PTG Treatments Ltd


PTG Treatments is the leading dedicated provider of industrial timber pre-treatment. Our processing centres throughout the UK cater for local and national markets with a range of timber protection products and processes to choose from.

Wood is a natural, versatile, sustainable and appealing construction material. Application of modern preservative and fire retardant treatments helps to ensure these properties are maintained for many years. At the same time we are helping to conserve the global forest resource, by extending the useful life of perishable timbers and wood based panels.


If you would like more information on how we can protect and add value to your timber at one of our existing treatment centres, please contact us.

PRESERVATION - Low Pressure Treatment

Low Pressure preservatives provide long term protection against wood destroying fungi and insects and are widely used in timber frame construction, roofing timbers and other lower hazard end use situations (further information on Use Classes).

Their key advantages are lower uptakes of water during treatment and a more natural colour compared with the green high pressure treatments. The waterbased preservative solution is applied to the timber in purpose designed industrial plants using a vacuums during the process. This provides an 'envelope' of protection and leaves the core of the timber untreated and dry. The low uptake of water as a result of the process quickly evaporates leaving the treated timber at it's original dimensions and moisture content.

To select the correct specification please use the table below or download our Guide to Low Pressure Treatment (PDF)

Treatment Code Use Class Typical Components
PV1 1 or 2 Internal building timbers, timber frame material, roofing timbers, TR26.
PV2 1 to 3 Plywood and other suitable sheet materials
PV3 3 Joinery or timbers used externally above ground and protected by a suitable surface coating

PRESERVATION - High Pressure Treatment

High Pressure preservatives provide long term protection against wood destroying fungi and insects and are used in almost all end use situations (further information on Use Classes) The waterbased Osmose AC500 solution is applied to the timber in purpose designed industrial plants using vacuum and high pressure processes. This maximises the penetration of preservative into the timber and provides long lasting protection.

To select the correct specification please use the table below or download our Guide to High Pressure Treatment (PDF)

Treatment Code Use Class Typical Components
PT1 1 or 2 Internal building timbers, timber frame material, roofing timbers, TR26, tile battens.
PT2 3 Cladding, soffit, fascia and barge boards, Fence rails, decking, pergolas above ground contact. Farm buildings, stables, frames and sole plates above DPC.
PT3 1,2 or 3 Plywood and other suitable sheet materials
PT4 4 Ground contact timbers, Fence posts and gravel boards and any timbers in contact with the ground or below DPC level.
PT5 N/A  
PT6 Up to 4  
PT7 Up to 4  

PRESERVATION - Treatment Selector

To select the correct preservative treatment for your timber, select the end use in the table below. Choose the recommended treatment and note the PTG Specification code. This can be used to write your specification and will ensure that your timber receive the appropriate protection at our Treatment Centre.

Model Specification Clause:
The timber as detailed is to be preservative treated to PTG Treatments Specification code (insert specification code from below) and Use Class (insert appropriate Use Class from below).

Following treatment any timbers that have been drilled, crosscut or notched must be treated with a suitable end grain preservative. Timber that has been rip sawn, regularised or planed must be returned to the treatment plant for retreatment. Fence posts must not be pointed following treatment.

Timber end use Use Class Recommended Treatment(s)  PTG Specification Code
Internal building timber, timber frame components, roofing timbers; above DPC  1 or 2  Low Pressure or High Pressure


External Joinery protected with a coating.  3  Low Pressure  PV3
External cladding, soffits, fascia and barge boards.  3  High Pressure  PT2
Fence rails, decking and pergolas above ground.  3  High Pressure  PT2
Decking and pergolas components in contact with the ground.  4  High Pressure  PT4
Plywood sheathing  1 to 3  Low Pressure or High Pressure  PV2
Fence posts and gravel boards  4  High Pressure  PT4
Sole Plates below DPC  4  High Pressure  PT4
Sole Plates above DPC  2  Low Pressure  PV1
Contact with fresh water  4  High Pressure  PT4
Brown fencing or landscaping timbers  3 to 4  High Pressure  PT6
Retaining wall timbers  3 to 4  High Pressure  PT7

PRESERVATION - Preservation Use Classes

Use Classes, (formerly referred to as Hazard Classes), have been introduced to help specifiers and users of treated timber, identify and confirm the level of protection their timber requires for a particular end use.

The table below shows the main use classes that can be specified.

Generally a greater degree of protection is required as the Use Class increases. These Use Classes are used throughout the industry to provide a common understanding of the level of protection that is required for a given application.

Use Classes:

1 Internal, dry e.g. upper floor joists
2 Internal, risk of wetting e.g. tile battens
3.1 Outdoor, coated, above ground e.g. window frames
3.2 Outdoor, uncoated, above ground e.g fence rails
4 Direct soil or fresh water contact e.g. fence posts

Fire Protection

Want to use timber for its aesthetic, structural and environmental advantages?

Concerned about Fire and Building Regulations?

PTG Treatments operates the latest treatment facility in Europe for fire protection to help you specify timber with confidence. We provide the full package from advice on specification and standards through to delivery of treated goods to site.

Osmose FirePRO used at our Treatment Centre in Tilbury, Essex, is an advanced fire retardant treatment applied in purpose designed equipment. It has been tested to BS EN 13501-1:2003 Fire classification of construction products and building elements and can achieve either Euroclass B or C.

Osmose FirePRO has been independently accredited and has the following features:

  • Can be used in interior or weather protected exterior situations
  • Fire Performance to Euroclass B or C
  • Low smoke development values
  • Strength Durability
  • Low Hygroscopicity
  • Resistant to fastener corrosion

FIRE PROTECTION - Standards and Classifications

1.  Osmose FirePRO fire retardant treated wood products (FRTW) have been tested to BS EN 13501-1:2002 "Fire Classification of Construction Products and Building Elements".

FIRE PROTECTION - Reaction to Fire Tests

These tests are commonly referred to as 'reaction to fire tests'. Reaction to fire tests are commonly called up in regulations of both the building and transport sectors. The classifications of flammability are detailed in the table below along with the UK transpositions of the more traditional BS476 Classifications.

Classification: (European)

BS476 UK Transpositions




Very Limited Combustibility


Class 0


Class 1


Class 3

Treated with Osmose FirePRO, timber and wood based panels can achieve either Class B or Class C. Osmose FirePro is suitable for treatment to WPA Fire Retardant Commodity Specifications FR1, FR2, FR3 and FR4.

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