check EPS/XPS insulation board supplied is the correct; type, grade and thickness.

2.15.1. Ground Clearances

Refer to RCS TradeSpec™ document 1.2.5 Ground Clearances

2.15.2. Wall Alignment

Using a straight edge, check joints are smooth and that the wall is flat and true.

2.15.3. Builder Supplied Flashings

Make sure all builder supplied flashings are in place. (Refer to RCSe TradeSpec™ document 3.2 Builder Supplied Flashings) for a list of possible builder supplied flashings.

2.15.4. Rockcote Flashing Installation

Refer to the flashings as outlined within the RCS RenderSpec™ section 5 and refer to their installation procedures in RCS TradeSpec™ document 3.1 Rockcote Flashings

2.15.5. Control/Expansion Joint Set outs

for more information about control joints refer to RCS TradeSpec™ Document 1.4 – Control Joints.

2.15.6. Substrate Installation

Insulation Fastener Installation – IDP's

If you are using an IDP fastener to secure the polystyrene to the substrate use a masonry drill with correct length & diameter drill bit in accordance with table 1, at centres specified in table 3.

Insulation Fastener Installation – Using a Powder Actuated Tool

If you are using a Powder Actuated Tool to fix an Insulation Fastener take care to follow all Health and Safety requirements of the Power Tool. Fix fasteners in accordance with table 2, at centres specified in Table 3.

Insulation boards

All insulation boards must be installed in a 'stretcher bond' pattern and butt-jointed hard against each other.

Any gaps between sheets must not be greater than 3mm. All gaps must be foam filled. (Refer to RCS TradeSpec™ 3.6 Low Expansion Adhesive Foams)

Fix insulation boards with fasteners and washers as given in the Table 1 – Fastener Sizes

Fix fasteners through the insulation board, and into the substrate at the fixing centres shown in Table 3 – Fastening centres.

Fixings must be flush against the insulation board, and pulls the sheet hard back against the substrate

3mm notched trowel coat application of Rockcote MultiStop Bedding compound applied to the entire surface of the insulation board prior to fitting.

Recommend the use of Insulation board sizes – 600mm x 1200mm – allows for ease and accuracy of installation


Table 1 – IDP Fastener Sizes

Substrate Thickness (mm)

Fastener type

Drill bit diameter

30mm IDP 2/4 * 8mm


IDP 2/4 *



IDP 4/6 *



IDP 6/8 *


100mm IDP 8/10 * 8mm


* Hilti Fasteners

Table 2 – Powder Actuated Tool Fastening – Fastener Sizes

Substrate Thickness (mm)

Fastener type


X-IE 6-40 *

50mm X-IE-6-50 *

* Hilti Fasteners

Table 3 – Fastening centres

NZS 3604 Building Wind Zones

Fastening centres (mm)







Very High



IDP 2/4 *