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mudslider 04-05-2013 04:47 PM

Hanging a beam between posts
First time poster looking for some advice. I am considering adding a floor into my "crawl space" I call it that because technically thats what is it, but the ceiling of the floor above is around 19' up, leaving ample room for full height room.

My question is regarding how to provide support for the floor. Existing ceiling above is supported by 4x6 beams over the top of 4x4 posts. These are set about 6' or so apart with an 8' span for the joists. For the new floor I would like to hang 4x6 beams between these existing posts, but not sure how to do that. I am an engineer so did the load calcs and I could use heavy duty joist hangers for the beams, but the nailing pattern on each side the post is the same, so the nails would hit each other.

Any ideas? Splicing the beams into the posts is probably the best way to do it, but given how high the current ceiling is it would take a lot of work to support that celing while I did that

jagans 04-05-2013 05:02 PM

I need a picture or a drawing, but I really don't get nails hitting each other. Just alter the pattern a little bit and they wont, unless I really don't understand what you are doing, which is probably the case. :huh:

GBrackins 04-05-2013 05:14 PM

what jagans said, some photos would certainly aid, I got lost in regards to a 19' tall crawl space .....

joecaption 04-05-2013 05:17 PM

A crawl space is not 19' tall.
When you say crawl space I'm thinking the area under a house.

GBrackins 04-05-2013 06:50 PM

did I read the right Joe?

SPS-1 04-05-2013 08:37 PM

Are you creating a ceiling or a floor, or both?

mudslider 04-06-2013 01:29 AM

3 Attachment(s)
Thanks for the response I have a few pictures here that might help

First the "crawl space" question. I wasn't sure what else to call it, its basically around 700sq foot of space inside the shell of the house, that is underneath the main floor level. The first picture shows it. You can see the height, the floor joists of the level above and how they are supported, ie long 4 x 4 posts and a 4 x 6 header. there are 4 of these beams total with 4 posts each, so 16 posts

You can see in the photo that there is already a room at the lower level and the plan is to add a new floor (and walls) into the space at this level.

To support the new floor I planned on hanging a new header between the existing posts. The second photo shows one sitting in place (not attached) but you get the idea. There would be another beam at the same level on the other side of the post and so on. This is the same area as the first photo, so you can see where the beam was added

So the problem is with the hanger I planned to use. The post is the same width as the hanger (4") so I need to use a concealed flange. The third photo shows the hangers. To get the load bearing I need I have to fill all the holes with 3.5" 16d nails, these will go most of the way through the post.

Bear in mind I will have a hanger on each side of the post, and as I want the hangers at exactly the same height then the nails will interfere with each other

I hope that clarifies the question. Any idea or further questions are appreciated

mudslider 04-06-2013 01:31 AM

Sorry missed one of the questions. This is in the Santa Cruz mountains, northern California. the original construction of the house was circa 1970

GBrackins 04-06-2013 07:22 AM

that is a 19' long 4x4 post? what does it support currently?

SPS-1 04-06-2013 07:27 AM

I am not a framer, but all the beams in my house are either sitting on steel posts, or on load bearing stud walls. None are hanging off joist hangers.

jagans 04-06-2013 10:46 AM

I still do not completely understand what you are trying to do, but if you are trying to extend the floor level out from the wall with the door, why dont you simply build a load bearing wall parallel to the wall with the door, and run floor joists over it to a load bearing end wall? Optionally, build a laminated girder upon which your joists would set by building a pier or two on the existing concrete floor? 16 x 16 inch Flue block filled with concrete will do nicely. You could use the space under for storage, or insulate it and use it as a plenum supply space.

wkearney99 04-06-2013 11:13 AM

Is the house built on a hill or something? Or is that space part of a garage or some other open space? Otherwise why would there be that tall an unfinished space present?

You'd better talk with a civil engineer before doing this. And get it properly permitted. California's building requirements are pretty specific and given the earthquakes, well worth following PROPERLY.

It's very likely the structure that's there already isn't engineered to handle what you're thinking of adding. Not that it can't be done, but that it'd have to be engineered to do so. Otherwise you risk putting loads onto structure that are already handling a LOT of other weight. The old "straw that breaks the camel's back" analogy comes to mind here...

mudslider 04-06-2013 12:42 PM

Again thanks fro the response

this part of the house is basically fully enclosed, not part of the garage. It looks to me like they simply ran out of money so stopped building. You can't really see it but the exterior wall of this even has headers installed for windows, just everything covered up with sheathing. The floor is uneven dirt. Based on what I can see this area was always designed to have a floor, they just never built it. It s a bedroom overhead.

In terms of the overall strength of the structure it cement block foundation (not sure how deep), we are around 15 miles from the center of the Loma Preitta earthquake many years back and the house came through unscathed. We had a geologist check the stability of the hill when we bought the house and its pretty solid sandstone.

I hadn't thought about building a load bearing wall. It would be kind of a pain as the the floor is dirt so I would need to dig out a good footing for it. The other option would be to put more posts in and put in beams that aren't tied to the current posts at all. The length from the door to the load bearing wall is around 18 foot, so I glue.nail some 2x8 or 2x10s together to span that

hand drive 04-06-2013 01:02 PM

your new room will have all of those posts sticking up through it. 19' is a long way for a 4x4, maybe they were added in later to keep the floor above from bouncing...

mudslider 04-06-2013 01:13 PM

No, the beams they support aren't continuous, ie they join over the top of the posts, plus they have them braced with 2x4s, presumably to help offset how long they are. The plan is to enclose the beams inside a wall on the new floor. Depending on how I do the floor I might make that new wall load bearing and not rely on those beams, which always seemed iffy to me!

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