The case for single-stair multifamily

None of the things he mentioned have anything to do with safety.

You already have shanty towns with all the regulation.

Making housing cheaper also means making higher quality housing cheaper.

There tends to be belief that housing regulations exist to limit supply.

It is often more the case that limited supply is an unintended outcome. People just don’t think ahead.

If we take deregulation and cheap housing to the extreme we end up with shanty towns.

That's possible, but, considering that all the most expensive places in this country were developed in the very way this article is advocating, I'm going to label it as improbable.

Many amongst my friends and family think I'm a bit crazy living in the inner city, but the truth is my equity has skyrocketed, and will continue to do so. Urban dwellings are in high demand. Given that many of these same urban dwellings are illegal to construct now / prohibitively expensive, we've handicapped the ability of the market to meet demand.

There tends to be belief that housing regulations exist to limit supply.

Also to enrich union tradespeople. See prohibitions against PEX plumbing and requirements for electrical conduit instead of Romex.

Physical safety (structural integrity and fire safety), noise transmission and ventilation. I think regulations around these 3 aspects can help more than they hurt. Beyond these items, I would be skeptical.

Having streets unable to be accessible by fire response vehicles doesn't seem like a good idea. What would be the alternative here? (genuine question, I'm not from the US)

If it makes you feel any better the oldest streets around here are wider than newer ones, because they had to be able to turn a wagon with a team of horses.

We can make them turn 360 degrees like the electric G-Wagon. If upgrading the fleet of firefighting trucks to do so costs less than the value brought by tighter spacing of homes, it’s worth it.

Hm.. couldn't a fire engine be driven in reverse? It could have an emergency driver's wheel in the back. I have seen crane trucks driven with a joystick from outside the vehicle, so it doesn't seem impossible.

looks like building heights haven't been held back...

I can’t control if my neighbor blocks the stairwell with a couch that gets stuck while he’s moving in and now I have no egress if my other neighbor starts a fire.

That is an extremely specific situation!

How is double stair MFH overzealous?

There is a cost to every regulation. The cost to this one is that housing is more expensive for all Americans. Stress, poverty, and homelessness all lead to negative health outcomes. Taken as a whole, those negative outcomes may very well outweigh the fire safety benefits of double-stair (which have never been proven to exist).

I’m in favor of greater freedoms, and the freedom to choose a single stair MFH if I want. > But I don’t want.

Right, so it sounds like you are in favor of removing the double-stair regulation?

A couch and a fire and that couch can't be pushed over or jumped over... That's quite a contrived scenario. I suspect that most of the improvements in the fire safety record of apartment buildings have to do with other factors like materials used, fireproof stair doors, etc etc. The reason I think the two stairs don't do much is that first world countries exist outside North America, they don't have this rule, and their fire safety is just as good or better than ours.

Same reason I'm extremely skeptical that our fire trucks need to be so grotesquely large, despite what the fire departments claim. If there were no countries with a good fire safety record outside North America, like sure, okay, maybe. But they're just as good or better at fighting fires in Europe, and manage to go this with human sized trucks that don't require extremely wide streets, wide turn radiuses, and aren't nearly as deadly for pedestrians as a result. Thanks for existing, Europe, Japan, South Korea, Taiwan etc! One day we'll accept that you to cities, building and engineering better and just copy you.

How is double stair MFH overzealous?

I suggest reading the article, which is intended to answer this question in depth. It provides concrete examples!

We should require two stairs for single family housing as well.

The elderly and disabled will also need to get furniture up stairs. Not to mention that the housing shortage forces more people to share a house with strangers.

The couch goes in the elevator, not the stairwell.

That doesnt help you because another neighbor is moving out and blocking the second staircase with another couch. This is the reason why you should have three staircases and only two neighbors. Though a problem arises if a neighbor is able to block a staircase and start a fire at the same time. That has to be checked beforehand.

Check out this video, which argues against double stair MFH - https://www.youtube.com/watch?v=iRdwXQb7CfM.

Also, which regulations?

The entire article is on the prohibition of single stair multi-family residential.

I'm not sure we need more high-end development - those tenants have plenty of options.

This is silly. When car makers couldn't make enough cars in 2021 and the price went up, was the solution to ban making new cars? Should we have prohibited making cars with fancy trim? Having enough housing for everyone is the only way to make sure affordable housing exists.

Err, I just enumerated many regulations I have a problem with in the very post you quoted, and evidence is pretty strong that it's the combined effect of all of those regulations that results in higher costs. [1] I realized I left off overuse of exclusively single-family zoning, which is the worst offender. [2]

I'm not sure we need more high-end development - those tenants have plenty of options.

Evidence is strong that market-rate construction causes richer residents to exchange their current unit for a higher-end unit, opening up supply at the lower end. [3]

The problem with BMR requirements is the increased costs borne by developers, who have to offset those increased costs by charging more for the market rate units. There's a limit to that market, so fewer units are constructed than otherwise would be. Middle class families are especially worse off, as they neither qualify for BMR lotteries, nor earn enough for the rapidly accelerating market-rate unit. [4]

Further, rents are lower in states that disallow BMR mandates (like Texas) than those that have BMR mandates (like California).

1. https://www.axios.com/2019/08/28/study-californias-land-use-... 2. https://www.cnn.com/2023/08/05/business/single-family-zoning... 3. https://www.lewis.ucla.edu/research/market-rate-development-... 4. https://escholarship.org/content/qt036599mr/qt036599mr_noSpl...

I don't know anyone starting a family happy with the situation. Most people I know are moving to suburbs only because they can't get 3 bedroom apartments in cities. If MFH's became broadly available I think many new families would flock there.

Sorry I don't understand - why would they be selling units, but also deliberately pricing them too high?

I think there is some of that certainly, but it's also worth being cautious anytime a developer says they want to abandon fire codes that were put in place to save human lives so that they can add greater density housing. Fire codes got where they are in part because developers were fine with packing people into unsafe housing situations. Let's not let our guard down entirely now.

Having lived in both places - Italy and the US - I think it's a natural question.

The answer I've heard that makes sense, is that if you do this in US buildings you need decent fire suppression systems even if those bump the price.

But it's well worth doing in terms of making more types of nice buildings viable.

I also have an instinct to avoid standing where I could fall a long way - it's probably a good instinct. You haven't provided evidence that the instinct regarding fire safety in single-stair buildings is flawed.

I totally agree with you that it's definitely instinctive. The article has a link to mass timber construction for fire officials. Coincidentally there is an office building near me with mass timber structure but whenever I tell people about it, they instinctively think of it as less safe than steel and concrete.

1. the height is generally determined by the height of the fire ladders available, providing a second means of egress

This is an interesting requirement and makes me wonder if some of the need for two staircases comes from the proximity - or lack thereof - to fire services. I'd be sitting in a burning home for a long time if I had to wait for a fire ladder.

also fire suppression system (sprinklers) and pressurized stairwells are mandated.

Keep in mind that Grenfell was the responsibility of the local council. It was not run by eg a multinational corporation, which usually have better management and a commercial reputation to defend (and deep pockets to go after in a law suit).

Big business gets a lot of flak, but they are honestly better on average than small businesses and many local governments institutions.

Which is why the article's call for "reform of defect liability laws that drive insurance costs up for condo developers" makes his whole position deeply suspicious.

Fire escapes haven't been a thing in a long, long time. Not in new construction.

Older buildings only.

and the other made of stone and steel

Not to mention european houses also have drywall over the concrete these days, the days of barren concrete or plaster over concrete have been over since at least the 90s.

What are your thoughts on sprinklers in these types of situations? Are they mostly to give people enough time to get out? Do you feel the safety reduction of moving to single stair is offset by requiring sprinkling?

The way I have seen the idea of single-stair multifamily proposed in US was that in areas where zoning requires sprinklers in multifamily dwellings anyway, all the extra hallway space required for the second stairway is an unnecessary burden cost wise for little marginal safety.

Wood captures carbon within it and has minimal energy cost compared to steel, glass and brick. Lumber can also be regrown.

So highly sustainable from a global warming perspective at least.

How does that compare to leaving the trees grow, say, 25 more years? You’re only comparing the action of using them in construction.

I’m curious: is there room for a middle ground involving non-enclosed fire escapes? How useful are these?

That ain't us.... kind of. That's the websites deciding to follow the letter of the law (or a spiteful, capitalist interpretation, taking it right to the line) instead of the spirit of the law.

OK, unintended consequences of legislation. But those cookie banners are not mandated, exactly. They don't need to be there. It's the companies deciding to do it that way, so they can keep gobbling data.

It's like if the building companies implemented the 2nd staircase, but only so they could measure who is going up and down it. Not for saving lives.

If they were opt in, or unnecessary tracking wasn't implemented in the first place, then the banners could be elegant or gone.

But I do agree that the legislation (especially the ultra focus on cookies specifically) was... blinkered & short sighted.

Another European here: I think the law is fine. How companies, specially US companies react to it, that is not.

1. A ton of Health related websites in US refuse to work in Europe, because they are NOT willing to let you visit without sensitive data being grabbed with cookies. I truly do not understand how US people are ok with this.

2. The law says that you can't make hard to refuse cookies, yet many US-based sites I visit have shady, shady practices, for example many you have to click a button to see all the sliders for individual cookies, and when you click that button, it switches the orders of the buttons, so that the button you just clicked become "accept all", and the previous "accept all" button becomes "save current settings". Thus if you double click/tap by accident you accept all.

3. The sites that most often piss me off with shady cookie banner that tries its hardest to force you to opt-in to tracking, are ones that use a company called "Admiral", that according to LinkedIn is from Florida. https://www.linkedin.com/company/getadmiral/

Yes, housing and web cookies, equally important for one's life.

The year is 3157. Each time you access a new resource on the shared data substrate, you are required to accept something called a "Cookie." You have no idea what they are or why. Your crewmates say it has something to do with the homeworld, but you just shrug and prepare for the hyperspace jump.

There is one solution for the cookie notices that is very seldomly talked about: just don't use any marketing cookies, then you don't need consent from the user :)

I'm often surprised when posters identify themselves as "European" which encompasses such a broad range of cultures, biotypes, and ecosystems that it makes any comparison of the US way vs the European way virtually impossible.

Many people in Europe do indeed identify as European. This has become more and more prevalent as people increasingly move around in Europe. I'd also argue that you are ignoring the cultural differences in the US (e.g. New Jersey vs Utah) something which I find Europeans are often guilty of.

That said, when looking at the reasons for fire safety in the U.S., there are many factors to consider which may or may not apply in parts of Europe

-- Frequency of wildfires. They are not uncommon in my southwest corner, so fire safety is taken very seriously

We are talking about multi (>4) story, multi family apartment buildings, how are wildfires relevant?

-- Proximity of emergency services. It can't be assumed that the local fire department is a few minutes drive away

Again we are not talking about requirements for some cottage in the woods, these are city buildings. The whole argument is for buildings where you have space constraints.

-- Building materials. Materials that are fire-proof are rarely earthquake proof.

Again I don't see the relevance, we are talking about a national building code, but only a tiny fraction of US cities are earthquake zones. The article also asserts that most Asian countries (which presumably includes Japan) have only one stairwell requirements.

Any of these may or may not apply in any particular case but "embafflement" seems pretty extreme.

I actually agree if one needs to grasp for straws like these for reasons for the 2 stairwell rule, it is pretty baffling. The article actually nicely described the history and why it's outdated.

Because of the European Union there's a lot more of common standards and regulations concerning things like buildings between European Countries than there are between American States.

Also, a lot more stuff is codified by law or treaties instead of by business and trade associations.

So, on this matter, it makes a lot of sense of speaking about the European experience.

The point was that Europe has all of these but no double staircases.

Don’t want to comment on missing emergency services in densely built areas but hope it isn’t the case it’s so bad you need an extra flight of stairs.

-- Frequency of wildfires. They are not uncommon in my southwest corner, so fire safety is taken very seriously

There is finally progress on building codes for wildfire safety (called “WUI” codes).

It still has missing bits. For example, try to find a standard for a building air intake in an area subject to wildfires.

Of course, as you allude, the US is a large and diverse country too, where those features may or may not apply in a given locality.

I suspect, though, that on both continents, when we’re talking about these problems with the dual staircase requirement in this context, we’re talking mainly about relatively high-density developments in space-constrained urban settings.

If, as the article claims, we’ve arrived at comparable fire fatality rates under the two policy regimes, it does seem like their prevailing standards neatly capture a tradeoff: it seems like you can add safety either by socializing a fire response infrastructure capable of quicker response, or you can privatize that extra margin of safety by imposing these second staircase costs on individual developments. I’d be curious how the total costs add up, I’m almost inclined to donate to the guy’s nonprofit just to get the answer to that.

I’d be curious how these changes would affect the economics of apartment blocks on huge greenfield suburban tracts, where parking requirements rather than staircase requirements seem to be the limiting factor space-wise. I’m thinking of the kind where space is cheap enough that they do surface lots rather than building parking decks into the structure. It seems like they tack exterior staircases on the edges of the building at not too much extra cost in those situations, but I suppose the floor plan implications must still come to bear.

That was due to missing stairs? And there is a difference between skyscrapers and 3-6 story multi-apartment buildings where in the worst case you can even exit fine with fire truck ladders or assisted jumps, but the article says even required for those, which would really feel ridiculous for those kind of buildings here. No need to be salty, we find each other alien on many levels :D

That had little to do with stairs, but it was caused by the use of inappropriate combustible materials, which were forbidden for buildings of that height in many countries of continental Europe, but they were allowed in Great Britain were regulations were much more lax.

So that event is strictly specific to UK and not representative for Europe in general.

Fire deaths per 100k in 2019:

US .82

UK .38

https://ourworldindata.org/grapher/fire-death-rates

It's the same for many European cities and towns. Many cities started to reduce it down to 0.5 parking spaces per flat or less, because many of those parking spaces tend to be empty in bigger cities. And just increase prices for housing.

The requirement is because if you don't mandate a minimum amount of parking, developers won't create it. Then the neighbors of your fancy new building can no longer find parking near their own home because the new building tenants take it. So they justifiably get angry and start voting in politicians that will enforce minimum capacity for new development.

We’ve really done a number to cater to cars and the auto industry in the United States. Some More News does a great job on outlining the history of cars, roads, and what can be done to make things better - https://youtu.be/sayw3TOhykg

Maybe I should say I’m from abroad instead? European seems to trigger something in some folks around here.

That aside, I fail to see any cultural or other reason to require twin staircases nowadays other than ‘that’s how we always did it here’. I admit it openly and state that I’m from somewhere where we don’t do that, and the world works just as well, except buildings have a higher useful to total area ratio.

NYC stopped building fire escapes a long time ago. There are still tons of them, but all on older buildings.

It certainly would be interesting to see them make a comeback though.

Second staircases are pretty good. I think most people should have them if they can afford them.

The classic example is the lot that sits empty or has a parking structure on it in Manhattan. Today, you pay very little tax on the empty land or parking lot because you’re taxed on that total value of the land and improvements. This discourages building stuff sometimes. With land value tax, you’d be taxed on what someone would pay you for that land with improvements similar to surrounding, so it’s advantageous to build something there instead of nothing, since you’re paying the same tax as the sky scraper next door.

In other words, the taxable value of the land is what it would be if it had similar improvements to surrounding lands, rather than taxing it based on actual improvements.

Someone buys a property:

    +-------------+------------+-------------+-------------+
    |    Type     | Land Value | Cover Value | Total Value |
    +-------------+------------+-------------+-------------+
    | Parking Lot |        100 |           0 |         100 |
    | Dump        |        100 |         -20 |          80 |
    | Skyscrapper |        100 |         100 |         200 |
    +-------------+------------+-------------+-------------+

    +-------------+------------+-------------+-------------+
    |    Type     | Land Value | Cover Value | Total Value |
    +-------------+------------+-------------+-------------+
    | Parking Lot |        150 |           0 |         150 |
    | Dump        |        150 |         -20 |         130 |
    | Skyscrapper |        150 |         100 |         250 |
    +-------------+------------+-------------+-------------+

it would increase the tax rate on land to be much higher. In the most extreme case, the annual tax on land value would so high that vacant land could be purchased for close to zero purchase price because the holding cost of the tax is high enough to capture all the value which is capitalized into a purchase price.

Well, one system taxes land value and improvement and the other taxes only land value. In the first system, all improvements have a tax cost of x * value(improvement). In the second system, they have a tax cost of 0. There's three possible outcomes: this increases improvements, this keeps them the same, and this decreases improvements. It depends on whether you think moving one cost component from positive to zero puts us in the first, the second, or the third worlds there.

I just tried it out and ChatGPT helps if you want to understand this. It is quite patient and will provide instant responses.

It's about incentives. In general, the best incentive scheme is one where people are incentivized to do things that other people find valuable. The worst incentive scheme is one where you get punished by a third party for doing things that others find valuable. Economists call this "deadweight loss", the number of beneficial transactions that do not happen because with the addition of a tax, the transaction is no longer beneficial for both parties. Ideally, the perfect tax is one where you are taxed on things that are negatively valuable for society (an externality or sin tax, as a way of disincentivizing you from doing those activities) or that you don't have control over (i.e. it doesn't alter your behavior at all), while not taxing any activities that are beneficial for others.

LVT is very close in structure to this perfect tax. There is a finite amount of land available, and no way to make more of it; taxes on land don't disincentivize land production, they just take a cut of the rent that you get from having conquered that land first or bought it from someone who did. And the land value (exclusive of improvements) is usually set by its location - what else is nearby, what community improvements have been made, is it in a pretty place, is there lots of pollution or crime? These too are things that the owner has no control of; arguably they are reaping the benefits of things that the rest of the community has built, and so they should be taxed on it so the fruits of those labor go back to the community.

By excluding the improvements, you let the land owner capture the fruits of their actual labor. So if they build a new apartment building and provide housing to those who need it, they can charge rent, and they won't be taxed on that rent, and so they capture the full benefit of those improvements. If it's a nice apartment building, they get to charge more in rent, and they can capture that money too.

Because improvements aren't taxed. So if you add improvements (read: more housing), you don't pay taxes and you become more profitable (more rent, same taxes).

So you move all tax to just the land value at a higher rate than present, then let people build to offset the tax.

A 2nd set of stairs split across multiple units is a trivial matter from a cost perspective. Height restrictions, adding more office space than housing, mandatory parking etc are the real issues.

Tiny increases in construction costs get wiped out when there’s insufficient housing stock.

Maybe, but there's a long tradition that suggests maybe it's necessary...

"229 If a builder builds a house for someone, and does not construct it properly, and the house which he built falls in and kills its owner, then that builder shall be put to death."

- Hammurabi's Code, ~1750 BC

Who would’ve thought that the way you house citizens has an impact on their interactions.

Of a civilization.

You would scream if those homeless died in a fire or tornado because the building lacked protection.

The two staircase rule increases costs, but not by that much - any place that allows building housing doens't have a homeless problem. That isn't to say there are no homeless people - there are many - but they are homeless because of other issues (mental). In California the homeless often are otherwise normal people who cannot afford a place to live despite the ability to work a job. Where I live you can rent a new two bedroom apartment in walking distance of Burger King that pays enough to afford that apartment and leave enough leftover for food - it won't be a great life, but you can live on one income (and since most people live as a couple that second income can buy some nice things)

This is what's called a false dilemma, pitting two non-mutually exclusive options as an either or situation when they're actually not opposed to one another.

We should get to reap the benefits of improved fire and personal safety and build more housing.

Yeah, that'll happen when no one thinks about women for a few hundred years. What year did your state make it illegal for a man to hit his wife?

In what other ways are they suffering?

In Europe they are also suffering from too long toilet stalls and as a result there are mass drug use problems as well as all sorts of unsavory characters having sex in there.

Mitigation isn’t the end result - the OP (as I read it) is saying that two exits provides for not being trapped by a stalker. You may still be stalked or approached by a malicious group of actors, but a second exit makes it much more difficult to be cornered.

The reason five over ones are popular in the US has nothing to do with staircase requirements. The reason is money, like always.

Yes it is money. More staircases remarkably increase the costs of buildings. Single stairway, cheaper buildings, more profitable to do other sorts of buildings, more variety of buildings etc.

(see also no parking mandates)

“maximize the available land”

Part of the author’s point is that single-stair buildings can be built economically on much smaller pieces of land. This increases the number of plots — especially in urban environments — on which you can build MFH, plots which developers today wouldn’t even think of.

Legalizing single-stair buildings would not really change the viability of big apartment complexes, you’re right. But it would allow for smaller ones.

It’s true that five stories is an economic sweet spot, but the idea is we could get five story point access blocks instead of double loaded corridor layouts.

The fire escape can count as a separate staircase too and it can go over windows.

Then find a place with an elevator. Not every home needs to be for everyone

Three-story walk-ups are common and legal in America, if that is where "Here" is for you. If you are in a wheelchair, you rent a ground floor unit.

It is generally understood that at 4 floors you need an elevator which is expensive. This is partially the ADA (which doesn't say this from what I can tell, but is generally understood to suggest it), and partially 4 floor is enough stairs few people would agree to walk up them.

We need two exits in Canada. Because a snow drift can easily block one exit. That's why there are exits on each side of a structure, not two, on the same side.

Boston and immediate environs is still pretty expensive but, at least historically, these sort of multi-unit houses tended to be in less expensive neighborhoods (many of which are now pretty expensive).

I suspect they're referring to this type of buildings https://en.wikipedia.org/wiki/Three-decker_(house)

Or just the non-Boston audience

boston triple deckers are not sliced vertically

Hard disagree. With WFH, cities now have beautiful but empty office buildings near public transportation. Those should be turned into housing first.

And more generally move zoning to a nuisance basis (as in Japan or Europe), euclidian exclusionary zoning is a root cause of suburbian sprawl and dead areas.

That means local shops can pop up, and city centers are able to progressively transition upwards at the edges (and plots can be upzoned) instead of having a sea of low-density housing suddenly becoming a bunch of skyscrapers.

Of course it is not realistic. To reduce housing crisis mean to decrease demand, to decrease prices of already built houses. No one will vote for that. Housing situation will be only worse.

How to ruin existing suburban neighborhoods in one easy step!

It does mean disabled residents are sort of screwed if there's a fire alarm and the elevators are shutoff--as a friend told me recently--unless the neighbors can help. But that's sort of ignored given lack of realistic options.

Which is the norm in Europe. One stair, one elevator. Even large and long buildings are divided in "stairs": there is central concrete tower with the staircase and the elevator shaft and a number of flats around it. Repeat like a pack of AA batteries. No way to move between them except the basement with parking for the cars.

Although a lot of houses outside of cities require you to go up a flight of stairs. I own a house with a single staircase and the only bathroom is on the second floor. Was on crutches for 6+ months once.

When I look closer, the newer the building the better it tends to do in general. And as the article itself points out, Europe doesn't use nearly as much wood which changes things (not always for the good - Europe tends to have terrible insulation and their construction materials are not helping - though newer buildings do well here)

I don't know if you'd consider him "progressive" enough, but President Biden is trumpeting National Environmental Policy Act reforms.

https://www.whitehouse.gov/ceq/news-updates/2023/07/28/biden...

Please see my use of the words “our” and “we”.

I am one of those progressives.

I just haven’t flip-flopped on sprawl and open space and environmental review based on my current economic outlook.

I mean, yes, legally, it's a fire escape. But, there's a full size door leading out to it, it's typically made of treated wood, and the staircase is a normal wood staircase, not some rickety metal thing.

These also have the added bonus of being generally a nicer staircase than the one that's actually built into the house. The interior, retrofitted staircases tend to be narrow with lots of awkward, angled steps.

Even as a compromise you could make a pretty good small building with 2 units per floor, single walk-up stairwell+landing+elevator on the front, and an exterior fire-escape on the back.

I guess I should clarify often in the US the "builder" and "designer" are the same entity. By "builder" I mean the people responsible for designing unsafe designs, and the people responsible for poorly executing good designs.

Find root cause, and make that entity liable

Correct. You're just not going to get into a bottleneck situation with ~4-8 people per floor/flight of stairs.

Dense, rural towns ftw

In the great state of Texas, as I understand the process:

-walk into a licensed firearm dealer

-show government ID (e.g. drivers license)

-fill out ATF form 4473 (approx. two pages)

-wait for background check (called NICS, Near Instance Criminal Background Check System)

-pay for firearm

Did I miss any steps?

> Lower costs for everyone. Including people you don't like. Yes.

Touche. They are two different contributors to costs, and I wouldn't have commented if I weren't currently frustrated by high housing costs.

Took a while to learn to "check your exit routes", then? Or, ignoring any snark, you've learned a lot since "Glasgow (Scotland) last [S]ummer"?

Presumably the family had always found the exit routes easy to locate until the incident in Glasgow. So yes, that would be when they learned the lesson.

Nit: according to https://www.grammarly.com/blog/are-seasons-capitalized/, "The seasons—winter, spring, summer and fall—do not require capitalization."

What is the rate of injuries per fire in single stair multifamily buildings?