Two pdf documents submitted by member Philip Perry outlining the design dimensions of the seatbase and seatcloth for an 88″…
Following additional information added by Ulrich FP via the forum…
For the wooden seat base frames do not use the jute straps, use a wooden board with some holes in it. Use hard stiff foam with a high specific weight, minimum 48kg/m³ . There exist two kind of foams (I don´t know the english terms) you need the more UV resistant one, the normal is cheaper, not that UV resistant and will become soft after 2 years. In German it’s called Kaltschaum (Coldfoam)= High-Resilience(HR) foams. Sweat, humidity and heat mean that these foams do not age well.
If you can get the brown Cocosfoam (Cocoa fibres embedded in latex) then use first a hard 3cm Cocosfoam and on top 3cm Coldfoam.
Use a a layer of 100gr. = 1cm white Diolen (wadding felt fleece?!) between foam and cover fabric ( so, foam and cover fabric will not grind itself). Do not use the grey recycling felt !!
For the metal back rests, before starting, protect the metal edges with a U-rubber profile, then again with 4cm foam ~ 35kg/m³, a layer of 1cm=100 gramm. white Diolenfleece and finally the cover fabrics.