T&G Pine Ceiling Sealing

[JRobyn]

Hi gang,

I have seen some conflicting info in web searches about this, so I need the collective braintrust of the forum to clarify! I am putting up a bunch (about 1400 sqft) of white pine tongue and groove ceiling. The ceilings are all vaulted with kraft-faced fiberglass batts between the framing (no sheetrock).

We have pre-sealed/finished the exposed side of the T&G with two coats of high-quality urethane. So is it really necessary to seal the non-exposed side? I am worried that the boards may cup due to moisture absorption on the non-exposed side. Will the fiberglass insulation kraft facing provide adequate vapor barrier? If additional sealing or vapor barrier is needed I'd prefer to add a layer of 3 or 6 mil poly as opposed to another coat of urethane.

- Jay

 

[GGB]

If it were mine, I'd take the time to seal the non-exposed side, and the ends of all boards. It seems like most of the issues I've seen with warping and cupping are from the boards not drying out evenly over time. By sealing all sides, the boards stand a better chance of avoiding that issue.

I'll defer egarding adding an additional vapor barrier, but I'd be concerned that you could be trapping moisture between the kraft paper and any additional layer you add. I'll be interested in other TBN'ers responses as I'm going to be doing the same pine/cedar ceiling in one section of our home.

Good luck!
GGB

 

[MarkV]

I did a cedar ceiling like you describe without sealing the unexposed side 10 years ago. No problems as of yet.

MarkV

 

[Uncle Doug]

My T&G pine has been up for 3 years with no issues.

 

[2manyrocks]

If nailed off correctly in a building with proper ventilation control, my guess is they won't cup.

Over time, roof leaks may discolor T&G pine ceilings, and that's something you might want to research to see if you can prevent. Roofs are like water heaters: sooner or later they are going to leak.

 

[TNhobbyfarmer]

I put up T&G pine ceiling in the getaway log cabin I built. I didn't finish either side. That's probably been 8-10 years ago. The exposed side still look like the day I put it up and there is no cupping or warping that I can see. I have a metal roof so I don't think there has been any leaking. In my opinion, finishing is strictly an option, not necessary.

The pictures were not taken to show the ceiling, but it does give you some view of the ceiling.

 

[boggen]

if memory serves, in my grandpas old log cabin / house. done 20 plus years ago.
i know there was a big debate of what todo thing like you are now in.

i do believe a 6mil plastic vapor barrier was put up. then T&G was put up. but i want to say the ends of the boards were urethane once maybe twice before they went up. once all up then was painted with 2 or was it 3 coats of urethane / stain to get desired texture? this was done in cathedral ceiling. i want to say 2x8s were used, and the entire depth of the 2x8s were filled with rolled insulation.

in bed rooms and bath rooms. it was regular generic flat ceilings. and i think T&G went up and then was 2 or 3 coats urethane. and then went up into attic and put down the insulation

==============
not really tongue and grove. but paneling that looks like tongue and grove on a small 21x24 foot cabin. with cathedral ceiling. it only had 2x4's as rafters in it. so rolled insulation put up. then 1" thick both sides foil hard board insulation put up after that. then used the foil tape on all seams. to create basically a vapor barrier, then the paneling was put up on the ceiling. then everything was urethane.

been way to long, i do not remember were a vapor barrier was placed for the bedrooms / bath rooms. i think it was between the T&G and the 2x4's / 2x6's in the ceiling. and the insulation went between the 2x?s and on top of the 2x?s

============
sorry no great help to ya. i just do not remember any more.

 

[retiredmgn]

Hi gang,

We have pre-sealed/finished the exposed side of the T&G with two coats of high-quality urethane. So is it really necessary to seal the non-exposed side? I am worried that the boards may cup due to moisture absorption on the non-exposed side. Will the fiberglass insulation kraft facing provide adequate vapor barrier? If additional sealing or vapor barrier is needed I'd prefer to add a layer of 3 or 6 mil poly as opposed to another coat of urethane.

- Jay

Question is, if it cups then what?
I wouldn't do an interior wall with out putting poly up. You are assured no drafts will be sneeking through. Also, without a continuous vapor barrier, any warm moist air from the iniside of the building will reach its dew point mid way through the insulation layer. This can cause a host of problems.
Any piece of wood, interior or exterior, is better served by having a cheaper balancing finish on the back side. An unfinished side nailed against poly will somewhat act as a finished surface. But not guarenteed.
Either way, my .02 is definitely put up the poly.
If it were me, I'd finish the backside with the cheapest urethane I could find. I lean towards the do it once, do it right.
Or one of my other favorites, 'the bitter taste of poor quality remains long after the sweetness of low cost is gone'.
(I got a bunch of these to tell customers ;-)

 

[randy41]

i have t&g pine ceiling (also is my roof deck) which is urethaned on the visible side only. its been there for over 10 years with no problems with cupping. there is roll roofing on top of it so that provides an excellent vapor barrier.(this isn't my roofing material, it was just temporary when i first installed it.)

 

[studor]

+1 on the vapour barrier - 6 mil plastic or better yet, thin foam. The facing on the batts does not form a good barrier. and the insulation will attract condensation. I have T&G pine over foam in my cabin -- no issues because the foam acts as the vapour barrier -- JMHO