Can I install an outdoor fireplace on a timber deck?

You've got a beautiful timber deck and you're dreaming of cosy evenings around a crackling outdoor fireplace. But here's the question that probably brought you here: can you actually install an outdoor fireplace on your existing wooden deck

The short answer is yes, but there's more to it than simply placing one and lighting it up. The weight of your chosen fireplace will be the biggest factor in determining whether your deck can handle it, and what modifications you might need.

How heavy is a fireplace?

When people search for how to build an outdoor fireplace on a deck, they're often surprised to learn just how heavy these units can be. Let’s list some real-world examples to give you an idea of what you're working with.

A lightweight option like the Mini Burton weighs around 1,000kg, the popular Douglas model sits at 1,500kg, and the Hudson weighs 2,500kg (not including accessories or woodboxes). For context, this would be like parking a car on your deck.

At the heavyweight end, models like the Single Peak (6,200kg) and Twin Peak (7,200kg) require serious structural consideration. Most timber decks just aren’t built to handle that kind of load. 

When your deck can handle it

Some outdoor wood fireplace options might work on a well-built deck with proper reinforcement. However, each situation requires individual assessment since factors like your deck's construction, age, and condition all play a role.

Your deck needs to be:

• Built to current building codes
• Structurally sound with no sagging or damaged beams
• Supported by adequate footings
• Designed with appropriate joist spacing and sizing

The challenge is that residential decks are designed for distributed loads rather than the concentrated weight that outdoor fireplaces present. Even lighter models create forces that may exceed your deck's design capacity.

Not sure if your deck can handle it? Our team can assess and guide you. Get in touch today.

Reinforcing your existing deck

If your deck is structurally capable but needs beefing up, reinforcement is possible. This typically involves:

1. Adding Support Posts: Installing additional vertical supports directly under where the fireplace will sit, extending down to concrete footings or existing foundation elements.
2. Strengthening Joists: Doubling up or adding sister joists to spread the load more effectively across the deck structure.
3. Creating a Load Path: Ensuring there's a clear structural path from the fireplace weight down to solid ground, not just the deck surface.

You'll want a structural engineer to assess your specific situation and provide drawings for any reinforcement work. This isn't a DIY job.

Building a concrete pad at deck height

For many situations, the most practical approach is creating a concrete footing that sits at deck height. This gives you the appearance of having your outdoor wood fireplace on the deck while providing the solid foundation these units need.

Here's how it typically works:

• A concrete pad is poured adjacent to or integrated with your deck
• The pad extends deep enough to provide stable support
• The fireplace sits on this concrete base
• Decking can be built around the pad to maintain the aesthetic

This approach works particularly well for heavier models and provides long-term stability without compromising your deck's structural integrity.

Some fireplaces are simply too heavy for any timber deck, regardless of reinforcement. The Single Peak and Twin Peak models definitely fall into this category. These statement pieces require concrete foundations from day one, and we can provide engineering drawings to ensure proper installation for ground-level installation. There is still the chance that an engineer could design a specific timber structure to take the weight of these units, depending on the situation in which you are installing them.

Making the right choice for your situation

When considering an outdoor fireplace for your timber deck, start by having your deck assessed by a structural engineer or qualified builder. They can determine:

• Your deck's current load capacity
• What reinforcement might be needed
• Whether a concrete pad solution makes more sense
• Which fireplace models might be suitable for your specific situation

Don't forget to factor in:

• Local building consent requirements
• Fire safety clearances from combustible materials
• Access for installation (these units often need crane placement)

The good news is that there are solutions for most situations. Whether it's reinforcing your existing deck, creating a concrete pad, or choosing an appropriate fireplace model, you can usually find a way to enjoy those cosy fire-lit evenings.

Getting expert advice

Every situation is unique, and what works for one deck won't necessarily work for another. Factors like your deck's age, construction method, existing condition, and local building requirements all play a role.

We recommend starting with a conversation with our team about your specific setup. We can help you understand which outdoor fireplace NZ models might work with your deck and what structural considerations you'll need to address.

Download our outdoor fireplace brochure to explore the full range of options and specifications that might work for your timber deck project.

Regulations and building codes can change. Always check the latest requirements and consult a qualified professional before installation.