Probably because this part of the house is in the 100 yr floor plain.
Plywood floor gap filler.
Wallpaper as floor paper.
If the gaps in your wood floor are smaller and more cosmetic a prefabricated wood filler or a wood dust and wood flour cement mix would be good options.
Step 1 sand the surface of the plywood with 80 grit sandpaper.
Wood filler can be used to fill gaps up to an inch wide and an inch deep.
My shop has 3 4 pt plywood for floor.
The next layer of filler to go down before the vinyl flooring is 1 4 inch birch plywood.
For best results use fine edger dust from the floor that is being sanded mix it with lacquer to form a putty and fill the floor as needed.
Birch plywood is extremely smooth with no surface voids visible grain or high sections.
However many woodworkers carve a plug or wedge from a solid piece of wood slightly smaller than the divot they are attempting to repair glue the plug or wedge in place and then use wood filler to fill the remaining void.
This filler is fast drying gives off a lot of strong fumes and is flammable.
It can be used to repair cracks gouges holes and other surface defects on furniture woodwork molding cabinets paneling plywood windows doors and painted surfaces.
Anyhow there are 8 joints about 20 long that i want to fill in.
While it s best to fill any voids prior to attaching pieces of plywood together you can fill voids between plywood sheets with wood filler.
For this stunning diy finish fill and smooth gaps in the plywood subfloor with fast setting drywall compound and a trowel.
Plastic wood 32 oz.
Lacquer based wood floor filler is a mixture of lacquer and very fine wood dust.
Natural latex wood filler dap plastic wood all purpose wood filler dap plastic wood all purpose wood filler is a high quality latex based wood filler that looks and acts like real wood.
For that reason any subfloor filler you use does not have to be particularly elastic.
For whatever reason the contractor left gaps between each piece 1 8 to 1 4 wide.