Modern homes are firetraps?

A Canadian wire-service article claims that modern composite materials used in house construction drastically accelerates the pace of house-fires when compared with traditional solid wood and other materials.
What that means for firefighters is the amount of time they can safely be inside a house on fire has dropped from about 17 minutes to three minutes or less.

That's when flashover happens -- the moment when a room or building is fully engulfed in flames...

[Ottawa Fire spokesman Marc Messier] said unlike 30 years ago, when homes, furniture and appliances were made of solid wood and steel, modern day versions are made with glue, plastics and synthetic materials.

Such synthetics not only burn faster but produce carcinogenic emissions as they burn.

"One of the biggest examples is floor joists," said Messier, who himself dabbles in home renovations.

"They used to be 2x8s and 2x10s, and now we're looking at composite materials which for the most part are made of wood particles, mixed in with glue. They're cheaper, which is probably why the industry is using these products."

New homes burn faster (Thanks, Fipi Lele!)

(Image: House on Fire, a Creative Commons Attribution (2.0) image from dvs's photostream)


  1. There’s another big reason that today’s homes are firetraps: the vast array of electronic gear and wiring. Made of plastic, which, when it burns, tends to emit hazardous fumes.

    Check your evac plan, folks.

  2. My house from 1900 has oak doors and is brick, mortar and plaster throughout.

    A pity that the wiring is insulated with cloth/paper.

  3. This is totally anecdotal, but I saw a house go up this summer as I drove home from work. It was brand-spanking new, and seeing how fast it went, I can totally believe these assertions.

    The simple fact of the matter is that the only organizing principle in today’s home construction is greed: greed on the part of the buyers as to “how many square feet can I get?” and greed by the builders (including “how many houses can I put up?”). When that’s the only organizing principle, other considerations take the back seat.

    I’m actually a little optimistic that the housing down-turn may cause people to re-evaluate the greed priority, which could result in much more livable spaces.

    1. I would agree that greed is a part of it but it’s also resource management. Large timbers come from large trees. Composite wood comes from wood scrap and sawdust. You can’t demand protection of forests and demand your homes be made of lumber from forests at the same time.

      1. I would agree that greed is a part of it but it’s also resource management. Large timbers come from large trees. Composite wood comes from wood scrap and sawdust. You can’t demand protection of forests and demand your homes be made of lumber from forests at the same time.

        I understand what you’re saying — and to an extent you’re right — but there are very sustainable/resource wise methods of building that would be very robust: cob and straw-bale come to mind. But you can’t pop those kinds of house out like a factory. What’s more, if you’re thinking about resources, you have to look over the life of the house. Up until a few years ago I lived in the house that was built in the 1790’s. Yes, a lot of wood was used, but the house has stood for over 200 years and is still standing. The houses they’re building today are almost “disposable,” and I can’t see many of them being around in another 100 years.

        Also (getting back to the greed thing), houses are just too big — regardless of what they’re made of — to be very sustainable in terms of resource consumption. I don’t know where you live, but where I am it’s hard to find a house being built that’s not 3000 square feet or more.

        1. Dear Ambiguity,
          I want to point out that houses made from Compressed Earth Block, SIP’s, ICF’s, Light Gauge Metal Framed, FCP’s, SCIP’s, and STEP’s among others can be popped out like a factory. These are all designed to be built by semi-skilled labor (the same kind of labor that builds the rest of our our houses).

          All of these are more fire resistant than stick built houses and some are practically impossible to burn down. Even the metal framed buildings will out last any stick built building made today.

          Wooden buildings from the 1790’s were not built with sticks. They were timber framed, which even today presents many advantages.

          I completely agree that houses today are just too big. But whether large or small it is ridiculous for Americans to continue to build with sticks. There are a lot better uses for wood in houses than in the frame, though it does make sense to use wood for joists and trusses where needed.

      2. You can’t demand protection of forests and demand your homes be made of lumber from forests at the same time.

        Sure you can. Tree farms. Natural, old-growth forests are left alone, and trees suited for construction can be grown for the purpose.

        A friend of mine has an older (1960s?) house that was run into by an SUV. The insurance adjuster said that she was fortunate, because houses of that vintage were built with cedar siding. A newer house would have suffered a nice big hole. Instead, the cedar siding provided enough reinforcement that all she had was some cracked drywall.

  4. just finished remodeling our 1923 home, and worked with the contractor to make sure that it’s minimizing these materials. Costs more, sucks less.

  5. Well I’m not keen on composite materials either, I think it should be mentioned that it prevents waste of scrap wood material. Not long ago, those leftovers would have been burned as waste.

    Maybe there’s a way they could make these materials with more fire retardant adhesives? Or perhaps they already do, but the companies making these houses just fail to use that variety to cut costs.

  6. Seriously?

    My house was built in 1910, yeah it’s got the solid wood 2×10 joists and plaster walls…..(and knob and tube wiring in parts).

    I guess when people make assertions like this they have never worked on an old house? Sure plaster doesn’t burn, but that 100 year old lathe behind it goes quick, much quicker than a 2×4.
    (Which goes to a different point, when a room is set on fire from the inside the paper covering modern drywall burns, not the actual gypsum inside of the drywall. Plaster has nothing to burn, other than the dozen or more layers of paint on it…including the lead.)

    Oh and those evil composite materials, how dare engineers build things that cut down on waste, are more structurally stable, and less prone to damage from insects and the basic elements? Or that fact that doing plaster is time consuming, requires much more skill, and is far heavier than simple drywall.

    Seriously, when I build a new house I’m going to demand 2×12 solid oak joists and plaster walls. I’m also going to install a solid gold toilet, because that’s how much money I’ll need to be rolling in to do all that.

    1. I think that the problem is not composites, many of which have quite admirable qualities; but the use of composites that burn with excessive enthusiasm and toxicity as structural materials.

      Demanding “nothing but the past!” is pure reaction; but it would be sort of useful to know how fast buildings of particular vintages burn. One would also hope that future fire codes will mandate sensibly in terms of flammability and toxicity.

  7. If nothing else, it seems to be simply intuitive physics.

    Denser objects, and objects with less surface, area don’t burn as easily. A big hunk of wood takes a lot of effort to light. Run that same hunk of wood through a mulcher and it ignites readily. Same basic principles behind steel wool burning but steel rods not.

    ~D. Walker

  8. Pfft. My home is made of poured concrete. I’m pretty certain it is more fire resistant than old wood homes. Granted the inside might go up completely, but the ceiling certainly isn’t going to collapse because of a little fire damage.

  9. Here in NYC we don’t have a lot of single-family structures like this. But the co-op and condo boom is pretty amazing. The construction is clearly crap and lots of buildings are having disturbing modern architecture problems. All glass windows that let too much heat in and such.

  10. I live in a coal cave that’s thousands of years old, does that mean it’s flammability is void?

  11. Compounding the material problem was the speed with which many of these houses were built during the boom times of the aughts. Chicago is rife with homeowners who bought new construction homes and ended up with barely finished plumbing, shoddy wiring, leaks, mold and a host of other problems.

    The focus was on the shiny bits, marble counter-tops and jacuzzi baths, not sturdy construction and safe materials.

    An anecdote; a friend of mine was looking to buy a condo and while at an open house ended up using the bathroom. When she was in there the realtor begged her not to flush saying that the toilets could “only be flushed during off-peak hours”.

    No, she did not buy that place.

  12. It certainly does seem like new homes go up quickly – and in cities like Calgary, they’re packed together with only a few feet between homes. One house starts on fire, and pretty soon the ones next to it have melting siding and burning roofs.

    Sprinklers would part of the solution. The fire department has been calling for it for a while, but the builders (and home buyers) are resistant to anything that would add extra expense to the cost of building a new home…they’d rather spend the money on marble counter-tops.

    The other part of the solution? Give building codes some teeth. Mandate fire resistant drywall in homes, and require more space between detached houses (rather than cramming as much house as possible on the lot) so you don’t take the block out the next time you decide to barbecue in your garage.

  13. I wonder how much logging would have to increase in order to accommodate demand for solid wood-only houses.

    1. Sorry to say that vinyl is not so hot. Toxic to make, toxic to dispose of and when it burns… you guessed it: toxic. IMO Fiber cement is a better siding option. But it gets down to, as it often does, cost.

  14. do not forget about cyanides which are much more likely produced when a fire breaks out in a “modern” house. i think it was in the seventies when the number of killed firefighters in london made quite a jump due to extensive use of cheaper composite materials in furniture.

  15. There are lots of problems with old houses too.

    Old houses tend to have untreated and (now) very dry timber, that burns very quickly.
    Old houses can have wood stoves in them without reflectors – carbonised wall studs with spontaneous combustion! YAY!
    Old houses have no ventilation, relying on leaky windows (read: DRAFTY) to “breathe”
    Old houses have chimneys where the mortar has turned to sand… In an earthquake zone. Wee!
    Old houses tend to have untreated lumber – Rot, termites, borer, etc! YAY!
    Old houses have floor joists that bend, resulting in uneven and squeaky floors.
    Old houses have no insulation, anywhere.
    Old houses have old wiring with a nasty habit of starting fires.
    Old houses have plumbing which results in geysers in your front lawn. Patching one hole causes the pressure to rise, and causes another part of the pipe to split!

    Yep, I’ve got a 1920’s bungalow here in NZ. Borer, original plumbing, original wiring, no insulation. We were the first owners in 5 years to make it through more than one winter in it.

    1. Did you see the 2010 remake of True Grit? Because at one point there is clearly a message in it about how chimneys can get clogged up by ambitious 14 year old girls who shove duster jackets in them.

  16. The article bases its claims on a National Research Council report, so I started rummaging around their site. This is all I’ve found so far (for *open* joist systems in basement fires):

    “The estimated time to reach untenable conditions in the tests using the engineered floor systems was similar to that in the test using the solid wood joist floor system. The change in floor construction basically did not change the estimated time to reach incapacitation for occupants. Data analysis indicates that tenability conditions and the time to reach untenable conditions appear to be the critical factors affecting occupant life safety under the fire scenario tested.”

    People do spend a lot of time thinking about this issue. All joist systems are rated for fire resistance, flame spread, etc., and they don’t seem much different from solid lumber.

  17. Actually further down there was one scenario where engineered joists failed more quickly:

    “With the relatively severe fire scenarios used in the experiments, the times to reach structural failure for the wood I-joist, steel C-joist, metal plate and metal web wood truss assemblies were 35-60% shorter than that for the solid wood joist assemblies.”

    This was in a basement with the door closed to prevent escape of heat, the joists fully exposed and ignited with burning polyurethane foam — basically every code-required safeguard removed, and a highly flammable substance ignited beneath them.

  18. Disclosure: I work for e2e Materials, a non-traditional, green composite building materials company.

    These days a whole helluva lot of building materials are composites. What people don’t actually realize is that the “glue” binding this stuff together is actually a petrochemical resin that offgases formaldehyde. Flame retardation is also a big problem with all traditional composites because they’re made of roughly 20-30% by mass of what’s essentially frozen gasoline.

    “Oh and those evil composite materials, how dare engineers build things that cut down on waste, are more structurally stable, and less prone to damage from insects and the basic elements?”

    Frankly, there are better things that people can do with sawdust waste, like make charcoal briquets or use it as filler for concrete. Also, if you think that an MDF sheet has a better young’s modulus and modulus of rupture than a two-by-four, I’ve got a bridge I want to sell you. And ever heard of pressure-treated lumber?

  19. There is no reason to build homes with sticks (composite, engineered or otherwise) unless you only want temporary shelter. The intransigence of home builders is astonishing. The positive side is that the houses built in the last 20 years will not last more than another 25 to 50 years so when they fall apart completely perhaps more solid construction will be in vogue.

  20. While I’m all for making things more safe I do realize things like price, functionality, and sustainability have to be taken into consideration.

    A company called TrimJoist makes an interesting alternative to engineered beams. It basically uses 2×4’s to create a sort of truss design to replace a standard 2×10+.

    In terms of flammability there is more exposed wood surface, so I’m sure it’s going to fail faster than a solid 2×10 in a high temperature test, but it would probably release less toxic fumes than an engineered beam…

    I suppose if I was building a custom home I would look into a sprinkler system of some sort. I don’t like government mandatory safety things, but I like to have the option to install them if and when I choose. Much like having to have a smoke detector in every room. You’d think by now companies would be making them look nicer or less obtrusive.

    If this is truly a problem for the firefighters then we need to look into designing building cores with only metal or concrete. Of course it would cost more, but they would last longer too. Which has a tendency to not be the rational design of most products.

  21. ““If there were 49 murders in 10 years, don’t you think there’d be an uproar?” asked Messier.”

    Uhhh… in the U.S. there certainly would be an uproar, because the murder rate would have dropped by several orders of magnitude or thereabouts.

    This seems like a very low number for murders in 10 years.
    Is this one of those “Canada is crazy safe and peaceful” things?

  22. Anyone remember the house from that movie “Synecdoche, NY” that was on fire for something like 30 years, with people living in it the whole time? We need more of those.

    (Although, I think the people living there eventually died from fumes…)

  23. On the other hand, last time I watched home construction, wooden studs had largely been replaced with metal ones, which are relatively non-flammable.

  24. As a firefighter I can tell you that this info is correct. Modern homes burn hot, fast and collapse much faster than pre 1970’s construction. The amount of time to escape is also far less…by an order of magnitude. That’s why modern homes should have sprinkler systems…to offset this fact. Sprinklers work. Where greed plays into it is that the building industry lobbies against them and convinces consumers they don’t want them.

    That said, there are a lot fewer house fires than their used to be: fewer smokers, self extinguishing cigarettes, improved electrical safety standards, etc. So, you see the effects less and perhaps they don’t play into the public mind as much.

  25. Flashover typically comes from burning contents, not burning structure, so it’s not right to suggest that composite floor joists are causing earlier flashovers.

    And I’d be surprised to find that engineered wood products are the primary source of toxic fumes in a burning house. Again, I’d look to the contents, which are likely to contain more plastics an other manmade materials than in the past.

  26. Also a factor in this is the quality of construction. Even among homes built with customary modern methods, you can have a variation of fire susceptibility. Some homes are built so cheap it’s a wonder they don’t spontaneously combust.

    I suspect that you COULD build a fire-resistant home with modern materials, but that it’s too expensive for most/all developers to even consider.

  27. Our house was built in 1913, so I don’t have to worry about this stuff. No glues or adhesives in the basements or walls

  28. I’m more surprised by this: ““If there were 49 murders in 10 years, don’t you think there’d be an uproar?” asked Messier.” My smallish American city has about that number of murders annually. The murder rate is really that low in Canada? Gotta go check this out a bit…

    1. As with the U.S., the murder rates in Canada vary greatly from region to region. The person in the article was talking about Ottawa, a city of 800,000 which only had 9 murders in 2009. So yes, an extra 49 murders a decade would definitely be noteworthy.

  29. But whether large or small it is ridiculous for Americans to continue to build with sticks.

    Stick-built homes are becoming a luxury in the US as more and more people live in mobiles. The reason for mobiles, of course, is that they’re much cheaper than stick built. And the reason for stick-built is that they’re much cheaper than reinforced concrete. If we stop stick-built, there’ll be nothing built but mobiles.

    Not that there’s the slightest danger of any changes in the industry. We don’t even require solar panels on new homes in the desert. My block could power Southern California in July and August.

  30. There’s plenty of room to discuss flammability of building materials and the contents within houses. However this piece and the accompanying video have the look and feel of those “free” canned stories supplied to local TV news and newspapers by industry groups & lobbyists.

    Plumber/steamfitter, fire safety, building official & manufacturer lobby groups are all pushing to have residential sprinklers made mandatory in the International Building Code, adding thousands of dollars to the cost of new construction or remodel projects.

  31. Probably true.

    Also true that we’ve pretty much cut down all the trees that could be used to make 2×10’s.

    So there’s that.

  32. This makes no sense at all. According to the National Fire Protection Association, deaths and injuries from fire are on the DECLINE. In fact, since the 1970’s both have been reduced by half! So maybe composites burn hotter the farther North they are installed. The total number of fires doesn’t seem to fluctuate that much,(admittedly from only browsing the graphs) even though deaths and injuries are on the decline. My guess is that it has more to do with fire/smoke alarms than with construction type, but still, why the freak out?

  33. As a person who has lived in some very old house I can you this is not true. Old paper warped wiring running through old dried out newspaper stuffed in walls to insulate…

  34. what shocked me some years ago is that the composite material is a good
    sound board and transmits sounds very well so the slightest noise
    is amplified this encroached on my sense of well being and private space ahmen

  35. I’ve never understood why so many houses in North America are built from wood, especially in hurricane/tornado zones.

    What is wrong with brick?

  36. Well, if we’re going to sling authoritative quotes…

    “Deaths from fires and burns are the third leading cause of fatal home injury (Runyan 2004). […]”

    These houses adapt all the lessons learned from the house trailer industry … so they burn just like ’em. Ever seen that? If your house burns faster, by an order of magnitude, you have less time to evac your children, elderly, and infirm. How close do you want to cut it?

    Do you really want to invest in something built of former trash glued together? Do you think it’s a good idea to skimp on the structure so you can afford to hang hot tubs and granite counters and fru-fru all over it?

    There won’t be a remodeling/restoration industry for these houses — nothing worth salvaging. Just demol & rebuild. How green is that?

  37. Who would have known Ray Bradbury’s novel Fahrenheit 451 predicted so many things? Read it again, you will be amazed.

  38. Quick counterpoint: solid wood burns longer, but also burns hotter. It’s like using charcoal over briquettes.

  39. OTOH, baloon framing without firestops (as used to be common)meant that the walls were basicly a series of 2 story chimneys>

  40. “What are you going to build your house out of- meat?”

    Oh, there are plenty of other materials… the most plentiful being beneath your feet. Earthen construction in all its various forms – brick, adobe, rammed earth, stone, and all their cousins and offshoots are pretty dang popular in most of the world and *if done right* can withstand some pretty serious earthquakes and other natural disasters.

    Or perhaps you’d like to consider other cellulosic materials, such as straw or bamboo? And don’t give me that three little pigs BS, or tell me that straw burns too – I was part of a team that ran a successful two-hour ASTM fire test on a cement-plastered straw bale wall a few years back as well as a one-hour ASTM fire test on earthen-plastered straw bale (the only reason it was stopped at 1 hour was because the plaster on the side away from the heat had developed a crack when the lab guys pulled the test wall up to the 10’x10′ oven, and the fire had started following the oxygen source. If it wasn’t for that it probably would have gone for three hours.) Try that with stick-built, even with fire resistant sh1trock.

    On the other hand, some nutcase (or maybe an artist – but I repeat myself) has probably tried building a meat house ;-)

    Personally, I’m vascillating between straw bale and one of the aerated cement blocks. Good insulation value, good thermal mass, resistant to fire, relatively low maintenance… The out of pocket cost is a bit higher, but the lifetime cost is lower.

    Oh, and in response to @Ambiguity: though you can’t pop straw bale homes out of a factory, there have been a number of companies over the past several decades which have made compressed straw SIPs panels (Stramit in Europe and Australia and for a little while in US, Agriboard in US), and machine made compressed earth blocks can be manufactured on site at a rate of just under a thousand an hour (see

  41. To chime in on balloon frames. Think two stories of 2″ by 4″s or 6″s going straight up from ground floor to attic, usually uninsulated until the 1960’s, plaster and lath. The second floor joists sit on on 1″by whatever let into the studs. No fire stops and the high end houses had gas lighting.

    Oddly enough, quite a few of them still survive.

    The captcha is getting well nigh unreadable even by humans……

  42. Re: Brick – Seismic regulations
    Re: Sticks – much less carbon intensive than the alternatives, both in embedded energy (how much to build) and in use, as it is a no-brainer to insulate
    Re: Sprinklers
    I’ve yet to see a design that didn’t create either bacteria breeding grounds or freezing hazards. The insurers in the US are kind of coming around to the idea of sprinklers in domestic homes, but until recently you paid a premium (because of the water damage risk without fire) instead of getting a discount.
    (BTW I’m one of those horrible people who think insurance actuaries actually know something.)

  43. Normal houses in South America (third world) are done with brick and mortar. Why don´t rich countries do that?, why they build doll houses made of plastic, glue and cheap wood?.

    Anyway, a normal fire in a brick house will mostly be limited to a room, or to the specific part of the room where the fire starts. It´s really hard to see houses engulfed in flames, it´s a really, really strange phenomena (imagine that when it happens it goes in the news, mehh).

  44. Having, as a firefighter, been in my fair share of burning buildings, the structural composition of the building has less to do with the outcome than the story claims.

    Matching an empty house (turn of the last century) with one from the turn of this century, and neither will burn that readily. The contents of said houses will make a huge difference, however, with 100-year-old furnishings less-likely to produce the high temperatures needed for a fast flashover (as well as the petroleum-based fumes, carcinogens etc) than current furnishings.

    Houses don’t tend to readily catch on fire. Furnishings do. Wiring does. Electronics all the time.

    And that isn’t even looking at the fact that room-sizes have tended to shrink over the years, with smaller rooms, lower ceilings, all helping to build heat much faster.

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