Why Do Architects Insist on Using Flat Roofs?

Because it's easier for the Secret Service to secure them

A big building has a lot of these drainage features, but not so much in residential settings. A friend of mine built a place with a flat roof 2 years ago, and he's already got water damage from the heavy rain we've been receiving in abundance in Australia. The gutters were also all clogged up because leaves easily settled on top.

I don’t know who told you that flat roofs are better than gabled roofs for heat, but they’re wrong. The trapped air between the ceiling and the roof serves as an intermediate layer that reduces the rate of heat transfer

I live in tropical county with heavy rain for 2-3 months and light rain for another 2-3 months. There are absolutely no snow here. But personally i want to build my house with flat roof. Idk if that the best choice.

Stewart, Why don't more architects make these flat roofs as green spaces with trees that can process water, make it a nice park/area for the inhabitants and help the earth by slowing global warming by processing CO2? Is it just cost?

You invigorate my passion for architecture like no one else! Thank you so much for sharing this. As a builder, this is such incredibly important information to retain. Cheers :)

I've learned so much with this video! Thank you Stewart!

Has someone who hates flat roofs this was a great explanation I see now the need it fixes

Arguements against flat roofs
1) Leaks if water can settle against perimeter walls.
2) Snow build up and having no where to go. In the wrong climate can lead to structural issues.
3) Esthetic reasons. This is mainly a residential and climate reason.
Arguements for flat roofs.
1) Cost of construction.
2) The mounting of air handling machinery and electrical equipment. The second is more an industrial issue.
3) Use of roofspace for social reasons. This can also be accomplished by means of a deck over a sloping roof.
In reality in any climate with significant percipitation no builds truely flat roofs.

"well maybe they are, but..." 😂

After I saw the quality of work of roofers in the USA, I understood why flat roofs are considered unreliable there. There is only one way to make a flat roof durable and secure. For the northern regions the assembly should be like this. Base - bitumen vapor barrier - insulation (XPS or Polyiso) - separation layer when using XPS (membranes can react with it) - membrane (PVC, TPO or EPDM) - ballast backfill. Dont use internal drain on residential

What I think I would now like to know a little more about is how this argument applies to more specific situations. It was touched on here and there, which I did appreciate, but I would like a slightly deeper dive. Is a flat roof definitely a bad choice in a snowy climate? Or have we found flat roof solutions that offer more benefits than downsides even in a snowy climate?

I'm not fond of flat roofs, but I suspect that where I live, they do make more sense but could be done better. A relentless scalding sun most of the year takes its toll on a foam flat roof that requires re-coating every few years. And because the roof is foam, it's not usable space and can accumulate puddles due to unevenness. It seems to me that there should be such a thing as a lifetime roof. If we can have space craft that leave the atmosphere and re-enter it, we should be able to have permanent roofs that are somewhat affordable.

Because geometry hurts their brains and squares are easier to digest than triangles

concrete houses with flat roofs is the reason hurricanes don't kill more people in the caribbean. In miami as well

Flat roofs in ancient Egypt? Uhhhhhhh, never heard of THE PYRAMIDS???

Flat roofs are good for hanging out and Rooftop gardens!

Like I'm fine with the flat roof, but use it then. Put in a rooftop terrace for outdoor activities and a garden. So many flat roofs are just ugly wasted space

Here in Australia, single family homes are suddenly being built with flat roofs, or at least made to look as if they have flat roofs.

Just wanna say this: I HATEEEE gabled roofs

As someone who owned a house with a flat bitumen covered roof. Never again. It leaked all the time constantly needed new rolls of bitumen put down to fix them.

hvac guy here. alot of times the air conditioning equipment is on the roof lol flat rooves are great for that.

I appreciate the information in this video, understanding how a flat roof is designed and engineered has been very illuminating.However, I must say that while I now have a greater understanding of the thought process, I think the video just kind of takes the architectural paradigm, and it's reasoning at face value. Yes, these roofs are well engineered, that doesn't change the fact that from a physics perspective a slopped roof would still be better. There are good reasons why flat roofs are designed, sure, but there are plenty of good reasons for slopped ones as well. If Japanese architects in the 16th century could design a huge slopped roof for a fortress that has lasted 400 years, I think modern architects should be able to do the same for a modern high-rise. We currently live in an architecture paradigm where modernism is seen as the standard that all buildings should follow, and we always get solutions within that paradigm presented to us, "this is how it has to be/ this is good design" there is a movement in Europe right now to reject the current paradigm and build beautiful again, forcing the conversation to evolve and challenging the status quo, challenging the paradigm, plenty of architects don't like this movement. Part of that movement is questioning whether we really need so many flat roofs, to which the answer so far has been no.This is not meant as a personal criticism against you, more so a general philosophical criticism of the architectural paradigm we live in and the outright rejection of anything that differs from it.

Architect and engineers. I understand why we need them but it'd be really nice to never run into one again 😊

Sadly those flat roofs are only functional for a few decades in northern climates without constant maintenance, all the fancy flat roofed shool and university buildings from the 70s and 80s I went to had a big collection of buckets that came out after every rainfall. The mold that was probably growing in the ceilings was ignored because you couldnt see it

As a service electrician, your flat roof adds 3x the cost to run wire if it ever needs to be added or replaced. Unless you install an ugly drop ceilings, it is the dumbest choice you could possibly make for your home.

So to sum up what different people are saying in the comments: if you live closer to the equator, conditions lend themselves better to flat roof. The further you go from the equator, the more gabled roofs become a better option.

First time I've heard h-v-a-c sounded out multiple times. I've always known it as h-vac

"All good architecture leaks". No wonder Frank Lloyd Wright is considered a genius.

Flat roofs, I like it!

My roof slopes at 23.5 degrees. Do you think this is by chance, or a wink from original owner?

How do we drain a flat roof on adobe style? Do we need a slight pitch or does it just drain from a center hole

I have lived most of my seventy years in sub-tropical and tropical areas. Storms can dump huge quantities of water in a very short amount of time. Gabled roofs seem to cope better than flat, but whichever style of roof it has, there must be wide drains and large down pipes to take the torrential rain away from the building.

Makes sense. In the warmer Southwestern states they can get away with a lot. In the cold Midwest, standards for quality of a flat rook are very stringent.

Here in Montreal Canada we have a lot of snow and rain and most buildings have a flat roof.
My house is 100 years old with a flat roof and is doing great.
It makes a lot of sense in an urban setting to have flat roofs.
Slopes tend to throw snow, ice or water at the people nearby.
Slopes make more sense in a suburban or rural setting where you can leave space in the yard for shedding.

FLAT ROOFS ARE NOT SMART FOR HEAVY SNOW.

Why? Beause most architects are secular humanist liberals and therefore glorify the ugly

The quote “ Form follows function” is the most misunderstood, misinterpreted quote of all time. It simply means if if you go the theater, the building should be grand. If you to a factory, the building should be functional, and if design a house,mit should personal.

I honestly never understood why so many were against the thought of "flat" roofs. For the claims of how they can't handle snow loads, I counter with "have them designed properly, and if it's an especially heavy snowfall, just shovel the snow off of it!" Yes, they don't clear the rain as fast, but once again, if you properly design it for expected weather (and then add in a safety buffer), if it truly is a problem (say a "once in a hundred years" rainfall), we have tools to deal with this. I argue the pros outweigh the cons, not just in commercial aspects, but also in residential. You want a patio or balcony? Why not have one the size of your house's footprint, and have the neighbours on it as well? Best part too? If you're using a BBQ, your neighbour can still have their windows open, as the smoke is 1+ stories above their living room windows!

Can they be problematic? Anything can be problematic if you cut corners. But no offense to those who love their asphalt tiles, a flat roof is rather easy to design for things like a natural roof, a rooftop patio, and better yet the maintenance of such doesn't require custom PPE to keep the workers safe. You can also keep that decent sized rooftop patio and also add in shading elements like you would for a deck, or even better, solar panels too!

tall buildings w sloped or conical roofs simply look stupid im sorry lmao theyd have to make the slope as flat as possible to make it look okay

as a civil engineer, its just easier to compute a slab than truss roofs.

Roof trusses can be designed to allow attic space in the center part if the attic.

Most flat roofs will eventually FAIL.
And be DIFFICULT and very EXPENSIVE TO REPAIR.
The only climate that flat roofs make sense is dry and warm.
(eg southern US)
Ask any Canadian or Pacific NW dwelling American.
The other situation that flat roofs make (sort of) sense, are new commercial building that are specifically designed to FAIL after 35 years.
Disposable architecture is what this Chicago School FOOL is pushing online here (CHicago is now infamous for its inherent corporate capitalist bias (aka Fascist)).

they are better. being reactionary is lame. give up please

Being from NM, I love the look of flat roof homes. Although, after living in a two story one, not having an attic made the upstairs hot. Regardless, still think flat roofs have their advantages (cheaper to maintain, giving balcony areas, hiding an ac unit, etc)… so, ultimately like everything else there are pros and cons one must balance out.

maximizing expensive sf land costs. thus.....no soffits, MAX box foundation footprints, flat roofs. Sad. in my rainy corner they fail constantly on SFR's and under sleepered walkable roof decks. The industries that run on obsolescence have convince the market a few extra sf is worth putting trust in Chemistry over Physics and nope...false promise. Great source of income for us that repair crap ideas tho.....so i guess it's kind of a gift horse. Know this, if we repair your roof deck and we are not allowed to follow our protocols your contract will have a long list of indemnity clauses.

Americans: don't do flat rooft
World: 🤦🏻‍♂Americans...sigh....

I've always viewed Form vs Function to be a false dichotomy. If something pleases the eye, then it serves a function. It is a functional psychological benefit to live and work in buildings we find attractive.