BS EN 492-2012 pdf download.Fibre-cement slates and fittings Product specification and test methods.
7.5.2.2.2.3.2 SupportIng construction, substrate and thermal Insulation
Both long and short wing frames are made out of timber, (50 ± 1) mm x (50 ± 1) mm. or larger available standard section sizes for vertical and horizontal members, providing sufficient stability for the frames is obtained. They are nailed or screwed together. A substrate is fixed to these frames which Is representative for a normal uriderlayer or wall construction.
For the standardized mounting and fixing of fibre cement slates, a non-FR-treated particle board for internal use (see EN 312) is used with a nominal density of (680 ± 50) kg/rn3. a nominal thickness oF (12 ± 2) mm and class D in accordance with EN 13501-1. The substrate shall have the dimensions of the frame. It is installed with a cold butted vertical and horizontal joint in it and it is fixed with nails to the supporting construction, The joints shall be at the locations as indicated in Figure 5.
When mounted into the test rig the space between the test ng backing board and the substrate shall be filled with mineral wool Insulation with a nominal density of (70 ± 20) kg/rn3 and class A2-sl ,dO according to
EN 13501-1.
A 80 mm x 80 mm x 2 mm (maximum dimensions) metal angle shall be put in front of the timber counter battens and behind the timber battens and the slates to close the open joint between the two frames (see Figure 7).
7.5.2.2.2.3.3 Timber battens and fixing of the slates
To the non-FR-treated particle board substrate, a number of vertical untreated counter battens are nailed with a thickness of (20 ± 1) mm. To these battens, horizontal laths (untreated tile laths) are nailed. Dimensions of the tile laths are (19 ± 1) mm x (38 ± 1) mm. The distance between the tile laths depends on the slate format that is to be tested. In this way, the thickness of the air layer behind the slates is (39 ± 2) mm.
The fibre cement slates are fixed with copper hooks or nails depending on the normal fixing of the slate and are laid in a pattern of overlapping which is normal for the type of slate that is to be tested.
7.52.2.2.3.4 Product orientation
For all end use applications, the testing is performed in vertical position. Products with identical surface finishes on both sides have to be tested at one side only. Products with different surface finishes or coatings on different sides shall be tested on both sides or with the side representative for the worst performance directed to the fire. The worst performance Is normally obtained with the side having the finish with the highest organic content per m2 surface or with the side with the darkest colour. The side with the highest organic content shall be derived from the composition of the different finishing layers or by determining their PCS value according to EN ISO 1716, takIng account of the respective applied dry weights of the finishing layers.
In case both sides are tested, the classification of the side with the worst performance can be used for the classification of the product, or the classification of each of the sides can be declared separately. In case only one side is tested, the classification of that side can be used for the classification of the product.
7.5.2.2.2.3.5 Product direction
The product shall be mounted such that the line corresponding to the roof pitch or the vertical wall line is
directed vertically in the test specimen.
7.5.2.2.2.3.6 Jointsloverlaps
The fibre cement slates are laid in a pattern of overlapping which is normal for the type of slate that is to be tested. The sizes of the overlaps are as in practice. At the bottom of the frames behind the first row of slates, a row of so called under eave slates is used as in practice. They are cut from the same product.
7.5.2.2.2.4 Number of tests
7.5.2.2.2.4.1 PrelIminary tests
Perform one test using slates with the largest surface area and then perform the next test using slates with the smallest surface area. Decide which case gives the worst test results, This worst case is then tested for classification and is the basis for the classification of the whole product range.
7.5.2.2.2.4.2 Classification tests
Three valid tests are required for classification. The products used for the construction of the three test assemblies are taken from standard production lots. The normal manufacturing tolerances apply.
NOTE Ths is for example the case for the overall thickness and thickness of finishes or coating layers.BS EN 492-2012 pdf download.