I replaced my floor now it’s spongy.

[brian.christopher]

I replaced the back half of my floor, rebuilt it like it was originally. I even used the old foam board.
One thing I’ve noticed is the floor is really spongy Modern day plywood is garbage compared to the vintage stuff.
Comparing the half inch boards they used on booth seats, to make it into a bed are like iron. They don’t flex at all. In hind sight I would’ve rebuilt it with 3/4”. Now I’m hoping the laminate floor I put on top adds some rigidity. Anyone seen this in their build?

[KYAvion]

I bet it will be ok and that it will be fine once the laminate is on top. Do you know what you’re going to use?

[silverloaf]

I rebuilt the rear floor in our trailer. I used 1/2" G1S on top,1/4" G1S on the bottom and new 1-1/2" foam board in between. Everything was bonded together with construction adhesive.

There is some compliance in the floor but I wouldn't call it spongy. There is a very wide span between the steel crossmembers due to the large footprint of the black water tank. I've accepted the small amount of "bounce"

If you are trying to compare your trailer floor to that in your home, you will be sorely disappointed. Unless you plan on living in the trailer year-round, is it something worth worrying about?

[Tarnished]

There a many different grades and manufacturers of PW. Most that I've seen in big box stores is low to mid grade.
There are 2 bldg supply stores near me, about 5 miles apart. The grade of lumber sold at one is superior to the other. The price difference, higher for the better grade, is to me negligible because of it's lower waste factor.

[ShieldArc]

I would only use marine plywood.