There’s nothing worse than getting ready to start your next project only to find that your wood is warped.
To understand how to fix warped wood, you’ll first need to know why it warps in the first place.
In this post, I’ll show you exactly how to fix warped wood, ways you can straighten warped wood, and much more. Let’s dig in!
In This Article:
Reasons Wood Warps
Humidity is one of the leading causes of warped wood. Because of woods porous nature, it can easily absorb moisture from the air which makes it more flexible.
Even if you’re using a manufacture wood with additional water resistance, if you surround it with too much humidity, it will eventually warp.
The excess water that’s absorbed by your wood isn’t necessarily why it warps, however. It’s actually the constant drying process that happens whenever your wood is exposed to water and then allowed to dry.
This constant change in your wood will cause it to warp and bend.
Wood isn’t supposed to be completely dry either!
Wood should have a moisture level of between 8% and 10%. You can use a wood moisture meter to find how wet your wood is to prevent future warping.
Heat and UV Exposure
Another common culprit that causes warped wood is heat and UV exposure.
Because wood retains some natural moisture content, whenever is is exposed to extreme heat or UV rays, the wood dries out and can contract and bend.
But the issue is even worse if only one side of wood is exposed. For example, if you have a fence that surrounds a tree and only one side of the fence gets exposed to the sunlight – this will cause only one part of the wood to contract and warp.
Insects and Pests
Are you storing your wood outdoors? Insects like beetles, ants, and other creatures can bore into your wood and cause it to warp over time.
As bugs and insects bore into your lumber, it can begin to warp wood over time. You might not notice it right away, but as months go by – you’ll soon notice it.
This is less likely to occur if you’re using pressure treated wood, but it’s still a possibility.
Storing Wood on Top of Warped Boards
If you have a large amount of lumber, you might be tempted to stack them all on top of one another for easy storage.
The problem is that if one board is already warped and you sit 10 more boards on top of it, the pressure from the other boards will cause the ones in the middle to warp too.
If you’re not sure how to store wood, check out these lumber storage ideas for a small woodshop.
Low Quality Wood
Some types of woods are better quality than others, which can play a part in how easy they will warp. Don’t be confused, the cheapest woods aren’t always the lowest quality – although there are a few.
Really, one of the more important factors in determining if wood will warp is how it is cut. Cheaper woods can often be cut differently than more expensive options, which can yield a higher potential for warping.
5 Types of Warped Wood
When shopping for lumber, you always want to be on the lookout for bow warping. This is a common type of warping where the wood is bent either inwards or outwards.
While you probably won’t run into this kind of warping often, it’s smart to know about. This type of wood warping occurs when the ends of the boards seemed to be twisted in opposite directions.
Kink warping occurs when a small portion of a board has been warped towards the end of the wood. It bends outward making the board uneven.
Cup warping is a type of wood warping that occurs on large pieces of wood when the center of the board is slightly lower and the edges cave inwards.
Crooked warping is a pretty uncommon type of wood warping that resembles a carving of the entire board of wood.
How to Fix Warped Wood
1. Add Heat
Using heat is one of the most common methods to fix warped wood. The best way to doing this is by utilizing the sun.
With the sunlight method, you’ll need a damp towel, a few days of sun, and some time.
Take your damp towel and wrap it around your warped wood. Place it in direct sunlight for a few days until the board has flattened. The amount of time it will take will depend on how bad the board is warped and how much sun their is.
Another option is to use another source of heat like a heat lamp or a steamer. These can also work, but require more supervision when straightening warped wood.
The advantage of this the heating method is how easy and cheap it is. The main disadvantage is that it takes more time than some others.
2. Use an Iron
This might sound a little weird, but did you know you can use an iron to unwarp wood?
That’s right! Here’s how.
Just like with other methods, you’ll start by wrapping the warped area of the wood with a damp towel. You can place the wood on an ironing board and plug in your iron so it begins heating up. Once ready, press the hot iron on the warped surface of your wood moving it back and forth until it begins to unwarp.
You can then use clamps to keep the board in place on the ironing board while it continues to unwarp.
The benefit of this method is that it can be quicker than others, but it’s more difficult for larger pieces of wood or wood that is extremely warped.
3. Use the Nylon Paper Technique
With this technique, you’ll start by laying your wood on a flat surface. Then you can wrap the warped surface in a damp towel (or paper towels). Next, wrap the wood with nylon paper over the damp towels. Finally, place a heavy object on the warped wood and let it sit until it begins to unwarp.
So why do you need nylon paper?
In simplest terms, this keeps the moisture in the wood, as opposed to evaporating off into the air.
4. Add Pressure
The pressure method is somewhat similar to others in that it relies on adding moisture to the wood. And similar to the sunlight method, it’ll take a few days to unwarp wood effectively.
Start by dampening a paper towel with water that can be used to put over your warped wood. You can also wrap the rest of the wood with plastic so the moisture doesn’t get on the straight areas of the board. You can then apply C clamps to the areas that need to be unwarped and either use a heat lamp or sunlight to add a little heat.
It’ll take a few days to unwarp wood with this method, but it’s cheap and effective.
5. Jack Plane
Using a jack plane can help in straightening warped wood, but this won’t necessarily work for every piece. First, you’ll need to own a jack plane. If you have a jack plane, you can run it over your warped piece of wood to remove the extruding portion.
Tips to Keep Wood from Warping
Store in a Cool Dry Place
The easiest way to protect your wood from warping is by storing it in a cool, dry location. In other words, don’t store your wood outdoors!
Keeping it inside will help to moderate the humidity and temperature of your wood so it doesn’t warp in the first place.
You can check the humidity of the room to ensure that it’s not too wet, but in most cases, if it’s inside your home – you should be good.
If you’re storing wood in an outdoor shed, you might need to double check the moisture content of the air just in case.
Inspect Your Boards When Purchasing Them
When visiting your local hardware store, it’s critical to check to see if the lumber is already warped. You might be thinking “it’s ridiculous that they would even sell warped wood!” but it’s more common than you’d think!
Check out this piece of warped wood from Home Depot. Yikes!
When purchasing lumber, if you find that it’s wet, it might be pressure treated. If it’s not treated and it seems wet – you want to avoid these pieces at all costs.
You’ll also want to visually inspect them for any obvious warps in the piece so you can avoid them.
Waterproofing your wood can help to reduce the amount of moisture content in your wood that causes warping.
There are many different ways you can treat untreated wood for more protection.
I recommend finishing wood with polyurethane to add water resistance to avoid warping in the future. While it can take some time, it’s well worth it.
Don’t Dry it Out Completely
As you know, wood mainly warps do to changing moisture levels inside of the wood. If it goes through too many wet and dry cycles, the chances are, it’s going to start warping.
If you want to reduce the amount of moisture in the wood, try not to dry it out completely to the point where it starts cracking or splitting.
The strongest woods have some water content in them. By removing every bit of moisture from them, they will become brittle and weaker.
How to Fix Warped Wood Furniture
If you have warped wood furniture, the best course of action is to try to disassemble the furniture and remove the warped boards so you can straighten them.
Once you’ve identified and removed the warped board, you can cover the piece in moist paper towels and add pressure on a flat surface until the wood straightens. This can take some time depending on the thickness of the wood and how warped it is, but it should begin to unwarp within a few hours. You can use clamps and heavy objects to apply pressure to the entire piece of wood and allow it to flatten out.
If you can’t disassemble the piece, you’ll want to apply heat, moisture, and pressure to the area and use clamps or heavy objects to flatten out the surface.
How to Fix Warped Wood from Water
Unwarping wood from water can be easier than you think. Many of the above methods will work for fixing warped wood.
In a nutshell, you’ll want to apply heat, moisture, and pressure to the warped area on a flat surface to unwarp the piece of wood. You can use sunlight, a heat lamp, or even an iron to add heat to the surface. Most methods will also require moistened towels that you can wrap the wood in to add more moisture. Finally, you can use clamps or heavy objects like bricks to add pressure to the surface and straighten warped wood.
Can you flatten a warped wood?
Yes! You can flatten a warped wood by placing it on a flat surface and covering it with a thin steaming towel and applying pressure to the warped area. Unwarping wood can take some time, but it can be done.
How long does it take for wood to unwarp?
The amount of time it takes to unwarp wood will depend on a few factors such as how bad the wood is warped, which method you use, and the thickness and size of the wood. In most cases, it can take less than a week to unwarp wood. In some cases, it can take as little as a couple of days.
How do you flatten warped wood without a planer?
To flatten warped wood without a planer, there are a few options. The easiest is by using a power sander to sand the surface to achieve a flat finish. You can also use a saw to cut it flat, although this can be more difficult. Finally, you can use some of the methods above to straighten warped wood without a planer.
How do you fix cupped wood?
To fix cupped wood, you’ll want to cover your wood board with warm, damp paper towels and add some pressure by placing a heavy object over the entire surface. Next, clamp the wooden board to a flat surface and give it time to flatten out.
It can be tough to straighten warped wood, but it’s not impossible! There are a few main methods you can use to straighten your piece of wood.
The easiest is by wrapping your wood in a damp towel and sitting in in direct sunlight. You can also use pressure to unwarp wood. Both of these will require a few days, but will get the job done.
The best thing to do is to prevent warping wood in the first place! Always check your wood when purchasing it and store it in a cool dry location to make sure you don’t have to fix your wood later.