How to DIY Cabinet Filler Strips for a Custom Look

Filler strips are an important part of any cabinet project.  Even with custom cabinets, there are still places where a filler strip is recommended, such as adjacent to a wall.  In our recent office desk build we used a ton of cabinet fillers to make our desk have a built-in look.  In this post, I will go through how to DIY cabinet filler strips for a custom look in your cabinet project!

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Table of Contents

Office Desk Project to Date

We just finished installing a bunch of filler strips in our office desk cabinet build, but before we get into the details of how to do a filler strip, I thought I would talk about the progress in this room since I haven’t blogged about it since I wrote this post on the plans.

Our office before – we decided to remove this closet to add a built in desk

We started this in November with a plan to finish up before Christmas, HA!!  I know that is funny looking back on it now.  Life has been busy and this project is substantial but we still have made some significant progress!

We started by demolishing the old closet.  We added some electrical for our computer and some lighting and then drywalled it all back up again.

After we removed the closet it looked like this!
Then we drywalled it all back up again

We removed the popcorn ceiling using our drywall sander (I wrote a post about removing popcorn ceilings here if you are curious about that process!)

I used my drywall sander to sand off the popcorn ceiling

Once all that messy drywall business was behind us we painted the walls and ceiling a nice warm white.  I chose Benjamin Moore Dove Wing because I love that colour so much in our ensuite, and this office faces the same direction and has the same light exposure.  

The walls and ceiling were primed in preparation for a light-coloured paint

We then installed some Ikea Kitchen Cabinets up near the ceiling.  We used lower cabinets for this because I wanted the additional storage space that they would provide.

We installed some Ikea cabinets high up inside the alcove

Since lower cabinets do not generally have a top on them, we cut a piece of melamine for the top, screwed that on through the side walls and then edge banded the front of it.  This is just so that when the cabinet doors are opened, you don’t see the ceiling and the base cabinets have a top on them.  

Ikea’s base cabinets do not come with a top so we added a piece of melamine for a top
We just screwed the top in from the sides (predrilling first.)

Ikea cabinets are very easy to install due to the rail system they use.  You install a rail level on the wall, using a stud finder to ensure that you attach it securely to studs.  Once the rail is up, you simply have to hang the cabinet box onto the rail using the hook that Ikea’s cabinets have on the back of the cabinet. 

We planned to install a library ladder in here so we added some framing along the bottom of the upper cabinets to make sure the ladder rail has something strong to attach to.  That was just some simple 2×4 framing that was firmly attached to the wall studs.

We added some 2×4 Framing under the cabinets so it would have good support for the ladder

The old cabinets in this room included a bank of drawers that we wanted to reuse for one side of the desk base.  We planned to use an Ikea base cabinet for the opposite side, but they were not the same height.  We assembled the Ikea cabinet and then cut the top off of it to make it the same height as the bank of drawers.  

We needed this white Ikea cabinet on the left to be the same height as the bank of wood drawers on the right so they could be used for the desk base, so we cut the Ikea cabinet down
We cut the cabinet after it was already assembled, which maybe isn’t the preferred way to do it but it worked!

We also made a base for the Ikea cabinet by ripping down 2×4’s to match the base of the old cabinets as well.  

Once those modifications were done, we removed the carpet from the area where the cabinet bases would go and screwed them down to the subfloor.  We used shim where necessary to make sure the bases were level.  

The base cabinets were installed and leveled

We installed both cabinets about 1 – 1/2″ away from the side walls to allow room to install a filler piece.  

Once the base cabinets were nice and level with each other we added an Ikea Countertop.  I chose this countertop because it is real oak veneer so it could be stained, but it didn’t have the typical butcher block appearance that I thought might make it look a little kitchen-y.  

We installed a countertop on the base cabinets

Once the counter was in place, I lightly sanded it and then stained it a little bit darker using Osmo Wood Wax Finish.  

Then it was time to add all the fillers!   We started with filler panels on the sides of each of the base cabinets and then added the filler strips next.  

What is a Filler Strip

A filler strip is just what it sounds like really, a strip of material that matches the cabinet doors that are used to fill a space.  

When you are using off-the-shelf cabinetry (like in our IKEA kitchen) you often have to get cabinets that are just a little smaller than the space you have available so that they will fit.  Different cabinet manufacturers have different standard-size cabinets that they use to piece together the kitchen.  Once you put all the cabinet boxes side by side, there is a little space left over between cabinets, and that is where you would use a filler.

Fillers are used to fill the space between cabinets to make it look built-in.  

Kitchen with Fridge built with fillers all arounda nd deep cabinets over the fridge, beige cabinets with a stove nook beside the fridge and built in spice rack and marble tile
There are lots of fillers around these two upper cabinets and around our fridge to make the fridge look built-in

Often there are spaces where you need to plan to have a filler, such as in the corner of a kitchen to prevent doors and drawers from running into each other, or up against side walls where you don’t want a drawer slide against a wall or hit a baseboard when it’s opening.

There are fillers in the lower cabinet corner here so the corner cabinets function well

How to Plan for Fillers

It is one thing to know that you need a filler piece somewhere, but another thing to plan the most aesthetically pleasing place to put it.  Function comes first but form is right behind, am I right?  

In our kitchen, the cabinets on the “business side” of the island was longer than the cabinets we wanted to use on the back side. We knew we were going to need some fillers.

Black island with wood top and wood floors, brass hardware, all drawers with skinny cabinets at either end
This side of our island dictated the size of the island

We could have put those kitchen fillers anywhere but what looked best in that case was to split the fillers between each cabinet and at each end.  That way the fillers look balanced and intentional instead of just a space filler closing up unsightly gaps.

On our island back we split the filler evenly instead of putting them all on one side

We also chose to bring our fillers forward so that they would be flush with the front face of the cabinet, and give the look of a face frame cabinet.  It looks a lot better to have those fillers flush with the doors instead of flush with the cabinet boxes and gives it a built-in look.

In our office, we had something similar.  We easily could have put the fillers on either end of the cabinets but instead, we chose to split them evenly between all the spaces.  We added trim pieces on the top and bottom of the cabinets as well so it does look like a face frame or inset cabinets (but they are just Ikea cabinets!)  

We could have installed the cabinets like this, with a filler against the wall on either side
Instead we installed the cabinets like this and placed a filler between each cabinet for a built in look

If you have an end cover panel like this one in our kitchen, if you make it deeper so it sits flush with the front of the cabinet doors instead of flush with the cabinets, it has a similar effect and has very minimal extra effort.  

We made our side panels deeper so they are flush with the door front and not the cabinet box

​If you have corner cabinets in your kitchen, make sure you include a corner cabinet filler.  The purpose of this is to ensure that your cabinet drawers don’t bump into each other when you are opening them.  Once you add hardware to your cabinet door it sticks out even further into the room so you want to make sure there is enough space there.

Make sure to include fillers in any corner cupboards so the doors open without hitting each other
A filler next to this drawer ensures that it doesn’t rub on the adjacent cabinet when it’s opened.
A filler gives more room for corner cupboards to open and not hit the adjacent hardware

How to DIY Cabinet Filler Strips

Filler thickness for Face Frame Style Fillers

When you order your kitchen doors and panels they will likely send along some MDF panels that are painted the colour of your cabinets that you would then use to cut to size as needed for the cabinet fillers.

If you are doing everything from scratch like we are, you can also use MDF or wood the same thickness as your cabinet doors to make your filler strips.  They must be the same thickness (or thicker) than your doors.  In our office, our doors are a full 1″ thick so we built up MDF by gluing and screwing together strips of MDF 1″ and 1/4″ so that the final strip was as thick as our doors.

To have the fillers “stick out” past the edges of the cabinet boxes to look like a faux face frame, you will need to attach something to the back as a nailer strip. The nailer can be anything – we generally use whatever scrap wood we have lying about to make some strips of wood.  

We built up our fillers so they would be thick enough to line up with the door fronts and then added nailers to the back to attach them

How to DIY Cabinet Filler Strips Between Cabinets

The easiest fillers to do are those between cabinets because if the cabinets have been installed level, the fillers will be perfectly square.

All that needs to be done is to measure the space between the two sides of the cabinets and cut a filler to match.

This is a filler installed between two cabinets. We were careful to ensure that the fillers stuck out past the cabinet frame so they would be flush with our door fronts, once they were installed.

What we found worked best for this type of filler is to start with a slightly wider filler and attach a nailing strip to the back.  We used glue and a few screws from the back to attach them.  Then, we cut the final size on the table saw, cutting the filler and the nailer simultaneously to the final dimension.

Once cut to size, you can screw the nailer from the inside of the side of the cabinet into the nailer to hold it in place.  Screwing (or nailing) from the inside of the cabinet ensures that your filler strips don’ have any visible nail or screw holes to patch.

We simply screwed from the inside of the cabinet into the wood part of this filler strip to secure it.

You can also install fillers flush with the face of the cabinet box, which is what most people do and it is quite a bit easier as you don’t have to add any kind of nailer.

In that case, you would line up the filler with the edge of the cabinet box and finish nail or screw from the inside of the box into the filler.

How to DIY Cabinet Filler Strips Between a Cabinet and a Wall

Fillers between cabinet and walls are a little more tricky to do because of uneven walls.  Most walls are neither straight nor square.  

If you measure your perpendicular gap and find it fairly square, the easiest way to cut this filler is to just cut it square and fill any space leftover with caulk, or leave a small gap.  

However, it’s likely going to be pretty wonky so you might want to try to scribe the filler to fit against the wall for the most professional look.

Scribing is the process of cutting a piece to exactly follow the ups and downs of an irregular surface.  It is a little difficult to wrap your head around, but it is not hard to do!  

This is how I marked this scribe piece that I installed next to the wall.  I cut my filler to be the largest dimension of the perpendicular gap between the cabinet and the wall.  

Next, cut a scrap piece of wood with the same dimension to use as your template to scribe with.

Hold or clamp your filler piece flush against the edge of your cabinet frame.  Hold your spacer piece of wood against the wall.  Grab a pencil and mark a line along the edge of the filler piece as you slowly run it down the wall.  The pencil will follow the ups and down of the wall and make an irregular line along your filler.

I tried to replicate the process to show you what I meant but the filler on this cabinet was already done. Imagine that the filler on the right was not there. Then, the one I am holding with my hand is lined up with the edge of the cabinet. The little block is the size of the largest gap. Run that block along the wall and follow it with your pencil

Once that has been done cut or sand your filler until the pencil mark disappears.  We use a belt sander to make this go quickly.  

Sand down the filler to the line you made, I used a belt sander to make quick work of it.

Once sanded the piece should be a perfect fit in that gap!  

You should be able to get a really tight fit with your filler by scribing!

Toe Kicks

Toe kicks that are made to come out flush with the cabinets are done the same way.  I wrote a whole post dedicated to toe kicks and how to do flush toe kicks, so you can read more about those here.  They are just a horizontal version of a filler and are done the same way you would do one along the wall.  

running a pencil along the floor to scribe the bottom of the cabinet toe kick
Scribing the toe kicks in our kitchen

What’s next for Our Office Project

Since we finished the fillers we have made our cabinet doors to match the ones on the Murphy bed wall.  It was our first time making cabinet doors and we learned a few things.  I am going to save the making of the doors for another post, as we have some tips and tricks to share with you!  

Progress picture of the desk build so far! There is still a lot of trim and finishing touches to add but it’s definitely getting somewhere!

​Next up we are going to make a keyboard tray (similar to the way I did it on my antique desk!).  I’m also going to add some planks to the back wall to add a little interest and add a shelf under the deep upper cabinets.

​Once all of the construction is over it will finally be time to PAINT!  After paint, the desk build will be complete.

I was about to say that the desk would be done at that point but I almost forgot about the library ladder and rail that we are adding.  

Once that is done, it’s only one side of the room and we will flip to the other side to work on the Murphy Bed wall.  My goal for 2024 might just be to finish this behemoth of an office project!  

Once the desk is done we will be adding more cabinets to build this murphy bed to the wall and to the ceiling, and then painting all the cabinets to match.

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  1. I love the color of your kitchen cabinets! Can you share what color that you used? It’s the tan/beige/taupe color. I am trying my best to get ideas to remodel my home. Thank you!

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