Why Do Architects Insist on Using Flat Roofs?

[Music] prior to starting an architectural centric youtube channel i was largely unaware of the general attitudes that people had toward flat roofs but thanks to all your comments i have learned that flat roofs are an obvious assault to common sense they leak and they look boring and it is utterly inconceivable why architects will continue to design flat roofs for buildings especially in climates like here in chicago where snow is a huge consideration flat roofs just don't shed water or snow very well and they're prone to collapse if the snow piles up some people hold this position with such vigor that to them architects must be subjecting everyone to self-serving masochistic agenda by continuing to incorporate these flat roofs into their designs there's just no excuse for violating this natural law which states that gabled roofs are always the answer well this video is going to try and blow the roof off why that's not true the many thousands of architects that have and do design flat roofs are not all dumb nor overly egotistical well maybe they are but it's not because that they use flat roofs and here's why flat roofs aren't always dumb [Music] i'm up here on a roof of a building braving this beautiful chicago fall day to take a look at some of the reasons that why flat roofs sometimes are the only solution for a building or at least the one that makes the most sense and while perhaps for residential construction it can seem like mostly a stylistic choice it is more often a choice rooted in prudent and pragmatic reasoning rather than stylistic whims first off flat roofs aren't new i was surprised to learn that it was basically the standard in ancient egyptian residential construction where they had little access to wood whether they developed a mud dried brick that worked really well for flat roofs the space above the roof became an integral part of the home especially at night where the inside would become very hot from a day baking in the sun they would choose to sleep on their cooler flat roof out in the elements where they could catch the evening breeze also ancient mesopotamian cultures had flat reed and thatched roofs but of course no one's chastising them today for deploying this cursed roof rather it's this willful choice to deploy them in construction in places and times like i'm in now that are the major offenders flat roofs as we know them now really came to europe and the us in the middle of the 19th century these were covered in layers of felt and tar that was applied with a mop today we still have built up roofs like this that's what they're called built up roofs they're often covered in gravel to protect the tar from the sun then other kinds have developed over the years that have fewer layers like bitumen roofs which are laid out in rolls epdm rubber roofs and then spray polyurethane foam roofs and also thermoplastic membranes pvc or tpo of course this corresponds with the industrial revolution and thus modern architecture and flat roofs have become synonymous with them and their fallout material performance and trust in products and workmanships are often very important to flat roofs because they are less reliant on the sloped shape to shed water rather it's reliant on the material qualities and details to keep out the water and the weather so in a way it's more of a technical solution than one that is inherent to the form of the building this is i think where people's minds go when they quote louis sullivan's adage that forms should follow function and flat roofs just seem to violate this and just a quick side note louise sullivan actually wrote that in an essay called the tall office building artistically considered the quote is part of a larger poetically written paragraph whether it be the sweeping eagle in his flight or the open apple blossom the toiling workhorse the blide swan the branching oak the winding stream at its base the drifting clouds over all the coursing sun form ever follows function and this is the law where function does not change form does not change the granite rocks the ever-brooding hills remain for ages the lightning lives comes into shape and dies in a twinkling however he goes on to clarify what he means by this poetic prose and the point that he's trying to make is that tall buildings have different interior programs for the first two floors of the building then a new kind of activities that take place in the middle and then at the top floor there's usually something different again so he argues that the these programmatic changes that are happening on the interior that they should be expressed on the exterior you shouldn't just change the way the building looks in the middle because that violates that form follows function law rather a tall building should have a base a middle and a top just like a greek temple this can be seen here at sullivan's auditorium building which is a very heavy-looking base with rusticated stone a consistent window pattern in the middle and then a new kind of cornice design and three-part window pattern at the top oh and by the way the auditorium building has a flat roof as does the vast majority of sullivan's buildings even so and as many of you already know flat roofs aren't really flat they're actually more accurately called low slope roofs their slope can actually vary between 1 and 10 degrees and the slope can be achieved either through the structure underneath having a slope to it or by sculpting the insulation or the other materials that are above the hard decking you usually can't see flat roofs from the outside of the building nor can you see their slope due to the elements called a parapet the parapit is a low wall that extends the facade above the height of the roof these have multiple reasons for being but one of the most important is that they help to protect the roof by disrupting the flow of wind which can actually cause uplift and pull off the roof we'll talk a little bit more about that problem with gabled roofs later on they're low slope means that they don't shed water as quickly and they do of course hold snow longer than steeply gabled roofs also if the roof gets damaged they might start to hold water in these depressed zones it is never a good thing to have standing water on your roof which can lead to accelerated degradation of the materials common location for leaks are at tears and the roof membrane obviously but then if there are seams between the sheets of the bitumen roof are moments where the roof meets the openings the walls or the parapet but of course that's true for any roof not just flat ones by now you're probably thinking that flat roofs still don't sound like a good idea well they aren't always but low slope roofs do solve the problem of drainage with a series of strategically located drains when it drains to an external opening through the parapet that's usually detailed with a scupper and a pipe to carry down the water some slopes however angle inward toward roof drains that connect to a pipe that carries water down through the building internally and out to the sewer system this is where things might sound counterintuitive i mean why would you bring water from the outside in through the building instead of just shedding it right to the exterior well as buildings scale up the distance that water needs to travel increases water traveling along a surface outside brings in all sorts of potential problems and as you increase the distance that the water travels you increase its speed to the point where it can face some pretty serious erosion issues so you always want to minimize the amount of surface travel of the water this is combined with the fact that you don't want to shed water from a large roof area in an uncontrolled way that can lead to water infiltration issues at the foundation and seriously difficult challenges for people trying to walk near a building so that water no matter what needs to be controlled and pipe down to a sewer system so in the end there isn't really much difference if this pipe is on the exterior of the building or on the inside when coming through the interior the drains are typically located within a chase or they're exposed which keeps them accessible as needed and they have filters on the roof that need cleaning every once in a while but so do gutters so it's not a big deal so my assessment is that flat roofs make much more sense as the scale of the building increases because as the buildings scale in size with a gable roof you either have to increase the height of the gable along with it or add a bunch of roof lines in addition to that being a little ridiculous seams are really the most leak prone areas so the more the roof lines the more seams you get and thus the more leaks while we all know that all good architecture leaks not everyone wants to live in architecture all the time so bigger horizontal buildings don't work well with gables because of water drainage issues but also if you think about the interior space gables are not usually kind to creating occupiable interiors they make great addicts for the storage of things like old sleeping bags but present all sorts of challenges when attempting to use the space under a sloped roof for people often the space of a gable roof is made up of trusses that make that space almost impossible to occupy and this brings me to another point flat roofs are pretty simple in their construction their structural systems can be calibrated relatively easy for the loads that they'll sustain and they can often continue the same kind of construction system as the rest of the building gable roofs on the other hand introduce angles that need to be accommodated structurally this builds in unique joints between the structural members which are more costly and they also introduce some loads which are a little more difficult to predict or at least behave counter-intuitively for instance wind when passing over a gabled roof can actually create suction on the leeward side that's why you see shingles or entire roofs lift off of houses during tornadoes so in tornado prone areas special details are required to keep gables in place all this adds up for gable roofs usually being a little bit more expensive to build at the outset than flat roofs of course this can be offset by maintenance costs or other factors but you should keep in mind that flap roofs are much easier to work on than gabled ones you don't need a harness or anything to hold you down while you're up there and of course flat roofs can be made occupiable in green while sloped roofs can trap unwanted warm air or allow cooler air to escape a flat roof means less overhead space for air to stagnate this means that it could make for a much more integral component of a sustainable building solution the roof i'm standing on right now is once a green roof the idea is that students would be able to come up here and have some critiques and there are these great images from the 1970s of critiques happening up on this flat roof in this way a flat roof can be thought of as another public surface for occupation and activity whereas a gable roof could never be anything other than a roof further large buildings often need a place for hvac equipment on the roof this equipment needs to be outside and not too far from the spaces that they're servicing so this roof is a natural location for them and the bulky equipment doesn't like to sit on gables so roofs have a lot of competing pressures placed on them structural maintenance accessibility hvac drainage costs and aesthetics it's a complex matrix of pressures and it may not be so obvious why a flat roof is the best solution and i'm not saying that we should trust the architects and just trust that they're making the right choice all the time but maybe the solution isn't as obvious as it seems and maybe sayings like form follows function aren't always as straightforward as they sound i want to hear your thoughts about flat roofs in the comments section below are there other reasons that you think they're the devil's shading device are you convinced that they sometimes make logical sense let's discuss if you've enjoyed this video might also enjoy some of these others a video drops every week on thursday and as always your engagement your likes and memberships really help to keep me be able to do this thanks for all the support and see you in the next video

Channel: Stewart Hicks

Views: 1,789,482

Keywords: architecture, architecture design, leaks, villa savoye, architecture 101, architecture concept, water architecture, rain architecture, good architecture, water damage, groundwater, basement, roof, roof leaks, architecture with stewart, stewart hicks, flat roofs

Id: QW0ydAMVQ2w

Length: 10min 51sec (651 seconds)

Published: Thu Nov 18 2021

Reddit Comments

[u/hazard224]

As a notheasterner flat roofs make a lot of sense for tall buildings. No one wants a sheet of ice falling from even a 5 story building to fall to the ground.

[u/joeblo987123]

For large buildings they make a lot of sense:

1.) Snow/ice sliding off the roofs will kill someone walking by

2.) Typically you have a bunch of equipment like AC handlers on the roof of a large building and you'd need to relocate those elsewhere - they have to be outside, and you may not have room other than somewhere on the building

3.) Angled roofs create the need (typically) for an attic, which has no real purpose in a commercial building - it's wasted space

4.) With flat roofs you can put usable space on the roof (rooftop decks, rooftop gardens) which maximizes the use of the building footprint in cities

[u/aussiekev]

Bloke uses a picture of a residential home in the thumbnail and then only talks about flat roofs on large commercial buildings.

[u/yeender]

I have literally never seen a flat roof on a house where I’m from (Oregon).

[u/wotmate]

Natural law that gable roofs are always the answer? LOL, like hell.

I don't have snow where I live, and given the choice I would have a single skillion roof. Complex gable roofs are a barstard to build, cost more, and massively limit the amount of solar panels you can put on them.

[u/VoxSerenade]

I haven't even watched the video but just from the title I know the video is shit

[u/TuckerCarlsonsOhface]

Friend of mine is an architect, and he refuses to do a flat roof on anything. He despises them. Maybe they try to force it on them in school.