Hiil cladding installation guide — washed and brushed panels

See also the maintenance guide

Overview

Hiil’s charred wood products are easy to install and maintain. Our products arrive installation-ready straight from the factory and behave like ordinary sawn and profiled timber. With proper care, charred wood remains beautiful for decades.

Which products this guide covers

This guide covers Smoke, Smoke+, Charcoal, Bark, Bark+, Frost, Soot, Snagwood, Autumn Glow and Moss cladding panels and boards in indoor and outdoor use.

Receiving and inspecting products on site

When receiving the delivery, inspect the bundles for any external transport damage. Damage reported afterwards may no longer be accepted as a claim by the shipping company.

Check the panel profiles and dimensions on site, and report any defects before installation. We are happy to investigate and resolve any issues before the products are installed.

Packaging and transport

Products are packed at the factory in bundles no taller than 120 cm.

Bundles may arrive with extra boards or panels on top as protective material. Any such protective boards are marked separately on the back of the timber and are not intended to be installed.

Storage and handling on site

If the products are not installed immediately, protect them from rain and dust. Allow air to circulate around the timber, and keep bundles at least 10 cm off the ground — for example on a pallet.

Do not store other materials or supplies on top of the bundles, as they may damage the wood surfaces.

Preparing for installation

Before fastening the products, cut them to length and protect the cut surfaces with a finish treatment. Charring only affects the surface of the wood, so cutting always exposes fresh, untreated wood that needs protection.

We recommend treating the cut surface with the same finish that the factory uses for the product. The finish can be ordered together with the timber order using the product’s surface name.

Confirm a suitable amount of finish at the time of ordering. You can also order oil after the timber shipment for maintenance purposes.

Cutting and end-grain protection

Use a sharp, fine carbide-tipped circular saw or mitre saw. Keep the workpiece firmly supported to avoid splintering at the cut edge.

Treat every cut end-grain with the finish before installation — even when the end will be hidden (e.g. when shortening an end-matched product). End-grain absorbs moisture much faster than the face, and untreated ends are the most common cause of local cracking and colour change.

WARNING — risk of spontaneous combustion of linseed oil

The special linseed oil used on Hiil products is a natural drying oil. Linseed oil is not manufactured by Hiil, but we draw attention to its use because it is used during installation to protect cut ends and later for maintenance.

Warning! Rags, sponges, paper towels and sawdust soaked in linseed oil can ignite spontaneously if left in a pile. This is a well-known property of many drying natural oils.

After use, rags and sponges must either be laid flat to dry one by one outdoors on a hard surface, or soaked in water and stored in a sealed metal container. Do not dispose of them in an ordinary bin.

Special notes for exterior cladding

Note! When installing exterior cladding vertically, cut the lower ends at a 15–20° angle. This creates a so-called drip nose that sheds moisture more effectively from the bottom ends.

Special notes for interior cladding

Wood is a natural material that changes shape — shrinks and swells — with fluctuations in humidity. The same applies to charred wood, as charring only modifies the wood a few millimetres from its surface.

Note! Wood materials destined for indoor use should be brought to the site only when the building has reached a stage where its temperature and humidity roughly match a normal living environment. The wood should acclimatise to the indoor conditions before installation. Acclimatisation typically takes about a week.

Scent of linseed oil indoors

Hiil products are factory-treated with special linseed oil. Linseed oil is a natural product that oxidises on the surface of the product for about 1–2 months after installation. During oxidation, the oil emits a characteristic linseed-oil scent into the room.

The scent is not harmful and does not affect the healthiness of indoor air. The scent can, however, be dissipated faster with stronger ventilation during the weeks following installation. Adequate airflow helps the linseed oil oxidise dry more quickly. Small spaces such as saunas should be aired after installation.

Installation orientation

Products can be installed horizontally or vertically.

For exterior cladding in a vertical orientation, the drip nose at the lower ends is described in “Special notes for exterior cladding”.

Battening for panel installation

Hiil panel products are always installed on a batten substructure. We recommend a batten spacing of 600 mm centre-to-centre for both indoor and outdoor use. The same spacing works for all Hiil panel widths.

When choosing the battens, remember:

• Use battens thick enough to allow the panels to be fastened securely and to remain straight along their full length.
• In outdoor use, leave a sufficient ventilation gap behind the battens so that moisture can escape from behind the panel.
• Level the batten substructure carefully before installation. Any unevenness in the battens will transfer directly to the panel surface and may also stress the tongue-and-groove joints at the fixing points.

Fastening methods and fastener selection

Charred wood products are fastened essentially like ordinary timber — screwing or nailing depending on the panel width.

Choose screw and nail length according to the thickness of the product being installed.

• Recommended nails: hot-dip galvanised cladding nails
• Recommended screws: thin-headed, black, stainless-steel self-drilling screws
• Steel grade: C1/AISI 410 works; if required, also A2/AISI 304 or A4/AISI 316

Note! When installing screws with painted heads, an impact driver easily chips the paint coating. A finer result is obtained by using a regular drill as a screwdriver.

Fastening: fully tongue-and-grooved panels ≤ 120 mm wide

Fully tongue-and-grooved panels 120 mm or narrower:

• Hidden fixing through the tongue, either nailing with cladding nails or screwing with thin-headed stainless-steel screws. One screw/nail per fixing point is sufficient.
• When screwing through the tongue, pre-drilling is recommended even with self-drilling screws.
• An alternative method is face-screwing through the panel face.

Fastening: wide panels > 120 mm

Wide panels (>120 mm), whether fully tongue-and-grooved, half-tongued or without tongue:

• Face-screw with two screws per fixing point.

This prevents the board from cupping or twisting across its width as humidity varies.

Notes on cladding boards

Hiil products manufactured without a tongue-and-groove can also be installed as cladding. In that case fastening is done at two points through the face of the board, regardless of its width.

On cladding boards, always install the tidier side facing view. Inspect the faces of the product by eye and install the cleaner-looking, nicer-feeling and more even-toned side as the visible face.

In Hiil-supplied board bundles the top layer is always face-down, and most of the products in the bundle have the better face facing up.

Contact

Hiil Oy
info@hiil.fi
https://hiil.fi

Up-to-date contact information is available at hiil.fi.