How to build a “custom” looking built-in with IKEA Billy Bookcases Hack
This post will go over how to build a “custom” looking built-in bookcase using IKEA Billy bookcase shelving as the base. Essentially, you are going to wrap the top and bottom of the bookcases with a wood skirt that you will then attach various trim molding and other trim pieces to give it that custom built look. There are a number of existing “hacks” that I looked at to draw inspiration but the main one is this one. I followed most of the instructions but came across a few steps that were left out or not covered that I am going to make sure you know about so you can end up with a finished project you’ll be proud of. Let’s get started.
Check out a quick tutorial on how we put this all together!
Everything you need to get started!
* Ikea Billy Bookcase (3 – white)
* MDF sheet cut into strips – 1/2 thick
* 1X2 inch board
* Nail gun – 16G
* Paint Caulking
* Wood filler
* Various trim (you can pick different styles to fit your look)
Keep in mind the amount of MDF you will need will depend on how wide you want to go with the “built-in”. The same will go for the trim. I will give you the measurements I used but please adjust accordingly for your room / build so you aren’t short or the spacing is off.
**** I used plywood which works but is much harder to get a smooth paint finish to match the Billy Bookcase (required a lot of filler and elbow grease to get smooth). I am suggesting you use MDF which is smoother to start with and should match the bookcase closer then what I have. So all the photos are of plywood – I know.
Step 1: Planning and measuring
First, you will need to measure the wall that you are planning to mount the bookcase to. Each Billy bookcase is 31.5″ width by 79.5″ tall and 11″ deep. Here is a link to Ikea for the specifics. I knew I was going to use three bookcases and I wanted 6″ between each so that would be 3 x 31.5 + 12 = 106.5″ in total width that I would be using on the wall.
For the height, this will also depend on the wall. The room has 8ft (96″) ceiling so not a lot of room to add a big top piece. I decided on adding 11″ top which would also give me a little wiggle room to place with the top trim design.
** This was not covered in the hack I used… so learn from my mistake.
If I were to do this over for the bottom, I would add a 3.5″ base board to wrap around the bottom. Now I adding some 1/2″ trim on top of this, so it would be flush with the bottom shelf. If the trim you use is bigger or smaller you will need to adjust your board cuts accordingly.
With the measurements figured out, I would need the MDF cut into:
– (2) 6″ wide by 75.5″ tall – these are the inner strips to cover the gaps
– (2) 3.5″ wide by 53.25″ – base
– (2) 3.5″ wide by 10.5″ – base sides
– (2) 11″ wide by 53.25″ – top
– (2) 11″ wide by 10.5″ – top sides
I used wood that was 1/2″ thick, that is why the side pieces are smaller to make the corners flush. If you use thicker MDF, adjust your side measurements accordingly.
I cut some 1″ x 2″ board into studs that attached to the tops of the bookcases. I cut them 10″ long to give a little wiggle room for the top.
Step 2: Assembly
First move the bookcases into position. Adjust that gap between each so that the total distance between the inside edge of one bookcase to the inside of another is 6 inches. This will ensure that the cover strip is flush with the bookcase. If you want a wider gap then adjust your bookcases and the size wood you use accordingly. Once the position is good, anchor the bookcases to the wall so they don’t move.
Nail the wood studs to the corners and middle bookcase to provide a place we can nail the tops boards to. I used a clamp to hold the boards in place as I nailed. I started with the front boards first and then added the side boards in case I need to move them a bit to get them flush. Take your time and get the seams and corners as tight and flush as you can. If they aren’t perfect, that is okay – wood filler and caulking will be your best friend soon.
Next, I nailed the cover strips over the gaps to seal in everything. At this point it is really taking shape.
** See the bottom. I should have boxed that in completely, and there would not have been a gap. Next time it will be better.
I then attached the bottom baseboards. First to the front and then the sides. If you are doing this on a carpeted floor like me, you may need to use a level to ensure the boards are attached correctly. Otherwise, you should be able to push them to the floor and nail them directly on that way.
Step 3. Trim molding
Knowing the total length and height, you can look at the various trim pieces that are available to you and put a design together.
Here are the trims I used from Lowes – you can use whatever works for you:
A couple of tips for cutting molding:
1 – use a miter saw. There a power ones, I used a manual one for $50 at Lowes. Since these are small trim pieces I didn’t need a heavy duty saw.
2 – try to make a few cuts as possible. If you can cut on long piece to cover the front, do that. Don’t try to scrape together pieces unless you have to. If so, look up scarfing trim on how to put two pieces together.
3- when you nail in trim, make sure the nail drive below the surface. You are going to fill those “holes” with filler and sand them flush.
There are tons of videos on how to cut trim molding for corners. Here we only have to deal with 45 degree cuts. As long as you keep the trim flush with the fence of the saw and you have it positioned correctly (there will be a top and bottom of the trim). Just know that you are going to have waste as you may need to cut an angle and loss some of trim to do it. That is normal. Just make sure you buy enough trim to cover this waste. Just because you need 10 feet of trim, buy 12 feet so you have some room for all the cuts that you’ll need.
Attach the trim molding to the base, sides, and top boards. Use clamps to hold long pieces in place.
Step 4. Fill, caulking and final paint prep
Now you are going to fill all the nail holes with wood filler. Mount all of the shelves in the place that you want and fill all of the adjustment holes with caulking. Caulk between every piece of trim and wood or bookcase. Caulk between the shelves and the bookcase backing. You are going to “smooth” out all of the edges, holes and imperfections. Once the filler dries, sand with 300+ grit sandpaper to smooth everything out. I used a power sander for the big sections and hand sanded the corners and small trim pieces. Use a microfiber rag to pick up all the dust before you paint.
Step 5. Paint and decorate
We used our trusty Snowbound paint and I had to apply a few coats to get everything smooth. Once it dried, Lisa took over and did her thing.