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About Wood

Constructive and architectural protection

An effective form of prevention is to make sure that the wood construction is correct. This means that by way of a particular construction type, you can make sure that as little moisture and water as possible, is allowed to reach and settle in the wood. In other words: the construction should be made so that water and moisture is led away from the wood surface as quickly as possible.

Illustration shows examples of protective construction:


Illustration shows examples of wood in the construction.

 

RISK CLASS 1
The wooden element is covered, fully protected against weather conditions, and not exposed to humidity. The wood and elements derived from it, attain a moisture content below 18%.
 
RISK CLASS 2
The wooden element is covered, fully protected against weather conditions, but occasionally the ambient temperature may be high, causing occasional – but not lasting - (surface) humidification. The wood and elements derived from it, attain a moisture content below 18-20%.
 
RISK CLASS 3
The wooden element is not covered and not in contact with the soil. It may be permanently exposed to weather conditions. It is always exposed to frequent humidification. The wood and elements derived from it, attain a moisture content above 20%, with relatively quick variations caused by periods of humidity and dryness.
 
RISK CLASS 4
The wooden element is in contact with the soil or clean water, and exposed to constant humidification. The wood and elements derived from it, attain a moisture content above 20% for long periods of time.
 
RISK CLASS 5
The wooden element is permanently in contact with sea water. The wood and elements derived from it, attain a moisture content above 20% for long periods of time.


Wood based products for outdoor use, which are not in contact with the ground – including balconies, benches, boxes, wall cladding, doors and windows – must be categorised in Class 3. Thanks to the treatment with GORI products, it is possible to use coniferours and broadleaved wood in 3 classes and use them as substitutes for hardwood, providing they receive the correct treatment with a GORI primer.
 
WOOD SPECIES CONIFEROUS BROADLEAVED CATEGORY OF
RESISTENCE
Norwegian Spruce X   4
Hemlock X   4
Pine X   3-4
Larch X   3
Oregon Pine   X 3
Mahogany   X 2
Oak   X 2
Dark Red Meranti   X 2-3
Light Red Meranti   X 3-4
Teak - Afzelia   X 1
Framire   X 2-3
Iroko   X 1-2
 
1: Very resistence 2: Resistence 3: Moderately resistence 4: Low resistence 5: No resistence
 

Construction in accordance with the standard EN335

According to EN335, only wood from classes 3 and 4 should be used for outdoors. For economic reasons wood species such as pine and spruce are often used. These species are not equipped with a natural defense against mould, fungi, insects and decay in the sense of the standard stated in EN335. Therefore they need chemical treatment to meet the requirements of classes 1, 2, 3, 4 and 5.

CLASS 1 Wood for indoor use - completely protected from moisture
CLASS 2 Wood for indoor use, protected against moisture in areas, where moisture can form
CLASS 3 Outdoor wood surfaces, not in contact with ground
CLASS 3.1 Protected, occisional wetting
CLASS 3.2 Unprotected, frequent wetting
CLASS 4 Outdoor wood surfaces in contact with ground
CLASS 4.1 Outdoor wood surfaces in contact with ground and/or fresh water (permanently wet)
CLASS 5 In salt water, after treatment with GORI products, use is possible