2x4 redwood floor joist on 30-36"


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Old 06-11-15, 11:45 PM
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2x4 redwood floor joist on 30-36"

I have an 1894 Victorian in Los Angeles. A lot of the house is redwood. The crawl space has about 2' clearance, and my house is on a concrete perimeter foundation. The foundation is not original to the house, although the foundation is old, lots of rock in the concrete.

Anyway, the house has stood for 120 years, so I feel it is solid.

However, I feel extra supports would not hurt.

- The house footprint is approximately 30x35'
- My floor joists are dimensional 2x4s
- The joists are a continuous span (35' east to west)
- The joists are roughly spaced every 30 to 36"
- There are 2x4s laid horizontally atop piers with posts (most of the posts are 2x4s vertically); these support the floor joists. There are approximately 5 such arrangements of this, they are piecemeal - not a continuous 30')

I was thinking of slinging 4x8s (maybe 4x6?) under the house, atop 4x4 posts on pre-cast foundation blocks. These would go in between some of the existing pier and post arrangements, particularly towards the foundation framing.

I was thinking of strapping all of this stuff in too, none of the foundation has those Simpson ties, and it is not bolted (although bolting and shear walls are also on the agenda).

Any chance my attempt to do more good could cause more harm?

Also, interestingly, the attic joists are 2x4s and they are perfectly on 16". I guess they figured they needed that for the weight of the lath and plaster? However, they do span 17' without support. Attic is huge too, with redwood porch boards, I think it may have been lived in when built last century.
 
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Old 06-12-15, 02:21 AM
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Are the foundation blocks that you plan to use, up to code? I thought that footings were required across the country. Your best bet is to have a local architect or engineer look at it. You may not need to do any work at all.
 
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Old 06-12-15, 03:53 AM
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Post some pictures.
Amazing they use 2 X 4's, that's about 75% or more under sized.
Any post or piers need to be sitting on real footings, post blocks would be useless.
 
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Old 06-12-15, 09:36 AM
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This is kind of the gist of it. The floor joists run left to right across the image, 35'. They are about 30-36" apart.

Atop that I have 1x4 T&G subfloor, and atop that my hardwood floor is 2x4" T&G.

The amazing part to me is that the 2x4 is a continuous span for 35'. Can you even get a lumber that length today?

None of these foundation blocks have concrete under them, they sit directly on dirt. There's 2 posts that have boulders or bricks beneath them - real shoemaker job. I was thinking - leave whats there as is - and add my own stuff in between - like add another row of piers and a 4x6 down the middle of this camera shot.

The house is small, only 960 square feet, single story, so I think that has helped it over the 120 years.

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Old 06-12-15, 09:55 AM
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They don't look like 2x4s, to me. They look like 2x6s or even 2x8s. Put a level on them to see if they are sagging. As soon as you change the current structure or even add to it, I don't think you can use blocks for the support. I'm 99% sure that you would have to use some type of footing, for the new supports. You could be opening a can of worms.
 
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Old 06-12-15, 10:03 AM
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They are 2x4, exactly. I've taken a tape measure to them.

What is the typical depth requirement for a footing, a few inches? I guess I'd have to look at my local codes for the City of Los Angeles.

Back to my question though, would adding additional pier and posts cause more harm than good, or consult with an engineer?

Thanks!
 
 

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