Built-in Upholstered Daybed DIY

Our attic guest room has two large dormers which I have always thought would be the perfect location for a twin-size day bed or window seat with a trundle bed underneath. Since I recently upgraded my son’s mattress to a full I now had two unused twin mattresses just asking to be used for just this purpose. In my head, this had always been a cabinetry project but because the space is about 12″ longer than a standard twin mattress I never could quite resolve what to do with the extra space. But then I realized this was the perfect spot to build a DIY Built-in Upholstered Daybed.

Then one day it came to me, if I did an upholstered arm at either end I’d have something to fill in the gaps while also creating a soft place to rest my head. The New Canaan Daybed with Trundle from Ballard Design would have been a perfect solution but unfortunately, it is no longer available so I decided to make my own upholstered daybed only mine would be built in.

I admit this was quite a big project with a combination of construction, sewing, and upholstery required to get it done but since I had some old curtain panels and some scrap wood to get me started I figured I’d give it a go. The first step was creating a simple platform. I screwed my ledger boards into the studs along the wall and used joist hangers to install supports in between.

Once I had the platform in I topped it with a thin layer of plywood and built frames for the arms out of 2x6s the same depth as the platform (for a twin bed this was 38″).

With the arm frames built I used upholstery stapping to stretch it across the frame for support. Then I wrapped the whole exterior of the arm in 1″ foam and a layer of batting. For the front edge of the bed, I added a 1/2″ square trim to the top to create a lip to keep the mattress from sliding and screwed another 2×2 underneath to bulk up the front. This all got wrapped in two layers of batting to soften the edges.

Then I upholstered it in the white twill from my curtain panels. I tend to hang on to old curtain panels for just this reason, they are a good amount of fabric and can often be reused for other things.

For the arms, I sewed a sleeve using black welting at the seams which I could slip. When sewing these I left enough excess to tuck under the front edge of the seat. At this point, the arms are not attached so once the sleave when was slipped on I could pull it tight and upholstered it to the backside. Once the arms were upholstered I put them back on and attached them from underneath. I pulled the excess tight tucking under any excess fabric and stapling it underneath the front edge.

For the mattress, I made a fitted sheet using black welting again at the edge. for the mattress below I was able to find a trundle pull out on Facebook Marketplace for $50.

Now all that was left was the skirt. I sewed a long panel and two small plackets for either end. Then I pinned them on to place my pleats. I chose to do one pleat at the center and one just below the welting line at the arm where I placed my smaller placket pieces. The reason I used the plackets is that I wanted the trundle to pull out easily so the plackets allow the skirt to separate when the trundle pulls out even if I decide the ends need to be attached to the walls.

Before attaching the skirt I decided to add a band of greek key trim about 4″ from the floor and another band of black welting where it attaches.

The result was a built-in upholstered daybed with some great contrast details…

And an absolutely perfect fit. Now I’m ready for a guest or two or just to relax and enjoy the view.

For a video of the whole process, you can check out my Instagram Stories Daybed Highlights and see the process from start to finish.