Finishing the attic, need some framing and HVAC advice

[massimofinance]

Hi all, not boat related, but you all always help me, so I am posting this here. I want to finish my walk up attic myself. I am pretty handy, so feel comfortable doing this myself. Making a kids playroom. The builder left the H VAC tubes laying on the floor, see the pictures (that grey tube going from left to right). I figure I will just cut them and run them up the knee wall, along the roof line, and down the other side. I will have to switch from the round tubes to the square aluminum box material. Is that OK? I plan to heat with an electric heater, so I will not be overtaxing my heating system. Also, see in the pictures, above the knee wall, the builder put in a 1 x 3 nailing board? I assume I can remove that, right? Also, I cannot use Sheetrock, too heavy I think, so I will use paneling on top of insulation. Thoughts? Thanks!!!

 

[jbcurt00]

HVAC duct not tubes

Is that a doubled 2 by 10 or 12 just laying on the floor or is it part of the structure?

Never seen a 1X4 nailed long the top edge of a knee wall before. Not sure why its there, but its unlikely to be frivolous or it wouldnt have been put up or left in place. Its continuous, the top plate of the knee wall isnt. Perhaps it was used to help align the knee wall?

Not an HVAC guy, but moving the duct and making it significantly longer going up and over may effect air flow and cooling/heating in the room it feeds.

Might check the size of the floor joists of the attic. IIRC, attics are static loads, usable living space is a live load.

 

[bigdee]

Is that a supply duct or is it a return. Strange that is the only duct I see. Yes nailer can be removed. Why do you think sheet rock is too heavy? That double 2x beam concerns me the most......what size are the ceiling joists?

 

[Tim Frank]

Odd construction.
I'd have a professional have a look before you get too far down a path that you shouldn't be on.

 

[rbh]

I grew up in a house with an attic like that, sure was a fun place to hang out as a kid.

Not a carpenter so I am just guessing-, put the square/rectangular duct in the floor joists.
There is the hot side and the cold side so you need to insulate and put up a vapor barrier on the warm side, as well along the roof joist you need to install baffles to allow the warm air to get to the vented area.
(Anywhere heat meets cool insulate and let the hot air move out of the upper area so your roof lasts)

 

[gm280]

I think the 1 x ? was merely an alignment usage board and nothing to worry about if it was removed. HOWEVER, I would most certainly investigate the 2 x ?'s running the lengthwise across the area for sure. While they look weathered, I can't see there usage unless there is something underneath that isn't visibly obvious. I would contact a Architectural Engineer first and get his or her assessment before I would get too far involved.

Secondly, I also would think about running the duct work under the floor, if possible, instead of over the new room. The duct work running at the very top of the roof trusses is going to increase the load on the source to push the air up that high AND the temperatures will certainly be effected by the roof temps. But running under the floor of the new room will help keep both the load and the temperatures more constant as well. JMHO!

 

[Tnstratofam]

Is this a prefab house? The duct you are showing in the picture looks like a crossover pipe for a return. If it is and you decide to run it up and over in between the finished ceiling and the roof make sure you have the new duct work insulated properly. There will be heat gain in the summer in that duct line as well as heat loss in the winter. Also if you go from round to square duct be sure to size the duct work correctly to carry the same CFM airflow as the round pipe currently does. Size it with the insulation and space you have to work with in mind. Under sizing your duct work can be detrimental not only to your systems performance, but also its longevity. As rbh pointed out putting the duct work in the floor joists would be acceptable again so long as it is sized and insulated correctly.

In the long run it might be advantageous and cheaper to let a HVAC professional come by and give you some pointers on how it should be done.

 

[Tnstratofam]

If it's a prefab house or Modular home as I suspect it is, That explains the odd joists running down the center of the room. This will make running the duct work through the floor joists impossible as the two center joists are actually structural headers. The headers may be removable or adaptable, but you should consult a structural engineer about them first.

These homes are similar in construction to Double Wide homes with better strength as well as better insulation. They can also be stacked to make two story homes using cranes, or the attics can be closed in and floored on site for storage.

 

[jbcurt00]

It looks like theres already a window roughed in at the fair end of the room in the 1st pix, even if you arent governed by city/couny code enforcement, this is a helpful read

http://homerenovations.about.com/od/...quirements.htm

Good luck

 

[massimofinance]

thank you all. Yes, this is a prefab house. The joists on the floor running lengthwise I was told are the two sides of the house that were pulled together when they built the house. I looked into cutting those flush with the floor but the company that built the house told me not to, so I was going to build a cabinet over it. The ceiling joists are 2x6. I will look into going under the floor, great advice, would mean cutting through that floor joist.the duct is a supply duct to a bedroom, there is another one on the other side (I did not take a picture of it) but I am planning to only finish half the space, leave the other part for storage.I thought sheet rock would be too heavy, hence the idea to use paneling over insulation.

 

[Tnstratofam]

One other option for running the duct work would be to build a duct chase along the back wall. In the first picture you could build it along that wall close to the floor and create a small sitting area or incorporate it into a wall cabinet. This would allow you to keep the same type and size flexible duct work as well as hide it in the process. The size of the duct work should be written on the side, and can be picked up at a local HVAC supply house in 25' lengths. They should have no issue selling a box of the duct work to you as it isn't EPA regulated like the refrigerant is. If you can't pick it up that way some Lowes, Home Depots, and perhaps even Menards may carry it. You can cut the duct work in the middle ( or anywhere really just leave enough room to tie the new flex back on) add the new flex to the old with duct tape or foil backed tape. Then it can be re routed any way you need.

 

[massimofinance]

tnstratofam, that is a great idea. I will look into it.

 

[bigdee]

I am finishing the attic space in my vacation home which is a modular. However mine does not have that beam,also the joists are 2x8's and 16" on center and no hvac ductwork in attic. So you should have a copy of the blueprints and design specs that gives you the live load data. I do not believe you can use this area for habitable living space. 2x6 joists over a 14' span are not adequate.

 

[Tim Frank]

2x6 joists over a 14' span are not adequate.

^^^^ +1

 

[massimofinance]

Just thought I would report back here. I had a structural engineer come out and give me an opinion. He said I certainly can finish it right (Sheetrock, etc.). I just cant cut that middle joint in anyway (I will build cabinets over it, etc.). I took the advice to run the duct work along the back walls and will box those in (that was an awesome piece of advice). I also had it spray foam insulated, the room is the perfect temperature without having to run any vents at all. That stuff is amazing, Thanks all again,