A quality pocket spring unit is usually 6 inches / 15cm in depth you then need layers of upholstery on top of that to provide the comfort layers. Let’s say at a minimum 3 inches / 7.5cm each side of that spring unit. That would give a minimum quality depth, pre tufted of 30cm. Obviously after tufting the mattress upholstery is neatly compressed to avoid movements, undue settlement etc. This reduces the overall height.
All of our pocket sprung mattresses are between 30 and 33cm after tufting. Their pre-tuft height would be a few inches more. There’s an excellent photo of the tufting process here. You can see how a massive machine has to compress the layers to then get the tufts in. A high-quality mattress, like John Ryans, are jam packed with fillings and this tufting machine is the only way to get the tufts in tight enough!
For foam, Hybrid mattresses you want to be looking at a minimum of 25cm and for Latex we would advise 20cm and above. Latex is far more responsive and progressive so you don’t need as much of it for the same effect.
Any mattresses that are 15-20cm should really be avoided as there is simply not enough material, upholstery or support to last long term. Compression and sagging will occur far quicker in thin mattresses.
We hope that helps Anne if you have any further questions please give us a call on 0161 437 4419.