You are well informed. Felt underlay is a more traditional type and a 42oz weight is used widely in commercial installations because it is hard wearing and firm whilst providing exceptional support to the carpet. It is environmentally friendly as it is made from 100% recycled fibres, and has excellent thermal and acoustic insulation properties.
The main reason you do not often see it available in retail stores these days is because it is not as aesthetically pleasing as more modern rubber and PU underlays and also carpet fitters have to spend more time installing it which ultimately reduces the retailer’s profits.
back to top