In some situations, either due to extreme weather or during an emergency, the only way to start and sustain a fire is by keeping it protected under a tarp.
However, if not set up correctly, the heat, smoke and sparks from a fire can damage or destroy a tarp. Also, the smoke can pose a significant safety risk to campers huddled underneath it.
So, if you absolutely need to build a fire beneath a tarp, here are list of hazards and some tips to do it safely.
Article Contents:
- Hazards of Starting a Fire Under a Tarp
- How to Setup a Tarp Over a Fire
- How High Should a Tarp be Over a Fire?
- What Tarp Configuration is Best Over a Fire?
What are the Hazards of Starting a Fire Under a Tarp?
Depending on its size and intensity, there are two major hazards of starting a fire under a tarp:
Hazard No. 1 - Damage or Ignition of the Tarp Material
The first and most obvious hazard is damage or partial ignition of the tarp itself. Large flames, a column of heated air, or sparks from a mismanaged fire can easily rise up and contact a low hanging tarp.
The heat can melt and warp some tarp materials. Sparks can rise up and land on the surface, burning and melting small holes into the tarp. Water can easily start to seep through these holes which degrades the water-proof aspect of the tarp.
Tarps are generally not rated as “fireproof”. Instead, tarp materials have varying degrees of resistance to heat, flames and sparks.
Here’s a quick comparison of the heat resistance of various tarp materials. The higher the melting point, the more resilient the material is to heat.
| Tarp Material | Temperature Rating (Celsius) | Source |
|---|---|---|
|
Canvas with Polyurethane Coating |
93 |
|
|
Polyethylene (Low Density) |
105 to 115 |
|
|
Polyethylene (High Density) |
130 |
|
|
Polyester |
260 |
|
|
Polyester with Flame Retardant Coating |
440 |
|
|
Vinyl |
100 |
|
|
Nylon |
220 |
|
|
Nylon Silicone-Coated |
450 |
Pro-tip: Waterproof coatings such as silicone are usually only applied to one side of a tarp. This leaves the other side more exposed heat and water.
Hazard No. 2 - Unvented Smoke Inhalation
The second, not-so-obvious hazard of keeping a fire under a tarp is the increased potential for smoke inhalation. If it’s not windy, and the tarp is not shaped in a way to promote venting, smoke can collect and pose a risk to those underneath it.
This is extra dangerous if campers sleep or are trying to recuperate under a tarp. The smoke displaces oxygen and can lead to partial asphyxiation. If exposed to smoke for an extended period, this can also lead to acute respiratory distress syndrome and potentially respiratory failure (Reference).
Another hazard of excessive campfire smoke inhalation is exposure to fine particulate matter. Microscopic particles can get into your eyes or respiratory system. This can cause burning of the eyes, runny nose, and illnesses such as bronchitis (Reference).
According to the US EPA, fine particles can also exacerbate asthma symptoms, trigger asthma and heart attacks, and heart failure in individuals at risk.
How to Setup a Tarp Over a Fire
The two key aspects of setting up a tarp above a fire are the height and configuration of the tarp above the flames.
1. How High Should a Tarp Be Over a Fire?
There isn’t a hard and fast rule for how high a tarp should be over a campfire. Fire intensity, amount of sparks, and windiness all affect how high it should be.
If you’re setting up a tarp before starting a fire, consider how big you want the fire to be. The bigger the fire, the higher your tarp needs to be.
However, a tarp height 5.5 feet off the ground should allow ample room for campers to walk underneath the tarp, as well as provide enough of a gap between the flames and heat and the tarp.
If you already have a fire started, you can measure the heat above the fire with your hands and select a suitable and safe tarp height while also considering any sparks generated.
But, be sure to maintain a fire no larger than the initial fire used to estimate the tarp height otherwise the material is at risk of melting or burning.
2. What Tarp Configuration is Best Over a Fire?
As mentioned above, unvented smoke inhalation is a major hazard of fires positioned under a tarp. This is especially true if and when the wind dies down and the smoke is able to collect under a poorly configured tarp.
To best combat this issue, a sloped A-frame tarp configuration is best. This shape allows for natural convection to pull the smoke and heat up and away. Smoke, sparks and excess heat is allowed to funnel out and away from underneath the tarp.
An A-frame shape allows rain water to shed easily off a tarp, preventing it from sagging under the added water weight.
Check out my article [link] and video (below) on how to hang a tarp in an A-frame configuration above a picnic table. This technique can be used above fires as well.
Do not hang a tarp flat over a fire. The heat and smoke can collect more easily underneath, which can lead to damaging of your tarp and increased risk of exposure to smoke.
This article contains affiliate links, which help support this blog at no cost to you!