EN 16755-2017 pdf download.Durability of reaction to fire performance – Classes of fireretardant treated wood products in interior and exterior end use applications.
The maintained fire performance of a coated product (with an ordinary paint) may be verified by fire
testing according to EN 13823 or Iso 5660-1.
Verification of DRF Class EXT is valid for thicker wood products than verified, but not for thinner.
5.2 Reaction to fire performance
5.2.1 Initial classification for reaction to fire
Classification testing for reaction to fire performance shall be performed. The products shall fulfil a specified fire performance according to a recognized reaction to fire standard. The recognized standards are for construction products EN 1350 1-1 and for maritime application the IMO Code FTP [12].
5.2.2 Reaction to fire performance before and after accelerated or natural weathering
5.2.2.1 General
Reaction to fire performance before and after weather exposure shall be performed according to 5.2.2.2. The weather exposure shall be performed according to an accelerated procedure, see Annex B, or according to EN 927-6 or natural weathering according to EN 927-3. If there is a contestation. the reference test method Is EN 927-3 wIth fire testing according to EN 13823 before and after weathering.
For the accelerated weathering, it is essential that the exposed samples are large enough to be fire tested. Thus, minimum width is 100 mm (minimum according to ISO 5660-1).
For the accelerated weathering, it is also essential that the exposed samples are large enough to fulfil the cutting requirements in 5.2.2.2.3 and Annex B.
For the natural weathering, It is essential that the exposed samples are large enough to be fire tested either by European standards or by small scale testing, see 5.2.2.2.2 and 5.2.2.2.3.
It is recommended that the natural weathering according to EN 927-3 is extended for at least one year as specified in EN 927-3, since experience shows that the fire performance may degrade during up to 10 years [21, 201.
For the natural weathering, exposure at 45° slope is recommended.
Natural weathering at relevant conditions for the specific end use is most desirable, but such data are usually not available. It is recommended that a set of the products going through an accelerated weathering procedure is also exposed to natural weathering, in order to gain experience on the relationship between accelerated and natural weathering.
Additional variations of the product, e.g. additional coating systems (with ordinary paints), could preferably be evaluated at the same time. Examples of weathering studies are given in [21, 20].
5.2.2.2.2 FIre performance testing according to European standards
The preferred test method is the same as for the initial classification according to 5.2.1, i.e. EN 13823. At least one replicate may be used for the fire testing after weathering. The same mounting conditions shall be used for the fire testing before and after weathering.
5.2.2.2.3 Fire performance according to small scale testing
Alternatively, fire testing may be performed in small scale according to the cone calorimeter ISO 5660-1. This alternative is justified by correlation studies with methods for classification test methods of many product. e.g. (21, 22, 231. Some data on limited correlation are also available (19J.
At least three replicates at a heat flux 50 kW/m2 for at least 1 200 s shall be tested. Conditioning for ISO 5660-1 tests shall be carried out according to EN 13238.
If this alternative is chosen, testing of the product before weathering is also needed for comparison of the fire performance before and after weathering.
The preparation of small test specimens of fire-retardant treated wood products Is very important for the test results obtained, since the amount of fire-retardant chemicals may vary between small samples. This is especially important for impregnated solid wood products. Such specimens shall therefore be cut in order to represent the fire properties of the full wood plank. A suitable procedure as specified in [13J is recommended:
— Specimens should be cut approximately 0,1 m from the end of the plank;
— Specimens should not have knots in the centre area – sound knots covered by the edge frame in the ISO 5660 series may be used.
5.3 Durability of reaction to fire performance
5.3.1 General
Three classes for the Durability of Reaction to Fire performance are defined:
— DRF Class INTl for permanent use in interior dry applications, service class 1 (e.g. wall and ceiling products);
— DRF Class INT2 for permanent use in interior humid applications, service class 2 (e.g. wall and ceiling products);
— DRF Class EXT for permanent use in exterior applications, service class 3 (e.g. facade claddings, exterior conditions).EN 16755-2017 pdf download.