What Even Is Torch Down Roofing?
Alright, let’s start with the basics.
Torch down roofing is a type of roof system made specifically for flat or low-slope roofs. It’s called "torch down" because a big flame torch is used to melt the roofing material so that it sticks right onto the roof surface. Think of it like laying down a giant sheet of super strong black tape and using fire to make it stick forever.
It’s made from something called modified bitumen. That’s a fancy term for asphalt that’s been mixed with rubber or plastic to make it more flexible and waterproof. Kinda like how Silly Putty is just bendy rubbery stuff—that’s what this is, but for roofs.
Why Do People Use Torch Down Roofing?
So why would someone choose to melt asphalt onto their roof with fire? Sounds wild, right?
Here’s why:
It’s super waterproof. Like, rain, snow, sleet—bring it on. This stuff keeps it all out.
It’s durable. It can last 15–20 years or even more if you take care of it.
It handles the sun well. Some types come with a layer that reflects UV rays.
It doesn’t have seams that leak. That torch actually seals it all up tight.
It can be walked on. You can go up there without worrying about damaging it easily.
This is especially useful on buildings where the roof is almost flat and water tends to just sit there. You need something strong and waterproof.
What Kind of Roofs Is It Good For?
Torch down roofing is perfect for:
Flat roofs (the ones that look completely flat)
Low-slope roofs (very slight angle so rain still drains)
Garages
Sheds
Commercial buildings
Porch extensions
If you tried using shingles on a flat roof, water would sneak in between the cracks. Torch down solves that by being one big smooth sealed layer.
What’s It Made Of?
Let’s take a quick look at what torch down roofing is actually made of. It’s usually in the form of big heavy rolls that look like black carpet rolls.
Here are the layers:
Base Sheet – The first layer that goes down. It’s kind of like the foundation for the rest.
Modified Bitumen Membrane – This is the torch-down layer. It’s rubbery asphalt mixed with plastic or rubber.
Cap Sheet – The top layer. Sometimes it has little granules on it, like sandpaper, to protect it from sun and damage.
There are two main types of modified bitumen used in torch down roofing, and here’s a deeper dive into what makes them different:
APP (Atactic Polypropylene)
APP membranes are made by adding plastic (polypropylene) to asphalt. This makes the membrane a little stiffer and more resistant to UV rays and heat. It's great for hot climates where the sun beats down on roofs all day.
Pros:
Excellent UV resistance
High-temperature tolerance
Long lifespan
Good for hot, sunny climates
Cons:
Needs high heat to install (so more torching skill is needed)
Not as flexible as SBS, especially in cold weather
SBS (Styrene-Butadiene-Styrene)
SBS membranes are made by adding rubber to asphalt. This makes the roofing material super flexible and stretchy. It can move with the roof as it expands and contracts during temperature changes, which is a big plus in colder or mixed climates.
Pros:
Very flexible and elastic
Better performance in cold climates
Easier to install and repair
Can be applied with cold adhesive or self-adhered systems too (if not torching)
Cons:
Slightly less UV resistance compared to APP unless granulated
Might not last quite as long in extremely hot climates
So, the choice comes down to climate and preference. Hot, sunny place? Go with APP. Cold or fluctuating temps? SBS is your friend.
There are also two system types depending on how many layers you use:
2-Ply Torch Down System
Has a base sheet and a cap sheet.
Faster and more cost-effective.
Still offers solid waterproofing.
Good for garages and small buildings.
3-Ply Torch Down System
Includes a base sheet, a mid-layer (interply), and a cap sheet.
Extra strength and durability.
Best for commercial buildings or where foot traffic is common.
How Is It Installed? (The Step-by-Step Walkthrough)
Let’s say you’re going to install torch down roofing. Here’s what happens, step by step. This isn’t a DIY job for most people—because, you know, FIRE—but understanding the process is super helpful.
Step 1: Clean the Roof
No leaves, no water puddles, no junk. The roof has to be clean and dry. Any debris under the material can mess it all up.
Step 2: Install the Base Sheet
This gets nailed or glued down. It gives the torch-down layer something to grab onto. Think of it like putting down a clean tablecloth before decorating a cake.
Step 3: Roll Out the Membrane
Start at one edge and roll it out a few feet at a time.
Step 4: Fire Up the Torch
Using a big propane torch (it looks like a leaf blower made for dragons), the roofer heats the underside of the membrane until it starts to melt. This makes it sticky.
Step 5: Press It Down
As it melts, they press it onto the base sheet using a roller or by stepping on it carefully.
Step 6: Seal the Seams
Every time two strips overlap, the edge gets torched so it melts and seals perfectly. That’s what makes it leakproof.
Step 7: Do the Cap Sheet
The top layer goes on and gets torched too, then rolled and sealed. This might be smooth or have granules (like shingle sand) for sun protection.
Tools You Need (And Why You Can’t Just Use a Hair Dryer)
This is not a project where you grab a hairdryer and some duct tape. You’ll need serious tools:
Propane Torch – The main tool. Used to melt the bitumen.
Propane Tank – Feeds the torch.
Heat-resistant Gloves – Your hands will thank you.
Roofing Knife/Hook Blades – To cut the rolls.
Seam Roller – To press the layers together.
Membrane Roller (75–100 lbs) – To squish it all down and make sure no air bubbles sneak in.
Fire Extinguisher – For obvious reasons. Always.
Safety Harness – If you’re on a tall roof, safety first.
How Long Does It Last?
If it’s done right? 15 to 20 years easy. Some roofs have lasted even longer. And it needs way less maintenance than shingles or rubber roofing.
But like all things, it depends on:
Sun exposure
Freezing and thawing
How well it was installed
If it was patched correctly when damaged
Is Torch Down Better Than Other Flat Roof Options?
Let’s look at some competitors:
Torch Down vs. EPDM (Rubber Roofing)
EPDM is cheaper but can rip more easily.
Torch down is stronger and more waterproof.
Torch Down vs. TPO
TPO is a white roofing membrane. Reflects heat better.
Torch down is heavier and usually more durable long term.
Torch Down vs. Built-Up Roofing (Gravel)
BUR uses layers of asphalt and gravel. It’s heavy and messy.
Torch down is quicker and cleaner to install.
Bottom line? Torch down is like the tough older cousin of the flat roofing world. Not always the cheapest, but definitely strong and long-lasting.
Real-Life Tips for Success
If you’re hiring a contractor or just watching one work, here are a few things to keep in mind:
Make sure they clean and dry the roof before anything goes down.
Watch how evenly the torch is used—too hot and the material burns; too cold and it doesn’t stick.
Ask if they’re using SBS or APP. (SBS is better in cold places.)
Check that they’re rolling the seams really well.
Pros and Cons
Let’s break it down real simple.
Pros:
Super waterproof
Long-lasting
Fire- and UV-resistant
Strong and walkable
Cons:
Can’t do it yourself (unless you’re a pro with a torch)
Not good on steep roofs
Needs skill and safety
Cost Talk: How Much Will It Set You Back?
Materials alone are about $1.50 to $3 per square foot. Installed by a pro, expect $5 to $10 per square foot.
So if your garage is 400 square feet, you might pay:
$600 – $1,200 in materials
$2,000 – $4,000 for the full job
Not cheap, but worth it for something that’ll last 20 years and won’t leak every time it rains.
Final Thoughts: Is It Right for You?
If you’ve got a flat roof and want something reliable, torch down roofing is a great choice. It’s not something you install on a weekend with your buddy and a six-pack, but if you bring in someone who knows what they’re doing, you’re getting a solid, leak-proof, long-lasting roof.
Plus, it’s kind of cool to watch someone walk around with a flame thrower for a good reason.
Need help finding the right tools, torches, or membranes? Let me know, and I’ll point you to the best stuff on the market!