New Studio Build Underway

[howiedrum]

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[Soundman2020]

[howiedrum]

What do you think of using Sill Seal under sole plates? Builder brought it up.

[howiedrum]

One window or two? Originally I had one 5'0x3'-6" window on North side of building. Then when I resubmitted as second unit they required two of those windows. Then when I resubmitted again as just a studio, the draftsperson left both windows even though none are actually required. I want at least one for some natural light, but I am concerned that having two windows will not leave me enough wall surface for bass traps and other room treatments. What do you think?

[howiedrum]

Glass thickness. I know that the glass needs to be thick to match my isolation needs. Here are my calculations from last year's planning. Are they correct? Will you advise which thicknesses I should go with?

Exterior walls are 2 layers of 3/4 OSB = 5psf. and interior walls are one layer of of 3/4 OSB and one layer of 5/8 drywall = 5.25psf.
According to igamerica.com, 1/2" thick glass = 6.46psf. 3/4" = 10psf. The gap between would be 8" - 5/4 = 6"-3/4. (It's been a year so not sure how I got this gap figure). Plus it is laminated. In your experience, what glass sizing would you use on this wall? 3/4" and 1"?

Thank you!!!

[Purelythemusic]

Wow nice build, look forward to the updates!

Yes the contractor relationship is tricky. He should have spent time to understand the fundamentals of studio construction. There is a fair bit of faffing about that you wouldn’t be used to. Put simply, the normal mode of operation is: crack on. With studio construction there is a lot of thinking before you do the norm, then thinking again of the implications and getting a method where you do it all in the right order and to a high quality.

I would say, unless it’s specifically been stated in the drawings/details that the contractor had when signing, then it would be most fair to try to create reasonable costs for the extra time and material. It would help the contractor to have as much information as possible so he can get his plan in order so he is efficient with his guys.

As a small contractor I have almost always been out of pocket in situations where I go the extra mile. I can assure you, the worst situations are when you have a lot of people to manage, high quality is needed, the job has a strict timescale and is on a tight budget...something there needs to give, in studio construction it’s better that the timescale is flexible : )

[howiedrum]

Hi Purely,

Thanks and good to get your perspective. I pretty much did as you suggest prior to getting this. He agreed to go with all of my building materials and then after the building is complete he will subtract the costs of what he would have used for insulation, caulking, windows, etc.. for a non-studio build from the amount spent on my required sound isolating materials. His builder will keep track of any extra hours like extra time caulking and making custom doors and window frames. We are trusting each other and I feel pretty good about it.

[Soundman2020]

What do you think of using Sill Seal under sole plates? Builder brought it up.

That's a light-weight foam: not much mass to it. It's fine for sealing out water, but not so good for acoustics. If there are areas where the foam is only slightly compressed, there won't be enough mass there to get good isolation. The density of the foam is only about 1/20th the density of wood (or even less), so even if the foam covers the full with of the sole plate, it can't ever have enough mass to provide acoustic isolation

On the other hand the density of caulk is about twice as high as the density of wood, so even if there are areas half the width of the sole plate that didn't get covered (which shouldn't happen if you caulk properly! But just assuming that it did happen....) then you'd still have the same mass as the sole plate itself, so isolation would not be affected.

For comparison, the density of polyethylene foam is usually around 30-60 kg/m3, the density of wood is around 700 kg/m3, and the density of caulk is around 1600 kg/m3. I'm taking about ordinary white or other colored kitchen/bathroom caulk here. The transparent stuff is lighter (since it does not contain the coloring pigments), at around 1000 kg/m3, so not quite as good... but still twenty times more dense that then foam.

In other words: no, don't use that. Caulk it properly, in the manner I mentioned above.

- Stuart -

[Soundman2020]

One window or two? Originally I had one 5'0x3'-6" window on North side of building. Then when I resubmitted as second unit they required two of those windows. Then when I resubmitted again as just a studio, the draftsperson left both windows even though none are actually required. I want at least one for some natural light, but I am concerned that having two windows will not leave me enough wall surface for bass traps and other room treatments. What do you think?

You could go either way: one or two, doesn't really make much difference. You have plenty of wall surface area, so it's not going to have a terrible effect on acoustics.

The decision is likely going to be based on cost, not acoustics! Don't forget that for EACH window you need TWO panes of glass (one in the outer leaf, the other in the inner leaf), and EACH of those has to be thick laminated glass... it ain't cheap!

I recently saw some very bad advice on another forum where a so-called "expert" stated unequivocally that ordinary window glass (commonly known as "float glass") is better than laminated glass for isolation: Totally wrong! Here's why:

coincidence-normal-glass-vs-laminated-glass-CUT.gif (13.75 KiB) Viewed 38977 times

coincidence-normal-glass-vs-laminated-glass-CUT.gif (13.75 KiB) Viewed 38977 times

That shows the difference in isolation for normal window glass (light blue line) and laminated glass (yellow line): you can see the very large difference in isolation in the mid range, referred to as the "coincidence dip". That's a rather complicated thing to explain, as it involves bending waves and the speed of sound and angles of incidence, but the graph above shows it clearly. In simple terms: it's a bad thing that can kill your isolation if you are not careful.

Every solid material suffers from this "coincidence dip" problem (even brick walls, drywall, plywood, MDF, OSB, concrete.. everything) at some frequency, but damping compounds can reduce it significantly. (That's why I designed your walls the way I did: to minimize coincidence (and other issues) and maximize isolation.) Ordinary glass happens to have that rather nasty coincidence dip, and in fact with THICKER glass the dip moves down to LOWER frequency (even though the thicker glass isolates better overall... its complicated!).

But laminated glass is much better for this, as it has a thin "interlayer" in the middle: it is made up from two thin panes that are bonded together with the interlayer, which is usually made from PVB. That interlayer greatly improves the isolation, as you can see in that graph. So no, the guy telling people that float glass is better than laminated glass is absolutely wrong.

There are actually different types of interlayer, that can improved things even more. The normal PVB interlayer does a reasonably decent job, but there's also "acoustic PVB" that does a better job, and there are also some more exotic compounds that does a very much better job, as you can see in this image:

coincidence-dip-plot-for-several-glass-types-GOOD-BGR.jpg (52.57 KiB) Viewed 38977 times

coincidence-dip-plot-for-several-glass-types-GOOD-BGR.jpg (52.57 KiB) Viewed 38977 times

There's several curves on that graph: blue is normal float glass, black is laminated glass with normal PVB, green is with acoustic PVB, and red is with something called "Sound Acoustic Film". There's pretty much no coincidence dip at all with that stuff. Of course, as you go up the product range here, the price increases! Acoustic PVB is about the best cost/benefit balance, but even then it's not cheap. So ordinary laminated glass is fine if you are on a budget, but if you can spare a bit extra, then go with acosutic PVB laminated.

About thickness: the good thing about glass is that it is very high density: roughly the same as concrete, in fact. The density of most types of glass is around 2500 kg/m3 (give or take a bit), so it doesn't need to be nearly as thick as your leaf material to have the same surface density. But there's also the issue that you can't have insulation in between the two panes of glass (!), so you need to compensate for that by increasing the thickness a bit. In you case, for your isolation needs, I'd recommend AT LEAST 16mm acoustic PVB laminated glass. That's about 5/8" thick. It's made up from two panes of 8mm (5/16") glass with the PVB interlayer bonding them together. But it doesn't have to be symmetric: it could also be made from one layer of 10mm (3/8") + one layer of 6mm (1/4"), or even more unusually one of 11mm (7/16") and one of 5mm (3/16")... any combination that makes up the total 5/8" thickness is fine. If your budget allows it, then go thicker for sure, but not thinner. 19mm (3/4") acoustic PVB glass would be great. 16mm is bare minimum.

So I'd suggest that you get some quotes for different types and sizes of 5/8" laminated glass, to see what fits your budget, then based on that decide if you want one window, or two.

Of course, windows in the non-isolated area can just be ordinary glass: no special needs there. So if you wanted to have a window in the bathroom, or even in the front door, that's no problem: ordinary float glass is fine for that. You only need the expensive stuff for the isolated studio area.


- Stuart -

[howiedrum]

Stuart,

Thank you so much! Do you have a source for laminated glass? Only 1/4" thick is available locally.

[howiedrum]

Would these sealant be ok for the floor plates? If so is one better than the other? We have the Skia Flex you recommended on order but it's going to take a while to get and the builder want to put up the walls soon. These two products are available locally.

Untitled.pdf

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Untitled.pdf

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Dymonic FC Sealant.pdf

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Dymonic FC Sealant.pdf

(186.65 KiB) Downloaded 1780 times

[Soundman2020]

Would these sealant be ok for the floor plates? If so is one better than the other? We have the Skia Flex you recommended on order but it's going to take a while to get and the builder want to put up the walls soon. These two products are available locally.

Definitely not the "Vulkem 116" product: It doesn't seem to be very flexible. I would go with the "Dymonic FC Sealant": That's much more flexible, and should do the job.


- Stuart -

[howiedrum]

Thanks for your quick response Stuart!

[howiedrum]

Things are moving along. The front and back porches were poured. The sill plates for the walls have all been marked showing where the doors and windows will go and the holes have been drilled for installing. The builder asked about renting a crane for a couple of days so he could lower the walls on top of the caulking but the general contractor denied that request, so the builder is going to construct the wall in sections and then he and his co-worker will raise and lower them by hand. He will be using the three beads of caulk as Stuart’s graphic illustrated, under the plate before screwing down.

The local lumber stores couldn’t find 12ft length ¾” OSB, so they ordered 8 ft. lengths. A question came up in regards to nailing the OSB on the studs. Do you leave any gap between panels and then caulk the gap or do you get the panels as tight as possible with caulk applied to all studs before nailing?

Seven cases of the Sikaflex caulk you recommended are on order.

I decided to only do one window instead of two due to the cost of two. I still have had zero luck finding a source for 5/8 or ¾ laminated glass. Anyone know of where I can order that?

I will give more updates and add photos soon.

Thanks,

Howie

[howiedrum]

The build has really picked up. Three guys worked today and all walls are up. The builder wants to build the inner leaf ceiling first and then work his way up instead of putting the roof on first and working his way down. I shared with him Stuart's modular concept of building the inside out ceiling on the ground in smaller modules and lifting into place, but he felt that would take too long. He said he would tarp the top to keep everything dry and they would work under the tarp if it rains. He also wasn't sure how we would get the silencer boxes in-between the lower and middle leafs if he built the roof and worked down from there. I made him a bunch of handouts with pictures of my HVAC plan, and Stuart's in-between leaf module concept. He said he would read up on what I gave him and discuss it with the general contractor. Any comments? Thanks.