(3) Essential Elements You Need Under a Fire Pit on a Deck + Best Recommendations


Enjoying the warmth of a fire outside is both comforting and relaxing. Watching the flames dance in front of you while you sip on a warm drink sitting on your composite deck.

But with fire comes heat. Composite decking can soften at temperatures as low as 176°F (80°C)Opens in a new tab. and outright melt between 250 and 350°F (121-177°C). Making the potential of a fire pit on a composite deck a dangerous proposition.

Unless you put something under the fire pit on your deck to protect the decking.

To protect composite decking from the heat of the fire pit on the deck, you need two things under the fire pit. Space between the fire pit bowl and the decking is essential to reduce heat on the decking. Plus, a fire pit mat under the fire pit reflecting heat away from the decking while being fire resistant.

There are two main risks that you need to protect composite decking from with a fire pit.

  • Excess heat
  • Sparks or hot coals

The type of fire pit or fire table also increases or lowers the risk of damaging the deck. Two popular fire pits are wood or propane. Each with its advantages and disadvantage. Along with specific requirements for what you put under the fire pit to protect the deckingOpens in a new tab..

I will explain the pros and cons and why I recommend each, but if you just want a quick answer of what to put under a wood or propane portable fire pit, here are my recommendations.

Best Deck Protection Under a Wood Fire Pit on Composite

Wood fires burn hotter than propane producing more heat for those sitting around the fire and the decking underneath. Because of this increased heat, you need the highest level of decking protection under the fire pit.

How DeckProtect Works
https://deckprotect.net/

Beyond the design of DeckProtect is recommendations.

“Wood burning fire pits should not be placed on top of Trex decking unless installed with DeckProtect™, a product designed to temper extreme heat and loose embers.”

Trex

A company will rarely recommend a product that they do not sell. But Trex, one of the leading manufacturers of composite decking, recommends DeckProtect.

This is extremely hard to ignore. No one knows Trex decking better than Trex. If Trex stakes their reputation on DeckProtection’s ability to protect their product, I cannot think of a more compelling reason to buy DeckProtect over other wood firepit deck mats.

But we will get to that more later.

Best Deck Protection Under a Propane Fire Pit on Composite

Propane fire pits or tables burn cooler than wood with more control. With lower heat and greater control, less protection is required. Plus no sparks or burning coal to catch. Under a propane fire pit, you only need to reflect the heat to prevent the decking from melting.

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There are lots of reflective fire mats to choose from. The three most significant features I like about these are.

  • REFLECTS up to 95% of HEAT
  • Only requires 2″ SPACING between the bottom of fire pits 
  • Fire Resistant for temperature as high as 2000 °F (1093°C)

Beyond these three features is who Roloway is. As a company, they are focused on manufacturing top-rated fire-resistant products. This is not something that they also do. This is as my Dad would say.

“Their bread and butter.”

Not an add-on, but their primary focus is protecting valuable from fire damage, period.

So those are my top two recommendations for putting under your fire pit on your deck. Now for the why. What is it about these two fire mats that I appreciate, and how well do they protect composite decking. They can also be used on wood decks, which are more flammable than many PVC or composite decksOpens in a new tab. but without the risk of melting. This is why with composite decking, you need increased protection, preventing melting. Because both composite and PVC decking will melt at a much lower temperature than burn.

Wood will start to be impacted by heatOpens in a new tab. at 320-500°F (160-260°C). Varying by wood type, but wood decking will begin to burn at 392-482°F (200-250°C). There is little temperature difference between smoking and blackening to full flames.

Except, of course, Ipe. Oh, Ipe, you are such an amazing decking material. With a much higher fire-resistance rating. Class A, think concrete. That’s how resistant to fire Ipe is. But I am of topic.

Portable vs Built-in Fire Pits

Before getting too far, there is a big difference between what you put under a portable fire pit and a built-in hearth on a deck.

When constructing a fire pit on the deck, you are options of material increases and durability. Designing the space under the fire pit and around it to not be damaged by the fire pit. Often built in deck fire pits are actually not on the raised portion of the deck but rather a few steps down to a concrete patio or some other hardscape surface where you can safely enjoy a roaring fire without worrying about damaging the decking.

On the other hand, a portable fire pit or table, because of its movability, needs more flexibility for protection. Decking protection under the fire bowl that can be moved with the fire pit around or off the deck. Portably options for portable fire pits.

For this article, we will look at moveable fire pit mats. Leaving built-in fire pits and fireplaces to your local expert who knows your local building codes and requirements are.

Design Space Under a Fire Pit and Decking

This is the simplest and most important way to prevent damage to decking from a fire pit. Putting space between a fire pit and the deck allows the heat to dissipate, cooling before reaching the decking.

Not universal, but often when a fire pit damages decking, it was either too close to the decking or the stand or legs become too hot. The legs then “branding the decking” with the heat from the fire.

As a minimum, a fire pit should have 6″ (150mm) space between the bottom of the bowl and the decking.

Propane fire pits will burn less intensely, requiring less space under the bowl. Allowing for a lower fire pit on your deck when using propane. Don’t worry. They still can produce over 50 000 BTU of heat, just not as much as a wood fire pit.

One of the advantages of a fire table on a deck is increased space between the deck and the fire. Often being twice the height of a fire pit. Keeping the decking cooler, preventing melting or damage with increase space.

Even fire mats made from fire-resistant material require open space between the decking and the fire pit. It’s just good practice and minimizes damage.

This is true even for raised firepit commonly called firetables. Despite being significanlty raised above the deck, if to tighly enclosed can trap heat and damage compoiste decking.

The better ones require less space but all fire pits, especially wood, require space between the decking and the fire bowl.

Add Heat Reflective Material Under a Fire Pit to Protect Composite Decking

Reflecting the heat away from the deck is the best way to lower temperatures under the fire pit. Material that only absorbs the heat will, over time, become hot and burn the decking.

If you are having a good time on your deck, lasting hours with the fire pit burning, anything that does not reflect the heat will eventually become hot. Even bricks that are great fire protection can become hot and transfer the heat to the decking.

I am constantly telling my kidsOpens in a new tab. when we are enjoying a fire on the patio not to touch the concrete blocks around the fire. They do not burn, but they do get hot. Hot enough to burn little hands and composite decks.

Material under fire pit not reflecting heat will not heat up to the point of burning the decking. But hot enough to blackening wood or composite decking.  

Often what more often will happen with composite decking is it will melt. Once melted, it is impossible to repair. Forever leaving an indent, discoloration or worse on the composite decking.

Reflecting the heat under the fire pit on the deck prevents this. With the heat being sent up and away from the decking. Keeping the decking cool, regardless of how long the fire burns.  

The more the fire mat reflects heat, the better. Simple math.

Put Fire Resistant Material Under a Fire Pit on a Deck

Even when reflecting the heat, the fire mat needs to be made from fire-resistant material to not start on fire itself.

A fire bowl can get pretty hot, especially a wood fire creating plenty of heat.

The fire mat being made from fire-resistant material provides just one more layer of defence. That it will not catch on fire.

Again, the higher, the better.

For safety, the rule of three is often applied. Whatever potential temperature the fire can get, the fire mat should be able to withstand three times the heat.

Three times is hard with a wood fire pit but can be done for a propane fire table or pit. Especially since you can easily dial down a propane fire pit. Something much harder to do if you add too much wood in a wood fire pit.

Not a concern with propane or gas fire pits, but for wood fires, the occasional spark leaving the bowl needs to have someplace to land that will not ignite. A fire-resistant mat can do exactly this. Catch the sparks and let them cool without starting burning the decking.

With Wood Fire Pits on a Deck, use a Spark Screen to Prevent Decking Damage

Sparks thrown from the fire bowl onto the deck can damage the decking or worse.

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Fire is unpredictable, especially wood fires. In a second, the fire can throw out a small amber unto the deck.

The easiest way to prevent this with a wood fire is a spark screen. Trapping the sparks in the bowl while letting the heat radiated out.

Even better, use a propane fire pit instead of on your deck, which will not spark. Making them much safer on composite or wood decks.

How DeckProtect and ROLOWAY Protect Your Decking Under Your Portable Fire Pit

I already mention it but the requirements of a wood or gas fire pit on a composite deck differs.

The biggest differences is wood fires have sparks, burning embers and coals. Gas and propane do not. Meaning the pad under a gas firepit only needs to protect the decking from heat only.

A real advantage and why despite loving the ambiance of a wood fire I would recommend using a propane fire pit on a composite deck over a wood. Wood fires are better in built-in fireplaces or a few steps away from the deck on a concrete patio.

But if you really want a wood-burning fire pit on a composite deck.

Why DeckProtect is so Good Under a Wood Burning Fire Pit on a Composite Deck

Let’s start with the obvious.

“Wood burning fire pits are not recommend on top of Trex decking unless using a product called DeckProtectTM

Trex Technical Services

Trex one of the largest manufacture of composite decking recommending DeckProtect says a lot.

Possible reasons why DeckProtect is recommended.

  • Made from fire Resistant volcanic rock-fiber.
  • ½” (12mm) spacing between the decking and the tray.

There are few products for under a firepit that can actually resist hot coals. DeckProtect can. With DeckProtect burning wood falling out of the fire bowl will not burn the tray. It is that fire-resistant.

A widespread complaint about many fire pads. Is that they will burn or melt with direct contact. I have read countless reviews and pictures of fire pit mats burned by fire pit coals.

 DeckProtect does not, desinge for lasting durability under and around a fire pit.

Speaking of around, a fire pad should not only be under the fire pit bowl but also extend past. Ensuring that the pad catches any coals or sparks from the fire.

Hate to add a log to the fire pushing a burning coal unto the decking.

DeckProtect has standard sizes to achieve this, but also custom sizes can be built to ensure they are correctly sized to provide full protection.

I also love that with DeckProtect order form, they ask you for the brand and model of the fire pit, for they can design the fire tray specifically for the size of fire pit you have.

“Less guesswork, more knowing.”

As I said before space between the fire bowl and decking is essential to protect the decking. DeckProtect goes one step further by adding space under the fire-resistant material.

Working like layer which we all enjoy to keep us warm in winter.

By adding an additional layer under the fire tray, the cooling is increased. The fire tray absorbing the heat from the air between the bowl and tray slowing heat transfer. Then the minimal heat that transfer through the tray is further cooled.

This air space has a further advantage of allowing the decking under the tray to breathe. Preventing mould and moisture build-up on the decking under the tray. A problem with mats sitting directly on the decking. Space under the mat minimizes discolouration of composite decking.

“So it is not a fire pit accessory; it is a sort of insurance plan.”

Phil Dickinson

DeckProtect Marketing

I think that says it best. Deck Protect is not cheap and may not be for everybody, but it’s one of the best protection against accidental decking damage from your fire pit.

If peace of mind, is top of mind, click on the link below to read more or order one for yourself.

How DeckProtect™ WorksOpens in a new tab..

Why ROLOWAY Fire Mat is so good Under a Propane Burning Fire Pit on a Composite Deck

With a propane fire pit or table, the level of protection required is less. This is why I offer an alternative to DeckProtect. For gas fire, you only need protection against heat.

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Roloway fire mat is a more economical alternative to DeckProtect at a fraction of the cost for a propane fire on your deck.

What’s to like about Roloway Fire mat?

There are more, but these are my top reasons.

Specialist in Fire Resistant Material, when comparing different mat options, this is one that grab me. Many mats are claiming similar performance, and without testing every single one, I could not tell you if they live up to their claims.

But I know there is a difference between a deck specialist and someone who also builds decks. Those who specialize often just know more. Those who build their entire company on one thing do a job of that one thing.

3-Layer of Fire Protection. Like an excellent layered jacket with each layer adding to your comfort, so is Roloway.

#1 is the reflective Aluminized Fiberglass Fabric layer. The first line of defence, reflecting 95% of the heat. Like the shell of your jacket breaking the chilling wind except the opposite.

#2 is the insulation layer. A thin layer of cotton insulating the decking from the remaining heat that isn’t reflected away. Like the inner layer on a jacket that adds warmth to the coat, except again, the opposite.

#3 layer, the comfort level is gentle on the decking and keeps it in place. A non-itchy silicone coated fibreglass layer resting on the decking. The comfort layer for your deck.

100% Money Back or Replacement Warranty. If it fails for some reason, it’s great to know you won’t have to pay for a new one. More importantly to me is what it says about the quality and testing they have already done.

“Putting their money where their mouth is.”

Just like warranties for composite decking. The better the warranty, the more I trust the company.

Waterproof.  Decks get rain on them. That’s a fact. It’s good to know if left out on the deck it will not be damaged. It also makes clean up easier.

Durable. What can I say? I like it when things last. Roloway fire mat is designed to last.

Portable. When its time to back up your fire table or pit it easy, clean up the fire mat. It can be folded and weighing less than 2 pounds (1kg). It is easy to carry. Coming with a handy carrying case to store it in when not in use.

One last thing, 32″ (813mm) round. Big enough to go under most fire pits while extending a few inches past.

Final Warning, Test Before Using on your Composite Deck

I hate accidentally damaging things, especially expensive composite decking. Fire pits vary in heat and how hot the bowl gets. Not knowing your particular decking or fire pit, I highly recommend safe testing first.

Since we are dealing with a portable fire pit or table, try it out on a safe location first off the deck.

Before firing it up enjoying all evening on your deck. One evening set it up on the driveway or patio, with the DeckProtect or Fire Mat under it. Fire it up for a full hour. Then test how hot it becomes under the mat.

If you don’t have an infrared heat gun. Carefully sliding your hand under will suffice.

To hot for your hand, to hot for your deck.

Even better. Place a cut off piece decking from your deck under the mat. See if it is damaged after an hour of heat. Better a scrap than the whole deck.

At the bare minimum, the first time you use it on your deck, regularly test under the mat to see how warm it gets. Don’t just set it and forget it. If it becomes warm, turn it off before it begins to melt.

With all that said.

Enjoy the warmth and glow of your fire pit on your low-maintenance deck. I see many delightful evenings under the stars in your future.

Ryan Nickel

A Red Seal carpenter, passionate about building decks to be enjoyed.

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