# Help with weak floor



## jpd123 (Mar 13, 2015)

Hi everyone,

I apologize if this question has been answered elsewhere, but I was unable to find an answer to my question, but it may be because I'm not using the correct terminology. 

Right before you enter my kitchen, I have a weak spot under the carpet where you can feel the plywood floor sink in when you step on it. Luckily I have a drop ceiling underneath and can see the floor flex when I have someone go upstairs and stand on the spot. The part that flexes is the joint between two pieces of plywood in between the joists.

How can I reinforce this area so that it feels solid like the rest of my floor? I've attached a picture to help visualize. Thanks in advance!


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## nealtw (Mar 13, 2015)

Welcome to the site. This looks to be engineered floor.
You should be able to find the thickness of the sheeting stamped on the underside of it..
How high are the floor joists, how big are the ribs on top and bottom, how far apart are they and how long are they?


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## jpd123 (Mar 13, 2015)

nealtw said:


> Welcome to the site. This looks to be engineered floor.
> You should be able to find the thickness of the sheeting stamped on the underside of it..
> How high are the floor joists, how big are the ribs on top and bottom, how far apart are they and how long are they?


 
Thank you for the quick reply.  I will have to take some measurements when I get home and get back to you.  I do know that it is 22.25" across between the two top ribs.


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## nealtw (Mar 13, 2015)

It looks like they have used the lightest weight products and stretched them to the limit. You will need to get up there with a straight something like a 2x4 that you can hold across the bottoms of 3 or 4 joists and have someone walk on top so you can see if the joists flex. That would be a different fix than just flexing sheeting.


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## jpd123 (Mar 13, 2015)

nealtw said:


> It looks like they have used the lightest weight products and stretched them to the limit. You will need to get up there with a straight something like a 2x4 that you can hold across the bottoms of 3 or 4 joists and have someone walk on top so you can see if the joists flex. That would be a different fix than just flexing sheeting.


 
Although I didn't hold a straightedge across the bottom of multiple joists, I'm fairly confident it's just the sheeting that's flexing.  I had someone go upstairs and lightly bounce on the weak spot and I didn't see the drop ceiling hangers or anything else that's connected to the joists move at all, just the seam between the two pieces of flooring.  

Assuming it's just the sheet that's flexing, what would be your proposed fix?


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## nealtw (Mar 13, 2015)

If it is just flexing there, I would think the tongue or groove is dammaged. Make a "T" out of two 2x4s  top one about 20 Inches and the bottom one  a tight fit between the joist. Glue the top surface and nail thru the joist to hold it in place. You can then toe nail a few finish nails thru the carpet or some screws with small heads


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## jpd123 (Mar 13, 2015)

nealtw said:


> If it is just flexing there, I would think the tongue or groove is dammaged. Make a "T" out of two 2x4s top one about 20 Inches and the bottom one a tight fit between the joist. Glue the top surface and nail thru the joist to hold it in place. You can then toe nail a few finish nails thru the carpet or some screws with small heads


 
Thanks again for the help.  Do you by chance have a picture showing what you're describing?  Or a set of keywords I can use to do further research?  I am a computer guy  and don't want to somehow damage something by fixing it incorrectly.


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## nealtw (Mar 13, 2015)

This guy is patching a hole but just check out how he does it all you really need is the span the joint so the two sheets move as one.
[ame]https://www.youtube.com/watch?v=LI7VUyzYA6U[/ame]


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## slownsteady (Jun 18, 2015)

Hi shinystar, and welcome to the site. Just about everything that I've seen on this forum is doable for either gender. Most things that require strength can often be handled with leverage and the right tools. if you read through the threads that interest you, you'll start to pick up the language and the tips that allow you to build a knowledge base.


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## nealtw (Jun 18, 2015)

I have seen some women do some impressive work.


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## joecaption (Jun 19, 2015)

That subflooring should have been Tonged and Grooved,  3/4" thick and glued to the top of the engineered joist.
If it's not T & G then the right way would be to go over that whole floor with 1/2 subfloor rated plywood making sure the seams do not line up with the seams below and it's not nailed to the beams.
It needs to be fasthened every 4" on the edges and from 6 to 8" in the field.


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