Hi Folks,
Drywalled a bathroom with one exterior facing wall in a 160 year old house. There is foam board insulation under vinyl siding on the exterior. I decided not to put in a vapor barrier, put in fiberglass batt insulation with paper side facing the exterior of the house, and drywalled with MR board.
Having thought a little about this, did I screw myself here? Should I have used a vapor barrier and will I have moisture problems now?
Is this a big enough problem that I should tear the drywall off and redo with poly vapor barrier?
Thanks guys,
Seth
Replies
Seth,
I'm not sure but I think you probably need to redo it. Someone who knows for sure will be along, but I'm betting it will help if we know where you are. Climate frequently makes a difference.
Another day, another tool.
Sorry, coastal Maine is the location. Low temps down to about -20 in winter. House is heated with forced hot air.
personally i think thats a big oops especially in a heavy heating area
and even more so in bathroom
obviously removing drywall and adding vapour barrier is a major hassle but the best long term solution
Check the bathroom for air leaks and seal them with a can of spray foam and for extra measure, install a slightly oversized bathroom exhaust fan.
Gabe
And maybe hook the fan and light to the same switch so that the fan has to be used.Any jackass can kick down a barn, but it takes a carpenter to build one.
If the bathroom has natural light, the lights may not be used all the times. Knew a fellow you put a pressure switch on the door so that when the door was closed the fan came on. A simple humistat switch will also ensure the running of the ventilation at all needed times.
It's all in the lifestyles.
Gabe
I like the idea of the humistat switch!Any jackass can kick down a barn, but it takes a carpenter to build one.
I'm in your neighborhood.
what is likely to happen is that airborne moisture will work thruthe drywall into the wall cavity to be stopped at the kraft paper. The paper is intended to go on the insdie of the wall towards the living space - source of moisture and heat.
Since this is a bathroom, you have a good chance that the amt of moisture will be more than average.
But it is only one room in the house. With a vent fan that actually gets used, you can prevent too much moisture build up. If it were mine, I would try not to use it as a sauna and not worry about it. I'm betting this was balloon framed. If so that works in your favour since the moisture that gets into the wall cavioty can vent upwards and out.
IF
You did decide to redo it all, you would want to turn the insulation around to have the VB on the inside. If you left it backwards and added a plastic VB on the inside, you could be making it worse. Moisture that gets into the wall would be trapped long enough to feed mold. As it is, moisture taht enters the wall cavity has a chance of drying to the inside again.
Sleep well, there are bigger things in the world to worry about.
Excellence is its own reward!
seth... don't worry, you can reframe it all in about 5 years when you have more time and money...
3 no-no's... the foam on the outside is a good vapor barrier, the kraft paper is a good vapor barrier except that it leaks like a seive around the edges, the fibers in fiberglass insulation are an ideal condensing surface..
all three are located EXACTLY in the wrong place for you...
on the wrong side of the dew point..
two solutions... rip it out and replace with foam in place or cellulose dens-pak.. then use a dry-wall vapor retarder
or try to make your present condition into a vapor retarder along the lines of what jeff and gabe were talking about .....
seal up every crack with caulk, apply a vapor retarding paint.. and make sure your fan is going to ventilate all of the excess moisture and that it ACTUALLY gets used
but hey, whadda i no ? Happy EasterMike Smith Rhode Island : Design / Build / Repair / Restore
latex paint qualifies as a vb.
throw on an extra coat of paint....
for baths and kitchens...I like Perma White.....tinited to what ever color ya like...
then remember to run the fan...which is ducted outside, right?
Jeff
Buck Construction Pittsburgh,PA
Fine Carpentery.....While U Waite
Don't start all over, but don't do that again either!
Definately not a good idea to put two vapor barriers back to back as the moisture that makes it thru one will be trapped between the layers and possibly lead to other problems like mold. In a climatic zone like yours the VB should always be put to the warm side of the insulation.
Apply a vapor barrier paint or marine enamel and seal the wall bases before trimming. Make sure your vent fan is rated for the size room but don't bother to oversize it.