We (myself and my girlfriend) decided to build this daybed after considering several options for a new sofa. With three big dogs we knew we wanted a big sofa and after looking at many $400+ options we saw several issues (besides cost), The biggest was the availability of slip covers for easy cleaning. We went with the daybed route because a mattress is far cheaper than foam for sofa cushions and twin sheets are readily available for low prices in many colors.
Obviously I altered the plans significantly as I wanted a chunkier, heavier frame that would withstand the abuse of day to day life. Also I removed the canopy as it's not needed indoors. The rear legs are 4x4 nominal which I resawed to 3x3 actual. The rear frame is 1x3 nominal horizontal pieces with 2x3 nominal boards as the verticals. These have rabbets cut in them to join with the horizontal pieces. The bottom support for the mattress is a 2x6 resawn to 2x5 actual and rabbeted to fit each vertical and the legs. Also, the top two horizontals are longer to fit into rabbets in the legs - this allows the back structure to be far stronger.
The sides are constructed of 1x3 horizontals with the leg and arm cap being 2x4 nominal resawn to 1x3 actual. The verticals were rabbeted like the rear to accept the horizontal pieces. The front crossmember is a 2x6 nominal block planed to match the front legs.
Joinerys consists of the following -
All rabbeted joints are glued and brad nailed together.
The legs and arm/top caps are pockted screwed to the horizontal crossmembers.
The front, sides, and rear join with 3 1/2" deck screws and 5 1/2" lag bolts.
Stringers/mattress supports are 2x3 nominal.
Finish is Behr premium plus interior latex eggshell paint/primer sprayed with an HVLP sprayer.
If anyone is interested I can take some measurements and more photos. Right now we just have our old futon mattress on (we're saving to do some other projects).
Paint applied with HVLP sprayer (the type used in automotive finishing).