Why We Use Spruce for UK Outdoor Saunas | KOVE

All KOVE outdoor saunas are designed with proper roof protection as standard — because in the UK climate, the roof does the majority of the work.

Depending on the sauna design, this takes one of two forms:

• Barrel saunas: fully shingled, weatherproof roofs
• Cube saunas: a concealed waterproof membrane beneath slatted roof panels

In both cases, the timber structure underneath is shielded from rain, UV exposure, and standing moisture. This means you don’t need to rely on expensive, heavily treated timbers just to survive outdoors — and that’s actually good news for performance and price.

1. Spruce Performs Exceptionally Well When Properly Protected

Once protected by a roof system — whether shingles or a waterproof membrane — spruce becomes an incredibly stable, clean, and reliable sauna timber. It’s been used in Scandinavian saunas for decades for good reason.

• Low resin content
• Stable at high sauna temperatures
• Bright, clean Scandinavian appearance
• Fewer knots than pine
• Excellent heat retention

In short, spruce delivers a high-quality sauna experience without the unnecessary cost of more exotic or heavily processed timbers.

2. Thermowood Becomes Largely Redundant

Thermowood is engineered for direct, unprotected outdoor exposure — constant rain, UV, snow, and freeze–thaw cycles. That makes sense when timber is fully exposed.

But KOVE saunas are not built that way. With either a full shingle roof (barrels) or a concealed waterproof membrane beneath the cube roof panels, the structure is already protected from the elements.

In real-world UK use, the additional cost of thermowood brings very little practical benefit. The roof system is doing the hard work — not the timber treatment.

3. Cedar Is Premium — But Mostly for Aesthetic Reasons

Cedar is a beautiful, aromatic, naturally durable wood and it’s a great choice for design-led or high-budget projects. However, once proper roof protection is in place, cedar’s advantages are primarily about appearance and scent, not structural performance.

For most customers, that price increase isn’t necessary. Spruce delivers the same core function, longevity, and sauna performance at a much more accessible price point.

4. Why KOVE Uses Spruce

This is the key reason we choose spruce at KOVE:

When combined with proper roof protection, spruce gives you the performance and durability you need — without inflating the overall sauna cost.

• Strong, stable timber for sauna environments
• Protected by shingles or a concealed waterproof membrane
• Lower overall cost than cedar or thermowood
• Clean, premium appearance without premium pricing

5. UK Climate Reality: Roof Design Matters More Than Timber Treatment

In the UK, most timber issues come from:

• Constant rainfall
• Moisture followed by frost
• Long-term UV exposure
• Standing water and damp conditions

That’s why KOVE focuses on roof design first. By keeping the structure dry — whether through shingles or a hidden waterproof membrane — spruce performs exceptionally well outdoors, without needing thermowood-level processing.

Short Version for Customers

KOVE saunas are properly roofed as standard. Because the structure is protected — either by shingles or a concealed waterproof membrane — there’s no need to pay extra for thermowood. Spruce delivers excellent sauna performance, durability, and a classic look at a much fairer price.