Practical Points

RELATED QUESTIONS


1. If the fire treated cladding timbers or plywoods are cut on-site do they need any extra protection?


2. Can I re-profile my cladding once treated?


3. Can you fire treat veneered plywood?


4. Can you fire treat green oak?


5. Do I need to increase my material wastage allowance to take into account changes in timber properties after FR treatment?


6. Is CE Marking of fire retardant treated timbers required?


 

 


 

 

 

 

 

 

1. If the fire treated cladding timbers or plywoods are cut on-site do they need any extra protection?

Providing that the cut edges are butt jointed no additional treatment is required to the cross cut ends of cladding of standard thicknesses or for plywood after cross cutting.

 

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2. Can I re-profile my cladding once treated?

No. Treated timbers can be cross cut providing the cut ends are butt jointed but they cannot be rip sawn or re-profiled after treatment.

Removal of timber via re-profiling would result in removal of fire treatment and hence the fire performance.

 

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3. Can you fire treat veneered plywood?

We do not recommend fire retardant impregnation treatment of pre-veneered plywood. The veneers are prone to blistering / delamination at the point of treatment.

However there are other options available. Please contact us directly to discuss your requirements further.

 

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4. Can you fire treat green oak?

The simple answer is no. Timber must be kiln dried before treatment.

Commonly kiln dried cladding is supplied for fire treatment with a moisture content of 13-19%. The nature of modified timbers is that they are manufactured with lower moisture contents typically ranging 6-10%.

 

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5. Do I need to increase my material wastage allowance to take into account changes in timber properties after FR treatment?

For the majority of species, customers should supply a minimum 5% extra material with each order to allow for kiln degrade, kiln samples and moisture content samples.

However, some species will require more of a wastage factor than others. We strongly recommend that you contact us directly to discuss project specifics.

 

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6. Is CE Marking of fire retardant treated timbers required?

As part of the Construction Products Regulation the CE marking of permanently installed construction timbers is now required.

Contact Lonza Wood Protection directly for further guidance, if required.

 

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