Q: I’m a new condo owner and would like to install hardwood (like the BR-111 Engineered Tigerwood or Triangulo Tigerwood). The builder didn’t offer hardwood on the main level, citing the need to minimize noise transmission from my unit to the unit below. However, there’s nothing in the building codes or condo bylaws to restrict the use of hardwood, except a line about “flooring must be replaced with the same type (e.g., carpet) and quantity (i.e., square footage) as originally installed.”
I’ve known a few other owners to replace their floors without problem, although they bypassed the builder and the condo association. But I’d like to get condo association approval to avoid any risk.
It’s a 4-story, townhouse-style condo (a 2-story unit over another 2-story unit), with wood frame construction and a gypcrete subfloor (ugh). The base carpet/pad is a 25oz plush carpet with a 6lb pad.
I noticed in a previous post that you suggested using Sound 6 plus 6mm cork underlayment. Assuming I opt for the BR-111 engineered Tigerwood, is this the underlayment you’d suggest for me? What about PadTech FloorArmor, or Maxxon’s own Acousti-Mat II, or one of the million other rubber underlayments? Shouldn’t the gypcrete help to isolate the sound as well?
Should I float the floor? Or attempt a glue-down installation? Is one better than the other for sound transmission/impact isolation?
What combination will make the engineered floor sound more like a 3/4″ solid (to me)? I’ve noticed that laminate floors (at least in the flooring showrooms) can be much more “clicky” than the solid floors.
I’m hoping that I find an underlayment/installation method/hardwood combination that can achieve STC/IIC ratings similar to the base carpet/pad installation. That way, the condo association would have little reason to deny the request. I’d really hate to spend $15,000 on hardwood floors and then have to rip them out.
A: Going through a process with your condo association ahead of time is a very good idea. In order to do this, we will need to dig up some information for the carpet currently specified to go into your condo, then compare them to the ratings for hardwood underlayment.
Its tough to find builders who are willing to glue to gypcrete. Although most gypcrete is approved for glue down by the manufacturers, but there can be some issues with it when it comes to adhesive curing because gypcrete will absorb more moisture than normal concrete – thus making the curing process for adhesives or thinset mortars different. So I would suggest going with a floating floor, and thus we’ll do the numbers based on use of floor and underlayment in a floating system.
With a bit of digging I was able to find some STC and IIC testing on carpet, which I will admit has been tough to find in the past. Let’s first discuss what each rating means, and how it will matter to your Condo board. STC or Sound Transmission Class, refers to the amount of sound absorbed by a partition or in our case, a floor. This typically applies most to air-born sound such as conversation, music, etc. IIC or Impact Isolation Class, refers to the amount of sound created by impacts, such as walking, which is reduced by a floor. It is important to pay attention to both of these ratings when it comes to sound control for a condo.
We’ll start by comparing some IIC ratings. Now with a hard surface floor, such as the BR-111 floors you are looking at, they have very little IIC when compared to carpet, so you are relying on the underlayment to make up for this. 6mm cork, over a 6″ concrete slab subfloor produces an IIC of 23 on its own, furthering the concrete’s IIC of 27 to give a total IIC of 50. Your gypcrete should give very similar results, which means 6mm cork is roughly equivalent to another 6″ of concrete.
For the carpet’s IIC, a 25oz carpet on its own over concrete provides an IIC of 22. Carpet padding is just as varied as hardwood underlayment, but most pads tested provided roughly 5 – 10 IIC, with the median being about 6 IIC. So using the same concrete slab, that would give us a total IIC of roughly 56. If we used a more premium carpet pad, this can be pushed upwards of about 60 or so IIC. Overall, very similar IIC ratings between your basic 25oz residential carpet with pad and 6mm cork.
Now let’s look into an STC comparison. Our 6″ concrete slab has an STC of 27, much like the IIC. 6mm cork’s STC on its own is 24, which gives us a total STC of 51. The carpet STC data I found is based on a wooden subfloor over joists with a suspended ceiling unit made from gypsum board. In similar tests with concrete subfloors, the suspended ceiling unit provided and additional STC rating of 14. wood over joists style subfloors will typically differ, and no data was provided for the raw bare floor’s STC rating, but we can speculate that this will be somewhere in the range of 20-24 total, including the suspended gypsum ceiling piece to represent the ceiling below the wood subfloor. The overall STC rating provided by the 25oz carpet with a 1/2″ thick 6lbs carpet pad was 49. With some quick math that means basic 25oz residential carpet with a typical 6lbs pad is going to provide an STC of roughly 23-29, but to be safe let’s assume its going to provide on the higher end and go with 29.
This would put 6mm cork pretty close when it comes to both STC and IIC ratings versus our basic carpet and pad which is why we so commonly recommend it for condo owners. As you mention, there is a myriad of underlayment out there, some of it is great, others not so much. Personally, I am big on how a floor feels when I walk on it, which is part of why I am such a big proponent for cork, it just feels more like a solid floor under your feet than any foam underlayment – even the best stuff like Sound 6 and similar modified foam underlayment.
When you walked over the laminate, part of that hollow or “clicky” sound is due to lack of good underlayment and also part of the raw thickness of the floor. A 3/4″ solid is just that, a thick, solid floor so it will sound more like it, whereas laminate is much thinner, normally 8mm – 10mm in thickness so the sound just has less it has to travel through. Now this gets alleviated by good underlayments, which is why we so commonly suggest against cheaper, foam underlays as they just don’t perform as well. So, what’s the best set up for you and what will pass your condo association needs while also fitting your own wants?
First off, your looking at a couple of very good floors, personally I’m a fan of the triangulo as it is a very good floor and can be installed as a floating with a 5″ wide plank – so you get an easier install method and a nice wide plank to make sure its very stable. Combine this with good underlayment and it will both sound and feel like a nailed down solid hardwood floor. If you look into other products, find ones with substantial plies, thicker plies can be very nice for getting that solid floor sound.
For underlayment, I would suggest going with 6mm cork as a baseline. If sound is your primary concern, using 6mm cork as a substrate with Sound 6 over the top is a great option, but you will get a bit more movement in your floor than using solid cork. Another option would be 12mm cork or 6mm cork with a 3mm cork layer over the top if your concerned with overall floor height. This secondary option keeps the more solid feel under foot while beefing up the IIC and STC power with a bit more cork. 6mm has met all basic condo standards that we have encountered in the past and the regulations would have to be very strict to rule it out – so adding onto it should put you in the clear, but checking first is always wise. On any of the other underlayments out there, make sure you get STC and IIC test results to get the real ratings for them as this will help you compared them to other underlayment options.