Not sure if this is the right forum area, so I apologise if it isn't.
I will try and be brief. We need a double (I think you call it a full size in the states) for my teen son, but it will also double as the guest bed, as every time we have someone stay the air mattress comes out.
My dilemma is the following:
Innerspring mattresses are expensive ($400-500), a 150mm (6") foam mattress is $99. If I made the farmhouse bed with slats and the layed over the top a sheet of ply (with air vent hole drilled in) do you think this would work? Or am I wasting my money?
Any help or suggestions would be appreciated, so thank you in advance!
it should work - I have a couple of single bed garage sales purchases as examples: a) a pine bed with slats (no ply) which came with a 100mm foam mattress - comfort levels depended very much on the weight of the sleeper, i.e. o.k. for smaller children only, b) a bed with drawers underneath which had a 19mm ply top with just a few additional cross supports underneath - I ended up drilling a quite few extra holes into it to allow for airflow & wouldn't recommend it for a humid area.
for what it's worth: I recently bought a new mattress ($AU 350 king size) which was one of these pocket spring mattresses which comes rolled up in a vacuum pack - surprisingly good - perhaps that's an intermediate option for you to look at.
I do not think you need a piece of plywood on top of the slats. Depending on how far apart the slats are and how firm your foam is. I just made a sofa with slats. They are 3.5 inches apart. On top of them, I have a 6 inch piece of foam (HR-33 from www.buyfoam.com) I love it. I actually think it is more comfortable to lay down on than my mattress.