Installation guide for decking and sauna bench products

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 Bark, Bark+, Soot, Snagwood and Autumn Glow board products used as decking and sauna benches.

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.

Decking joists and substructure

Hiil decking boards and planks are installed on a substructure where the recommended joist spacing is 600 mm centre-to-centre. The same recommendation applies to both 26 mm boards and 43 mm planks.

When building the substructure, also note:

• Hiil Oy products may be used for the substructure provided they are not in ground contact.
• For timber in ground contact, use material intended for that purpose.
• Make sure all joists are at the same level. Adjust before installing the boards so that no stress is introduced into the boards.
• Leave an air and water route under or between the joists so that no standing water can collect under the deck and the structure can ventilate.

Fastening: decking boards and planks

Hiil decking products are delivered dry from the factory. The product may therefore expand slightly after installation as it takes up moisture from the outdoor air. In outdoor use, leave a 7–8 mm gap between boards or planks.

Other decking principles:

• Fasten with two screws per joist at each fixing point.
• Pre-drill holes near the ends to prevent splitting.
• Use A2/AISI 304 or better decking screws — a deck encounters more moisture than a façade.
• Ensure the substructure under the deck is not exposed to standing water and that air can circulate beneath the boards.

Sauna benches

Hiil board products can be installed as sauna benches in the same way as any other sauna benches. Follow the usual principles for bench installation:

• Fasten the boards from below or countersink the screw heads so that heated metal does not touch the skin.
• Use stainless-steel fasteners.
• Leave a gap between the boards so that water can drain away and the benches dry after use.
• Protect cut ends as described in “Cutting and end protection”.

Ventilation of new benches is covered in “Scent of linseed oil indoors”.

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.

Contact

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

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