I'm in the process of building our home/cabin. The exterior walls (so far) are 1/2" plywood over 2 X 4 studs. I started some stucco work at the base: some has tarpaper between the sheathing & mortar and some does not. Most of the ext. walls are still bare plywood.
I noticed that whenever anything is in contact with the walls on the inside that moisture and mold appears. I recently put insulation on 2 of the walls and yesterday reached behind it and discovered moisture and frost.
I've read about stucco walls and learned about the tarpaper allowing the interior moisture to escape, but it seems there is this moisture problem on all 3 areas of wall we have. the bare plywood, the strait stucco and the stucco with tarpaper. I need to fix this problem, and hopefully without demoing what I've already done. There is no rot damage as of yet.
I am wondering if I can get away with leaving the stucco I have on the lower 4' on 2 walls and adding some sort of insulation, then tarpaper and stucco on top of that, or do I have to tear off all the stucco and tarpaper the whole thing?
I want to take care of this problem as soon as spring arives and things dry out, and before any rot occurs. ******************************************************* 01-29-07, 08:33 AM aminator2002 What is the temperature where you are?
Stucco has very strict temperature limitations.
01-29-07, 09:01 AM Raven we're in Missouri. This problem has occurred recently during winter. I know the moisture laden warm air coming in contact with the cold outer wall is the culprit, and I know that tarpaper should allow the moisture to pass through and weep off on the outside, but this isn't happening. Many homes here are stucco and some are old. Temps are usually mild but we have had single digits, teens and 20s this winter. Summers can get 90s to over 100. But I think it's the winter months causing the problem.
I think I just need the right moisture barrier and/or insulation.
Thanks.
01-29-07, 10:43 AM Walks On Water Here is the problem.
Warm, humid air in the house it being attacked to the cold dry outside. As the warm moist air starts cooling off, the moisture will start to condense on the first thing it comes in contact with. It could do it right on the tarpaper or with in the insulation itself.
The moisture barrier needs to be right behind the interior wall. A polyethylene vapor barrier is usually installed on the wood studs just before the wall board is hung.
Not only does this cause water damage but wet insulation is like no insulation. It can even turn to ice if cold enough outside and cause ice damage.
There are paints available that are classified as “Vapor Barrier” to be used when blow in insulation has been put in the walls in older homes that did not have insulation.
Remember that any hole in the wall such as light switches and outlets can allow moisture to penetrate to the outside wall unless the have been vapor sealed.
The following site is long but really explains it.
01-29-07, 01:02 PM babthrower Yes, you need vapor barrier -- usually plastic sheeting by the roll -- so that when the vapor condenses on the wall, it will not penetrate to the insulation. So the vapour barrier is put on the 'warm' or interior side of the insulation.
Don't short-cut repairing the work you have already done. Mold in insulation can be very hazardous to your health. Also, dry rot can affect the wood framing between interior and exterior walls. (Dry rot does not mean rot that occurs in dry areas. It occurs where there is no standing water, perhaps, but where there is very high humidity.)
01-29-07, 01:13 PM babthrower (Can't seem to get this system to work to edit my last post. Sorry.)
One other thing about vapor barrier - it should be continuous. So where electicals and plumbing pass through the walls, and at other breaks in the plastic film, use tuck tape or some such to patch it. Also, overlap at edges and where walls and ceilings meet.
01-30-07, 08:27 AM Raven Thanks all. I had read that Wikipedia article before, but also several others that spoke of putting the terpaper between the sheathing and stucco on the outside of the wall. So it seems what I would have to do is remove the 1 X 12 boards that are on the interior wall... but then what about drying behind the insulation where there is some moisture? Right now it is just way to cold to expose that area without insulation (Our 1 year old sleeps there and it is the ONLY place for him, plus our bed is along that wall. House/cabin consists of a 12 X 16 room and 2 smaller unfinished/unheated areas that are 5 X 10 and 5 X 16, so the only living area is the room where the moiture problem is.) I don't think I should put up plastic while there is still moisture on the interior sheathing. If I take down the insulation to dry it, that would require a couple days and my wife works, and our son cannot be exposed to that. In other words I think I am stuck for another month or so until it warms up. I just do not want the insulation damaged. I was hoping I could do something on the exterior without taking down the boards and insulation.
01-30-07, 10:08 AM Walks On Water Yes, you do put tarpaper between the stuco and sheeting. This is to keep the moisture from the stucco away from the sheeting.
I think it's to late now to do anything with your moisture problem. Wait until Spring/Summer when you can dry it out good.
I think it would be easier to work from the inside where you don't have to disturb the stucco
You have to remove any wet insulation as it will not dry out and any other wet materials.
Correct any wet areas, re-insulate and properly install a good vapor barrior.
01-30-07, 10:54 AM aminator2002 Walksonwater is right. You definitely have to wait, but you should get the wet insulation out of there as soon as possible.
You don't need a vapor barrier in the unconditioned areas of the cabin. If they are truly not heated and kept close to the outdoor air temp then I don't think you should install a vapor barrier. It might actually create problems if you do. Perhaps Walksonwater can weigh in on that - I don't use stucco often at all.
01-30-07, 11:08 AM babthrower You are truly between a rock and a hard place. If you leave wet insulation in a heated area it WILL get moldy. Breathing mold spores can cause allergies, even lung infections. If you remove the insulation your son will be dangerously cold.
If it were me I would put my child in care for a few days while dry insulation and vapor barrier are properly installed.
By the way, after the wet stuff is removed you should heat the room for a full day to try and dry out the wall cavity as much as possible.
01-30-07, 12:56 PM Walks On Water I am starting to have a real issue with your cabin. How are you heating it? Fireplace, kerosene space heater or electric space heater.
Remember when you install a vapor barrier, it must be floor to ceiling and not just a few feet up the wall that you had to open.
While you insulation is wet, I think it would be too cold to present mold problem.
Anytime there is a temperature or humidity differential, you need to have a vapor barrier. May not be as important but you still need one.
In a closed room, when you exhale in cold air you can see the humidity condense right in front of you. This will be pulled to the coldest area and condense on the first thing it can. Cold air can not support any more moisture. While it is true, the likely hood that you will get moisture in you walls is less, it can still happen under the right conditions.
As I said in another thread, 26 grains of water at 40 degs is 70 % humidity. That same 26 grains of water is 100 % humidity at 31 degs. And that’s all the moisture the air can hold. The only thing changing here is the temperature..
02-01-07, 08:45 AM Raven We heat by wood stove. We also have a small electric oil radiator but that doesn't give off enough heat when it's in the teens and 20s as it's been lately. Oh, the insulation is not wet - yet. There is some condensation and even frost on the inside of the plywood when I reach my hand behind the insulation. the insulation itself seems pretty dry so far. I tarpapered the entire 2 walls on the outside a couple days ago. It actually seemed to help that day as it was sunny and the surface of the tarpaper was very very warm to the touch.
But I've had a nagging question.... I worked quite a bit of construction over a good 20 year period of time, some as an employee and some as a subcontractor (painting & renovations). I worked on a couple new buildings and the rest was mostly demo, removal of old walls and replacement. Most of this took place in New England where the winters are cold and the warm air certainly must have to contact some cold point in the walls. Now, here's my question - why did I never find plastic or foil or any other form of vapor barrier in those walls between the wallboard and insulation? The only time I've seen it was in finished basements, or stapled to the floor joists in the basement over insulation. Never in walls. I've worked for professional contractors who never installed a vapor barrier in walls where we did replacement. And I never saw any moisture damage except when there was water damage caused specifically by ice dams in the roof that leaked down through ceilings and walls. So, why over 20 years in a region with cold winters did I never see these moisture barriers in the walls, and never saw water damage or mold from condensation? The walls I worked on were mainly sheetrock, or old slat & plaster walls we demoed and replaced with sheetrock. Some few had wainscoat (wood)on the bottom part of the wall. It was ALWAYS the wallboard nailed directly to the studs over insulation, whether paper or foil backed insulation. Like I said, I only saw plastic in basements, and that was only in a couple.
This is why I am somewhat baffled. The moisture is happening due to the cold weather and the warm air on the interior coming in contact with a cold outer wall. But why did I never witness this same problem working on homes in New England?
02-01-07, 09:14 AM aminator2002 Paper is also a vapor barrier. It is more common. It's just a preference issue, if you install the paper faced insulation properly then you shouldn't have any problems. The company I work for has used many methods including foil backed drywall, foil faced batts, paper faced batts, solid fill insulation that doesn't require a vapor barrier and visqueen. I think visqueen is the easiest to insure a quality installation - too often people do not properly seal the edges of the paper batts and don't get all the way up to the underside of horizontal structure. I find that it is easy to see open spots and areas not covered. Sometimes people will even take the paper faced batts and cram them into a hard to reach area. The vapor barrier in that instance is compromised (as well as the insulation value) and you can get condensation. It only takes a small break in the vapor barrier to cause problems down the line. I am surprised that you haven't seen this before in your experience, it's been the most common issue I've seen.
There are also old buildings that don't have vapor barriers at all because they utilize an air space and that air space is weeped to allow any water that collects to leave the space. The typical problem with these walls is that sometimes secondary owners think they should plug the holes in the outside of the wall and stop the wall from shedding the water thus causing problems with the water locked in the wall.
If you are comfortable with paper faced batts then use them. I've had many return calls for warranty claims where vapor barriers weren't installed correctly so I err to the side of caution and prefer to see visqueen stapled and glued over the studs.
02-01-07, 09:42 AM Raven Yes, the air space. I know some old apartment buildings I worked on had spaces in the wall between the siding and frame. But some didn't. Are you saying the paper side of the insulation can act as a vapor barrier? If so, then I would still have to seal the top & bottom. The insulation is stappled over the studs and overlapped with the next piece of insulation - rather than stappled inside each stud leaving the studs wood exposed as I've seen some people do.
I just waould like to be able to avoid having to remove the 1 X 12 boards that are nailed and screwed into the studs... some are nailed with 2 1/2" ring nails... and you know how hard those can be to pull! I'm afraid I would crack some boards and have to replace them so if there is ANY way to avoid having to remove the interior wall.....
I am wondering if when spring comes if I do a thick coat of stucco & stone over the tarpaper on the exterior, will this form enough insulation in the outer wall that moisture will not congregate on the interior of the plywood but between the exterior tarpaper and the mortar? Or could I make some sort of insulating barrier between 2 layers of mortar that will keep the cold from reaching the sheathing? I know it sounds like a lot of work either way but I have wanted to have a thicker stone & concrete wall on the west & south sides - it will make the place more tornado resistant.
02-01-07, 09:53 AM babthrower
quote: Originally posted by Raven: ...the insulation is not wet - yet. There is some condensation and even frost on the inside of the plywood when I reach my hand behind the insulation. the insulation itself seems pretty dry so far.
If there's condensation and frost, the insulation will get wet. Repeated heating and cooling will distribute this moisture throughout the insulation over time. That frost and damp is what you need to get rid of by ventilation and heating before you close the walls.
quote: I worked quite a bit of construction over a good 20 year period of time .... I worked on a couple new buildings and ... removal of old walls and replacement. Most of this took place in New England where the winters are cold and the warm air certainly must have to contact some cold point in the walls. ....why did I never find plastic or foil or any other form of vapor barrier in those walls between the wallboard and insulation??
As for the old construction, the practice of making a conscious effort to make buildings draft-proof was not introduced until the 1950's. After that, old buildings were most cheaply insulated with blown-in particulate insulation such as vermiculite. Vapor barrier is only necessary on buildings that are quite well-built. Old drafty buildings have the moisture that condenses carried away by the wayward breezes when it evaporates.
I have an old set of 'handyman's encyclopedia' published 1963 and it deals fully with the principles of draft prevention and moisture control. Even in those days you could buy batt insulation with a built-in vapor barrier, a 'wrapper', with the 'warm side' treated to be vapor-impermeable or constructed of foil which added a heat-reflective property.
Today if we use fibreglass insulation with no 'wrapper' we use vapor barrier.
As for why you haven't seen it in new construction -- ask the contractors. Maybe they used batts that had built-in vapor barrier (foil or impregnated-paper one side of the batt -- the 'warm' side.) I hope you installed this right-side-in!
Batts with built-in barrier are better than no barrier, but plastic sheathing does a better job.
The contractors may have made vapor barrier optional to the homeowner, to cut costs. At the very least, it should be used in the roof. Costs saved at the construction level will certainly be lost many times over in heating and air conditioning expense over the years.
quote: The only time I've seen it was in finished basements, or stapled to the floor joists in the basement over insulation.
I hope it was installed between the upper floor and the insulation. It should always be applied on the 'warm' side, and in the case of a heated room and an unheated crawl space, that would be immediately beneath the floor and above the unsulation.
quote: Never in walls. I've worked for professional contractors who never installed a vapor barrier in walls where we did replacement.?
Maybe they used batt insulation which has a built-in vapor barrier. It's a bit tricky doing a good job with sheet plastic vapor barrier when you're tearing out wallboard and trying to minimize replacement of wood trim, etc.
Or maybe you worked only for, ummm, how shall I put this, rather minimalist contractors? Were you usually paid 'under the table'?
quote: And I never saw any moisture damage except when there was water damage caused specifically by ice dams in the roof that leaked down through ceilings and walls.?
That's rather unlikely. Never saw dry rot, in 20 years?
quote: It was ALWAYS the wallboard nailed directly to the studs over insulation, whether paper or foil backed insulation.
As I said above, in 'wrapped' batt insulation, one side of the paper envelope is usually impregnated with material to act as a vapor barrier. Did you notice if it had a 'right' side and a 'wrong' side printed on the batt? Foil is a vapor barrier. It should be installed foil-on-the-warm side.
In general, it's best to go by the building code and the instructions that come with a product than to go by what professional contractors do. OUr crawl-space leaks at one corner because our carpenter didn't know how to cure concrete. He learned his trade working for a contractor, who didn't want to take the time to do it right.
EDITED LATER: Didn't see Aminator's excellent post until after I had written this. Smile
02-01-07, 02:42 PM aminator2002
quote: Are you saying the paper side of the insulation can act as a vapor barrier?
Yes. And from what you describe you are installing it correctly by lapping it over the face of the studs.
"I just waould like to be able to avoid having to remove the 1 X 12 boards that are nailed and screwed into the studs... some are nailed with 2 1/2" ring nails... and you know how hard those can be to pull! I'm afraid I would crack some boards and have to replace them so if there is ANY way to avoid having to remove the interior wall....."
There are 1x12 boards facing the inside of the cabin that are nailed to the studs? Is this a paneled look? Please clarify this.
If so then there is another option but please do not attempt to make a thicker coat of stucco thinking that will solve anything. Stucco has very little insulating value (even if it seems that it would) and applying it thick will just result in cracks and other big problems.
You can do a system on the outside using rigid foam under a Exterior insulation system rather than stucco - (commonly called "dryvit") This system might get you the R value you need to move the dew point of the wall to an air space on the exterior side of the wall. You might also be able to use rigid foam under conventional stucco.
Please answer the question above and I'll get you more information.
02-02-07, 08:34 AM Raven Thanks for the posts. Let me try to answer babthrower first: yes, a lot of those old buildings were drafty especially in the outer walls. Some of the insulation was paper and some foil, but mostly paper. I have no idea if the paper ins was impregnated or not. last i worked one of those jobs "officially" was in 1995. It's been awhile. Anything since then has been work done on own place(s) or friends. The basement plastic was actually on the lower side, or the "cieling" of the basement itself, so, No, it was not on the warm or floor side.... however, the oil burner would keep the basement quite warm so maybe not really a problem. Who I worked for - it varied. First construction job was at my private school when I was 14 and 15 years old. We built 2 buildings from the foundation up and the "supervisors" were some of the school staff. These buildings were made to code and were inspected and passed. Some of the more temporal jobs I worked were for "fly by nighters" many of whom went out of business, and some in the lead paint removal industry were fined for breaking OSHA regs. (We did removal and replacement of wall material on some of these jobs). I did a bunch of little jobs for my landlord on the 2 buildings they owned. The last I worked for in 94 - 95 was a professional & licenced restoration company - so basically I've been on all sorts of job sites.
Animator2002, yes the 1 X 12s are nailed on the studs on the inside for a paneled look... with liquid nails caulking between the larger creacks and in the corners.
Rigid foam ins under conventional stucco... I was hoping this might help. Now should this be applied OVER the existing tarpaper? I must also say that yesterday I checked behind the insulation and while there is still moisture there it seems a lot less than there was beofre putting up the tarpaper the other day. Smile
02-02-07, 08:47 AM aminator2002 Yes, the tar paper acts as a draft stop and will keep the cold from migrating as easily. I will look into details using exterior insulation.
I am not sure but I think the tarpaper stays put and the insulation goes over it, but as I stated earlier - I don't have much experience with conventional stucco. I will look up some details.
02-02-07, 09:05 AM Raven
quote: Originally posted by aminator2002: Yes, the tar paper acts as a draft stop and will keep the cold from migrating as easily. I will look into details using exterior insulation.
I am not sure but I think the tarpaper stays put and the insulation goes over it, but as I stated earlier - I don't have much experience with conventional stucco. I will look up some details.
Yeah, that's been my problem... not having (any) experience with stucco. They just don't have stucco homes in the Northeast or Northwest. However there were a couple rich folks homes with thick stone or brick walls I worked on in the Boston suburbs.... unfortunately I never got to see the inside of walls in those because we were fixing ceiling damage or clearing ice dams on the roof instead.
02-02-07, 01:18 PM aminator2002 You've said that you can check if the insulation is wet. From which side did you install the insulation?
You can get it out, right?
You can install insulation again right?
02-02-07, 01:50 PM aminator2002 Mold/Moisture on interior sheathing Okay, as I understand it this is what you have, please confirm.
From inside to outside: 1x12 interior paneling Paper faced batt insulation stapled over 2x4 studs. 1/2 plywood sheathing tar paper
and then you want to apply the stucco?
You need metal lathe installed with proper weeping details - you might want to look into this at a public library or ask at a building supply store. Especially important is how it is installed at the bottom of wall and around windows.
Then you install the first coat of stucco to the thickness recommended. This is called the scratch coat.
Then you apply the finish coat. (This information in proper installation can be obtained from a manufacturers website.
Does this sound like what you are planning?
Please also answer if you didn't use tar paper under the stucco that you had the mold problem with?
02-06-07, 08:46 AM Raven
quote: Originally posted by aminator2002: Okay, as I understand it this is what you have, please confirm.
From inside to outside: 1x12 interior paneling Paper faced batt insulation stapled over 2x4 studs. 1/2 plywood sheathing tar paper
and then you want to apply the stucco?
You need metal lathe installed with proper weeping details - you might want to look into this at a public library or ask at a building supply store. Especially important is how it is installed at the bottom of wall and around windows.
Then you install the first coat of stucco to the thickness recommended. This is called the scratch coat.
Then you apply the finish coat. (This information in proper installation can be obtained from a manufacturers website.
Does this sound like what you are planning?
Please also answer if you didn't use tar paper under the stucco that you had the mold problem with?
Yes that is how it is constructed, and the insulation was installed from the inside.
I know how to do the stucco. Around here we use chicken wire. I also notice around here many stucco'd homes have the stucco coat going strait INTO the ground so I don't think they have a weep system. (??)
Yes, there are some areas I applied stucco directly to the plywood after running out of tarpaper. However, I notice NO difference between the moisture on the inside in these areas compared to the moisture where there was tarpaper under the stucco, or where there was only bare plywood. I tarpapered over that stucco rather than demo it so in a couple areas it goes : plywood sheath/stucco/tarpaper (and will stucco over that) and in others it goes: plywood sheath/tarpaper/stucco/tarpaper, and then in the higher parts of the walls it is just plywood/tarpaper. (Right now.)
ok, it probably sounds like something that around here is called "Ozarked" meaning we do with what we have or what we can afford at the time... like the toggle switch hanging from the dash that turns off the heater blower that's stuck on high setting because the mechanic couldn't find the ground wire a mouse chewed ..... now THAT is an example of "Ozarked." Roll Eyes
I can feel behind the insulation because the 1 X 12s are not completely installed to the top of the interior wall. there is also one wall where it has the insulation without any paneling yet. I can feel a little moisture behind both on the exterior sheathing side, not the interior paneling side.
And as I've said before I really could not remove the insulation under the panneling without demoing the panneling, and the panneling is installed with ring nails, in corners it's pieced in and nailed diagonally into the next walls panneling, and nailed/screwed in one place to a horizontal shelf. In other words it would be very difficult.
The insulation paper does appear to have a black inner surface between the fiberglass and paper backing - tar compound?
02-06-07, 08:59 PM aminator2002 I'm scared now. Big Grin
I think the insulation with paper face is fine and I think as long as you continue to install the stucco over tarpaper that it might work out. I don't agree with the concept of applying tarpaper over a layer of stucco in place, but it certainly seems like I'd have a hard time talking you out of it.
I strongly urge you not to install your stucco below or even touching the ground, but it sounds like you have in place examples to overrule me.
Good luck! Hopefully your work will last a good long time.
02-06-07, 10:16 PM babthrower Travelling hopefully can be overdone. Oh, well, people do it all the time. I would suggest a savings account to set aside money for modifications as needed in future. Frown
02-06-07, 11:38 PM DvdGStwrt Stop. Just stop what you are doing right now. No more paper, no more stucco no more anything.
Get a dehumidifier, set it up in the affected room. Leave it for a few days and see if running that dries up the moisture.
Now lets look at it from the side that there is nothing wrong with your insulation, nothing wrong with the wood, nothing wrong with the stucco and tar paper.
Just how humid is it in the house?
We live in 450 Square feet of space, in that space we have two adults and a big dog. We also have the kitchen sink, bathroom sink and shower. Along with two people showering every day and doing dishes by hand everyday I also cook, which a lot of steam is released. For the relatively small space and all of that water vapor being released we would (if this place was sealed up tightly) have a serious problem with condensation in/on walls in the winter.
I can boil the kettle to make a cup of tea and effectively fog up every window in the house. Small house, not enough room for too much water vapor. Thus a little water is actually a lot of water given the volume of air space.
I'm thinking you need to ventilate the house a little more to compensate for two adults, one kid and the space you have to work with. You say cabin I picture a small building, one living space, two small bedrooms, a small bathroom all compact and relatively close together. I'm also thinking that you may have paid particular attention to sealing up the house to keep it warm. You may have sealed it too tightly resulting in too much water vapor to the volume of air inside.
The materials you work with might be working properly if they were under the conditions that come with a larger house with better ventilation. However they may be over taxed, being asked to handle far more water vapor for the volume of air thus are failing miserably in their job of keeping condensation to a minimum.
Tell me what you think.
02-07-07, 08:02 AM Walks On Water My last comments on this. Read my other comments.
In the North, in the winter, we need to HUMIDIFY the house as it is really to low for healthy living. I try to keep my house around 30-40% but the colder it is outside the less chance I can maintain that with the humidifier I got.
Do you, anybody out there, get more nose bleeds in the winter? More congestion in the winter? My ENT (Ear, Nose and Throat) doctor gave me a PERSCRIPTION for my humidifier do to dry nose syndrome. Good for my taxes and my nose problems.
Why is it low you may ask. Because cold atracks humidity.
Insulate and vapor barrier is the answer in the cold northern climate otherwise any mositure in the house, cottage or cabin will migrate to the cold exterior walls, condense and freeze there.
Now it's time to through another log on the fire. Bye.
02-07-07, 08:18 AM Raven I would say the room gets fairly humid...but boiling tea water does not steam up the windows at all. My wife recently bought a humidifier because on really cold days it gets so dry from the wood stove that even the pan of water we put on the top does not help. The baby especially gets dry throat, and we do also. I'll try and see if I can post a picture of the place, though it won't show the particular work we've been discussing. This has actually bee a pretty hot topic and I notice by past threads others have had similar problems. Those of you who have said it might be sealed up too tight may be right. In the fall I went around sealing every little hole and crevice with caulking or tar depending on where it was.Or else I nailed a piece of wood over a gap and caulked it. I stopped 95% of the drafts,especially around the bed and crib but by doing so I probably allowed the moisture no way of escape Frown
This is the main wall in question. This pic was taken last summer. The stone room is now enclosed except for a small area in the back, and the wall stucco'd about 4' high with tarpaper attached up to the roof:
This is what was built as of November (we have extended that hall area since). The area in question is the left side wall of main room and under the window in front (top left)
This is a picture of the front as of the end of December. You can see the partial stucco on the front... this is the stucco without tarpaper under it. It is now covered with tarpaper, and like I said it seems to have less moisture now but still some. Oh, the total sq. footage of enclosed space we have at present is only about 327' so it is small at present.This does not include the stone room which is still in the process of being built.
Moderator's Note. The pictures were remove as they would not open and were locking up the post. I believe the picture are to big for our system. To post large picture, please just include the URL code to the site where they are posted. I tried the link at photobucket.com and it would not open for me.
This message has been edited. Last edited by: Walks On Water, 02-07-07 08:26 AM
02-07-07, 10:32 AM babthrower The too-humid or not-humid-enough issue is misleading.
Air contains water vapor, and the warmer the air, the more vapor it can contain. So warming the air will increase the amount of water it can take up from the surroundings: human breathing, cooking, washing clothes, cleaning, pans of water on the stove.
So water will evaporate faster from pans on the stove, from drying clothes, from sweat-dampened bedding, etc. , when the air is heated than when the air is cool.
But...
...now this moisture-loaded air hits an outdoor-facing windowpane or wall. The air cools. It can no longer 'hold' as much water as it could when it was warm.
You can see this process in action. When a kettle of water is steaming, place a cold surface -- the side of a metal pan that has been outdoors will give a good example -- in the steam. You will see that the surface gets cloudy. Eventually the cloud on the surface gets so thick it forms little droplets that run down the surface. This process stops when the metal gets too warm to condense the steam.
Back to the warm, moist air in the room as it encounters the outer-facing windowpane or wall. It drops some of its moisture on the cold surface. Window panes and wall surfaces become wet with condensation. The walls themselves warm up.
Now we need to consider what happens with the air pressure inside the room. A 'roomful' of air expands as it heats. This means that air pressure is greater as the air heats. The greater pressure will drive the moist air into the wall cavities themselves. (Wall cavities are the enclosed spaces between the framing 2x4's, the exterior siding, and the interior wallboard.)
*
Once inside the wall cavity, which in winter is cooler than the room itself, the remaining moisture in the air condenses into water.
As the air in the wall cavity warms and cools with weather conditions and indoor heating conditions, the water trapped inside the wall evaporates and condenses; in time it is evenly distributed in the insulation and in the wooden materials.
This is the damp condition that encourages the activity of dry-rot and various molds. (Dry rot is a fungus, not a mold.)
Dry rot can destroy wooden materials -- framing, floor joists, inside of sheathing and reduce them to dusty rubble. Both dry rot and mold produce tiny spores that can cause illness in humans.
The spores in the wall cavity can enter back into the room (where the people live) by the same air pressure in the cavity: when the weather warms outdoors, the wall cavity can become warmer and the pressure of the expanding air can force the spore-loaded air back into the room. *
The effect of a vapor barrier on the interior, or 'warm' side, of the wall helps prevent the destructive process at every stage flagged above by an asterisk (*) above.
02-07-07, 11:52 AM aminator2002 "The effect of a vapor barrier on the interior, or 'warm' side, of the wall helps prevent the destructive process at every stage flagged above by an asterisk (*) above."
We have established that he has a vapor barrier. Paper faced batts are a vapor barrier. The problem was caused by the lack of tar paper on the outside - I am sure that this allowed moisture through the sheathing. That moisture may not dry immediately. Wall pressurization, humidity, lack of humidity will not be an issue if he completely installs a tar paper moisture barrier under the stucco and also completes the installation of the paper faced batt installation.
Remember - the primary problem was mildew appearing on the outside of the wall where he did not put tar paper. The insulation is dry - in the case where the vapor barrier is the problem it is almost always a case that the insulation soaks first.
I understand all the indoor humidity comments but I really don't think they are relevant since he did not have a moisture barrier under the stucco. Now he does and buying a dehumidifier, ventilating the house, etc are not necessary especially since the windows aren't fogging.
Raven - Are you lapping the tar paper sufficiently - you have to create a surface that will shed water so horizontal joints must be lapped in a manner that doesn't allow water to flow in. This is what I meant by the weeping system of the wall. Using chicken wire might not be a problem but you have to install that tar paper like it's a roof. Lapping around windows and lapping joints to shed the water - horizontal joints being critical.
02-07-07, 01:49 PM babthrower You're right, of course, Aminator. I posted as I did because Raven had said in his immediately previous post "I would say the room gets fairly humid...but boiling tea water does not steam up the windows at all. My wife recently bought a humidifier because on really cold days it gets so dry from the wood stove that even the pan of water we put on the top does not help. The baby especially gets dry throat, and we do also."
So I wanted to clarify the idea of inside and outside moisture, because I thought Raven was not 'getting' some of your suggestions about stuccoing.
Sorry if I cluttered up the thread. Red Face
02-08-07, 09:25 AM Raven I'm not sure if it is entirely due to there being no tarpaper. Like I said, there was moisture also where there WAS tarpaper between the wall and stucco.
the mold spore issue sounds frightening. Since we do not have a plastic vapor barrier on 1 1/2 walls is this going to be an issue in a few months?
As for the batts being a barrier.... I can see this if they are completely sealed to the studs, but mine are only stappled in on the sides. They are not stappled on the top and bottom.... they are 8' pieces fitted into 8' sections of wall and the ends of those insulation pieces do not have the little 1" flap like the sides do that allows you to stapple them to the studs.
While the moisture seems to be disipating somewhat I am now concerned with the mention of dry rot and other uglies that could potentially damage the wall in the future.
One things for sure: when I insulate and panel the remaining walls I will make sure the sheathing is completely dry, put up plastic inside, as well as tarpaper on the outside.
02-08-07, 09:37 AM Raven
quote: Moderator's Note. The pictures were remove as they would not open and were locking up the post. I believe the picture are to big for our system. To post large picture, please just include the URL code to the site where they are posted. I tried the link at photobucket.com and it would not open for me.
Hmmmm. First I've heard of that happening. See if these work...
This is the main wall in question. This pic was taken last summer. The stone room is now enclosed except for a small area in the back, and the wall stucco'd about 4' high with tarpaper attached up to the roof: http://img.photobucket.com/albums/v302/elfinzone/photo125.jpg
This is a picture of the front as of the end of December. You can see the partial stucco on the front... this is the stucco without tarpaper under it. It is now covered with tarpaper, and like I said it seems to have less moisture now but still some. Oh, the total sq. footage of enclosed space we have at present is only about 327' so it is small at present.This does not include the stone room which is still in the process of being built. http://img.photobucket.com/albums/v302/elfinzone/11.jpg
02-08-07, 01:15 PM aminator2002 Now that I've seen the pictures, I have to wonder why you have chosen stucco for this place. It seems a poor choice for your skill set and also for the size of the place given stucco's inherit permeability and the size of your place. Why not just put siding on it and be done? Is stucco cheaper? Why did you decide on this course? Siding sheds water much more effectively than stucco and it also will not mildew with as little exposure to moisture. Especially a good idea for this application would probably be vinyl siding - economical and very effective at keeping water out.
babthrower - I meant no offense. I just am having trouble with the confusion in the thread. Very sorry.
02-08-07, 01:19 PM babthrower Heck, Aminator, no offense taken! I was frustrated by the confusion, too. Confused
Yeah, Raven, stucco is out of place! You could easily make your own shingles (do you have a species of cedar where you live?) and shingle the walls. This would shed water and provide insulation because it's wood. Also it's easy to get help from the neighbors with shingling. It's a cinch if you just snap a chalk line parallel to the ground on the tarpaper at the bottom of a course of shingles. And work from the bottom up, of course. Then you could stain or oil them later -- no rush -- to preserve them. There are some beautiful stains around these days.
02-08-07, 01:44 PM DvdGStwrt A picture is worth a thousand words.
You need to install ALL of the tarpaper first. Tar paper itself will provide enough protection for up to a couple of years from weather (dew, fog, rain, snow). Right now you have a small bit of tarpaper and the rest of the wood is exposed to the elements. Plywood is the very worst thing to be exposed to the elements, even the exterior grade plywood – it already has pores due to the cellular structure of wood and it has gaps and holes between each layer of wood.
If you are not going to stucco for a few weeks/months (which really you should wait until temperatures are warmer) then I would refrain from stapling/nailing up wire until a few days before you start stuccoing, each nail and/or stable put in the tarpaper leaves a hole that increases the chance of water seeping through.
Of course if the tar paper starts to get ragged it will need to be replaced before you stucco, but as for a short term “siding” tar paper alone works.
Tar paper is hung in strips side to side, not up and down. You start with the lowest course, starting at an opening (door or window) If there are no openings then start in the middle of a wall, stabling and unrolling as you go in one continuous strip until you reach an opening (door/window) where you cut the tar-paper a few inches longer than it needs to be. You staple it snuggly against the frame of the opening. Overlap ALL edges, ends, top and bottom where ever possible. Of course your bottom course (as example) has to end somewhere.
The next course (strip) starts either at an opening, or at another place on a wall, anyplace else but on the lower course’s seam. It overlaps several inches over the lower course. This is basically acting like shingles on a roof where they over lap a bit so water will run off in the middle of the next shingle.
Ideally you are treating the whole structure as if there are no openings, you are aiming to unroll the whole roll of tarpaper in one continuous strip “wrapping” around the structure. Practically you have to cut for windows and doors. Usually in construction projects what really happens is that the house is fully wrapped before windows and doors are installed. The paper is hung then the openings are cut open: http://members.shaw.ca/ourpics/pages/032%20Around%20and...he%20tar%20paper.htm
However in your case you already have doors and windows and frames there is a tidy way to hang tar paper around existing frames. This guy has over lapped his tarpaper around the top and sides of the window frame with narrow strips of tar paper: http://members.shaw.ca/ourpics/pages/033%20And%20a%20couple%20of%20doors.htm he will come back again with the next course (strip) and over lap, this doubles the protection above the opening and to the right side.
I would open up the finished interior wall if I suspect moisture trapped behind it. The consequences of keeping it sealed will be more costly and time consuming (if not a risk to health of family members) than being certain that it is dry.
02-10-07, 08:30 AM Raven
quote: Originally posted by aminator2002: Now that I've seen the pictures, I have to wonder why you have chosen stucco for this place. It seems a poor choice for your skill set and also for the size of the place given stucco's inherit permeability and the size of your place. Why not just put siding on it and be done? Is stucco cheaper? Why did you decide on this course? Siding sheds water much more effectively than stucco and it also will not mildew with as little exposure to moisture. Especially a good idea for this application would probably be vinyl siding - economical and very effective at keeping water out.
Oh, speaking of the size of the place - it is not finished yet. Smile Here is a drawing of what we hope to have by the end of the year, and as you see it will be twice the size it is now or approximately 600 - 700 sq. feet. http://img.photobucket.com/albums/v302/elfinzone/floorplans3.jpg I will probably make some minor changes to this to make it more square rather than have the present corner angles in the drawing though....
babthrower - yes, we have Cedar but I was hoping for something that is both fire and wind resistant. In fact I had considered making the stucco wall a stone wall of approx 4 - 6" thickness but that is so much work. They do sell those boards that make a house look like a log cabin... I think for around $69 a square. I am going to make at least part of the western wall stone as this has already been started.
DvdGStwrt - Those pictures are not recent. On the walls that are tarpapered it is fully covered, and of course I work from the bottom up. I do not understand how people overlap tarpaper or any form of shingle from top down so water gets under it. I have overlapped each sheet by 1' - maybe a little more than usual but this probably offers better protection. I also used the heavy tarpaper (2 square roll as compared to the 4).
This message has been edited. Last edited by: DorianGreyed,
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