Atlantic-need your opinion on markd's comments about my vapor barrier?
Could you clarify the comments from markd about my vapor barrier in my pics on my other post.
He suggested to remove the vapor barrier because it could cause mold.
The basement had blanket insulation for the past 3 years and at times, during the very humid weather I would notice moisture underneath the plastic and then it would disappear.
And I never had any problem with mold.
Would really appreciate your comments.
That information they gave ... is incorrect and against ANY cold climate building code regulations.
A vapor barrier facing the warm side of the living environment is required by code...and makes sense if one understands the reaction that warm air has when meeting cold air....
That person evidently finished off their basement with no code oversight... simply based on their own personal opinions....
Read up on the need for an insulation vapor barrier:
(You might note the point made in that article:
" ....One of the most important vapor barriers in the home is the one between the wall insulation and the interior side of exterior walls. Because wall cavities are sealed and have no means of allowing accumulated moisture to escape, an effective moisture barrier is crucial in preventing warm, wet air from entering the walls.")
Thanks once again.
Great article on vapor barrier.
atlantic - you are the know it all who has so much to learn!
Actually YOU are wrong. I am right! Atlantic-you jump to conclusions saying I remodeled my basement and claim to be an expert. That is not true. Maybe you should keep your comments to yourself. I am trying to help, and I base everything on facts. I dont need to bash you unless I am bashed!
Everything I stated is correct. Maybe you need to get out of the stone age with your techniques!
The poly barrier is so wrong below grade! Dont you get it?? This is a no brainer!!!Yumm mummy stated that they witnessed water droplets on the old insulations barrier. Duhh!!!! Lets see...if I put poly over it and totally encase it so it cant evaporate maybe the insulation will get wet and moldy and feed on the wood and drywall paper! ahhhh-yep!!
Well the old system yummy mummy described probably could still "breath" to the interior where it evaporated and..yeah you guessed it...no mold.
Yumm mummy-why do you think Atlantic is such an expert? Dont assume that a contractor knows what they are doing. I have seen so many "licensed" contractors that I wouldnt hire to replace a doorknob! I think you need to get more advice from someone else who knows what the heck they are talking about. I would not take his advice!!!
I think Atlantic give me great advice and support.
So do a lot of other people here.
a quote from bob villa for what its worth!
Question to bob villa: My question is whether it is advisable to install a vapor barrier below grade on the inside of an insulated wall? for example, my basement wall is a block wall. I framed the inside walls with 2X4's. I then insulated with fiberglass batts. Should i install a vapor barrier over the insulation
bob villa:"You do not need a plastic sheet vapor barrier over the insulation.
If you used simple unfaced fiberglass batts between the 2x4s, then you would still not use a plastic polyethylene sheet vapor barrier."
He doesn't know what he is talking about.
markd, I will let you know if I ever get mold, how about that?
"Both of these are good advice. Not only don't you need a vapor barrier you're one step better toward eliminating potential mold problems. I'm not sure if the article covers it but something I've done on jobs is use the XPS, use P.T. 1x4 as strapping (with Ramsets through the strapping and through the XPS in the walls). If you can find a source use DensArmor Plus or DensArmor or equivalent instead of sheetrock or blueboard...a few extra bucks per sheet...this also eliminates potential food sources for mold to breed on. A few squirts of canned foam insulation and you're virtually airtight, depending on how you finish off around windows and along the sill/joints. You might have to rip the PT sills for the floor to accommodate the difference between 3-1/2 inches and the thickness of the XPS and whatever you use for strapping"
Use rigid foam (expanded polystyrene or extruded polystyrene) against the concrete. Do not install any plastic sheeting -- no poly -- anywhere. Do not install any fiberglass insulation. For more information, visit www.buildingscience.com."
"IX. VAPOR RETARDERS AND INSULATED BASEMENTS
Below-grade basement walls differ from above-grade walls in that they are vulnerable to ground moisture wicking into the wall or basement floor. Because of this, it is important to maintain the drying potential of the wall since one never knows if the long-term moisture drive will be from the outside or the inside. A masonry wall is capable of absorbing large quantities of water due to the capillary action of concrete. If the masonry wall unit has hollow core, air movements within the wall also increase the thermal and moisture movement. For this reason, it is recommended that a vapor retarder not be used in a wall that is partially or fully below grade. If a wall is above grade, such as in a walk-out basement, then that wall may use a vapor retarder, if the climate dictates a vapor retarder in the above-grade walls.
If no stud wall is available, the insulation can be applied in blanket form with a perforated flame-resistant facing. Applied directly onto the wall, this is often used on the top half of the wall only, which may take it to the depth of the local frost line. If hollow core masonry units are used because of the air convection that takes place within the wall, the insulation should be applied on the entire wall.
While it is sometimes suggested that an airspace should be maintained between the masonry wall and the stud wall insulation in order to keep the wall dry, in actuality this may make matters worse. This vertical airspace can lead to a convective air loop, thereby increasing not only the thermal but also the moisture transfer within the wall. If a full height stud wall is used in addition to the masonry wall, this stud wall is often inset an inch or so, increasing the depth of the cavity to be insulated. The entire depth of this wall cavity should be insulated. This also insulates the back of the studs, reducing the thermal bridging of the wall.
If a stud wall is placed on a partially below-grade masonry wall, the stud wall should be insulated the same way as other above-grade walls in the house. When a vapor retarder is not desired, slashing a faced product's sheathing is not recommended, because narrow cuts are unlikely to signficantly increase vapor transmission. "
Lately I have read considerable debate about vapor barriers. When I started college in the early 1980's it was gospel that you needed a vapor barrier to prevent not only loss of indoor humidity, but also the heat that such vapor carries along with it as it wafts out of your walls.
And the rule is:
- put the vapor barrier on the warm side of the structure, that is:
- on the inside for houses in the north, which need heating more than cooling,
- on the outside of houses in the south where the predominant need is for air conditioning.
But... what happens when the conditions are reversed? Like Minnesota, we get some pretty hot and humid days here in Northern Michigan. Anybody up north with an air conditioned house with a sheet plastic vapor barrier is likely to have condensation just behind the vapor barrier.
And whether or not your house has air conditioning, your basement has a "de facto air conditioner" because it is kept cool by the all the massive amount of masonry and cool earth nearby.
So you will probably see moisture behind that vapor barrier whenever the weather has been warm and humid for a few days. Is this a problem? That's a tough question to answer because it depends on many variables. Since the moisture probably is not going to occur very often, I'm tempted to say it's not a problem. But then, consider this: if the moisture content of an untreated piece of wood gets above 29 percent, fungal growth WILL begin. It's not a matter of cleanliness... the fungus spores are everywhere. If the wood dries out quickly then the fungal growth stops soon and rot never has a chance to occur. But in a tightly sealed wall, the condensation may not dry out very fast, giving the fungi a chance to grow and maybe cause decay. It could also invite termites. My experience is it takes several weeks, possibly months, of persistent wetness to make wood decay.
One reason many old houses have lasted so long is that with no insulation the inevitable rain intrusions get dried out by all the draftiness. Fill the wall cavities with insulation and add a vapor barrier and now those little drops of water can't evaporate into the house, so they've lost one of two escape routes. Not the end of the world, just a reason for caution when insulating.
And it's possible that the moisture you've seen is caused by rain intrusion that evaporated and condensed on the vapor barrier. If this is true you should see the condition more often that just the dog days of summer, however.
So... what should you do? Perhaps nothing is the best choice. Monitor the situation, check the walls once in a while to see if the moisture only occurs after a few days of hot and humid weather (I bet that's the case). When you see water droplets, check the walls every day or two to see how long they linger.
If water stays there longer than a couple of weeks, I would consider some action. One thing you could do is violate the vapor barrier in a controlled manner. What I'm thinking is: take a dinner fork and poke some holes near the bottom of the insulated wall section, and some more at the top. You'll need to poke a couple of hundred tiny holes to be effective.
Another option is to change the vapor barrier. Polyethylene vapor barriers (such as Visqueen) are virtually impervious to water vapor. But there are materials that are vapor retarders. The paper facing on kraft-faced insulation is one such example. This paper has a thin layer of asphalt on the back side, which deters but does not stop vapor transmission. With such a material there should be less condensation, if any. I think you can buy rolls of this kraft paper vapor retarder, but I can't say I've seen it. One other product that is a vapor retarder is roofing felt (a.k.a. tar paper). But this gives off an odor so you might not like it.
There may be other products sold (look beyond Home Depot and Lowes, look at the contractor-oriented lumber yards) that allow some vapor to pass through. I'm just not aware of all the products out there. I see things advertised in trade magazines and I know that those lumberyards carry a lot more than Home Depot would ever stock.
Maybe you won't see any more water until next summer. This could be a trivial issue or something bigger. I'd hate to take chances though, so keep an eye on the situation."
BUT....I GUESS I DONT KNOW WHAT I AM TALKING ABOUT.
I apologize if I have caused you any annoyance.
unbelievable-pray to atlantic
I did not know that they where construction gods!!
Let me sum up this debate. I surely will not end the debate but maybe close the discussion for now.
Atlantic and Marcd both have valid points first of all.
What is the reason for a vapor barrior? What potential problem is trying to avoid? What is the potential gain/benefit? Personally I do not have good answers to those questions in my mind.
The main benefit of a vapor barrior is to stop the passage of AIR that contains water vapor. The elimination of air movement makes HVAC more efficient and comforable and should keep any moist air from going where it shouldn't.
The key thing is to NOT to apply a vapor barrior in such a way that it can trap moisture. A wall (Any wall) must be designed to dry to at least one side, to the interior or the exterior. Doesn't matter which.
In Yummy_Mummys case her walls are designed to dry to the exterior. She has a space between her insulation and the foundation I presume. This air space hopefully will allow enough ventalation to allow her wall to dry in that direction. This is why we use a vapor impermiable insulation when we attach directly to the block wall.
Another important consideration. If the vapor barrior is installed on the "cold" side of a wall there must be sufficient insulation to keep the humid, inconditiond, space from condensing moisture on the barrior itself.
I'm sorry - I am rambling - my original intent was just to provide a qucik summary of the debate. The main point is different situations, climates, construction techniques, etc call for different aproaches. There is no one size fits all answer.
Sorry - I'm not even going to grammer spell and punctuation check this post.
You presume correct. I have left a space of 3 inches all the way around the perimeter walls.
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