Proposed acoustic treatment of attic room - overkill?

[Cal Weldon]

Looking at this particular product, which seems to be the sheathing product.

STEICO – engineered by nature À Overview

It states:

Enhanced vapour transfer

Which is a blessing. Not having that around here I can only guess that in your parts they do things differently and hopefully, a reputable Contractor knows about the rate of transfer and if it is sufficient to deal with the unvented area between it and the insulation.

 

[Preamp]

So you don't have this stuff around and use OSB instead? We call it 'Pavatex', which is also the name of another manufacturer. All of the companies round here use this stuff, so I guess my roof is allright then? Assuming it is fine, what would that mean wrt. putting fiberglass absorbers directly to my walls then, with no additional air gap? Still not a good idea?

 

[Cal Weldon]

It appears to be a different way of thinking than on this side of the pond. If it does breathe as well as I can gather from the literature, it's probably ok. It probably wouldn't hurt spend spend a couple nights beer money and have someone local review it as we have here.

Roof deck sheathing here is either plywood or OSB and both require the vented space.

Tile roofs generally do not have sheathing. Directly over the rafters goes a slightly draped, reinforced synthetic underlay (with the gap for airflow), then cross strapping to support the tiles. That's it. I can't be certain why yours has as many components as it does. Was this originally a different type of roof?

I think the others can help you with the diffusiers, absorbers and the such as the only concerns I have are with what's beyond the OSB on the interior walls.

 

[Tromperie]

If it were me, I'd use the attic for storage and another room for music. The attic seems so small as to be lower than head height.

 

[Cal Weldon]

Sometimes you have to duck in a cave.

 

[tomchr]

It probably wouldn't hurt spend spend a couple nights beer money and have someone local review it as we have here.

I'm with Cal on this one. Getting a second pair of eyes on this would be a good move. It doesn't take much moisture to create a problem. Having to tear out your listening room to fix the roof and ceiling would suck. As would having to fix the moisture damage when you move (assuming it's caught in the home inspection).

Granted, modern European homes are air tight and have ventilation systems to suck out the moisture. But I bet the humidity in the house is still enough to create condensation if in the wrong spot.

Cool project, though.

Tom

 

[Cal Weldon]

Granted, modern European homes are air tight and have ventilation systems to suck out the moisture.

Not sure this is quite the same situation but your point is well taken.

Remember the R2000 fiasco? Airtight is an unnatural concept. Just like butter warmers inside refrigerators. Why do something wrong on purpose and have to do something more to correct it?

The rules of moisture control haven't changed. Our desire to conserve energy has and it is compromising our well being.

Let your building breathe now, and you'll be better able to later.

 

[Preamp]

Was this originally a different type of roof?

No, it was planned and built as a tiled roof. The other prevalent type round here are thatched roofs, but they're too expensive for a humble craftsman like me. And even they are built with pavatex nowadays, albeit with a little more space for venting between the thatching and pavatex.

If it were me, I'd use the attic for storage and another room for music. The attic seems so small as to be lower than head height.

Unfortunately this is the only (and biggest) room I could claim for myself. The height in the middle is actually 2.23m, so it's plenty to stand upright.

I'm with Cal on this one. Getting a second pair of eyes on this would be a good move. It doesn't take much moisture to create a problem. Having to tear out your listening room to fix the roof and ceiling would suck. As would having to fix the moisture damage when you move (assuming it's caught in the home inspection).

Except for some unforeseen events I won't move anytime soon. It will take me another 30 years or so until this shed is paid off. I'm living here for two years now; maybe I should make a hole somewhere and have a look with an endoscopic camera? I'll talk to some other roof maker when I meet one and invite him for a beer then.

 

[Preamp]

If there is an LED strip running along the top, then I wonder if you could use plastic baffles or attic vent chutes running vertically along the slanted ceiling to space out fiberglass equivalent insulation (or some folks on the Gearslutz forum seem to like Caruso Isobond or sometimes Basotect in some applications) a little from the OSB. These could potentially allow ventilation of moisture but would need to be relatively unobstructed at the top and bottom.

Yes, that's basically the next best idea. I'll keep an eye out for those baffles or chutes. Don't know how expensive they are or if our hardware store stocks them at all. Thinking about it now, I've never seen them 'in the wild' around here...

Another way would be to add vertical battens along the slanted walls, add a layer of fabric, then some horizontal battens with the fiberglass interspersed, and finally another layer of fabric on top and wrapped around the horizontal layer. That would seal the fiberglass on all sides with fabric and the additional cavity would allow for ventilation and probably even increase the effectivity of the absorber for lower frequencies. A little more work than originally intended, but still interesting to find out...

(...) also so that if and as desired, you could also later cover them further with binary amplitude diffusion panels or grating, which require little depth and could be done on one's own with a little homework if inclined and not inept like me.

Good point. Let's hope I won't need to, though .

 

[PLB]

Hi Lasse,

This link shows a method of reducing the level of low frequency modes in a room and is the method I shall be exploring should I run into such problems.

DP_woofer_room

Peter

 

[Preamp]

DP_woofer_room

Looks like an interesting approach. Will this work with two additional subwoofers together with a stereo full range setup? Or are the two subs the only speakers to deliver the bass and the main speakers must not go down as deep (ie with an active crossover)?



Here's another idea that just came to my head, regarding the sliding doors that I'm planning to install to get rid off the prevailing chaos . Being arranged vertically as they have to be to function properly, they would introduce some parallel and reflective surfaces to the room. So I was thinking: What if I made those doors out of Basotect instead of OSB/plywood/acrylic/whatever? Would that be beneficial in terms of absorption or even bass trapping because of the cavity behind? Or could I just as well use much cheaper wood instead, because it's simply a reflecting surface?

 

[youngho]

Depending on how it's mounted, as well as the presence of absorption behind it, gypsum and OSB can actually absorb a little of the bass frequencies.

If you really wanted to address the bass frequencies, and if you have access to a metal shop, you could consider vibrating panel or plate resonators (VPRs), essentially a metal (like steel) sheet sandwiched between damping material (Basotect is one option). These could be covered with perforated metal or possibly wood panels to limit the higher frequency absorption and potentially add some Helmholtz effect. One such commercial product is here: http://www.rpgeurope.com/downloads/download.html?id=19

Young-Ho

 

[Preamp]

(...) you could consider vibrating panel or plate resonators (VPRs) (...)

I've read about those. I consider them a little more 'advanced' than what I'm planning to do right now . But who knows, maybe I become obsessed about room treatment...