Building in Mexico · what I learned
My tin roof cost more than concrete — and I’d choose it again
Most people assume a tin roof is the cheap option and a poured concrete roof is the “proper” one. On my own build in San Cristóbal de las Casas, Chiapas, it was the other way round: the tin roof cost me more — and after living under both, it’s the one I love.
The surprise
One thing almost nobody guesses about my house: the tin roof — lámina, as it’s called here — and its metal frame cost me more than pouring a concrete one would have. I went in assuming the opposite — and I was wrong by about MX$10,000. The roof was one line in what the whole house cost me to build; here’s what surprised me most.
Why I can compare
I have both kinds of roof on the same house — roughly half tin, half poured concrete — which is the only reason I can compare them honestly. I chose the tin for the half I cared most about, mostly for how it would look and feel inside. And now, having lived under both through several rainy seasons, the tin is the one I’d choose again, while the concrete one is the one I lie awake thinking about. This is what I actually learned, including the costs, the mistakes, and the freak accident I couldn’t have planned for.
The roof verdict
Cost surprise
My tin roof came to about MX$40,000 ✓, against roughly MX$30,000 ~ for the concrete slab I’d assumed would be the pricier one.
What I’d choose
Lighter, cleaner for rainwater and lower-maintenance. The concrete half is the one that cracked and needs repainting.
The exception
Planning another storey later? A concrete slab gives you a floor to build on. Tin doesn’t.
Why tin
Why I chose tin in the first place
By the time the walls were up and the house was taking shape, I’d relaxed into managing the build and started enjoying the parts where I could improvise. The roof was one of those decisions. I wanted to put an exposed industrial-style metal frame inside the house — beams running across the structure — and a tin roof let me do that. It looked the way I wanted, and it had two practical advantages I talked myself into as well.
The first was weight. A tin-and-metal roof is far lighter than a slab of poured concrete sitting on top of your walls. In a region with regular earthquakes, that felt sensible to me as the person managing the build. I wouldn’t treat it as structural advice — the whole building has to be designed properly, walls and beams and foundations together — but I liked the idea of reducing unnecessary weight overhead.
The second advantage was the one I got wrong: I assumed tin would be cheaper. It seemed obvious — no slab to pour, no truckloads of concrete. That assumption is where the lesson is.
The cost
Where the money actually went
From the actual build
The tin roof cost me about MX$40,000. The equivalent concrete roof would have come in closer to MX$30,000. Here’s why, because the savings and the costs don’t land where you’d expect.
A tin roof does save you real things. I saved roughly two weeks of labour by not having to build and pour a slab — and pouring a concrete roof means first building a whole temporary timber platform underneath it to hold the wet concrete while it cures. That platform eats dozens of planks and supports. Skip the concrete roof and you skip all of that.
But then the tin roof spent the savings back, and more. Under the tin I put a layer of plywood — partly to soften the sound of rain, partly for the look inside — which was a real cost. The metal beams themselves weren’t cheap, and I painted them and helped the builder lift them into position. Then I had to pay someone for a full day of welding to join the metal frame together. Add those up and the “cheap” roof had quietly become the expensive one.
The honest summary
Tin saved me labour and timber, then spent it back on plywood, beams and welding
A tin roof can be built cheaply if you hold it up with a simple, economical structure. Mine wasn’t simple — the exposed metal frame was a design choice I paid for. Both wood and metal frames swing enormously in price depending on the quality and the craftsmanship. So “tin is cheaper” isn’t a rule; it depends entirely on what you hang it from.
From the actual build
Tin vs concrete
Tin vs concrete, side by side
After living with both, here’s the comparison I wish I’d had before I started. These are my conditions in San Cristóbal — your climate and prices will differ — but the trade-offs are the part that travels.
Tin vs concrete, side by side
| Tin (aluminium & zinc) | Poured concrete | |
|---|---|---|
| Cost (my build) | ~MX$40,000 ✓More, because of the metal frame and plywood | ~MX$30,000 ~Cheaper here, despite the slab and platform |
| Lifespan | Many yearsAnd you can often lay new sheets over old ones if they wear | Long, in theoryBut cracks change everything — see below |
| Maintenance | Very low so farDoesn’t crack or absorb water; fixings and flashing need an occasional eye | Repaint ~every 4 yearsFlexible waterproof paint, ~MX$3,000 in paint and labour each time |
| Weight | Very lightLess mass on the walls — better in earthquake country | HeavyA full slab sitting on top of the structure |
| Captured rainwater | Much cleanerWhat I send to the cistern for the house | DirtierI only use it for washing clothes |
| Sound of rain | Wonderful — mostlyPlywood underneath helps; heavy rain can still drown out the TV | SilentYou won’t hear the weather at all |
What people here call lámina is usually galvanised or zinc/aluminium-coated sheet metal, depending on the product you buy. The better versions are made not to rust quickly, and a well-installed roof lasts many years. If the sheets eventually wear, replacing them is far simpler than repairing a failed concrete slab — and in some cases you can fix new sheets over the old ones if the structure underneath is still sound.
The freak accident
The week I thought I’d made the wrong call
A week after the tin roof went on, a neighbour hired someone to clear boulders from their plot with dynamite. The explosions threw rock high into the air, and three pieces came down through my brand-new roof, punching clean holes in it. I was devastated, and for a while it made me question whether I’d chosen wrong.
I want to be clear about this, because it’s easy to draw the wrong lesson: that was bad luck, not a flaw in tin roofs. Falling rock from a dynamite blast would have damaged almost anything, and the holes in tin are, if anything, among the easier things to patch. It felt like a verdict on my decision at the time. It wasn’t. It was just a bad week.
Concrete cracks
The concrete roof is the one that haunts me
Here’s the part that really settled the argument for me. The poured concrete roof — the “proper” one — is the roof I struggle to sleep over. A few months after it was poured, I found large fissures running through it. The likely causes were heat, not keeping the concrete damp enough while it cured, and possibly the slab not being supported well enough during the pour and curing. Whatever the exact mix, the result was a cracked roof and leaks.
I fixed it, and the way I fixed it matters, because my first attempt failed.
How I fixed the cracks — after getting it wrong once
Chase the crack, fill it, then protect it
My first go used a cheaper, tar-like filler. It sealed perfectly for about a year, then kept shrinking after application until it was useless. Don’t bother with it.
What actually worked, for non-structural cracks like mine: open each crack out with an angle grinder and a cutting disc, fill it with an adhesive made specifically for concrete — I used Fester Sellador y Adhesivo FT-201, about MX$300 on Amazon Mexico — then cover it with geotextile cloth and roofing paint. That combination has held. But if a crack is wide, moving, sagging, or looks structural rather than just a surface fissure, get someone qualified to inspect it before treating it as a simple waterproofing job.
Maintenance is the quiet difference the brochures never mention. The concrete roof needs repainting with flexible waterproof paint roughly every four years — around MX$3,000 in paint and labour each time, depending on size — or the cracks come back. The tin roof asks for nothing.
Exposed-ceiling trick
A trick for an exposed concrete ceiling
One advantage of managing your own build is that you can experiment as you progress with the build. Over my dining area, which has a low ceiling, I wanted a smooth, modern grey concrete finish on show rather than something to be plastered over. So I had the mason use plywood as the formwork to pour the ceiling against.
The cooking-oil experiment
A thin smear of cooking oil stops the concrete gripping the formwork
I painted the plywood first to protect it and let me reuse it. Then, just as they started pouring, I rubbed a thin layer of ordinary cooking oil over the wood with my fingers. The oil stopped the concrete bonding to the plywood, so it peeled away cleanly — leaving a smooth exposed ceiling and plywood I could use again instead of writing off. It cost almost nothing and worked.
Cleaner water
The bonus I didn’t expect: cleaner water
Because I capture rainwater, the roof material turned out to matter in a way I hadn’t planned for. Water coming off the tin roof is far cleaner than water off the concrete one — concrete is more porous and holds dust, residue and surface grit, while metal sheds water straight off. So I route them differently: the tin roof feeds my cistern, which supplies the bathrooms and kitchen, while the dirtier concrete-roof water goes to a separate tank for washing clothes. How that stored water then gets pumped up and fed to the taps is its own build — I cover it in the water system for a house in Mexico. If you’re going to harvest rainwater, the roof you choose quietly decides how clean that water is — and the catchment, filtering and dry-season storage are their own build, which I cover in off-grid water in Mexico.
One caveat, so nobody takes this too far: cleaner doesn’t mean automatically drinkable. Whether roof water is safe to drink depends on filtration, storage, a first-flush system, animals, and what’s in your local air — not just the roof. What I’m saying is narrower: for capturing cleaner water to store and filter, the metal roof wins clearly.
And if you’re buying land with no water connection at all — as I did — the roof is only half the picture. Whether a plot has water, or needs a well or catchment, is one of the biggest hidden costs in buying land in Mexico as a foreigner.
After every rainy season I’m more sure of it: the roof that cost me more is the one I’d build again, and the cheaper one is the one I have to keep an eye on.
The verdict
So — would I choose tin again?
Yes, without much hesitation — but not because it’s cheaper, because it usually won’t be once you account for the frame. I’d choose it for what it gives back afterwards: no cracks, no porousness, no maintenance, cleaner captured water, less weight on the walls in earthquake country, and the sound of rain on a high ceiling, which I find genuinely lovely even on the nights it’s loud enough to bury the television. The concrete roof was meant to be the safe, solid choice. In practice it’s the one that cracked, the one I repaint, and the one I think about when it rains hard. The tin one just sits there and does its job.
There’s one case where I’d still pick concrete, though: if you might build another storey on top later, a poured slab gives you a floor to build on, and tin doesn’t. If there’s any chance of going up a level down the line, that can outweigh everything above.
What I’d change
What I’d do differently
Two things, both about deciding earlier. I’d make the roof decision sooner, and I’d think about rainwater catchment before the walls were finished rather than carrying it vaguely in the back of my mind. Where the water drains, where the gutters go, how the slope works, how the water reaches the cistern — all of that is easier to get right while the structure is still open than to retrofit afterwards.
And I’d price the roof as a whole system, not as sheets of lámina. The real cost isn’t the covering — it’s the beams, the welding, the wood underneath, the paint, the labour, the gutters, the drainage, and the waterproofing if you go concrete. Adding all of that up in advance is what would have saved me the surprise of the “cheap” roof turning out to be the expensive one. That’s the part I underestimated, and it’s the single thing I’d tell anyone starting out.
Also in the building series
Written by Luke Burchell
I self-managed the construction of my own house in San Cristóbal de las Casas, Chiapas — coordinating the masons, the metalwork, the plumbing and the finishing myself, while living locally. Everything here is from that build: what I paid, what I’d do again, and what I’d do differently.