Understanding Our Declaration of Performance for Timber Cladding

When you’re choosing timber cladding for your home or project, you want to know that what you’re buying is fit for purpose — strong, durable, and made to the right standards. That’s where the Declaration of Performance (DoP) comes in.

Every piece of our Larch, Douglas Fir, and Western Red Cedar cladding is backed by a DoP — an official statement confirming how our timber performs and the standards it meets under UK law. This article explains what a DoP is, what each part means, and how it gives you peace of mind when choosing cladding from Logie Timber.

1. What is a Declaration of Performance (DoP)?

A Declaration of Performance is a legal requirement under the UK Construction Products Regulation (UK CPR) — the regulation that replaced the EU version after Brexit.
It applies to construction products like timber cladding, insulation, or windows that are permanently built into a structure.

In simple terms, a DoP tells you:

• What the product is
• What it’s designed for
• What standards it’s made to
• How it’s expected to perform

It’s your reassurance that the product you’re buying — in this case, natural timber cladding — has been assessed and manufactured under controlled, verifiable conditions.

2. The Key Sections of Our DoP Explained

Let’s take our Larch cladding as an example.

Product Type

This identifies exactly what you’re buying — Solid wood cladding – UK-grown Larch (Larix spp.).
Each species we use (Larch, Douglas Fir, and Western Red Cedar) has its own natural strength and durability, but all are grown, sawn, and processed here in Scotland.

Surface and Finish

Two surface options are listed:

• Off Saw (Bandsawn) – a textured, natural finish with visible saw marks and a natural look.
• Planed Smooth – a more refined finish, suitable for contemporary designs and better for applying finishes like oils or paints.

Both types meet the same performance standards — it’s just a matter of visual style and texture.

Intended Use

All our cladding is for external use above ground, meaning it’s suitable for façades, gable ends, and outbuildings but not for direct ground contact or buried applications.

This is defined as Use Class 3.1 in BS EN 335, meaning it may be exposed to wetting from rain but is designed to dry out naturally between wet periods.

Durability Class

Each timber species has a natural durability rating defined in BS EN 350:

• Larch – Class 3 (Moderately durable)
• Douglas Fir – Class 3 (Moderately durable)
• Western Red Cedar – Class 2 (Durable)

This tells you how resistant each wood is to decay and insects without chemical treatment. It’s one of the main reasons these species are chosen for exterior use — they naturally stand up to the weather.

Moisture Content

• Off saw boards are typically green or air-dried (above 20% moisture).
• Planed boards are kiln-dried to around 16% ± 4% for better stability and finish quality.

This difference affects how the boards behave — kiln-dried cladding is more stable, while green cladding can continue to season naturally on the building.

Reaction to Fire

All untreated softwoods, including Larch, Douglas Fir, and Western Red Cedar, achieve reaction to fire class D-s2, d0 under EN 13501-1.
That’s typical for natural timber — safe for external cladding when installed correctly and not chemically treated. For higher fire performance (e.g. Class B or A), specialist fire-retardant treatments can be applied.

Standard Applied

All our cladding is manufactured to EN 14915:2013 + A2:2020 – Solid wood panelling and cladding.
This standard governs how timber cladding should be produced, tested, and marked, ensuring consistency across manufacturers in the UK and Europe.

Assessment System

Our cladding is UKCA-marked under System 4 — this means it’s a self-declaration system, where the manufacturer (Logie Timber) takes responsibility for internal production control and compliance.
For natural, low-risk products like untreated timber cladding, this system is the norm and entirely appropriate.

Durability & Compliance Statement

This part summarises all the above in plain terms — listing the timber’s expected lifespan, compliance standards, and key installation advice.
For example, our Larch cladding has a conservative expected lifespan of 25 years + when installed correctly and kept above ground with good ventilation.

3. Understanding “Use Class” and “Durability Class”

Two of the most technical-sounding terms in the DoP are also the most useful.

• Use Class describes the environmental exposure of the wood in service.
  • Class 3.1 = Above ground, subject to wetting (e.g. external cladding).
  • Class 4 would be for ground-contact or permanently wet conditions.
• Durability Class describes the natural resistance of the timber to decay.
  • Class 1 = Very durable (e.g. Oak, Teak)
  • Class 2 = Durable (e.g. Western Red Cedar)
  • Class 3 = Moderately durable (e.g. Larch, Douglas Fir)

By combining these two, you can see whether a species is suitable for a particular job — in this case, all three species are perfectly suited to cladding in the Scottish climate when detailed and installed correctly.

4. Installation Guidance and Lifespan

Each DoP includes simple guidance that makes a big difference to the lifespan of your cladding:

• Keep cladding at least 150 mm above ground level.
• Allow for airflow behind the boards (open rainscreen principle).
• Use stainless-steel fixings and pre-drill ends to prevent splitting.
• Cut an angled drip line on the bottom of vertical cladding to reduce moisture ingress to the end grain of the boards. This is normally a 15 degree angle cut back toward the building along the bottom of all the boards so the water runs down the face of the boards and drips off the end and doesn’t get a chance to be absorbed by the end grain.
• Install vertically or horizontally depending on the design — vertical helps rain shed faster.

If installed well and allowed to breathe, untreated timber cladding can last many decades —depending on species and exposure.

5. Visual Grading and Appearance Standards

Our Larch DoP also references BS 8605-1:2014, which defines how timber cladding should be visually graded and specified for both structure and appearance.
This ensures consistent quality for architects and builders — including knot size, wane allowance, machining finish, and absence of defects.

At Logie Timber, every board is visually inspected by trained staff to meet these standards before it leaves the yard.