# Do I need Soffit's? I need lights and HVAC!



## grinthock (Dec 17, 2010)

Without a fancy drawing -- square HT, it's a new install, doing double walls with 2x5/8 W/GG drywall and everything thus far is decoupled. Ceiling is clipped.

I don't need soffits. There is no HVAC trunk, plumbing, anything above my head. It's all on the other side.

That being said - I do have other concerns. "Every time you make a hole you damage the integrity of the insulation" --- Dammit --- I keep reminding myself of that.


Ok so without a soffit

1) How do I run a dead vent into the room - there is no way to make it long enough to muffle the sound.... I need to have forced air -- IN somwhere, and exhaust somewhere else... Without a soffit -- how do I do that (I'm assuming with a soffitt the air would come IN the front and exit the rear or something similar, with a muffler all the way down the inside of the soffitt) 

2) Lights -- I was going to use wall sconces, but isn't that going to be a problem if I put 4 wall sconces on my nicely sealed DD/GG wall ? If I used pot lamps on the soffitt, then it's nice and sealed (pot lamps in a soffitt with a muffler has it's own issues of heat thou, don't think i could fit the heat box + insulation + muffler running past)

I'm getting down to the details now -- need to button it all up - spent the last two months learning and planning, and I want to get building.


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## bpape (Sep 14, 2006)

Well, sounds to me like you just identified a couple reasons that you DO need a soffit  Seriously, they're terribly handy for just what you described. The trick is to leave additional row of clips on the ceiling to attach it to.

If you're doing a dead vent, just suck air out of the room and naturally draw the from the other room. Creating a low pressure zone in the room will let physics work for you.

Bryan


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## grinthock (Dec 17, 2010)

You are wise as always Bryan.

So I really should do the soffit and some pillars for sconces so I can avoid breaking the seal as much as possible. 

the other option was to build two dead vents one for intake, and one exhaust, at opposite ends of the room on the exterior side -- but that still doesn't help me with the lighting, I guess if I did like a backerbox around the outlet box that would deal with it.


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## grinthock (Dec 17, 2010)

OK so I need to get a little more "serious" about my soffit design.

Somehow I have to get the vent into the room - and somehow I have to light the room. Every time I consider something I end up running around the same thing --- make a hole -- compromise the seal.

1) Ok so let's say I build a soffit, and I decide to run the vent within the soffit -- unless it's a really big soffit, how would I run the vent if I also have to put pot lights in there -- because the pot lights need a heat box, so then the vent tube won't fit in as well... 

2) If there really is an acoustics reason for pillars -- I could do that, and mount sconces to the pillars and then avoid the pots - but I see people with pots on the soffit, and i like that --- the room is only 11FT wide -- so i don't want pillars eating my space.


Thoughts?


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## bpape (Sep 14, 2006)

If you do can lights in the soffit and the soffit is built AFTER the room is drywalled, problem solved. Any out in the middle should have MDF backer boxes in them.

Pillars can hold outlets to again minimize penetrations assuming they're built after the room is drywalled.

You can do a soffit as small as about 8" high and say 16" wide. Can lights run in either the inside or outside portion and vents run in the other section. You're going to want to do smaller cans - like 4-6" ones rather than the standard 8" lights - though those could be done if the soffit is made taller.

Bryan


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## grinthock (Dec 17, 2010)

Bryan;

I see where you are coming from on that... So if I make a wider soffitt - I can jam both in there. Option #2 is backer boxes - could be done - maybe might still do it.. 

I would like your opinion on the dead vent issue. 

Similar to the suggestions of others if I had a dead vent system on the outside - do I still need a soffit inside or is the dead vent system enough to muffle... Also, if I did a dead vent - that handles the exhaust (we pull through the dead vent), but how do I handle the intake, do i build a similar dead vent with no fan?


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## bpape (Sep 14, 2006)

Correct. Another inlet on the opposite end of the room to allow the suction from the exhaust fan to draw air in.

No matter where you put the vent, you'd ideally have at least 15' that is inside an isolation box and with at least a couple of bends in it. This goes for both inlet out outlet.

Bryan


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## grinthock (Dec 17, 2010)

Bryan;

Sounds like the best option for me if I want to avoid Soffits, is to do exterior dead vents for intake and exhaust and do my wall sconces with backer boxes.


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## bpape (Sep 14, 2006)

That's certainly another option. You just have to have all the additional space outside the room. Soffiting also makes a great place to route wiring for outlets, IR repeaters, speaker wires for surrounds, video cabling to the PJ, etc.


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## grinthock (Dec 17, 2010)

Bryan;

Yes I keep going back to that. The soffit would need to be sealed however because the vent would be inside it no? I suppose I could build the closed soffit for the venting, and then still put a ledge above for the ceiling ambient lighting + wiring runs.

When you do a Soffit design - where do I put the exhaust fan, obviously not in the room - but now I don't have a 15' dead vent outside the room either to put it in.


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## bpape (Sep 14, 2006)

For a dead vent regardless of location, the fan is on the end of the run outside the room to be as far from the room as possible.

For the soffit - if you build something say 16" wide and 9-10" tall, you build a center divider so that the area with the ducting is separated from the rest. Then the soffit itself becomes the box. The other 1/2 of the soffit can be used for lights, wiring, etc.

Bryan


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## grinthock (Dec 17, 2010)

Good idea Bryan! Then I avoid having to box my pot lights, plus I can do the overheat lights, plus I have cable trough. I could build my equipment cabinet up to the bottom of the soffit and then i'd have a way to run my cabling -- all in the sealed space..


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## grinthock (Dec 17, 2010)

Well I think I have a compromise... I think i'll do a double dead vent for the ventilation, and still build a soffit as well - but the soffit will be very shallow, only enough to house the pot lamps for the room...


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