My wife and I are building a new house with a basement (10 ft poured concrete walls). We were there looking at the progress today and one of the sub’s working on the basement told us our builder was putting steel support beams in place prior to starting the framing.
Here is my question: My wife thinks that steel instead of engineered lumber is bad because she says that if there is a fire the steel will fail much more quickly than lumber would. (her former volunteer firefighter father told her this I think) Is this true?
thanks,
Keith
Replies
yes... most fireman hate a steel building... an old timber frame usually has alot more time before it fails.... That being said... once it's to the point of the steel fail'n there ain't much left to save
p
If you're concerned about it, pad the steel in wood and then wrap with sheetrock. A little over 1000 degrees and steel turns into spaghetti. I doubt an engineered beam would do much better. A significant fire in your basement is probably going to take the entire house either way.
I hadn't really thought that through. A fire that hot in the basement would probably mean the end of the house anyway. It's not really something I'm worried about, it just seems counterintuitive for steel to be worse than wood in a fire.
thanks for clearing that up for me guys.
Keith
steel melts and twists ...
wood chars and that's a bit of a protective coating ... a real temporary protective coating.
like already said ... pad it out and wrap with one or two layers of taped and mudded 5/8th drywall.
make sure the ends are grouted or blocked in.
Jeff Buck Construction
Artistry In Carpentry
Pittsburgh Pa
I have no idea of what your configuration is, but I'm betting that an engineered wood beam would not span nearly as far as the steel will. - which would mean more support columns. Wrapping the steel beam as described above is the answer.
Next your FIl is gonna say no engineered joists and no trusses...
but I'm betting that an engineered wood beam would not span nearly as far as the steel will.
I'll take that bet. Let's make this a five milkbone bet!
I get to call out the sizes.
blue
Edited 10/2/2005 9:24 am ET by blueeyeddevil
I'm not gonna take you up on the bet - besides, last time I tried to get some milk bones outa-ya you wern't too generous. My 2 best friends were very disappointed. Seriously, what would be a typical engineered basement beam for lets say, a 30 x 40 2 story house, 40' beam up the center, two columns, one either side of the center stairs, meaning that the joists are ~15' span and each span of the girder is ~18'. Not challenging you, just trying to learn something...
I really don't think he is intending to use steel. I would think he would have mentioned that in our discussions during the house design. However, I have complete faith in him and have told him to do whatever he thinks is best in these kinds of decisions.
I will be speaking with him one day this week, I am sure, and will ask him about it. Our house will be 2 stories and the main support walls are at the same place in the basement and on the main floor. By that I mean they are directly lined up vertically
He did mention there would need to be one LVL (I think he said) going across one room to support a point of load bearing for the second floor that is a column on the main floor and falls in the middle of a room in the basement.
He is a great builder...he started out as a carpenter many years ago. I lurked on here for a while to try to learn a little about the process we were entrusting to him and as far as I can tell from what I have read on here, he is doing everything the "right" way.
You guys are a great group.
thanks again for the replies.
Keith
>>I really don't think he is intending to use steel<<
There is nothing wrong with using steel, other than the issue of a horrific fire. By the time that basement beam melted the whole house would be toast anyway. Occupants would either be fried or out by then. Fireman dislike certain building materials because they have to go in the structure sometime after the fire is well underway. For that matter I believe many common building materials give off poisonous gas when burned. But that is a whole other conversation. The fireman's view of the situation is just one aspect. The builder's job is to take other things into account too, like head height with respect to the beam, running of utilities around the beam, cost of the beam, etc.
Your house plans undoubtedly specify what beam goes there. Something like W10x33 would mean steel. Something like (3)1.75x11.25LVL would mean an engineered wood beam. Your building codes will not allow something that is inherently dangerous. I believe you use the IRC2000 or newer, which is a pretty modern code.
Re your statement, >>we were entrusting to him and as far as I can tell from what I have read on here, he is doing everything the "right" way. << Take what you read here with a grain of salt. You will find guys saying that the "right way" is to screw your framing together rather than using nails, and another saying that spending $10k on insulation in a mild climate is perfectly acceptable, and that all other methods are substandard etc, etc... when in reality the only thing some of these guys have built in their life is a small addition, or a shed out back. Absolute crackpots! There are some very qualified guys here too, like Blue, who responded earlier.
You have the right attitude toward your builder though. Just keep a constant eye on things. Then if something comes up, you can ask the question in a timely fashion. Like for example, I recently had a HO say that he wanted corbels (decorative brackets) installed under his kitchen counter bar top "like the other house your building". The tops had been installed for a month and all trim and paint was complete. My response - "Little late now. I can install the corbels for <insert some ridiculous price>" Whereas I would have maybe given him the brackets if he had said it before everything was done. Really though, if there were questions about some basic structural elements, those questions should have been asked when the plans were being drawn.
Edited 10/3/2005 7:41 am ET by Matt
Matt, you fell for the oldest trick in the book. Send me those milkbones!
I qualified my bet by having the final say about sizing. The point is that you made a generalized statement, without setting out any specifics. As such, the conversation is pointless.
I'll trade you those milkbones for two treats.
blue
OK - you give some numbers - sorry I didn't follow instructions... or maybe just didn't nderstand what you meant. Maybe just pull em off some plans that you have? No wimpy spans though...
two big problems with steel in a fire - starts to lose strength at about 1000 degrees F and will "deform"(1000F not really that hot once things get going) - conversely, steel lengthens when heated and can "push" down walls
additionally most steel that gets heated has to be replaced since the strength in effected by the heat and changes the "temper" of the steel - wood can be evaluated on the basis on the depth of the char and more wood can be added to the framing
that being said - wrapping the steel in drywall will give it some protection in a fire - just have to be sure the entire surface is enclosed
another fire concern is penetrations between floors that end up acting as chimneys/conduit for spreading the fire - all penetrations should be sealed with a fire rated caulk (no, expansion foam is not fire rated, usually just rated for smoke containment)
The fire resistance of a beam is based on the idea that the beam is thick enough and wide enough so that sufficient strength remains after the outer inch or so of the beam is turned to charcoal. The charcoal then serves as insulation and slows down the charring of the central part of the beam giving the required one hour rating or whatever is required. The theoretical fire resistance of each beam (and column) must be calculated using a number of factors such as loading, type of wood, etc. A formula is given at:
http://www.awc.org/Publications/dca/dca2/DCA2.pdf
A rule of thumb that I have seen is that to achieve a one hour rating, a beam must be at least 6"x8". Of course, that is an extreme simplification and would not hold for all types of wood and situations.
Edited 10/3/2005 1:27 pm ET by CaseyR