Got plywood or OSB subfloor that is warped or bumpy and can’t be sanded down? I can sand the high spots down, but just have to rent a sander since I don't have one. In either case, the leveling process will be similar to what herein follows. For dips in the floor, you’ll want to use a self-leveling compound, and make sure to let it dry sufficiently before proceeding with the flooring installation. If they’re not level, sand down high spots and fill low spots with an underlayment patch. Use a straight-edge like a six foot level to find the high spots and mark them with a pencil. Back to addressing the high spot. There is still a slight variance, but it's minimal compared with the original floor. Grinding Down High Spots Small variations in height probably won't be felt under hardwood, but large ones will, and they can cause laminate sheets to separate. Many contractors use a 6-foot level or accurate straightedge to help them locate high and low spots in a subfloor. Plywood can usually span slight imperfections and waves in the concrete, but check to see each 4x8 sheet is level and the same height across the floor. The joist underneath the hump may appear thicker than the joist on either side of it because of moisture. level 1. This type of joist can receive wedges on top to bring the level up. Thoroughly vacuum the existing floor, and use a long floor leveler and tape measure to ensure the subfloor is level within 3/16 inch for every 10 feet. So some shady contractors replaced a beam that was under the house by coming through the top. I have seen amazingly effective (and some extremely expensive) tools for leveling and scarifying concrete that can be either purchased or rented. In order to properly install hardwood floors, the plywood subflooring must be even, or level. Add a layer of plywood. Can You Add Chlorine to a Pond as an Easy Way to Keep It Clear? Tip: Do not try to sand down old vinyl flooring, as it may contain asbestos. In our situation we laid the subfloor parallel to the joists which creates a weaker subfloor. The plywood becomes the new subfloor with the hardwood floor laying on top. It really doesn’t matter how ugly a job this is–you’re going to cover it up anyway. Spread it on, trowel it smooth. Plane refers to the flatness of the entire surface, and any high and low spots must be remedied before installing rigid flooring. His crew puts water on the floor to find the high spots. As it dries, sand down any high spots to make them flush with the rest of the subfloor. If you have a drum sander on hand, this can level out any bumps in the subfloor, but you need to have a steady hand to control this. Then vacuum the floor with a wet-dry vac or sweep it with a broom. From here, you should be able to mark out any discrepancies on the subfloor itself; giving a good indication of what alterations will be necessary. Once the compound is dry, make another sweep with your electric sander to shave down slight differences in the height of the subfloor and even out rough patches. I like to talk a lot about the benefits of layering and how layering can save your butt (in other words, if you mess up this layer, there will be another, covering layer atop to cover up your mess). Fix the Problem Spots. Use leveling compound in areas where the dip in the old flooring or subflooring is 1/4 inch or more. Dealing with bumps and depressions in your subfloor is your last chance to smooth things out (both figuratively and literally) before laying down the finish floor. Using an angle grinder to level a sub floor - Duration: 4:05. Fill any low spots with a cementitious leveling compound following the manufacturer's directions and allow it to dry before proceeding. Use a circular saw to remove the subfloor to expose the high joist. Then you have access to the bottom of the floorboards. Leveling high spots in concrete or wood subfloor Before you install file flooring, follow the directions above for fixing high spots and low spots in a wood or concrete subfloor. Wood subfloors: Sand down any high spots until they are completely level. Floor leveling compound is made for just such a thing. The gouges can be filled in…or if small enough, the finish floor may be able to bridge them, as long as you’re installing solid wood or engineered wood flooring. Is there a quick, low-cost way to do this? Use a wet-vacuum to clear up dust and debris and use a level to be sure all the low spots are gone. Make a final check with the level to be sure all the high and low spots are gone. Any depression that is more than 3 or 4 inches wide is, in my opinion, too wide. When you have depression that are three or four feet in diameter or more, it’s the joists that are the problem. Fixing a low joist is pretty straight forward: jack it up and sister join another joist to the original one. If it's a glue-down project over a wooden subfloor, I have scarified the substrate with 16-grit paper on a buffer. All high spots that don't meet a 1/4-inch-in-10-foot tolerance have to be removed. I know one option is to belt sand but I'm not sure if that'll work on this one. Unlike a concrete subfloor, you can usually knock down high spots on a wood subfloor by sanding, and you can always fill depressions with patching compound. Concrete subfloors: As with wood subfloors, grind down high spots and fill low spots with leveling compound. If your floor is fairly level, but not very flat, a layer of plywood can even it out … Sand from one end of the room to the other, pushing the sander along in a straight line and reversing your direction each time you reach the opposite wall. What we found is that one technique is to pull up the subfloor and shave down the top of the joist. A bunch of screws and a quick sanding your subfloor should be good. If your subfloor is of the solid wood variety (i.e., not plywood or OSB), you can single out a floorboard or two that are creating the bump, and which cannot be easily sanded or planed down, then you can pop them out and replace them. A high joist is a different conundrum. Use a trowel to level the compound as much as possible while it is still wet and pliable. I typically use 36-grit on an edger to sand the seams and high spots. Only use small amounts at a time to prevent quick drying before it is level. level 1. The compound will break out or crumble, with the vibrations from nailing a floor down. You want the joist at the same height as the other ones. Know Name 5,119 views. Dry Building Modern - a Modern DIY Renovation Blog, Kitchen pantry demo, foyer door expansion, & raising a few joists, Master Bedroom: Jacking up some floor joists, Building Modern - a Modern DIY Renovation Blog. You need to get access to the bad joist(s) and replace or repair. 3. Have a crawlspace or basement? If you place one end of the level or straightedge on the benchmark high spot and slowly rotate the level around the floor, you'll discover both low and high spots. Actually, if you go overboard and gouge out some of the subfloor, it’s not the end of the world. Sand the entire floor. High Spots and Bumps in Subfloor If you need to bring down your subfloor, you can try either a hand plane or a power sander. Camo Deck Fastening System: Easy Way to Install Cheap Decking. Hardwood floor over sub floor with high spots I'm installing hardwood floors on top of 3/4" CDX plywood sub floor that has several high spots. (Learn more about sanding abrasive quality, materials and selection: As long as it’s level, you can forgo the sanding. Loading... Unsubscribe from CORVAIRWILD? For sanding high spots in the wood, you can start with 40 or 60 grit. Directions on how to flatten a plywood or OSB subfloor before installing wood flooring. Wood Floor Business Magazine ... Wood Floor Sanding Wood Floor Sanding. Lowell Brakey, a Kansas concrete contractor, has developed a slick way of doing this. While it’s probably fruitless to try to straighten out these warped joists, you can most certainly sister them and prevent them from warping any more. Nail or screw every 6″ along joists to avoid squeaking. ... Easy job. Sanding the subfloor can remove minor swells or high spots in the wood, but any low spots in the floor must be filled in order to level the plywood. Belt Sanding The High Spots... CORVAIRWILD. It is good practice to sand all of the abutting seams on every job throughout the entire layout. The conventional way of removing high spots in concrete is by means of grinding/concrete planes. If this were a high traffic area bearing load, you would want to do it correctly). Sometimes a joist will be bowed simply as a function of aging. Guides often tell you to sand it smooth–but what’s the point? Most wood subfloors are constructed from plywood or particle board. Step 3 Shave down the higher joist. Wood subfloors must be dry and well secured. Hey guys, About to install some laminate flooring in my living room. Sand the floor diagonally across the grain. It’s not the depth of the depression that matters; it’s the width. In your low spots depending how low, I would use roofing felt to shim them up. When the high spots are excessive, 12 mm plus, a fast effective approach can be adopted. Long Straightedge. You'll need to know how to level a floor: Just sand any high spots and fill the low spots with leveling compound. With wood subfloors, your first plan of attack should always be to sand the high seams. If your low spots are a 1/4" or better you might consider redecking the subfloor and fill the low spots before you deck. Some flooring, such as solid wood or engineered wood, can bridge small depressions. ... we checked the difference between the high and low spots just as we had in Step 1. So, you really have to make this one count, because you’re at the next-to-last layer. Casey_jones291422. These bumps or high spots are right on top of the floor joists - for example if I lay a level down on the floor, centered on a floor joist, the level will rock on both sides (like a see saw). However, we are laying 3/8″ plywood on top of this OSB, and 3/4″ hardwoods on top of that for a very high strength floor. Choose for Me: Laminate or Luxury Vinyl Flooring? 1 … And yes the flatter the better for laminate. Be sure that the sub-floor is fastened well first. As you can see by the attached photo I have a high spot at a floor joist when the wood subfloor panels come together. High Spots: Use a sander to deal with high spots. The high spots should be cut down with an electric planer, setting nails first with a quarter inch punch and hammer so the blades don't get chipped or an edger with coarse sand paper. Sand the floor with a drum sander and 20- or 36-grit sandpaper, depending on the condition of the boards and their hardness. Typically, the floor must be level and uniform within 3/16 inch every 10 feet. Step 2 Look at the joist. If you have alot of high spots I would suggest grinding them. High spots are mostly where the plywood boards meet. If there are many high spots, or if they are extremely bad, consider renting an orbital sander. Hardwood floors add style and a distinct look to a room. The moisture content of a wood subfloor must not exceed 12%, while concrete moisture content must not exceed 3 lbs. You’ll need to drill through the wood and into the concrete to fasten it down. If the subfloor is unlevel, you can fix low spots with a self-leveling product and sand or grind down high spots. Instead, remove the pre-existing vinyl flooring entirely if it is not level. You likely need to choose a coarser grit for smoothing the spots with added materials: 16, 24 or 40. Then either screw the thing out or pry it out and replace it. A grinder can be used to sand down bumps in dried compound. If you have a drum sander on hand, this can level out any bumps in the subfloor, but you need to have a steady hand to control this. However, this type of equipment can be expensive to rent and will require many passes to remove high spots. If you need to bring down your subfloor, you can try either a hand plane or a power sander. Check your wood flooring manufacturer’s recommendations and sand any high spots with a concrete grinder. Depending on the situation, you can either sand down areas of the subfloor that are too high, or install shims beneath the subfloor so that the entire floor is brought up to the same level. Always use as fine a grit as possible but as coarse a grit as needed, for any sanding job. As fine a grit as possible while it is still a slight variance, but just have be... Drying before it is still wet and pliable or bumpy and can ’ t matter how a. Above for fixing high spots, or if they ’ re at the same height as the other ones pretty. Type of equipment can be adopted in concrete is by means of grinding/concrete planes, remove pre-existing. You would want to do this are extremely bad, consider renting orbital. Subfloor should be good slick way of doing this flooring, such as solid how to sand high spots on subfloor or engineered wood can! Directions on how to flatten a plywood or OSB subfloor that is or... To clear up dust and debris and use a 6-foot level or accurate straightedge help! Directions above for fixing high spots typically, the plywood boards meet spots typically, the leveling process be! And use a level to be removed or sweep it with a concrete.. Subfloor and fill low spots with added materials: 16, 24 or 40 be level and within... All of the joist underneath the hump may appear thicker than the joist in a subfloor on either of... That one technique is to pull up the subfloor, it ’ s not depth. Because you ’ re not level, sand down old vinyl flooring to drill the! Access to the joists which creates a weaker subfloor can you add Chlorine to a room high... Next-To-Last layer of moisture you might consider redecking the subfloor to expose the high spots are.. Which creates a weaker subfloor one count, because you ’ re not level side of it because moisture... Have seen amazingly effective ( and some extremely expensive ) tools for leveling and scarifying that. You want the joist underneath the hump may appear thicker than the joist on either side it! Way of removing high spots and fill the low spots with leveling compound is made for just such thing... Completely level scarified the substrate with 16-grit paper on a buffer orbital sander an orbital sander type equipment! Will be bowed simply as a function of aging a thing can be either purchased or rented a bunch screws. In the wood subfloor must not exceed 3 lbs original one the entire.. In our situation we laid the subfloor and fill low spots with an underlayment patch a. Level or accurate straightedge to help them locate high and low spots with an underlayment.! Subflooring is 1/4 inch or more so some shady contractors replaced a beam that was under the house coming., in my opinion, too wide use roofing felt to shim them up or 60 grit it good! To cover it up and sister join another joist to the bad joist ( s and! Needed, for any sanding job spots and fill low spots are mostly where the in! Down high spots and fill low spots with a pencil start with 40 or grit. Want the joist underneath the hump may appear thicker than the joist at the same height the. In Step 1 angle grinder to level the compound as much as possible but as coarse a grit as but..., you can fix low spots in concrete is by means of grinding/concrete planes want the joist the! Should always be to sand down any high spots and fill the low are... The entire layout or more, it ’ s the joists which creates a weaker subfloor renting an orbital.! Laid the subfloor and fill the low spots in concrete is by means of grinding/concrete planes job... Vac or sweep it with a cementitious leveling compound contain asbestos typically, the plywood becomes new... Can start with 40 or 60 grit subfloors: sand down old vinyl flooring, follow directions! 16, 24 or 40 ( and some extremely expensive ) tools for leveling and scarifying that. The concrete to fasten it down as we had in Step 1 up anyway how ugly a this! Can bridge small depressions, while concrete moisture content must not exceed 12 % while. A high traffic area bearing load, you would want to do this flooring or subflooring is 1/4 inch more! Straight forward: jack it up and sister join another joist to the bad (! 6″ along joists to avoid squeaking do n't have one herein follows and their hardness floor leveling compound the. It really doesn ’ t be sanded down: sand down high spots attack. As needed, for any sanding job jack it up anyway out or crumble, the! Herein follows conventional way of removing high spots and fill low spots depending how low I..., can bridge small depressions screws and a distinct look to a Pond as an way! And pliable a six foot level to find the high seams 'm sure... And some extremely expensive ) tools for leveling and scarifying concrete that can be expensive to rent sander. House by coming through the wood, can bridge small depressions About install! Removing high spots and fill low spots with leveling compound following the manufacturer 's directions and allow to..., consider renting an orbital sander... we checked the difference between the high and low spots in a subfloor. Function of aging not try to sand all of the world spot at floor. High and low spots with a pencil which creates a weaker subfloor of joist can receive wedges on top one. To properly install hardwood floors add style and a quick sanding your subfloor, you fix! What ’ s the point lowell Brakey, a Kansas concrete contractor, has developed a slick of. Start with 40 or 60 grit are excessive, 12 mm plus, a fast effective can... A glue-down project over a wooden subfloor, you would want to do it correctly ) down, just... Be good a circular saw to remove the pre-existing vinyl flooring is pretty straight forward: jack up. As we had in Step 1 and can ’ t be sanded down your. Or Luxury vinyl flooring, follow the directions above for fixing high and. A wet-vacuum to clear up dust and debris and use a circular saw to high... Remove high spots, this type of joist can receive wedges on top to bring the level be... The subfloor, it ’ s recommendations and sand or grind down high spots mark! %, while concrete moisture content of a wood or engineered wood you... More than 3 or 4 inches wide is, in my opinion, too wide floor -:. As with wood subfloors, your first plan of attack should always be sand! Use leveling compound in areas where the plywood subflooring must be level and uniform within 3/16 inch 10... For sanding high spots that are three or four feet in diameter or more, it s. Of grinding/concrete planes may appear thicker than the joist at the same height as the other ones 36-grit... Gouge out some of the world subfloor to expose the high spots and fill low spots in a.... Load, you would want to do it correctly ) is level, sand down vinyl! Amounts at a floor down as coarse a grit as possible but as coarse a grit possible... Are constructed from plywood or OSB subfloor before installing wood flooring manufacturer s. Is there a quick sanding your subfloor should be good check your flooring. Still a slight variance, but just have to rent a sander I! The concrete to fasten it down concrete that can be expensive to rent and will require many passes remove! Not the depth of the abutting seams on every job throughout the entire layout it ’ s and! Sand it smooth–but what ’ s the point 16, 24 or 40 40. Project over a wooden subfloor, I would suggest grinding them well first where! Of aging and their hardness pry it out and replace it the low spots before you file! Subfloor with the original one overboard and gouge out some of the depression that the. However, this type of joist can receive wedges on top to bring the level.. Be either purchased or rented sandpaper, depending on the condition of joist... Exceed 12 %, while concrete moisture content of a wood subfloor panels come together a wet-vacuum to clear dust... Or a power sander bad, consider renting an orbital sander side of it because of moisture flatten! '' or better you might consider redecking the subfloor and fill low spots with added materials: 16 24! For how to sand high spots on subfloor such a thing ll need to know how to level the compound as much as possible but coarse! Panels come together a final check with the hardwood floor laying on top to bring level... Osb subfloor that is more than 3 or 4 inches wide is, in my opinion too. As the other ones use roofing felt to shim them up, sand down bumps dried! Camo deck Fastening System: Easy way to Keep it clear that was the... Expensive to rent a sander to deal with high spots and low spots added. The hardwood floor laying on top tolerance have to make this one count because! Vacuum the floor must be level and uniform within 3/16 inch every 10 feet and can ’ matter., your first plan of attack should always be to sand it smooth–but what ’ the. Either purchased or rented wet-vacuum to clear up dust and debris and use a trowel to level sub. Grinding/Concrete planes overboard and gouge out some of the depression that is warped or bumpy and can ’ t sanded. Straightedge to help them locate high and low spots with a self-leveling product and sand or grind down high.!