Replies

1. 
   Mike_Mahan | Dec 15, 2014 11:10am | #1

   Why couldn't you omit the concrete?

   For the simple reason that almost all codes require certain clearances from earth to wood. In a basement head room is often at a premium and basement walls and water proofing get more expensive the deeper they are. Space under a wood floor would be wasted for no good reason. The question should be why build a basement at all rather than a crawl space.

1. 
   oops | Dec 15, 2014 04:19pm | #2

   Like you. Why basements?  Seriously.

   They have water / moisture problems.

   They never seem to have enough head room.  (Why don't they dig the hole deeper in the first place)

   Can they meet code for living space? (Ingress / egress requirement etc.)

   Is it cultural / historical / geographical / economics, all of the above?

   I know why they are not built in our area.  Our freeze line is 6".  We have terrible heavy clay soils, It would be cost prohibitive.  Not historical.  Even crawlspace foundations are as scarce as hens teeth.  (99.9% structural monolithic waffle slab on grade)

1. 
   Mike_Mahan | Dec 15, 2014 07:10pm | #5

   Frost line

   The only reason a basement makes sense is if you have a deep enough frost line to justify the excacvation. Your frost line is 6" more than mine. So slab on grade makes the most sense. Lately I've been dealing with slopes most of the time. I've found that it's often less expensive to build foundations on the existing grade and used a raised subfloor than do the engineering, grading and compaction to do a slab. Soils work has gotten quite expensive. Often access for machinery is an issue. A couple of years ago I built a garage with a zero stem wall on the high side and an 8' cripple wall on the low side. It was alot cheaper to engineer an build the subfloor for vehicle loads than to build an 8' + retaining wall and bring in god only knows how much fill.

1. 
   oops | Dec 15, 2014 09:39pm | #6

   lumber floor garage

   That's neat Mark.  I've thought of doing that, but it always seemed so out of the box for single family homes, I discarded the idea.  Do you run into any code problems?

   Here the developers cut and fill, stepping down the slope, to create flat lots. If it is sever enough, they have to build retaining wall at the property line.  Basiclly making the lot fit the house instead of making the house fit the lot. Of course they wipe out all of any trees on the site.

   It is quite a bit more economical to grade the lot, but it would make for a more architecturally divirse neighborhood to fit the house  to the lot.

   Too eliminate the cost of compaction etc, when necessary, they set the slab on piers down into understurbed bearing soil.

   Please forgive my hijacking the post.

1. 
   Mike_Mahan | Dec 17, 2014 09:08am | #10

   New topic

   This thread seems to have gone way off track elsewhere. I'm gathering some images and will start a new thread soon since our discussion here should be continued.

2. 
   calvin | Dec 17, 2014 09:29am | #11

   Mike

   Thanks

2. 
   bski | Dec 15, 2014 04:29pm | #3

   I live in an area where basements are in just about all new construction.  I am talking about new construction in particular here, so headroom would not be an issue.   People build wooden foundations all the time.  Why wouldn't a wooden floor work, too?

1. 
   mark122 | Dec 15, 2014 06:44pm | #4

   mostly cost and long term exposure to at times high levels of humidity and water. how long do you thing someone would guarantee a wood basement?

   water and humidity are a life long battle with many basements, concrete withstands those issues much better and MUCH longer than wood does. 

1. 
   deadnuts | Dec 16, 2014 12:32pm | #7

   wrong verb

   Actually, concrete does not "withstand" water and humidity. In fact, most concrete readily absorbs it. Concrete would be more accurately be discribed as tolerating water and humidity. Moisture & Vapor barriers withstand water and humidity. That's why they are critical component for a basement floor system whether it's made of wood, concrete, stone, etc.

1. 
   mark122 | Dec 16, 2014 06:52pm | #8

   ACTUALLY...

   well, aside from the fact that you constantly reply on different post with unbelievablly absurd comments, dont contribute to the posters concerns, and are an never ending fountain of bull chit, you are mistaken again.

   concrete withstands (resists, remains undamaged or unaffected) the issues I was refering to better and longer than wood does.

2. 
   deadnuts | Dec 16, 2014 10:55pm | #9

   still hungry, huh?

   Wrong again. You never stop devoring that foot, do you? I'd be surprised if you can still put a shoe on it.

   In some cases, wood can tolerate (or remain undamged or unaffected as you have added) moisture just as well as concrete. In fact, there are old growth logs being harvested from the bottom of the Great Lakes that sank during the logging boom of the 1800's. These logs are quite valuable and being milled into perfectly good structural timbers and trim. The reason they never rotted and haven't  been structurally affected by moisture is because they never saw atmospheric conditoins that allowed them to rot. What wood cannot do is tolerate repeated wet dry cycles (which would require their abiilty to give off rather than just receive moisture) or the presence of microganisms that can devour it's cell structure. Icy waters and low oxygen levels prevented this from happening.

   Of relevance to the O.P. : You can create structural floor systems in a basement that allow wood to peform the same function as a concrete slab. I wouldn't say it is the best choice, but it can succesfully be done. The main challenge is to continully prevent wet-dry cycles from compromising untreated wood.

   For your continued edification, bozo, here is a Merriam-Webster definition of "withstand" :

   WITHSTAND

   transitive verb

   1

   a :  to stand up against :  oppose with firm determination; especially :  to resist successfully

    

   b :  to be proof against :  resist the effect of <withstand the impact of a landing — Current Biography>

   2

   archaic :  to stop or obstruct the course of

    

   Concrete does not withstand the issues you originally referenced. However, it normally does tolerate (or remains unaffected by) the presence of moisture allowing it to remain structurally stable. That is a more accurate description and a relevant point to the O.P. which you appear usually incapable of delivering.

2. 
   Mongo | Dec 17, 2014 11:42am | #12

   I think concrete, being "fluid", is one of the easiest and fastest ways to get a level, durable, and construction-site friendly surface.

   I'm not sure of the logostics and man-hours of trying to level a wood floor, it certainy depends on base prep work and materials used in your flooring layer.

   I'd think that the added expense of a rat slab as a base for a wood floor might even be cost efficient. Then the argument gets extended to "if a rat slab, why not pour a full thickness slab.

   I'm sure there are locations or circumstances where a wood floor would make sense.

   In certain climes, perhaps termites, carpenter ants, etc, could be an issue.

1. 
   DanH | Dec 17, 2014 03:11pm | #13

   And keep in mind that a concrete slab serves to help prevent soil pressure from pressing in the walls.

1. 
   deadnuts | Dec 18, 2014 12:26pm | #15

   not necessarily

   Dan,

   What about failure at the mid height of full height basements that are predominatley below grade? A slab won't prevent that from happening. I believe that would be more common of a failure (particularly with unreinforced CMU and poor waterproofing) even if no slab was poured. The failure at mid height would be in bending while a wall kick out at the base would be from shear failure. I shouild think the axial load from house above and friction of foundation to wall connection (particuarly if you add in a keyway or steel dowels which are common) would easily overcome shear force of backfill. The slab could work to restrain the wall, but I don't think it usually gets to the point of being necessary. If it were, it would seem to have to be written into the code. Is it?

   Also, slabs are usually isolated from walls with 1/2" fiberboard to reduce plastic shrinkage stress cracking of slab pour. I would think that the fiberboard would have to compress at least half its material thickness before any amount of stress could be transferred to the slab. That means the wall would have to move 1/4" out of plane before being restrained by slab. I just don't see engineers or inspections letting that happen. In other words, this isolation board would be a "no go" from a structural perspective..and I am not of aware of code issues against it.

1. 
   john7g | Dec 20, 2014 07:34pm | #16

   Midheight failures come from poor perimiter drains, poor backfilling, and poor surface grading and bad downspouts and a high clay content soil or high water content frost heave, nothing is going to stop the wall from caving if these isses come to that.  Wall failures are the excpetion and not the norm for basements.  

   Slabs may be isolated in your part of the country but that's not the case everywhere.  Shrinkage during the cure process usually leaves a 1/8" to 1/4" gap between slab and wall (which can be a great avenure for termites).  Not sure if there's any advantage to adding the r-board/fiberboard below the edge of the slab as an isolation process.  

   Cal, when you gonna get the spillchecker working here?  LoL

1. 
   calvin | Dec 21, 2014 07:26am | #17

   John

   spellcheck?

   Funny you should ask when.  While I don't have any idea as to the when, I've been informed yet again that there is interest some where in the smoky back rooms of Taunton.........for a compiled list of suggestions for forum improvement........

   now b/4 some of the expatriates wander in and kick the dog, let me wish you and yours a very Merry Christmas and hopes for yet another prosperous New Year!

2. 
   john7g | Dec 21, 2014 10:07am | #18

   Merry Christmas to you too!

   Merry Christmas to you too Cal and everyone else!  

   You sure have stuck to your guns here with patience I don't have.  We could ask Santa for this current place to get built up to the performance level it once was. 

   I'll setttle for just a Merry Christmas.  Hope we don't leave too much of a mess for you to clean up.  

   Best to you and yours

   7G

3. 
   joeh | Dec 21, 2014 11:52pm | #20

   Site improvements

   I've been informed yet again that there is interest some where in the smoky back rooms of Taunton.........for a compiled list of suggestions for forum improvement........

   Calvin, I'd suggest  ridding yourself of deadnuts could be a major step in the right direction.

   Guy knows all about everything, seems to be mostly interested in irritating anyone he can. The world is long on AHs, get rid of this one.

   From long ago & far away, Joe H

4. 
   deadnuts | Dec 21, 2014 07:36pm | #19

   Your concerned about spelll check?? How about what happened to reading comprehension?>

   My point wasn'tt that wall failures are normal, but rather that mid point beinding failures are more common than base of wall kick out as a result of soil pressure. That distiniction involves a degree of relativity because both conditions aren't "normal". What's yours?

   BTW, if "shrinkage during the cure process usually leaves 1/8" to 1/4" gap between slab and wall" (which is plausible), then it's going to be hard to reconcile Dan's point that "a concrete slab serves to help prevent soil pressure from pressing in the walls"; isn't it?. Seems to me it would be awful tough for these materiasl to transmit any force between one another if they aren't touching.

5. 
   Geoffrey | Jan 11, 2015 11:26pm | #21

   deadnuts,

   there's a time to argue and a time to stop and re-think one's viewpoint. Now would be that time for you. You

   have some knowledge, but it seems to be limited in application and experience in this particular matter, 

   more reading, less typing.

   Thanks,

   Geoff

6. 
   deadnuts | Jan 12, 2015 10:22am | #22

   Thanks, but no thanks.

   I would reconsider my position if there was a relevant and intelligent counterpoint to my own. I haven't seen one yet. The least relevant and intelligent thus far happens to be yours.

   Cheers!

3. 
   Shoemaker1 | Dec 17, 2014 05:39pm | #14

   Well Here is what I did.

   1983.  Our luv shack got taken out by a storm.   Great lot location, older part of town.

   A freind from school was finishing his archy degree.  His family has a well known home, and apartment  builder.

   So my bud drew up plabs for a pressure treated basement, with a suspended wood floor.  All PT framing on a concrete footing.

   A graded crawl space to a sump pump and detaile weeping system.

   local soil is high clay and frost line 4 feet down.  Last cople years 7 feet.  Block basements get eaten alive, concrete sightly better.

   We then did a double stud wall 1 foot thick and r40 ceiling.

   We lived there for 13 years and had 0 issues with anything.  When we sold I brought in a P.eng and got an all clear for the foundation for prospective buyer.

   All this was so out of the norm for this area, people still build concerte and expect some heaving as part of life ???

   Anyway As we were putting the house on the market, the city decoded to rip out the 70 year old sewer, water, storm sewers 8 ft down.  then fill and new sidewalks road etc.  AS part of this they inspected every home prior work starting, to look for existing problems that all this earth work would do, and CYA incase of litigation.

   The inspector came when I was not home.  He did comment to my wife, that he has never seen a home in this area with out and drywall cracks of stuck doors.  Also the dry basement was in steller shape.

   Cost wise it was much cheaper to do what we did.  Part of it was having them do every thing from footing to shingles.  No subs.  after they were done I subed out the plumbing, electrical and dryall and took it from there.

   I still drive by that house and it is untouched exept for a new front door.

   Also some friends had just brought the first air to air heat exchanger to market and I got to be a tester.   Even free air change and quality testing.  We had exceeded the R2000 standerd for Canada as it was being drafted.