When a floor joist or joists are too long and extend past the center beam, they can cause a hump in the floor. A wood floor joist will deflect or sag near the center of the joist under the weight of the flooring and furniture.
Here's the most common reasons: Solid wood is a natural material, and as such it is very susceptible to moisture in the air and walls. If you have a damp problem in your house, or there is otherwise too much moisture in the room, the wooden floor can absorb this, and over time it will cause the boards to buckle.
So the problem probably stems from moisture in the basement air during the warm, humid days of summer. Wood fibers in the base layer of the flooring swell as they absorb this moisture and shrink when the air is drier.
Subfloor Delamination
When the glue releases, due to moisture or a fault of the manufacturer, the sheet swells, or “delaminates” and creates a hump in the floor. The only way to fix a subfloor delamination problem is to cut out the affected part of the sheet and replace it.
Paper Shims and Plywood Strips
Minor high spots for hardwood and laminate floor installations are easily fixed with tar paper shims. The most basic method is to take a piece of tar paper, fold it in half and then push that underneath the flooring material being installed over the subfloor.
Re: how best to level subfloor hump
Another way is to add a couple of layers of extra felt paper on either side of the hump to make it more gradual or a combination of both of these. Using a non concrete floor leveller could also work but be sure it dries very well before installing over it.
How do I know if My Subfloor is Rotten? A water-damaged subfloor feels spongy underfoot. It might bounce or squeak when you walk across the room. Sagging boards, damp spots and unpleasant musty smells are also signs of a rotting subfloor.
Your floorboards squeak – loudly.
As you walk across the floor, the nails move in and out of the wooden joists, causing the awful, familiar sound of creaky floorboards. If you notice squeaking throughout the entire room, this could be a sign that the material has warped.
If you're considering purchasing a home with uneven floors, don't wait to investigate the potential issues beneath the home's surface. The slope or slant of the floor may be a minor cosmetic issue, or it could indicate water damage or major problems with the home's structure or foundation.
The kitchen has heavy cabinets and appliances in addition to the kitchen furniture. The concentrated weight in the kitchen pushing down on the floor joists that are too long often leads to a humped floor in the room next to the kitchen. A floor joist should overlap the joist next to it by only three to four inches.
These conditions include oxygen, proper temperature (often between 65 and 90 degrees Fahrenheit), moisture, and “food” (wood, in this case). Lab experiments have recorded that dry rot spores can germinate approximately seven to ten days after the wood has become damp enough.
Subflooring can last a very long time. Under normal conditions, a subfloor can last as long as the house itself. However, should a subfloor be damaged or defective, it may only last 20 to 30 years. Should this be the case, a homeowner might need to peel back the layers of flooring and get to work.
Vinyl is susceptible to temperature changes in its ambient environment which will cause the vinyl flooring to expand and contract with normal hot and cold fluctuations.
Flooring cupping or buckling occurs and a subfloor moisture problem worsens when there is impermeable flooring like vinyl, laminate, or a typical polyurethane finish on wood. When the floor finish is impermeable, moisture can't get through it, so the subfloor just gets wetter and wetter all summer.
Laminate can be installed on an uneven floor; however this can degrade the quality of your new laminate. The finished product may become warped as a result, causing the floor to shift and become damaged when walked on. For this reason, it is best to level the subfloor prior to installing laminate.
For concrete slabs: If there are only a few problem areas in the concrete, you can mechanically flatten them by grinding, bead-blasting, abrading, or using a patching compound. If the entire slab is uneven, you may have to use a self-leveling concrete compound to smooth it out.
To check for small high or low spots that may not even be visible, place a long level or straight pipe on the subfloor. Move it around to different areas and mark any high or low spots you find with a pencil or marker. Most floors will have at least some slight variations.
Underlayment
The underlayment material is installed below the floor covering and placed on top of a subfloor. Under the visible covering, there is a layer made of soft or foam-like materials with a thickness of between 1/4 – 1/2-inch.
Partial Subfloor Replacement
In many cases, the damaged subflooring can simply be cut out so that new subflooring can be patched in. Ideally, the cuts can be made over the centers of the joists so the joists can provide backing for the plywood patch and its screws.