Please help with acoustic baffle box...

Plans and things, layout, style, where do I put my near-fields etc.

Moderators: Aaronw, kendale, John Sayers

Gregwor
Moderator
Posts: 1501
Joined: Wed Feb 01, 2017 6:03 pm
Location: St. Albert, Alberta, Canada

Re: Please help with acoustic baffle box...

Post by Gregwor »

The hallway might be your only way. It's not ideal and I won't write on here that I suggest or encourage it, but it is better than no ventilation.

Hallway for supply or return, that's going to be your call because you know what is connected to that hallway. Hopefully there aren't any heavily used/occupied spaces near by.

Greg
It appears that you've made the mistake most people do. You started building without consulting this forum.
atomicus
Posts: 39
Joined: Thu May 03, 2018 10:44 pm
Location: South of England, UK

Re: Please help with acoustic baffle box...

Post by atomicus »

Gregwor wrote:The hallway might be your only way. It's not ideal and I won't write on here that I suggest or encourage it, but it is better than no ventilation.

Hallway for supply or return, that's going to be your call because you know what is connected to that hallway. Hopefully there aren't any heavily used/occupied spaces near by.

Greg
No, it's right next to the front door, the stairs to upstairs almost opposite that, and there's also small office at the front of the house (to the right of the front door looking down at that diagram).

What are the considerations, and more so the CONCERNS, regards supply/return from/into this space then? It seemed to me that having this as an exhaust would be easier to implement, and using the fresher air from the space behind the door as my supply. Again though, which side the the fan should optimally be in this scenario I'm not 100% clear on.
Gregwor
Moderator
Posts: 1501
Joined: Wed Feb 01, 2017 6:03 pm
Location: St. Albert, Alberta, Canada

Re: Please help with acoustic baffle box...

Post by Gregwor »

What are the considerations, and more so the CONCERNS, regards supply/return from/into this space then?
The concern would be pumping oxygen depleted air into your living space. What I would suggest doing if you decide to dump stale air into the hallway would be to set your home air handler unit so that the fan is always running. This would cause your system to replenish fresh air into your living quarters.
Again though, which side the the fan should optimally be in this scenario I'm not 100% clear on.
Either location would work. However, the fan is typically at the far end of the exhaust (return) system. I can't remember the exact details about why without digging for endless hours through my notes, but from what I do remember, the difference between having it on your supply vs return is minimal. But, as you know, even if we can get 1% better, then we will try to do it. Basically, don't lose sleep over the fan location :thu:

Greg
It appears that you've made the mistake most people do. You started building without consulting this forum.
atomicus
Posts: 39
Joined: Thu May 03, 2018 10:44 pm
Location: South of England, UK

Re: Please help with acoustic baffle box...

Post by atomicus »

Gregwor wrote:
The concern would be pumping oxygen depleted air into your living space. What I would suggest doing if you decide to dump stale air into the hallway would be to set your home air handler unit so that the fan is always running. This would cause your system to replenish fresh air into your living quarters.
Well, UK residential properties don't have air handler units or anything like that. It's just not something you ever really see, even in new builds, and the property I'm in is nearly 30 years old. We have gas or electric central heating (a main boiler unit + radiators) as a means of heating our houses, but no dedicated air ventilation mechanism other than small self contained ducts for shower extraction fans and kitchen cooker hoods, plus windows of course lol!

Our building regulations stipulate all habitable rooms have something called 'purge ventilation', which should be capable of extracting a minimum of four air changes per hour, per room to the outside. However, an openable window meets these requirements in almost all cases. It is only in kitchens and/or bathrooms where a dedicated mechanical means of extraction is seen. Obviously in my situation, that is what this solution will resolve... at least that's the plan ha! :D

If you think it might be preferable, there is technically no reason I couldn't have the hallway as my supply, and have the extract go into the space behind the garage door? If that's the best way to go, I can do that.

One other thing I was curious about... should the boxes I have on the outer leaf not have some kind of vapour barrier? Will they be OK just sitting 'bare' in the space as I intend, either if I go with MDF or ply with an extra layer of plasterboard? Is moisture not ever a concern with these things?

Is there just the one filter? So if I had that on the extraction side, the passive intake would consist of nothing but the silencer boxes?

Should some sort of mesh be used at either end to stop insects, spiders etc. making their home inside the boxes?
Gregwor
Moderator
Posts: 1501
Joined: Wed Feb 01, 2017 6:03 pm
Location: St. Albert, Alberta, Canada

Re: Please help with acoustic baffle box...

Post by Gregwor »

Interesting how different HVAC is there compared to where I live!
If you think it might be preferable, there is technically no reason I couldn't have the hallway as my supply, and have the extract go into the space behind the garage door? If that's the best way to go, I can do that.
I don't have an opinion on which would be best. You'll have to make that call.
One other thing I was curious about... should the boxes I have on the outer leaf not have some kind of vapour barrier? Will they be OK just sitting 'bare' in the space as I intend, either if I go with MDF or ply with an extra layer of plasterboard? Is moisture not ever a concern with these things?
If you're sucking fresh air from that side, there shouldn't be any moisture issues but I would probably build that exterior box out of OSB.
Is there just the one filter? So if I had that on the extraction side, the passive intake would consist of nothing but the silencer boxes?
If possible, put one on the intake of your supply box as well as one leaving your room. This will prevent your silencers from getting dirty. As you can probably imagine, it would be a hell of a job trying to clean them if they got dirty!
Should some sort of mesh be used at either end to stop insects, spiders etc. making their home inside the boxes?
I would put a mesh, yes. But the filter should help that as well.

Greg
It appears that you've made the mistake most people do. You started building without consulting this forum.
atomicus
Posts: 39
Joined: Thu May 03, 2018 10:44 pm
Location: South of England, UK

Re: Please help with acoustic baffle box...

Post by atomicus »

Gregwor wrote:
If possible, put one on the intake of your supply box as well as one leaving your room. This will prevent your silencers from getting dirty. As you can probably imagine, it would be a hell of a job trying to clean them if they got dirty!
What kind of filter are we talking about here? Would it be one like this?

https://www.amazon.co.uk/GVS-Filter-Tec ... B07DRNN72P

I can see how that would be fitted on each end of the box, but it seems like something I would need to access in order to change periodically.

There are also these, which I have seen used as part of a fan-set up, which in my case would only be suitable for the extract, but would I need something this?

https://www.amazon.co.uk/Ram-100-4-inch ... B00MNJ4TO4

I'm not suggesting these exact ones, just the type.

Also, I couldn't see mention of it before, but in regards to the boxes themselves and assembling, what glue would you advise? Do you also nail around the edges?
Gregwor
Moderator
Posts: 1501
Joined: Wed Feb 01, 2017 6:03 pm
Location: St. Albert, Alberta, Canada

Re: Please help with acoustic baffle box...

Post by Gregwor »

What kind of filter are we talking about here? Would it be one like this?
Any air filter should work.
There are also these, which I have seen used as part of a fan-set up, which in my case would only be suitable for the extract, but would I need something this?
I can't really tell how that filter works. But it looks expensive.
in regards to the boxes themselves and assembling, what glue would you advise?
Any reputable brand/model of wood glue will work great. When I build stuff out of wood, I always tell myself that too much glue is just about enough. Use tons and wipe up any excess.
Do you also nail around the edges?
When I've built silencer boxes, I used my brad nailer and put nails probably every 2" or so. So to more clearly answer your question, yes, glue and nail it. You want it strong and sealed.

Greg
It appears that you've made the mistake most people do. You started building without consulting this forum.
atomicus
Posts: 39
Joined: Thu May 03, 2018 10:44 pm
Location: South of England, UK

Re: Please help with acoustic baffle box...

Post by atomicus »

Gregwor wrote:Depending on your design, either you will connect more duct work, or else it would have a grille/diffusor on the sleeve, or heck, you could just leave the sleeve with nothing on it.

The following picture is of a silencer box for an inner leaf that lives between the leaves. So, at one end of the box it's just a round duct inlet that flex duct connected to. The other end of the box has a sleeve on it (just a square made of 1" MDF) that penetrates through the outer leaf sheathing. The sleeve has some duct work on it because it had a fan attached to it. This allows us to penetrate through the sheathing without compromising the surface density of the system.
Big Silencer Done.jpeg
Here is a different box. It is an inner leaf box that has one big sleeve on it (sized for <300 ft/min air velocity).
Nook Ceiling.JPG
Youll need to leave a 1/4"-1/2" gap around the sleeve and REALLY fill it up with caulk. This will maintain the seal, surface density (as caulk has pretty much twice as much surface density as drywall), and it will decouple the sleeve from the sheathing.
I'm currently waiting on some supplies being delivered, then I can get on with building these things. However, something is confusing me regards these sleeves.

I will be going with the 4 boxes, so 2 on each side of the inner and outer leaf, but I'm not sure how I connect everything? From the picture you posted above, the sleeve is built into the box... so if I do this, and the box is up against the wall, how do I get to the gap around the sleeve to fill it with caulk?

Is there a correct order to doing this? Should I have all my insulation/plasterboard up, then cut the holes in it for the sleeves, or have all the boxes and necessary sleeving in place, then build the walls around them?

Regardless which way I do it, I'm having trouble imagining how I will seal ALL gaps with caulk, plus get access to that bridging point on the sleeves between the inner and out leaf box and deal with that properly.
Waka
Senior Member
Posts: 408
Joined: Sat May 20, 2017 7:47 am
Location: Lincolnshire, UK

Re: Please help with acoustic baffle box...

Post by Waka »

Hi Atom,

I've just read through your posts and your dilemma.

Looking at your photos and diagrams, there's seems to be an inconsistency. The drawing shows the garage door the entire width of the wall, but you have what looks to be 8 - 12 inches of block wall on the right hand side of your garage door in the photo. If this is the case can't you simply drill a hole through this block wall for your fresh air duct?

I've dropped some shapes onto your pictures to show you what I mean:
PicsArt_12-21-12.30.14.jpg
PicsArt_12-21-12.29.29-1200x634.jpg
Dan
Stay up at night reading books on acoustics and studio design, learn Sketchup, bang your head against a wall, redesign your studio 15 times, curse the gods of HVAC silencers and door seals .... or hire a studio designer.
atomicus
Posts: 39
Joined: Thu May 03, 2018 10:44 pm
Location: South of England, UK

Re: Please help with acoustic baffle box...

Post by atomicus »

Waka wrote:Hi Atom,

I've just read through your posts and your dilemma.

Looking at your photos and diagrams, there's seems to be an inconsistency. The drawing shows the garage door the entire width of the wall, but you have what looks to be 8 - 12 inches of block wall on the right hand side of your garage door in the photo. If this is the case can't you simply drill a hole through this block wall for your fresh air duct?
Thanks for the note. Unfortunately, we cannot make alterations to the front of the house due to legal restrictions, but even if that were possible, that section of brickwork you've highlighted isn't proportionally reflected on the outside, as you can see from the picture below.
Waka
Senior Member
Posts: 408
Joined: Sat May 20, 2017 7:47 am
Location: Lincolnshire, UK

Re: Please help with acoustic baffle box...

Post by Waka »

Ah I see.

Have your actually checked with the council that you can't put a ventilation grille in the garage door? You can get a white one and it would be barely noticeable.

Just drill a big hole with a core drill bit in the garage door, and fit the grille plate in the hole.

Like this one:
https://www.ac-one.co.uk/outside-air-lo ... gKVRfD_BwE

Definitely the simplest way of achieving fresh air.

Dan
Stay up at night reading books on acoustics and studio design, learn Sketchup, bang your head against a wall, redesign your studio 15 times, curse the gods of HVAC silencers and door seals .... or hire a studio designer.
atomicus
Posts: 39
Joined: Thu May 03, 2018 10:44 pm
Location: South of England, UK

Re: Please help with acoustic baffle box...

Post by atomicus »

Waka wrote:Ah I see.

Have your actually checked with the council that you can't put a ventilation grille in the garage door? You can get a white one and it would be barely noticeable.

Just drill a big hole with a core drill bit in the garage door, and fit the grille plate in the hole.

Like this one:
https://www.ac-one.co.uk/outside-air-lo ... gKVRfD_BwE

Definitely the simplest way of achieving fresh air.

Dan
It's something I could enquire about, but the problem then would be that I couldn't open the garage door, which was always the intention. Plus I don't know it would be possible to even construct this solution without then sealing yourself in the space lol!
Waka
Senior Member
Posts: 408
Joined: Sat May 20, 2017 7:47 am
Location: Lincolnshire, UK

Re: Please help with acoustic baffle box...

Post by Waka »

atomicus wrote:It's something I could enquire about, but the problem then would be that I couldn't open the garage door, which was always the intention. Plus I don't know it would be possible to even construct this solution without then sealing yourself in the space lol!
You could use flexible duct to connect the silencer to the grille in the garage door. And make it extra long so the garage door can still be opened. As long as you used insulated duct you shouldn't have problems with condensation in it. Each end would be attached with a hose clip and aluminium tape to keep it secure, and you should be able to open and close the garage door occasionally for replacing filters etc.

Dan
Stay up at night reading books on acoustics and studio design, learn Sketchup, bang your head against a wall, redesign your studio 15 times, curse the gods of HVAC silencers and door seals .... or hire a studio designer.
Gregwor
Moderator
Posts: 1501
Joined: Wed Feb 01, 2017 6:03 pm
Location: St. Albert, Alberta, Canada

Re: Please help with acoustic baffle box...

Post by Gregwor »

I think Dan's idea would work great!
It appears that you've made the mistake most people do. You started building without consulting this forum.
atomicus
Posts: 39
Joined: Thu May 03, 2018 10:44 pm
Location: South of England, UK

Re: Please help with acoustic baffle box...

Post by atomicus »

Gregwor wrote:I think Dan's idea would work great!
It's a good idea, and I can enquire, but I know the rules are quite strict, so ultimately it may not be something that I'm allowed to do. For argument's sake though, if I were able to do this, this would then be the passive intake I presume?

My query a few posts back might have got lost, but just to ask again as something is confusing me regards these sleeves between the silencer boxes.

I will be going with the 4 boxes, so 2 on each side of the inner and outer leaf, but I'm not sure how I connect everything? From the picture you posted above, the sleeve is built into the box... so if I do this, and the box is up against the wall, how do I get to the gap around the sleeve to fill it with caulk?

Is there a correct order to doing this? Should I have all my insulation/plasterboard up, then cut the holes in it for the sleeves, or have all the boxes and necessary sleeving in place, then build the walls around them?

Regardless which way I do it, I'm having trouble imagining how I will seal ALL gaps with caulk, plus get access to that bridging point on the sleeves between the inner and out leaf box and deal with that properly.
Post Reply