[D-O'Brien]

"Will my floor cave in?" Sounds crazy, but if you knew you'd be calling in a professional right now on me. I plan on hiring an engineer for my upstairs projects but this hopefully won't be too diy difficult. I am concerned about allot of weight along one outside wall in my kitchen. The house is a 1960's 4 bedroom central hall colonial. It has two steel beams going from the front to the back. With the wood floor joists parallel to the front walls of the house. I have two sections of 12 foot wood joist going towards the center- with a 6.5 foot wood joist span going to the steal beams in the center for stairs and central hallway. Hopefully I named everything right- Now in my kitchen I plan to put my sink, dishwasher and fridge along the same outside wall. I included a quick diagram- it looks like there will be only one joist under them with one in the back and front a few inches away. I have 1/2 plywood and 1/4 luan floor. My floor joist are 2x8's (1.5x7.5). I know(thanks to this forum) about dispersion. But will I need more support- too many pipes in the way to simply sister the joists?
Thanks in Advance

 

[Underdog]

Do you have any reason (besides just being worried) to think that your floor would collapse? I'm not being facetious, I'm just looking for more information (i.e., are there big notches in the joists, is the floor excessively bouncy, did another part of your house collapse, etc.)

Based on what you told me, I wouldn't be worried about my floor collapsing. You have to remember that the load from your appliances aren't being applied to just one joist--they are being applied to subfloor, which in turn distributes the load to multiple joists.

Also, if we assume that your joists are Douglas Fir #2, your 2x8 is sized correctly to span 12'7" @ 16" spacing with 40 psf live load, 10 psf dead load, and a deflection of L/delta=360.

 

[joecaption]

That subfloor is way to thin, sure hope there's no plans for any tile.

 

[GBrackins]

I myself would not be concerned about your floor collapsing. What you may end up with is more "bounce" or vibration in your floor than you currently have. That depends on if you are adding more weight to your floor than currently supported. Bounce or vibration is a subjective item and is not addressed in the building codes. the codes are only concerned about whether the framing assembly will fail when code imposed loads are applied. I see this when people use a lot of stone/tile/granite in their kitchen, especially when the length of floor joists are near their maximum spans for the size and species of wood used.

should this happen you have a few options available such as installing a beam under the floor joists at mid span of the joists. this will reduce the bounce. addition option is to install additional floor joists. based upon your comments a new beam would probably worked the best if needed.

have your engineer perform an evaluation as they should be able to determine the species of wood.

 

[Underdog]

That subfloor is way to thin, sure hope there's no plans for any tile.

Good catch with the subfloor. The subfloor is thinner than current IBC requirements and may lead to more deflection than what a tile floor can handle. I still seriously doubt that the floor will "collapse," but it may ruin the OP's new tile.

 

[TrailerParadise]

You sound like me when i first got my house. Fiance laughed at me because i was worried about having my stove, sink, couch, washer, dryer, and dresser all on one wall of the mobile home. The other wall would only have my closet, three cabinets and the fridge. He took me to the side of the trailer and showed me the support system, and how tight the tie downs were, and i saw that there was no possible way the trailer could fall or collapse or move at all. Im going to say the same to you. Unless there is a plausible reason for your fear, like compromised joists or broken foundation or something similar, there is no way your floor is going to collapse. That steel beam is a lot heavier than anything youre gonna put in that fridge, friend.

 

[tony.g]

Timber floors rarely "cave in", unless the timber is decayed, badly split, excessively notched or has insufficient bearing length. They just deflect excessively. Codes usually limit deflection in domestic floors to around span/360, which is usually enough to stop excessive bounce.
As pointed out, the subfloor is a bit thin. Check if there is adequate bridging, which helps to distribute the load between joists.
If it does bounce too much, try adding a beam underneath at mid-span, if this is possible.

 

[D-O'Brien]

A big thanks to all those who chimed in!:thumbup:

Moved the fridge over not problem. I did however measure the bottom of the joists in several places to the basement concrete floor to check over time if there is any sagging.

Thanks Again

 

[woodworkbykirk]

if your going to measure if their sagging you'll have to do it several times over a week or so.. because it will show up.. you'd be better off stringing a dry line from one end of the floor to the other from below using feeler blocks.. this will tell you if joists are sagging better than simply measuring,, reason being theres a very slim chance your basement floor is dead level