Floor soundproofing options for new build house

I'm looking to add noise insulation to the floors in our new build 3 stories house. It's a brick/block build with eco-joists. The builder made it clear there is no sound-absorbant material between the joists and I'm not planning on lifting the underfloor boards to add any, as I suspect the underfloor boards are glued and screwed in place.

I'm looking to lay down 12mm laminate on the upper floors, because carpet is not an option. I want to dampen the sound leaking between floors using the laminate underlay. I'd like both impact and airborne noise to be dampened. I'm well aware of the need to tape/seal everything for best results.

I noticed there are at least 2 options for soundproofing mats that could qualify as laminate underlay. Both options claim to meet part E of the UK building code for soundproofing between dwellings.

• 3-layer sandwich mat - a layer of rubber foam sandwiched between 2 layers of mass-loaded vinyl, 15 Kg/m2, 12mm or 15mm thick. A few examples of this are: E-Board Timber, Noisestop Acoustic Underlay, ProSound SoundMat 3 Plus, Quietfloor PLUS, Acoustilay 15.

• 1-layer mat made of thick uncompressible rubber foam, 15 Kg/m2, 15mm thick. A few examples of this are: dB Matting 15mm, Hush-Mat 15.

I'm trying to decide between the two soundproofing mat types above, so I have a few questions, if anyone could share from their experience.

Some manufacturers claim the 3-layer sandwich mat can be placed directly under the laminate; others claim the mats can be placed directly under the laminate, but the laminate planks need to be glued together; yet others claim a layer of 6mm MDF is required between the mats and any laminate. Youtube videos show samples of these mats being quite soft and easy to squeeze by hand. The problem with the 6mm MDF requirement is that it would raise floor level by an additional 9mm (6mm MDF + 3mm underlay between MDF and laminate). This would be on top of an already quite high floor rise of 24-27 mm (12/15mm for the underlay mats, 12mm for the laminate).

Q1: Since all models are variations on the same basic idea, I wonder whether some manufacturers are more conservative with their claims, or if it is indeed not recommended to lay down laminate directly on top of the sandwich mats, as they might be too soft and have too much give.

Q2: The 1-layer mat option seems stiff enough that it seems plausible it could go straight under laminate with no extra MDF boards. It is also on average quite cheaper than the 3-layer sandwich mat options. Given that: a) mass is generally what dampens noise, which in this case is the same 15 Kg/m2; and b) dB ratings for both options are comparable; I wonder if there are practical differences in soundproofing results between the 2 options described above? Why would somebody use one over the other, if budget was not a constraint?

Q3. Talking to a carpenter about the 2 options it seems he has zero experience with anything of this sort and finds the idea altogether quite exotic. I've only lived in homes with solid concrete floors, so the idea of a hollow timber joist floor with its drum effect has me quite concerned. What would be the typical floor soundproofing strategy for a new build when carpet is not an option?


I would appreciate any experience or feedback you can share.