Sealing OSB for plenum use?

[Angelfire]

I'm working on my addition and have a plenum for the furnace/AC constructed using OSB. Just wondering if there's something I should use on the OSB to keep it from "shedding" over time and ending up with dust blanketing the house?

 

[pattenp]

Is using OSB for a plenum on a furnace okay? Seems to me it wouldn't pass code as fire safe.

 

[ddawg16]

I would assume that there are some code issues.....but, besides that, I see lots of other issues.....besides fire, it's a rough surface....more resistance (drag)...will absorb odors.....

I think it's just a bad idea all around...

With that said....I understand your thinking...it crossed my mind as well.....I'm in the middle of a 2-story addition and I have to get forced air from my existing house to the addition...I will be making my plenum's out of metal.

 

[StaggeringGoat]

I'll have to agree with the fire issue. Have you ever set fire to a piece of OSB? Burns like a freakin' tire...

 

[Angelfire]

It's how it's done here and right or wrong, it passes the inspections. I'm already planning to top the OSB platform with sheetmetal (over durock) so maybe I should consider the same for the interior of the plenum or just use type X sheetrock inside. It is a return air plenum (probably should have mentioned that). It's very tight inside obviously so I'm really trying to avoid trying to hang anything in there although that may be the best option. Better fast for a few days before tackling it!

 

[pattenp]

It's how it's done here and right or wrong, it passes the inspections. I'm already planning to top the OSB platform with sheetmetal (over durock) so maybe I should consider the same for the interior of the plenum or just use type X sheetrock inside. It is a return air plenum (probably should have mentioned that). It's very tight inside obviously so I'm really trying to avoid trying to hang anything in there although that may be the best option. Better fast for a few days before tackling it!

Being the return makes a difference. I have seen wood returns. I just automatically assumed it was on the output side. One problem with wood is it does collect a lot of dirt because of the rough surface. Just be sure to put the slick side of the OSB on the interior.

 

[mayday0017]

Painting the inside of it wouldn't hurt... would seal things up pretty good, but honestly if your filter is right before it and you are changing it like you should, you won't get much dust in there & the drag is whatever, HVAC systems are anything but smooth inside.

 

[Toomanytools?]

Well you should use tin ducting, but if it's OSB use a Low VOC Latex paint or water based polyurethane to seal it and make it slick inside. Don't know codes in NM, we had a return between floor joist here WA, that was lined with a 1/2" foil faced insulation. We had a new system installed and had to remove that 10' section and add metal duct. That method was done a lot in homes built in 60's-70's.

 

[Milton Shaw]

At the very least get a roll of flashing and cover the inside with that. Attach either with glue or you could use heavy duty stapes to the inside. That's going to be as easy as paint and will be a lot easier to keep clean from dust buildup

 

[Angelfire]

At the very least get a roll of flashing and cover the inside with that. Attach either with glue or you could use heavy duty stapes to the inside. That's going to be as easy as paint and will be a lot easier to keep clean from dust buildup

Are you thinking something like this:

http://www.lowes.com/pd_12522-205-6...hing&pl=1&currentURL=?Ntt=flashing&facetInfo=


That might work and would certainly be simpler than trying to maneuver SM panels in there.

 

[ddawg16]

Any reason you can't just use the flexible insulated ducts?

 

[Angelfire]

Any reason you can't just use the flexible insulated ducts?

Not sure why I would. One of the returns is tied directly into the plenum already and all the ductwork for the rest of the system is in place. I'm not about to re-route things as I just got done insulating the whole place!

 

[PAToyota]

Not sure how that is allowed by code since they won't even allow you to just box in a stud or joist bay for the return ducts any more.

 

[srmofo]

What about using particle board?

 

[Boomer343]

I'd use Thermopan to line it and use it for transitions as well.....lot easier to work with.