Soft Spot Question(s)

[JanetSanCarlos]

Great! Thanks so much!

I have friends with lots of tools...I'll see if someone has one of those saws. If not, I'll be up in the states in a week or so.

[silverloaf]

Great! Thanks so much!

I have friends with lots of tools...I'll see if someone has one of those saws. If not, I'll be up in the states in a week or so.

Janet-
Here’s what a vibrating/oscillating saw will do. I was able to cut through the 1st layer of wood ( including under the wall) and foam while preserving the bottom layer of plywood.

[JanetSanCarlos]

That is so cool! I bought a Dremel Multi-Max oscillating tool last week-end and a piece of plywood. Hoping to cut the floor out tomorrow. I will post pictures if I am successful.

Other big news is that I plugged in to power this week and lights and a/c actually work!

[silverloaf]

Wear a good pair of ear protectors when using the saw!

[JanetSanCarlos]

So, here is what I found today. Once I got the first layer of plywood out, I could see that the foam layer was sagging. The foam looks good and when I poked through it, the plywood underneath felt firm.

So, is the next step to cut the foam out and see what is underneath?

Thanks!

[silverloaf]

Janet,

The foam board should be flush with the bottom of the plywood you removed. Your picture shows a gap which is probably the reason for the spongy floor.

In our trailer, the foam board is 1-1/2" thick. I suspect someone did a repair (possibly from underneath) and used a thinner sheet of foam. If you are confident the bottom layer of plywood is sound, I would find a piece of foam board of the correct thickness to fill the gap. Since the gap appears to extend beyond the opening you created, slip pieces of foam board into the gaps to fill the void.

Before install the new plywood patch, install a wood spline approx 1-1/2" wide along the edge of the existing plywood. Half the spline should be under the edge of the old plwood and 1/2 outside. This provides a nailer for the patch. Screw the new and old plywood to the spline. For added stiffness, apply a bead of construction adhesive between the spline and both pieces of plywood.

The other option is to remove the top layer of plywood and rerplace all the thin foam with the correct thickness.

[KYAvion]

As Silverloaf said, the mystery behind the soft spot
appears solved.

In addition to sheet foam, you can also use spray foam to build the area up. The foam will expand a lot, but any excess above floor level can be removed with an undercut saw (just a few bucks at HD or Lowes).

[JanetSanCarlos]

So, how do I get the foam board out? I cut through a section and thought it would lift up, but it doesn't. Is it glued to something? What is the secret? I also took out the dinette bench because it looks like the problem continues underneath it. I want to see what is under the foam before I cut up any more of the floor. Help!

Thanks

[KYAvion]

Now you don't HAVE to remove the foam board. If you press on it, does it recess any further? If not, then you could fill the void on top with spray foam as mentioned in my prior post. The purpose here is to fill the void and provide support for your subfloor.

If you are set on removing that section of foam board, just cut to a depth until you hit the plywood underneath, and then dig it out. Odds are it's just stuck due to friction along the perimeter.

[silverloaf]

Janet-

You can use your new oscillating saw as a power scraper as well. I purchased a 2” wide blade for mine.

Most oscillating saws will have a feature to rotate the blade approx 270 degrees; great for tight spots.

Think of it as giving the plywood a real close shave!