Are you worried about how to level uneven subfloor for cabinet installation, if so then read on. When it comes to uneven subfloors in your kitchen then you have 3 choices on how to fix it. We will walk through each of them from most expensive to more affordable.
3 Options to level uneven subfloors in kitchen
Replace or Adjust Joists Underneath Subfloor
Depending on how old your home is you may want to consider replacing the wood joists that are supporting the uneven subfloor. The way most homes are built are by using rows of joists running in parallel form from one side of the house to another, sometimes stopping to meet at other load bearing walls in the center of the home foundation.
Another option is that maybe your joists moved over time as most homes do and maybe need better reinforcement to stay in place better. Over time the joists of a home tend to drop down or shift either due to humidity, change of foundation landscaping, weight of home, or other environmental factors. So you can adjust them by removing all the subfloors and finding the hangers where the joists are attached to and add metal brackets to each joist and lift them one by one and make them level. If the joists are bowed then they are not adjustable and need to be replaced.
(Please consult with a foundation expert to inspect your home prior to taking action to see if this can be done in your situation.)
Building Codes may come into play here
Keep in mind that building codes have improved dramatically all over the country and now require better building practices due to what we are learning on a daily basis of all the old homes we have built and how good they are holding up and standing the test of time. So the same home you are living in right now may be not up to code and its up to the contractor that does any work on your home affecting that area , it is up to them to bring that area up to code so that why some contractor rather not open subfloor, walls, or roofs because you never know what you will find and could possibly run into a surprise that will cost everyone more money than expected.
How do I know If I have Joists under my subfloor?
If you have a subfloor then that means you have joists. Because there are only 2 type of foundations used for homes and they are a concrete slab foundation running 4 inches to 16 inches deep in dirt depending on where your load bearing walls will be installed.
So if your home kitchen is on a 2nd floor or if it is suspended in the air off the soil by a brick or concrete wall then this means you have floor joists supporting your house floor.
Reinforce Uneven Subfloor Sheets
The most uneven subfloors areas are always found on the edges where the subfloor sheets meet and that is because the humidity or grain of that wood will move and expand over time and the edges will begin to bend upward.
How to reinforce uneven subfloor
The best way to reinforce uneven subfloors is to add more screws to them on the edges making sure you are screwing through the subfloor and onto the joists or hangers underneath. Some sheets may require more screws than others because it is hard to know which subfloor sheets will begin to bow out.
Why didn’t the builder screw down the subfloor properly?
Sometimes the sheets will act differently over time. When your home was being built all the sheets were completely flat laying in large heavy stacks on a pallet somewhere in a warehouse, so they were compressed into place for a long time. Now that the sheets are free to expand or move due to humidity then some will be the outliers over time. As long as your flooring is not already installed then this will be an easy fix.
Replace Damaged Parts
Why?
Subfloors that have been damaged by water will make them swell up and expand which will make those areas seem thicker and higher than the rest of the boards, including the darker colors will help identify the wet surfaces over time.
If your house had gotten wet one upon a time due to leaving a window open in a heavy rain or storm then this might have caused some damage to that subfloor. The other silent and creeping factor can be that leaky hand sink , toilet, water or drain line that may have been dripping just barely for days, weeks or even years with out anyone every noticing.
How?
To replace a damaged part of a subfloor simply cut out an area that is larger than the affected area making sure that the edges you cut off are landing on joists underneath if not then you will have to add small joist supports running perpendicular to joist to allow for all the edges of your new subfloor piece to be landing on a joist and supported all around. Simply screw down with flat head screws all around the border and sink the screws to where they are flush with surface of subfloor and do not over sink them too deep into wood because it will allow for the support to weaken and the wood will pop up again as before.
Adapt the Kitchen Cabinets to Subfloor
When we say adapt the kitchen cabinets we mean you can successfully install them on a uneven surface and still make them perfectly level.
How to raise your cabinets and still make them level
The correct method of raising your kitchen cabinets are by using a wedge type piece of wood called a “Wood Shim“. They run from about 1/4 inch in thickness all the way down to a 1/16th of an inch or less.
The purpose of this shim is to first find the highest point of your kitchen and and start from there. This means that you the spot of your floor that is most elevated either due to any reason and start from there. So you will draw that imaginary line all across the kitchen as it acts as your anchor balance point so there will be areas that have gaps underneath that imaginary line and you will have to fill that gap with a wood shim. Only push in the wood shim enough to help you balance and level your kitchen cabinet into place and leave the remainder of that wood shim sticking out so later on we will remove it but cutting it off.
Once you have laid your base cabinets level then give yourself 2o inches of space from the top of the cabinet to the bottom line of your wall cabinets to leave enough space for a backsplash tile design , maybe a marble countertop or perhaps you would like to add some more lighting underneath your wall cabinets. This means your wall cabinet will also be level.
How to cut down cabinets and still make them level
Another great method to adapt your cabinets to an uneven floor is to find your high point of your kitchen floor and this time you will not use shims. Now instead of shimming the cabinets off the floor now you will be cutting down the sides, back and front walls of the base of cabinets where the they interfere with the highpoint.
So if your kitchen floor is 1/2 inch too high on a certain area then you will be removing 1/2 inch from the bottom part of the cabinet wall or toe kick that is touching that high point. Once you remove that 1/2 section from the cabinet wall then that means you should be able to lay the cabinet flat on floor and it will be completely level if done successfully. Remember you only have a few shots of doing this right before you run out of cabinet walls space to cut out.
Is it safe for my subfloor to be unlevel?
As a professional kitchen cabinet installer let me share with you that majority of homes are not 100% level or plum but they still pass the inspections because they are engineered to withstand slight movement over time and still hold up the structural integrity with out a problem. This fact is also true on the multi-level skyscraper buildings you see in popular cities across the world, they are designed to with stand maximum high winds during a storm and almost unsightly move back and forth to remain balanced.
Overview
Do not be discouraged about having unlevel floors, walls, or ceilings because honestly this is pretty normal and it will not affect the stability of your home or foundation as long as its not literally bowing downward in a very visual manner. anything between a 1/2 inch to a complete Inch of unlevel points running from one side of your house to the other is totally fine I see it all the time in new homes being constructed so do not be alarmed if this is your case. Preferably this is not acceptable but small scenarios like this will easily pass any home inspection either for your own safety concern or if you are trying to sell a property.
We hope this information has been useful and if you have any questions let us know and will reply. Come check us out if you need help with any other part of your kitchen cabinet installation.
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