Replies

1. 
   dIrishInMe | Dec 21, 2004 12:32am | #1

   For a crawlspace situation, concrete footers with block piers that support built up wood girders is the normal method.   When I say built up wood girders, I mean something like triple 2x10s.  Strip footers with stem walls would be a waste as it would add virtually no benefit for the increased cost. 
    

   Matt
1. 
   CapnMac | Dec 21, 2004 12:58am | #2

   Strip footers with stem walls would be a waste as it would add virtually no benefit for the increased cost

   Ssshhh!!  Don't tell that to the Buildign Science people . . . <g>

   In "true" pier and beam, as you are describing; isn't the tricky part he termination of the exterior finish at, or near, ground level?  (That's between the piers.)Occupational hazard of my occupation not being around (sorry Bubba)

1. 
   dIrishInMe | Dec 21, 2004 03:50am | #3

   I thought he was asking about supports across interior spans.  In other words, for example, you have a 30' wide X 40' long foundation, and a max of 16' joist material available - how do you support the middle area where the joists are lapped?

   It sounds like you are talking about what we call a peir and curtain foundation.  We see pier and curtain some around here, but more toward the coast. 

   Now that I re-read his initial question, I really don't know what he is asking about. Matt

2. 
   masterofnon1 | Dec 21, 2004 04:16am | #5

   I am just referring to the interior support, not a perimeter foundation.

1. 
   dIrishInMe | Dec 21, 2004 05:38am | #6

   OK, then see my .2 post.

    Matt

2. 
   CapnMac | Dec 21, 2004 08:53pm | #12

   to the interior support

   Ok, 10-4, carry on <g>Occupational hazard of my occupation not being around (sorry Bubba)

2. 
   masterofnon1 | Dec 21, 2004 04:15am | #4

   That was my thought.  However, I lived in a house were they had used a short stud wall on a continuous footer and I friend just built his own house were he used one as well, so I asked?

   The only advantage I could see is if you are runing drain lines parralel to the joist and need to cross over or under the built up beam you could run into the beam.  Most of the time you could just go lower, but I suppose there could be times when it is a problem.  Perhpas large forced air ducts as well.  Where as with the stud wall, just runn stuff through.

2. 
   slykarma | Dec 21, 2004 06:51am | #7

   My current project is a 4500 SF dental clinic. Half the area has 9' basement and the rest is 4' crawl space. It is continuous footings and 2x6 pony walls on 12' centres, carrying TJI floor system. There are also some separate pad footings for glu lam columns supporting roof point loads. Engineer says beams would have been more expensive.

   Wally

   Lignum est bonum.
1. 
   dIrishInMe | Dec 21, 2004 04:09pm | #8

   Interesting... I have some Qs:

   I'm assuming the strip footers for the pony walls have to extend all the way down to the frost line?  How deep is your frost line? I'm guessing it varies widely in BC... I'm also assuming that the pony wall framing material needs to be treated lumber.  Here, anything that is within 12" of the soil needs to be treated.  So, how does that work - does the pony wall extend below grade, or does the strip footers come up to grade?  You said 2x6 pony wall - is it on 12" or 16" centers, (or some metric measurement) and how many stories is the structure.Matt

1. 
   slykarma | Dec 21, 2004 05:01pm | #9

   You're right, the frostline varies a lot in BC. Here in the semi-desert Okanagan, bottom of ftg only has to be 24" below finished grade. In this case we have 4' crawlspace with subfloor essentially at grade. The building has one main level with basement access just under 50% of floor space.

   Ftgs were 16"x10". Exterior concrete fdn walls were poured to subfloor elev and blocked out with styrofoam and PT ledger already bolted in (big PITA). Interior ftgs had no concrete wall, just the 2x6 pony walls with PT bottom plate and studs @ 16" o/c. 2" mud slab with 6 mil poly moisture barrier poured flush to top of ftgs to seal crawlspace - no exposed soil. Exterior walls coated with tar dampproof spray up to grade line. Interior side covered with 2" rigid styro full height, notched out for 11-7/8" TJI joists.

   Because they run the full length of the crawlspace,  the four interior pony walls had to have two openings let into each to permit easy travel from one area to another. Rather than put in conventional headers and further reduce headroom, we used lengths of PSL rimboard on top of the pony walls and hangered the TJIs on either side.

   Sorry, I don't have pictures from this phase of the job. Small crew, busy hands.

   WallyLignum est bonum.

2. 
   masterofnon1 | Dec 21, 2004 07:38pm | #11

   Dirishinme, I have seen it done with a presure treated bottom plate.  O.C. eqaul to teh OC for teh joists.  The footer was the same depth as the perimeter footing, and was set within a couple of inches of the grade in the crawlspace.  Come to think of it, my last house had teh footing just floating on the grade in the crawlspace.

3. 
   JohnSprung | Dec 23, 2004 01:58am | #13

   > I'm assuming the strip footers for the pony walls have to extend all the way down to the frost line? 

   It varies with local conditions.  Here we don't have a frost line, but we do have earthquakes.  Older buildings often have a perimeter footing with pier and post interior.  Not allowed any more for new construction.  The interior footings and pony walls are a pain for access and working in the crawl.

    

   -- J.S.

    

2. 
   masterofnon1 | Dec 21, 2004 07:35pm | #10

   As several have said post/pier/beams are the norm, but it does seem that throwing a continuous footer in and simple framed stem wall would be pretty easy and could be cost effective.  But there must be a reason people use teh beam approach.  Just curious.