Fixing a Springy Floor

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  #1  
Old 12-21-16, 11:07 AM
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Fixing a Springy Floor

My kitchen floor is springy ... when I walk across the room anything that is on the table shakes and moves. I want a tile floor with radiant heat. As it is now the tiles would crack from being flexed when walked on.

I had intended to sister the joists to stiffen up the floor. I can't do that because I can't get a 2x8 up into position because of a lot of electrical and plumbing and the main beam that runs across the room.

Can I block this up with 2x8s cut to fit between the joists? I know it is usual to have some of this type of blocking, although there is none at all here in this nearly 100 year old house.

If I did this blocking would it be stiff enough for a tile floor with radiant heat beneath it?
 
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Old 12-21-16, 11:14 AM
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So the joists are 2x8? What's the spacing, species and unsupported span? What's the composition of the current flooring? Natural stone tiles or manufactured (ceramic or porcelain)?
 
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Old 12-21-16, 11:46 AM
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What is below the kitchen floor? can you add a beam to help support the joists?
 
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Old 12-21-16, 12:28 PM
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I've added lots of micro lams across the joists with adjustable posts to stiffen up floors.

It's easy and cheap and 100% effective.

Only possible issue is head room if you have a low basement!
 
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Old 12-21-16, 02:19 PM
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Blocking will do nothing. I agree with mark and marq that a beam to cut your span in half is your best option, if you can do it.
 
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Old 12-21-16, 05:59 PM
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Great ideas here - I think adding beams is possible ...

but what about a footing for them.

I will assume I need to break through the concrete floor and then dig out enough for a footing. Am I right on that? It would be a lot easier to just rest it on the cement floor ... that sounds like a recipe for disaster later on though.

What would I need to do?
 
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Old 12-21-16, 07:36 PM
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A load bearing post (or column) needs a footing... but technically, your beam is not going to be load bearing in the strictest sense. It is simply going to stiffen the deflection on a number of joists that may or may not be overspanned, undersized or overspaced. The amount of load is going to be minimal.

However adjustable posts are not meant as permanent fixtures, (even though you commonly see them installed in that manner) and the correct way to install them is so that they cannot be knocked out or amount dusted in the future... so I that sense, the post bases ""could" properly have a footing that is poured below the surface of the floor (2'2' is a good size), so that once the post is set and adjusted, the rest of the concrete floor could be filled in around it, making the post permanent and immovable.

Permanent columns are bigger, beefier, and are rated... while their smaller cousins are not. You often see these smaller ones used where price was the driving factor and codes were not taken into consideration. If you have questions about what your local code is, you can call your local building department and ask... or at least ask what code must be followed for permitted work.
 
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Old 12-22-16, 02:32 AM
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The idiots that framed up my living rm extension run the joists the longer direction which gave the floor a slight bounce. Because of the difficulties of excavating in a crawlspace I cheated on the footer [4-5"], laid block and a beam to support the span mid way. That was close to 25 yrs ago and the floor is just as solid/level as it was when I first shored it up.

While cutting the slab and installing the proper footer is best, I think it would be ok just going over the slab ...... but then I am just a painter, not a carpenter/builder
 
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Old 12-22-16, 02:05 PM
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but what about a footing for them.

Exactly as mentioned, the additional posts are not load bearing, they are there just to add additional stiffness to the floors and if you think about it would only transfer the amount of weight that would cause the floor to deflect, like if a person walked on it.

Setting them on the slab is perfectly safe. In my basement I put up 3 additional micro lams and then build them into the wall when I finished the basement so they are out of sight.
 
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Old 12-22-16, 02:22 PM
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Instead of using adjustable columns just frame underneath each end like an interior wall header would be.

Dont know how we all got fixated on adjustable columns... at least I was.
 
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Old 12-25-16, 01:34 AM
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Other than the ease of being able to crank them into position there is no reason you could not frame them up, guess that just the way Ive always done it!
 
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Old 12-25-16, 04:21 AM
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However you achieve the stiffness it is imperative that this take place before you attempt to tile. Any bounce will be detrimental to the tile floor installation. How about adding some span numbers as originally requested. We know 2x8 but not the span.
 
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