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Comment by WalterBright | Hacker News Reader

In Seattle (Rain City) it's becoming more fashionable to have flat roofs. It may be because of height restrictions - people build up as high as they can to get the view.

Flat roofs always leak. My roof has a 45 degree pitch, as I hate leaks. I also replaced the asphalt shingles with metal, because metal is lighter (less earthquake damage), doesn't burn, and will last the rest of my life.

Another oddity around here is vanishing eaves. My house has 2 foot eaves. This keeps the exterior walls dry, and they last a lot longer. Keeps the windows from rotting, too. And the house shaded in the summer.

New houses are lucky to have a 1 inch eave. I don't get it. Eaves are one of the cheapest ways to reduce maintenance costs.

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> Another oddity around here is vanishing eaves.

Up here in Vancouver, they decided to start counting the area under the eaves as part of the permitted square footage back in the '90s. No surprise, eaves immediately disappeared from new construction and we had a decade of water damaged buildings that needed expensive remediation.

https://en.wikipedia.org/wiki/Leaky_condo_crisis

Some of that was inappropriate materials (EEFIS?) and really stupid detailing, apart from the Eaves thing. Essentially, the water would collect inside the wall and rot out the structural support. When I was a civil engineer in the Pacific NW, our company had a rule: No work on condos. Not worth the risk.

> It may be because of height restrictions - people build up as high as they can to get the view.

Here in London, a flat roof means you can add on an extra floor (raising the property value) without towering above adjacent homes (which would make it hard to get approval to build)

Does it leak? Not in the first few years - and if you're a house builder, anything after that is the buyer's problem.

Exactly. Depending on where you live it’s hard to impossible to get permission to go above the existing ridgeline of the house, leaving people to poke flat roof dormers out the side.

Flat roofs don’t have to leak. I’m doing an EPDM roof on my garden office at the moment. It’s a single huge sheet of rubber.

As others have pointed out, the lack of eaves is the real killer. My dad was over from NZ in the summer and he was saying that fashion is there too. It’s causing all sorts of water issues for buildings.

There is one style of flat roof which is designed to hold water, with gravel on top to protect the rubber. Apparently very good, but you have to get it 100% right.

Flat roofs also bend a lot more under snow load. This bending opens up cracks in the roofing material - i.e. leaks.

I had a garage with a flat roof once. There was a big snowstorm. So much snow landed on the roof that it bent so the doors wouldn't open. After I got on it and shoveled for a couple hours, the doors would then open.

Triangular shapes are very resistant to bending.

Another thing are gutters that require constant maintenance, and fail anyway. With good eaves and correct drainage around the house you can build without gutters like they did for centuries, and eliminate this finicky maintenance problem.

yes, my gutters are a constant issue. Sigh.

My gutters filled with roof grit that dammed the water which pulled the screws out.

> Eaves are one of the easiest...

None of the responsible architects, nor developers, nor builders, nor Realtors pay those maintenance costs. And most of the folks buying houses these days are either indifferent, or oblivious, to the problem.

Maybe they assume "they wouldn't have built flat roofs if it weren't practical".

I've had my house for 25 years now. There are a lot of inexpensive details in it found nowhere else that have paid off handsomely.

For example, the washer and water heater are in the basement. The concrete floor under them is slightly sloped, leading to a drain. I've had multiple failures with washing machine hoses and leaks, and leaking hot water heaters. They resulted in zero damage, unlike in other places I lived.

Another one is Seattle homes always have wooden decks. The decks rot after a while, sometimes killing people when they collapse. The rot comes from being endlessly damp, and the local ants nesting in them. The last such deck I had I sawed off of the house, and it collapsed into a pile of sawdust. I was horrified.

So my current house has a concrete deck. Yay, no problems at all!

Here's another goodie. Never, ever, ever have the driveway slope towards your garage. Your garage will inevitably flood. A gutter in front of the door won't help, as it will clog with leaves, sticks, ice, and slush, and your garage will flood.

Also have the garage floor slope ever so slightly towards the door. The only way you can tell mine is sloped is its a lot harder to push the car into the garage than push it out. The slope helps if a car has a major malfunction, and you don't want oil/gas/antifreeze soaking into the walls.

What was weird is the architect and the general contractor were completely uninterested in these things.

I'm bookmarking this comment for the time when I build a house from vacant land. Maybe it'll be ten years before I attempt such a project.

It's fun doing this stuff. I read a book years ago "Common Sense Pest Control" which remarked that the highway for termites and bugs are the cracks in the foundation walls, which they climb up and then bore into the wood framing. The cure was a stainless steel sill plate (it's usually just a piece of plastic). So my house has a stainless steel plate there. The GC thought I was an idiot. But it works, and it's not like you can add it after the house is built.

I did the low voltage wiring myself because the electrician didn't understand it. Every room has 2 sets of cat5 and RG6 coax. Wifi has improved considerably since then, but I still enjoy the reliability, privacy and speed of wired connectivity.

GFCI breakers on all circuits in the circuit panel.

I failed to add wiring for a generator, this later turned out to be an expensive upgrade. Puget Sound Energy uses overhead wires, which fail regularly.

French drains around the basement, as a damp basement is a relentless horror.

Have you ever scraped the bottom of your car pulling into a driveway? I have. I told the concrete contractor to not have any abrupt changes in slope, and if my car scrapes he's going to have to redo it. He laughed, and said no problem. And it was no problem, he did a beautiful job just as I asked! The neighbors scrape their cars on their driveways.

Another little thing is the edges of the driveway are rolled up an inch or so. This means you can back up, and know when you're at the edge by the feel. Nobody else does that. This is so valuable because of the slope and soft ground off the driveway - you'll get hung up if you drop the wheels over the edge.

The house is designed to make use of the "stack effect" to keep it cool in summer. It works ok, but it could have been better. Houses used to be built to be naturally warm in winter and cool in summer, but the advent of A/C has caused it to be forgotten.

Oh, and fire sprinklers. I did a search and could not find any instance of people dying in a sprinkled building fire. They're expensive though. Ouch.

Thanks for sharing all of this, typical HN at its best. Off the top of your head can you think of any other books like "Common Sense Pest Control" that served you well in a similar capacity?

We need a "Common Sense Home Ownership" book.

I wish there were more such books! That book has been worth gold.

I wish there was a similar book for weed control. When I research it, I get two extremes - spreading deadly poison, or ineffectual methods.

Thanks for considering it then, and yes I totally agree. Depending on circumstances, I'm not always sure that I'm accomplishing anything when weeding the yard without pesticide.

While most people came to Walter to ask about programming languages and their design, or Empire, you knew better and focused on his true talent: tactics and strategy of North American residential structures.

Haha, I'm a born engineer and am always redesigning things in my mind that I encounter.

Being able to influence the design and construction of my house was immensely satisfying. Both the architect and the GC thought I was nuts with a lot of the ideas, but since I wrote the checks I prevailed.

Another one was the counter tops were inches higher than normal. They're just easier to work on that way, and the bonus was they were too high for The Cat to jump on. I also hate kitchen islands, and so don't have one.

A big mistake I made was not making it wheelchair accessible. That would have cost nothing extra, but I know people who had to remodel their home or were forced to move because they got stuck in a wheelchair.

There were still mistakes. The bathrooms have MDF baseboards. Whaddya know, MDF swells up when it gets wet. It all needs replacing. The GC should have known better. MDF also swells up with cat pee. OMG. I'm currently tearing that stuff out and replacing it with wooden baseboards.

I should write a book - "Things Your Architect Doesn't Know and Your General Contractor Won't Tell You"

My previous house had two structural weak spots that resulted in the house bending and sagging. I identified one in this house as it was being built and had it fixed. Being a mechanical engineer has its advantages! I discovered that architects know nothing about structures. The structure was also compromised when the plumbing was put in, so I worked with the GC to design a fix.

Leave a heater on in the bathroom to keep it 5 degrees warmer than the rest of the house. This keeps the bathroom dry.

I think its better to design the bathroom to deal with the moisture instead of wasting energy baking out your bathroom. Crack a window or leave the vent fan on.

Cracking a window doesn't help if you live in a damp climate. My bathroom is in a basement so the vent fan would just bring in more damp air. The heat isn't to bake out the moisture but to force it to disperse.

> "Things Your Architect Doesn't Know and Your General Contractor Won't Tell You"

...by WalterBright.

Sold! When can I pre-order?

Alas, I am overbooked several times over already.

> For example, the washer and water heater are in the basement. The concrete floor under them is slightly sloped, leading to a drain. I've had multiple failures with washing machine hoses and leaks, and leaking hot water heaters.

In Japan I saw a washer in the 2nd floor of an apartment sitting on top of what looked like a shower basin. If the machine leaked it is caught by the basin. Granted that will not stop a leak in the water line from spraying beyond the edges of the basin but something like shower stall walls could mitigate that.

Two of my washer leaks were spraying out sideways. First the hose had split. I switched to braided stainless lines, and then the brass valve on the wall split.

Besides, who needs the dang noise it makes. Banish it to the basement.

I grew up with washers in the basement and only ever put them there. Though washers on the same floor as the bedrooms sounds more ergonomic. I suppose you could simply make the washer room a shower closet complete with floor drain, tiled walls with green sheetrock but cost goes up and exercise goes down ;-)

At my current Seattle-area house I have an area laid out with paving stones instead of the deck and it's great!

Another pro-tip for Seattle is never buy house on the bottom of the hill or on top of the hill (yes, this only leaves hill-side). On the bottom you'll always be flooded during the winder, on the top you'll get crazy winds and rain banging during the storms.

Also get a soils geologist to evaluate the hill behind your house. $300 will save you a zillion if the hill gives way and engulfs the house. Or having the house slide down the hill.

If I were to design/build my own house the first thing I would specify is that EVERY room with designed water ingress (kitchen/bathrooms/mud room/workshop/washer/dryer/water heater et al.) must have a floor drain. Over the 41 years I've lived in my 1967-built house I've had too many replays of repainting downstairs ceilings after bathtub overflows on floor above....

This may be a generational thing, I am GenX. I grew up my entire life hearing "Flat roofs always leak" from the men in the family (none of whom were roofers). Their generation had strong opinions on the right way to do things (This applied to anything). I miss them and I am sad they are gone.

> I miss them and I am sad they are gone.

Do you mean the roofs or the boomers?

Technology changes though. PVC membrane roofs require less maintenance and last longer than older shingle roofs.

Flat roofs probably did always leaked when they learned this saying -- but today it's not true.

Many people will tell us flat rooves perform no worse under a given load or precipitation condition than pitched rooves, they both just have to be designed right for it.

But if flat ones are harder to design right, then they're more likely not to be designed right, so we end up with a larger number of edge cases where they're going to perform worse.

In my neighborhood they built a deck which has standing water and does not drain. Builders don't care.

Are slanted roofs with PVC membrane a thing?

We have a similar weird thing going on over here east of the mountains... building generic suburban houses with wood in a climate that a) has no trees (IE: materials have to come from far away) and b) because it's desert, really would benefit from design that better channels heat and breezes through the house. So point being much like flat roofs in rainy Seattle, builders / architects are not actually building for the local climate.

> Flat roofs always leak.

“Much of the social history of the Western world over the past three decades has involved replacing what worked with what sounded good.” - Thomas Sowell

funny how that applies in other areas of life.

Somehow I suspect that people have been saying this about flat roofs dozens, maybe hundreds, of generations before Sowell was born. It's not like multiple roof-types are a 20th century invention....

However we used to build houses in very regional styles. Flat walkable roofs in the middle east where it barely rains. Angled roofs in rainy Europe. Steeply angled roofs in snowy Sweden and Norway. Constructions that encourage drafts to form in houses in the Southern US.

Now, especially in the US, we just build the same types of houses everywhere.

Further context for that quote (from 1993):

"Much of the social history of the Western world over the past three decades has involved replacing what worked with what sounded good. In area after area - crime, education, housing, race relations - the situation has gotten worse after the bright new theories were put into operation. The amazing thing is that this history of failure and disaster has neither discouraged the social engineers nor discredited them."

So how much you agree with the applicability of the quote might depend on whether, say, you think the education and race relations in 1993 were better or worse than they were in 1963.

Reduced eaves reduce the possibility of ice damming and AIUI, make it easier to air seal the building envelope between the walls and the roof. Note that that's an air barrier, not a vapor barrier. The air barrier is pretty universally done outside of the insulation, whereas the vapor barrier location depends on the climate you're in.

As you note, this does come with tradeoffs, like most things.

Not a builder, nor do I have any particular knowledge of building science beyond reading Fine Homebuilding.

I have a flat roof in Seattle -- no, flat roofs do not always leak. But they do require you keep your drainage clear (something a sloped roof homeowner can get away with ignoring).

Modern membrane roofs last longer, leak less, and are more energy efficient.

Good luck!

Are you sure about energy efficiency? A properly designed peaked roof can make use of the "stack effect" to keep it cool. The slope accelerates the breeze, and sucks the hot air out of the ridge vent (or cupola). The attic still gets hot, but that gets hot instead of the upper floor.

The requirements for new built houses are much stricter for air tightness and insulation. Instead of using wind cooling they have AC.

Also all the rooms have at least 2 opening windows so cross-ventilation works. It's pretty obvious - open one window and nothing happens. Open both, and ahhhhhh!

I open opposite windows and leave the doors open upstairs. With a fan in one of the windows it can drop the temperature by >10 degrees in an hour.

You can get a box fan from the thrift store for $10. They help a lot indeed!

Asphalt shingles are awful in terms of insulation. They absorb heat in the summer and bleed heat in the winter. Membrane roofs are better for both.

Asphalt shingles are such an out-dated technology, people should really try to avoid them on new builds. They don't last long, the thermal characteristics are bad, and they're prone to leaks.

How is the metal roof mounted? I heard that typical installs use metal nails with rubber gaskets, and that needs replacement every couple of decades.

Look up "seamless metal roof," where the screws are installed beneath the sheathing.

Most metal roofs I've installed use rubber-gasket-screws, but clients that can afford "seamless" do [it will shed water indefinitely, with no screwholes to eventually leak].

The metal shingles in mine have grit bonded to the metal, so one can walk on the roof with much less risk of slipping off. Since it's a recent innovation, I knowingly took a risk on it. I suppose over time the grit will come off, but that won't cause a leak.

The asphalt shingles will crack over time, and crack when you walk on them, leading to leaks.

I hate the cedar shake roofs, because they mildew and wasps nest in them.

The metal and epoxy will thermal cycle at different rates. Curious to know how long this will last.

So am I :-)

Some things I was warned about but did anyway. The insulation is icynene foam. Some foams disintegrate over time, but this one has not at all. It's far more effective than fiberglass, no breathing in fiberglass, no mildew. I'm very pleased with it.

(The GC made me take full responsibility for it!)

The shingles are nailed at the top, and the overlapping one keeps it dry. (On mine, they're screwed in.) High winds could drive the water up under the shingles, but that happens rarely so they aren't kept wet.

Anything that goes through the roof disrupts this, so skylights, vents, chimneys, fans, antennas, etc., all are points of concern.

The water barrier roof is actually the tar paper. The shingles are just there to protect the water barrier from the elements. Mostly UV.

you can sell the flat roof as an amenity for more usable square footage.

That's right. See my comment on height restrictions :-)

I think even if people did not have height restrictions they would still be plenty attractive. It's why balconies are also everywhere; people like outdoor space, and if you don't have much of a backyard to speak of your options are sideways or out.

most of the new Seattle flat roofs are townhomes with no backyard to speak of, because there are townhomes where that would be.

In my neighborhood of single family homes, the new ones are all flat roofers with little or no eaves.

since when have Americans turned down excessive square footage? see: McMansions and McModerns

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