Two twin mattresses when laid side by side on an extended ikea daybed are about 5” shorter than a king bed. I am thinking of buying an ikea daybed with 2 thin spring mattresses as recommended, then also getting a 3” king sized foam mattress topper.

The trick is that I’ll add a removable 5” wood extension off the end of the bed so the mattress topper can be laid out at full king size, including with king size fitted sheets. The 5” extension will be raised by about 3” from the height of the bed slats so it matches up well enough with a single thin mattress that’s in use, and have a 3” lip so that it looks good with king size fitted sheets wrapped around it. The 3” topper should also eliminate the feel of a gap between the spring mattresses.

That’s the concept at least. We have tall people in our family and want a real king size guest bed with a thick mattress, and I figure 3” foam plus 5” spring will be real enough. Before I buy everything, has anybody else tried something similar? Is this idea genius or stupid?

I'm looking for a sturdy king-size (or close) sofa bed with strong support when unfolded. Most models I've seen have flimsy metal legs or an unsupported section underneath, which feels unstable. I want something solid that can handle movement without risk of breaking.

I considered the IKEA Friheten, but it lacks full support on one side, and reviews mention sagging and discomfort from the wooden frame. Many IKEA sofa beds seem to have durability issues, which is disappointing since I’ve had good experiences with their beds and mattresses.

Ideally, I want a sofa bed that unfolds as one solid piece. Something like a modular design where rectangular sections simply extend into a bed. This would provide even support without empty gaps underneath, and I could add a mattress topper for extra firmness. It also needs to be comfortable in sofa form since I’ll be using it to watch TV and play PS5 in the bedroom.

Murphy beds aren’t an option due to ceiling height, and folding mattresses aren’t practical for storage or aesthetics.

Key requirements:

• Sturdy and well-supported in bed form

• King-size or close when unfolded

• Comfortable and firm (I’m open to adding a mattress topper)

• Works well as a sofa for watching TV and gaming

• Budget: ~£600 new or ~£300 used