If by noise from creaking boards. Only a well secured floor will stop that. Until it ages but then its fair game. Cork wont stop that. It will dampen noise from walking or rolling things across the floor. Wont eliminate it. One thing to consider is if it is a nail down product (the floor) then you need to think about the length of staple or cleat to use. A standard 2" cleat wont secure the floor well enough through cork. That extra height the cork has takes away from the amount of bite the cleat will have on the subfloor. Not a huge issue in terms of price but its an easy oversight that some may not think of.

And just to be helpful (probably not...but here we go), a 5" wide hardwood needs "glue assist" with a nail in place install. So there must be some gluing going on. The extra cost of the sound reducing membrane isn't what is driving the cost up. It is the two layers of glue (yes the acoustic underlay must be glued and then the hardwood glued over top = double stick) and the extra labor to do everything "twice". Twice the labour, twice the glue = twice the budget. A glue down hardwood is the most expensive form of hardwood install we have. Nailing is the cheapest. A floating method is between the two. A glue assist for a wide plank (ahem...5" ranks as wide plank = needs glue assist) is more expensive than a float...but not as expensive as a full spread glue down install. Check to ensure the quote for the nail down includes the glue assist. If it doesn't, then they could be missing a step. The 1/4" cork underlay (from iCork Floor) = $0.66/sf. Some shipping costs (maybe $0.45/sf) brings it to about $1.10/sf for the cork. The other $5/sf is the glue (assume $1/sf per layer = $2/sf) and the extra labor to do all this gluing. The material only adds $3/sf. The labor is the other $3/sf. $3+$3 = $6/sf for this install. If you MUST HAVE acoustic insulation + solid hardwood, then you must have the extra $6/sf. There is a possible solution: floating hardwood. Yep. Float the hardwood (very few solid hardwoods are allowed to float...so you need to look at engineered for this) and you FLOAT the cork underlay. No glue = reduce the material costs by $2/sf. Since floating a hardwood is just SLIGHTLY cheaper than a "nail + glue assist" install, the cost of labor for the floor itself won't change. Switch to an engineered hardwood that can float and then add the 6mm cork underlay. It will add $1 - $2/sf to your current quote. My calculations indicate you have 2500sf of flooring. The cork underlay will only add $2500 to your material costs. Compare that to $15K for the double stick total. The solution = floating engineered hardwood. You can have your cake and eat it to.

If you choose to buy yourself some time (7-10 years) I would suggest screwing down the boards that squeak. The sound comes from METAL (ie. nails) rubbing up and down on wood (the flexing boards). If they are screwed down, the movement AND the rubbing stops. To do this you will walk over the floor (in grid like pattern) and with a red pencil/pen you will circle the areas the create noise AND the areas that make all the movement. You will then go back around and screw down those areas until your noises are reduced to the point of acceptable. Once that is done, you can then have a look at the 'flatness' rating of your floor. If it meets the needs of the laminate then feel free to put down your new floor. Personally, I like to see 6mm cork underlay used over top of the old wood. This does two things. It helps "eat" 1mm or so of flooring deflection (taking it from 'not flat' to 'acceptably flat") and it offers noise reduction should the old floor continue to make noise. It is an added $0.90/sf but it is well worth the cost. Even the WORST $0.79/sf laminate over 6mm cork can feel like a dream floor. Just a little FYI for the DIY.

@shead, it is not an either/or between engineered and onsite finishing. I am planning to get an engineered floor — that will be supplied with the raw white oak top layer (to the thickness I specify) and it will be finished on site. There will not be bevels between the planks. I can specify the quality of the wood of the white oak (character grade or less knots — I’ve forgotten what all the grade levels are called). It is my understanding that if I want boards over 3 or 4” wide, the engineered boards help prevent cupping, curling and etc distortions. The humidity in the house also needs to be controlled. Although I love the look of really wide planks, I understand that people have more problems with 10” and wider boards so I plan to stay around 7”. There are various companies that offer this raw wood engineered product. The color of the white oak varies from where the trees are grown so that may impact your choice (and mine). I haven’t yet decided on what sealer (or stain) I’ll use — the installer will provide samples on site. If I go with Bona for the sealer, I also plan to use the Bona water-based protective coat (leaning towards 3 coats of Bona Traffic HD as the installer uses that a lot and is not as familiar with the similar quality Loba product). The installer also uses Rubio Monocoat; I haven’t researched that yet to see how it compares to Bona. So far, I haven’t heard a downside to taking this route — if there are any pros out there that think differently, please let me know.