How to Sand Between Deck Boards

September 18, 2022

Sanding the edge gap on two deck wood boards.

If you’re looking for the ultimate DIY backyard project, you might as well consider building a deck. Building a deck, of course, isn’t meant for the weak-hearted and weak-bodied, for it entails some hefty works. You must plan this project well and execute the plan to perfection. It is also essential that you know how to sand between deck boards. 

The reason is that you must ensure that each board is smooth. Each deck board must have a similar width relative to the other deck boards to achieve an excellent level. However, sanding manually between deck boards might push you to the limit of your stamina and strength. Moreover, it is time-consuming. Nevertheless, you can facilitate the sanding process if you got the right tools and equipment.

Steps on Sanding Between Deck Boards

If it is your first-time sanding between decks, you might be at a loss on how to go about it. Below are the simple steps you can follow to accomplish the sanding between deck boards with ease and efficiency:

Step 1: Prepare the Deck Surface

Before sanding, you need to check the nails and screws of the decks. Make sure that they countersink several millimeters below the level of the deck. If one or two nails or screws are not countersinking, chances are, they will tear your sandpaper while you sand. If there are protruding screws or nails, you can nail stamp them. 

Afterward, you can sweep the deck to prepare it for sanding. Use a broom that comes with stiff bristles to do away with loose debris or refuse. Remove all the pieces of furniture and other things from your deck to ensure you can sand all surfaces.

Step 2: Strive for Similar Deck Board Measurements!

When using the planer, take extra effort to measure the decks. In this way, you can ensure that the deck boards are of similar dimensions. Depending on the size of deck you are working on, it may take around an hour or two for this measurement process. Yet, with this process, you can ensure that the boards will come out level with each other after nailing them.

Step 3: Start Sanding Between Deck Boards

To sand the gap between the deck boards, you can glue your sand paper on a thin hard board which enable you to slip and slot the board into the gap to sand the vertical edges between the beck boards.

Remember that an excellent wood stain finish will always start with the proper sanding preparation. You can use a power sander for sanding the decks. You can sand difficult-to-reach areas by hand. Use something that does not exceed 90 grit sandpaper. 

If you have used a deck cleaner, you can assure yourself that the deck gets cleaned well. However, one downside of using a deck cleaner is that it can raise the PH level of the wood. You can reverse this effect of deck cleaners by using a wood brightener. 

When sanding, you can use an electric or manual sander. The electric sander, of course, is more efficient and is less tiring to use. You should ensure that you leave around one-sixteenth of an inch over the width you would like to achieve with every board. 

The sander will remove the excess width, leading to smooth edges of the board. The sanding process may take several hours of hard labor. Yet, you can go about the sanding process more efficiently if you are using a planer or an electric sander.

How Would You Sand the Board’s Edges?

You should not have any illusion that the sanding process will be easy. As I mentioned earlier, it is an enervating task and a bit cumbersome, especially if your deck is large. Moreover, it will be challenging to sand if the rails feature a low baluster railing, making access difficult. 

If the orbital sander doesn’t fit well along those areas, you can use a smaller detail sander in such areas. You can use up to 80-grit sandpaper for the end grains. Wipe the end grains again to do away with dust before proceeding with the staining or sealing process.

How Would You Sand the Deck Surface?

It will be best to aim for the sleekiest deck surface possible when sanding the hardwood. Yet, if you sand a deck surface (exterior), you need to sand the deck floorboards using 60- to 80-grit sandpaper. Refrain from using fine-grit sandpaper as that of 100-grit sandpaper. 

If you use something like that, you will end up smoothing the wood so much to a point wherein the wood pores start to close or get plugged. This closing down of pores will prevent the stain from imbuing the wood surface. 

You can apply medium pressure when sanding manually. Inspect if the wood surface appears even while sanding. Afterward, you should vacuum the surface before you apply the sealer or stain.

Which Tools Will You Need for Sanding Purposes?

Before embarking on a sanding project of the deck, you must prepare the tools you will need. Some of these tools might be of the industrial size. However, you can choose tools and equipment that will allow you to operate within a cramped space. So, you need to plan and rethink your plan. 

You can first run the lumber through the planer to resize the deck boards. But if you would do the sanding manually, you need to go for different tools. You can go for a hand planer or a thumb planer. 

You can also choose a power planer which can enable you to do it quickly. Moreover, you will need a sanding device like an electric sander. You can also simply use sandpaper to sand each board.

How Would You Begin with the Sanding Process?

If you decide to do the sanding manually, be prepared for a heavy workout. The sanding of the deck end grain might take time. It can last for several hours. If your body isn’t conditioned for such a task, you might have sore back and muscles afterward. 

But if you are adamant about doing it manually, you can do it, one deck board at a time. Start with the edges, then proceed to the sides. Then, engage with the ends. Ensure that the deck boards have similar height, width, and length so that the deck boards will fit well. 

You can use your T-square if you have one and use a level to ensure that the sanding is going on the right way. It may take you thirty minutes to completely sand a board. However, if you would use an electric sander, you could speed up the process and reduce it to just ten minutes.

What is the Most Crucial Aspect of this Project?

You might deem the board’s length as critical to this project. Yet, you can constantly adjust the board’s length. Nevertheless, it is a different story if you have already screwed down or nailed the deck boards, for you can no longer adjust the height variations of the deck boards. 

If you can no longer change the height of the boards, you might end up with some boards on the deck higher than the other boards. Thus, if you want to make the deck look professionally made, you should ensure that the boards are level with each other. 

Make sure that the boars are within 1/16″. Once you’ve meticulously measured, you can ensure that the deck surface would exhibit an excellent flatness and will be flushed all across its surface.

Tips on How to Ensure Same Measurements of Boards

You might fall into the temptation of assuming that you can get a perfectly leveled deck surface after using a planer. Yet, this is not always the case. So, it will help if you make the extra effort to measure the deck boards’ height after planing. In this way, you can ensure that the deck boards will be identical to each other. 

This extra effort to measure the boards after planing may take a couple of hours. Yet, if you do it, you would only need to nail down or screw the boards without having to worry about the deck having an unleveled surface. 

Once the deck boards are of similar sizes, you can begin the sanding process. As mentioned above, you must allow for at least 1/16″ over the desired width of the board to achieve a perfect fit for the deck boards. The sander will remove this excess dimension, and each deck board will be perfectly smooth and fitted with each other. This sanding process may take several hours likewise.

Sanding Using Fine Grit Sandpaper Might Reduce Stain Penetration

One issue you might encounter after sanding the deck boards is the inability of the stain to penetrate the boards. One reason behind this issue is the use of fine-grit sandpaper. If you use fine-grit sandpaper, the pores of the panels might close, preventing the wood from absorbing the stain. So, it will be best to use 60/80-grit sandpaper when sanding the boards. Anything more than these would lead to the closing of the pores of the wood. 

If you want to achieve excellent stain, you should sand well. Begin with a power sander and always end up with manual sanding to access the hard-to-reach areas. Afterward, you should vacuum the surface of the boards to remove dust and debris. 

You can use deck cleaners to clean the boards. Yet, deck cleaners can upset the wood’s PH level, leading to the darkening of the wood color and difficulty for the stain to penetrate. You can reverse this process by using a wood brightener that neutralizes a higher PH balance.


Everything is created twice, first in mind, then in reality. Similarly, if you want to build an excellent backyard deck, you should plan everything and execute that plan to the letters. Moreover, it will be best to check with the local building department for a permit and underground utility lines. 

Once your layout gets done, check for pressure-treated lumber because this lumber is more resistant to rot and has longer life. When sanding the board’s edges, you need to follow the abovementioned tips and steps. Moreover, you should never waver in your practice of the essential safety tips, for it pays well to be always on the safe side when engaged in this type of project.  

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