Replies

1. 
   Guest_ | Sep 01, 1999 10:05pm | #1

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   John - there is nothing inherently wrong with running floor joists parallel to the ridge. Off the top of my head, I would say there are at least two reasons why the majority of floor joists are perpendicular to the ridge.

   1) At least in my area, probably the majority of houses have a bearing wall parallel to the ridge, usually in the middle of the house. This may be a gross generalization but many ranchers or capes built from the 40's to the 70's in my area are just a rectangle with a gable roof, and a bearing wall running right down the middle. Thus the shortest span is from the front and back walls to the middle.

   2)A good number of houses, particularly the ones described above, rely on the ceiling/floor joists to act as collars and counteract the natural tendency of the rafters to spread the walls.

   Again, probably an oversimplification but I think this is probably what you are seeing in most houses.

2. 
   PRP | Sep 02, 1999 06:02am | #2

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   Rarely is there any correlation w/ floor joist and ridge beams running perpendicular, the exception is noted by Nick, the more common coincidence sees the floor joists typically running the shorter span.

   In the newer homes we have being built that seem to be deeper (or wider) than older homes, we change the floor joists to run any which way to achieve the shorter span. Purely economics is this issue in these homes, or a resultant of hvac ducting, which too is a result of economy.

1. 
   PRP | Sep 02, 1999 06:11am | #3

   *Oh, and I wanted to also remind ya that in many instances with older homes, you don't even have a ridge "beam."More often, like in most small bungalows you have a ridge board that is not carrying ANY load. This "board" (not "beam") is in place just to supply a nailer for the rafters and a solid surface for the roofing at the ridge, it's not a beam, right. The rafters carry all the load to the sidewalls and the floor/ceil'g joists span the width of the roof and keep the walls from kicking-out (thrust). We've seen many older homes w/out any thing at the ridge, just two rafters, one from each side, coming together and fastening at the top - no ridge beam nor board.Just decided to point this out because if you have a true ridge "beam" then the ends of that Beam have to be carried by a post or solid support of some type and looking for this post is one way to determine what down below has to be sized for Roof Load.

3. 
   Guest_ | Sep 08, 1999 07:38am | #4

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   There were a lot of ridge board constructed houses in the area where I lived in Calif. - you could tell which houses by the "sway back" of the roof on the older houses...

4. 
   Philip_Lawrence | Sep 09, 1999 03:01am | #5

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   CaseyR:

   Not familiar w/ "sway back," can you tell me? description?

5. 
   Guest_ | Sep 09, 1999 06:43am | #6

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   Casey,

   The sway back has nothing to do with the ridge board. It is caused by the rafters spreading at the base, from lack of, or insufficiant coller ties. See PRP's post #3 above.

   John

1. 
   Guest_ | Sep 09, 1999 06:47am | #7

   *I mean that the ridge of the roof in the middle sagged a couple of inches below the ends. My house had a beam running along the ridge, but my garage had the ridge board. In its 24 foot width, I would guess that the center point on the ridge sagged a good three to four inches - all of the other houses in the small subdivision had the same "feature"...("Sway back" is a term commonly used to describe some of the old horses in my area - the ones with a "U" shaped back from not doing their back exercises...)

1. 
   Guest_ | Sep 09, 1999 06:55am | #8

   * John,

   Ditto!

   Joseph Fusco View Image

1. 
   Guest_ | Sep 09, 1999 06:59am | #10

   * John,

   Actually the problem is compounded at the center more then at the ends because the corners of the building tend to resist spreading better then the center even with adequate collar ties.

   Joseph Fusco View Image

6. 
   John_Budnik | Sep 09, 1999 06:59am | #9

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   I've noticed that floor joist all seem to run perpendicular to the roof ridge. Is there a reason for this? Is there something wrong with running the joists parallel to the roof ridge beam.