If you have really, really uneven floorboards, you should start by sanding (with the large drum sander) diagonally to the floorboards to even the floor out and then move on to sanding in the direction of the boards. As a general rule, you always sand with the grain of the wood!
Coarse sanding (cont'd)
Start to the left of the room and sand in the direction of the wood. If the floor is very uneven, we recommend to sand diagonally. Walk slowly forward and lift the drum gently as you reach the wall. Lower the drum again and return in the same path that you sanded.
The Drum Floor Sander is a heavy duty item that's great for any tough sanding job. It's the best choice for uneven or damaged floorboards that you want to smooth or a heavy varnish finish you want to remove. For a professional finish, it's recommended to go over the boards again with an Orbital Sander, explained below.
One of the advantages of sanding wooden floors is that they become much easier to maintain and clean. Once your floors have been sanded and refinished, they are less likely to harbour dirt, grime, and allergens, making them easier to keep clean.
The Golden Rule of Sanding
The golden rule for choosing your sequence is to never skip more than 1 grit. For example, if you start with P80, and need to finish at P240, rather than using every grit from P80 – P220, you can do P80 – P120 – P180 – P240. This sequence cuts out P100, P150 and P220.
Uneven or sloping floors are very common in older homes, and while it's often a sign of structural damage, it doesn't have to be a dealbreaker.
If you want to raise the height of a floor, the cheapest and easiest way is to add a thick underlayment designed for the job. There are other options too like adding a framed wooden subfloor or floor leveling compound before installing new flooring.
Average Cost to Level the Floor in a House
On average, you are looking at about $3 – $5 per square foot. So, for a 100 square foot slab, it would generally cost between $300 and $500.
When leveling floors made of wood, you'll need to sand down any high spots. If you expect to create a lot of sawdust, wear a dust mask and use painter's tape to tape plastic sheeting over doors and air vents so the dust won't spread.
Despite the fact that sanding the floor by hand sounds like a lot of hard work and too much time and energy to invest, the truth is that hand sanding a wooden floor is sometimes actually more efficient and quicker process.
One of the best ways to fix the issue of uneven floor is to use floor patch product. It can be used in concrete subfloor or wooden subfloor. It is best for leveling floors that has dips, slanting issues, cracks and chipping problems.
You can spot-sand down to bare wood with 100-grit sandpaper, and spot-recoat with polyurethane matched to the gloss of the existing finish (use an oil-based polyurethane to patch an existing oil-based finish, and a water-based poly to patch an existing water-based finish).
Flooring professionals can sand away as much as 1/16 inches of wood with the coarsest paper. However, some engineered floors cannot sustain more than one heavy-duty sanding, as they may have a surface veneer of only twice that thickness. Refinishing these floors more than once poses a risk of wear-through.
Floor leveling is a relatively easy DIY project, although some subfloors with rot, insect damage, or structural issues may require professional attention.
No subfloor is perfectly level, but any signs of unevenness and high or low spots must be remedied. Please follow these requirements: Subfloor unevenness cannot be greater than 3/16 of an inch over a 10-foot span or 1/8 inch over a 6-foot span. Subfloors must not slope more than ½ inch per 6 feet (25 mm per 1.8 m)
Uneven floors in a house are usually a sign of a foundation problem, but not always. For example, if you live in a house with a crawl space foundation, uneven floors might be a sign the support posts in your crawl space have settled, or the screw jacks have deteriorated and rusted out.
If the slope is caused by foundation settling, it could be an indication that the foundation is no longer able to support the weight of the home. This could result in further damage to the home, including cracking walls or windows and even collapse in extreme cases.
The best flooring for uneven floors due to its attractiveness and durability is epoxy, which can also be designed to mimic a wide variety of appearances. Not only will epoxy finish out the floor, but it'll also even it out.
You can leave the baseboards in place unless you're planning to replace them. You need a pristinely clean floor before sanding, so sweep it and then dust mop it to get up all debris and dust. Make any necessary repairs to gouges and cracks in the floor before sanding.
The better ventilation you have in the room, the faster the finish will get dry. Clean – Pre-cleaning your floor is as important as cleaning after each stage of the sanding process. You do not want dust and dirt particles scratching the bare wood or staying trapped in the finish forever, right?
An average-sized room (bedroom, lounge or hallway for instance) should take a day to sand and a further day to hand finish and varnish/wax or oil. However unforeseen circumstances such as repairs to the main body of the floor or the replacement of some boards may mean the job will take longer.