Replies

1. 
   Kgmz | Feb 05, 2007 08:55am | #1

   I am assuming that this house is 28' deep, has a wall exactly in the center with 14' floor joists and does not have a load bearing wall above supporting the roof. And figuring a 50 lb. load per sq ft.(40 live 10 dead), and a wall opening for the doors at 8 to 9 ft.

   You will need a load capacity of at least 700 lbs per foot of beam span.

   A beam made with double yellow pine #2 2x12's with a 1/4" flitch plate will do this and support 750 lbs per foot of beam. The beam is bolted together with 1/2" bolts space 10" apart along the top edge 2" down, and double spaced along the bottom 2" up, with 2 bolts at the ends.

   With a 5/16" flitch plate will support 870 lbs per foot.

   With a 3/8" flitch plate will support 980 lbs per foot.

   With a 7/16" flitch plate will support 1100 lbs per foot.

   I would definitely go with a bigger plate than minimum just to be on the safe side.

    

   Also these specs are from the NAHB beam manual

1. 
   gtownwillie | Feb 05, 2007 05:11pm | #4

   Thanks for the really good detail onthe fitch plate and capacities.   Apparently I left out of my original message that this is a two story house and there is a second story wall directly above.  The second story wall supports the inside ends of the second floor ceiling joists but does not have direct support of the free span attic roof.  Roof is straight rafters placing load on exterior walls.  Does this change your recommendation?  Thanks,    Gtown willie

    

2. 
   BillBrennen | Feb 05, 2007 12:59pm | #2

   Why not just use LVL's instead? The flitch plate is strong, but a pain to do. All the bolts are going to need to be countersunk on two sides, but the LVL's are just nailed together.

   You can also use a single 3-1/2" wide PSL for more strength, less nailing.

   Bill

1. 
   gtownwillie | Feb 05, 2007 05:19pm | #5

   Thanks for the response.  Help me out.  I know what an LVL is but if I knew what a PSL is that knowledge has gone on vacation.  Care to spell it out for me?  You where right to assume that I'm trying to keep this in the existing 3.5" framing.   Gtownwillie

1. 
   JohnT8 | Feb 05, 2007 05:35pm | #6

   if I knew what a PSL is that knowledge has gone on vacation

   Parallel Strand Lumber.  Like plywood, except in beam form.

    jt8

   "One of the fondest expressions around is that we can't be the world's policeman. But guess who gets called when suddenly someone needs a cop." -- Colin Powell

1. 
   woodguy99 | Feb 05, 2007 06:03pm | #8

   Actually PSL is more like toothpicks glued together.  LVL's are more like plywood, except all the veneers are oriented in the same direction.

2. 
   BillBrennen | Feb 06, 2007 05:59am | #11

   PSL is, like another poster said, like toothpicks glued into a mass, all going the same direction. Parrallam is the most common brand name. It is very heavy (for wood) hard, and stronger than LVL's. It looks kind of cool, like some exotic species or something.Bill

3. 
   Framer | Feb 06, 2007 06:07am | #12

   Here's a link for you.http://www.trusjoist.com/PDFFiles/1048.pdfJoe Carola

3. 
   Piffin | Feb 05, 2007 12:59pm | #3

   The header would be 8'10" but the clear span it covers is only 8'4".

   I would skip using flitch and use a double LVL. Much easier to work with

    

    

   Welcome to the
   Taunton University of Knowledge FHB Campus at Breaktime.
    where ...
   Excellence is its own reward!

4. 
   RalphWicklund | Feb 05, 2007 06:02pm | #7

   Most structures with an interior bearing wall have an additional footer poured along that wall in addition to the slab on top. Also usually a monolithic pour.

   Do you know if that is the case with your home?

   It's rather important since you are now contemplating taking an evenly distributed floor/footing load and moving to two more or less point loads at the ends of your header. Although it might work out, I wouldn't have that weight supported by just a section of 4" slab.

5. 
   panchovilla | Feb 05, 2007 08:51pm | #9

   As others have essentially indicated, the first step is calc. the loads:

   Second level:
   LL=30 psf (sleeping areas per International Residential Code)
   DL=15 psf (a touch higher than suggested by Kgmz)
   TL=30 + 15 =45 psf.

   Bearing wall above @ 8 sf:
   8 psf x 8’(height) = 64 #/ft

   Attic load: (20 psf)
   TL=20 + 10 = 30 psf

   Combined loads:
   Floor + Attic + Wall =
   (45psf x 14’) + (30psft x 14’) + 64 #/ft =
   630 + 420 +64 = 1114 #/ft = 1.11 k/ft (1k=1000#)

   Beam moment where:
   W= 1114 #/ft
   L=9’
   M= WL^2/8
   M=1.11K/ft x (81 ft^2)/8=11.24 k-ft

   Section Modulus:
   Fb= 1250 psi (Southern pine, No. 1)
   S=M/Fb = 11240 #-ft x 12”/ft /1250 = 107.9 in^3
   Or
   b= beam width; d= beam depth
   S= bd^2/6
   Set b =3.5” (2-2x + ½” plywd spacer)
   Solve for d:
   d^2= 6 x 107.9 /3.5 = 185
   d= 13.6” (required depth)

   Although this does not negate the use of LVL as others have suggested, assuming you are inclined to use conventional lumber, this would work:

   Provide temp support ea side. Create opening 12’ long.
   Cut out ceiling one side to provide access to top of top plate
   Remove bottom plate of exist. top plate (assuming double top plate).
   Construct beam:
   2-2x12 w/ ½” plywd spacer.
   1-2x4 bottom -Glue and screw (2-1/2” deck screws @ 4” oc staggered). Suggest pre-drilling 2x4’s.
   Place adhesive on top edge to bond to existing now single top plate. Likewise screw exist top plate to beam.
   This sets bottom of opening at 81.5” +/- and beam depth at 14.5”
   Use 12’ length centered over 9’ opening. Install 2x4 studs 12” oc ea. Side of 9’ opening. This will spread load out over slab.
   Good luck.

1. 
   semar | Feb 06, 2007 03:05am | #10

   Very good

   but the footing mon, the footing!!! where is all the pointload resting on?? 4" slab?maybe little sand subsoil?

6. 
   IdahoDon | Feb 06, 2007 06:30am | #13

   Is the wall 2x4 or 2x6?  If it's 2x6 simply frame the pocket with  full height studs (turned sideways) and it can be load bearing except for the opening, which would then be quite easy to span.

   Of course if there is plenty of room for deeper LVLs then I'm usually a fan of more wood vs. less.

   Good building

    

   Beer was created so carpenters wouldn't rule the world.

7. 
   MikeMicalizzi | Feb 06, 2007 01:54pm | #14

   I would use two 14 inch LVL's and double my jack studs