Humidity question

[luckydriver]

Originally Posted by Perry525

The mirror showed that if the surface is warm enough the condensation from your hand and breath just fades into the air.
The bottle test showed that if a surface is cold enough the humidity in the air will soak it. (And if this happens without a warm patch to dry it out = the mould that is present every where can take root.)

i have no idea what mirror and bottle you are talking about as i dont remember running those in my tests

Originally Posted by Perry525

Your measuring the temperatures in the crawl space, shows that the floor is warmer than any thing else in the crawl space and that the floor above would not be cold enough to become damp and the puddle is not warm enough to turn into water vapour.

this seems to support that blowing hot air into the crawl with my fan may help get rid of my remaining water down there by increasing the temp in there. Though I still wonder why it's not draining because i'm 100% sure it does drain out over time (per your post it's not evaporating). and since all they installed outside my house was a 'hole' and a ton of stones, that should in theory make it empty faster! But even after it's dry, i hope the RH goes down or i'll be upset

and yes we know the floor temp in june but i have no idea what it is in january so cant wait to find out what RH and temps are down there then. At this rate i think until i have 4 seasonal numbers, i cant really take any steps as it would be pointless. But if in winter there is no water in there and the RH is 'reasonable' then it's clear i can clean the tons of mold then put a barrier down there to help the water droplets stay out.

Originally Posted by Perry525

Running the dehumidifier in the crawl space, is like opening the freezer lid, all the humidity in the crawl space and in your yard (and every where else for that matter) will make a dive for that freezing space, you can never collect it all.

i dont understand the metaphor. The dehumid. pumps out vast quantities of heat so it will actually heat up the crawl if i put it down there. So i dont get what freezing space you are talking about. Unless you just mean the air pumping through the coils? Speaking of which, i think it's safe to say even with one screen in there is zero air flow into that crawl (ie 50% RH outside and still 95% in the crawl) so i'm not even worried about sealing up my screen that good once the dehumid. is in place and running.

Originally Posted by Perry525

The same thing happens in your home, the water vapour comes in through the walls, through holes in the lower walls and goes out through holes in the ceiling and upper walls.
You can't stop it, you can slow it down - you can make life easier on your dehumidifier so it doesn't have to work so hard.

from your quote, it sounds like my foundation blocks are likely saturated with water and the water comes thru my walls and into the rooms. Now that the crawl is waterproofed, they should dry out and thus the living space start to dry out?

sound more likely than anything else i've heard. Plus would explain the high bathroom RH since the downspout known to be previously be pouring water against that side of the house is right near the bathroom.

Hmm we may have solved the mystery.

[Perry525]

Sorry, see 6.28.09 paragraphs three and four

[Perry525]

"and since all they installed outside my house was a 'hole' and a ton of stones, that should in theory make it empty faster! But even after it's dry, i hope the RH goes down or I'll be upset."
=================
I explained way back to an earlier post of yours that, what you require is a French drain.
Your yard is covered with concrete - it needs to be removed along the upper side of your house and the wall waterproofed.
I said to remove the back fill along the wall to a depth of four feet, either waterproof the wall using paint or better still fix plastic sheet along it, then refill the hole with clean stones. This French drain should be continued down hill to enable the ground and surface water to move round the house into the front lawn.

I have tried to make the point that high humidity does not matter!

What matters is the relationship between the air temperature and the wood temperature.

If the wood temperature is lower than the dew point/temperature of the air then the humidity in the air will settle on the wood.

As long as the wood temperature is higher than the air temperature the wood stays dry.

You measured the temperatures in your crawl space, the wood is warmer that the air.

This means that the wood stays dry.

When winter comes the wood will be much warmer than the air - there is no way the wood can become wet from the humidity in the air.(while you heat your home)

Why not buy a temperature gauge with a built in humidistat and two external wireless sensors that you can access at any time from your house.
Fix one sensor to the sub floor/joist and dangle the other from one of the joists on a piece of string.
This will enable you to see how warm/cold/humid the air is under your house.
It will also enable you to see how warm/cold the joists and sub floor are.

Better still buy a Weather Station with external wireless sensors that you can connect to your computer, then you can see exactly what happens 24 hours a day, you can see how the humidity and dew points change during the night.

Then you will know exactly what happens.

[luckydriver]

I'm unsure what you mean by my yard being covered in concrete...but i have so many posts i forget what's posted where so let me bring you up to date since your most recent post indicates you dont have the most up to date info (french drain /sensor discussion etc):

all my concrete in back of my house was dug up and i have a new 3 tiered drain system around the entire house and only porch pads repoured (ie 95% of my patio is gone). A membrane has also been installed. I'd think water getting in the crawl is now an impossibility but i cant tell since the old water is still in there and i cant tell if any new has come in or not until it dries out.

a few months ago i got a RH multi sensor gauge and have monitored each sensor with diligence. The one in the crawlspace has been suspended, via a homemade device, so it's above the floor (in case of the hopefully impossibility of new water down there). Also the joists have measured 68 degrees while the water itself measures 63..air temps are between those two. Upstairs floor temps are low 70s

the crawlspace joists are coated in mold so if you believe that wood must be colder than air to get mold on them, then the temp of the joists is absolutely, at some point in time, getting colder

however, at this point i think your own logic is disproving your statement that you need colder wood than air to get mold. I think we would all agree in warmer months, the joists are warmer than the air and the floor/water of the crawl. I also have the actual data to prove it. But since i didnt have my sensors in winter, i dont really know what happens in winter. However, even you stated in winter the uninsulated joists likely are warmer than the air and floor. I agree with this especially since the hot water from the boiler circulates around down there.

so if my joists are theoretically warmer than the air year-round, where did some of the worst mold my inspector ever saw come from? I think the only answer is that even if the wood temp is higher than the air, that 95% RH is not good for a crawlspace and mold will grow on the crawlspace joists regardless of wood temperature. If thats not true, then how did the joists get so bad?

i just cant fathom a circumstance where the wood is colder than the air and floor/water down there for the past decade.

[Perry525]

The reason the joists are covered in mould is down to history!

One: The house was flooded at some time, a leaking roof or burst pipe.

Two: The house was left empty for probably a year or more and during this time the joists reached the same low temperature as the rest of the crawl space. Result. Mould.
I would guess the second is most likely.

The solution is: Mould dies when it can no longer feed, eat the cellulose in the wood, or when it is deprived of water, both of these are unlikely to happen. Due to the high humidity in the area and lots of wood to feed on.
The recommended solution is professional cleaning - this will cost a lot.

Trying to dry out all the humidity in the world with one dehumidifier, will never work!
Water vapour has a built in tendency to equalize but, look at the sky all the cloud shapes are different, the same patten is repeated on ground. The moisture is forever moving from one warm place to the next cold one, from one area of high pressure to the next area of low pressure..... trying to equalize and never succeeding.

Unless you have a sealed room, humidity can only be controlled never beaten. Sealing the crawl space and the floor above plus the ground below is too expensive.... I guess.

I do wonder who inspected this house prior to purchase
and if they are liable in law. Certainly, a lot of insurers do not include mould damage in their policy now.

OK So, you have all the gear and winter will come soon enough.
Here is a bit of information that seems to be missing.

Dew Point Calculation Chart (Fahrenheit)
%RH AMBIENT AIR TEMPERATURE IN FAHRENHEIT
20 30 40 50 60(70)80 90 100 110 120
90 18 28 37 47 57 67 77 87 97 107 117
85 17 26 36 45 55 65 75 84 95 104 113
80 16 25 34 44 54 63 73 82 93 102 110
75 15 24 33 42 52 62 71 80 91 100 108
70 13 22 31 40 50 60 68 78 88 96 105
(65) 12 20 29 38 47(57)66 76 85 93 103
60 11 19 27 36 45 55 64 73 83 92 101
55 9 17 25 34 43 53 61 70 80 89 98
50 6 15 23 31 40 50 59 67 77 86 94
45 4 13 21 29 37 47 56 64 73 82 91
40 1 11 18 26 35 43 52 61 69 78 87
35 -2 8 16 23 31 40 48 57 65 74 83
30 -6 4 13 20 28 36 44 52 61 69 77
From the above you can I've put brackets round 70 degrees farenhite and 65% humidity
and when you go to where they cross you find a dew point of 57 degrees farenhite. Any surface temperature colder than 57 degrees will have condensation and get wet. Now you can really monitor your crawl space without going down there.

[ecman51`]

I have a mobile home rental that has wet ground under the trailer (lush area with springs in the area/high water table) is causing the particle board flooring to disintegrate in areas and swag between the joists.

For now, even though some of the skirting is vented, it does not have enough such panels, so I have propped open the skirting in areas in hopes the wind can sort of dry it out better under there. Very disgusting, that's all I know.

I can't imagine having to crawl under that trailer (nor pay someone else), which has been dug out of the ground at the front end, to plastic sheet the ground, getting it good at all the axles, and blocking. That be a royal-most pain in the you know what.

On another trailer we bought from some ex-owner, he had the ground plastic sheeted, and animals got under there and peed on the plastic. And I'd have to crawl under there sometimes to unthaw frozen water pipes. I've had a rough life - but I guess the good has outweighed the bad.

[ecman51`]

Originally Posted by luckydriver

so if my joists are theoretically warmer than the air year-round, where did some of the worst mold my inspector ever saw come from? I think the only answer is that even if the wood temp is higher than the air, that 95% RH is not good for a crawlspace and mold will grow on the crawlspace joists regardless of wood temperature. If thats not true, then how did the joists get so bad?

i just cant fathom a circumstance where the wood is colder than the air and floor/water down there for the past decade.

This is the crux of the matter I guess.

Maybe the joists DO get cooler, say at night - and the ground stays more equalized in temperature overnight. I like Perry's suggestion about temp testing at both locations. I am going to try this on the trailer. This is fascinating, and I have always enjoyed collecting data.

Now if this turns out to be the case, and those joists (and in my case under belly or what is inside the underbelly)does become colder at times, then what do we do economically to solve this?

[Perry525]

ECman, you can see from my table, the facts.
In summer.
Sun shines on ground during the day, ground gets hot, moisture is released.
Some moisture being lighter than air rises and joins clouds.
Some moisture preferring cold moves under trailer and condenses onto nearest surface that is below "dew"point.
Ground under trailer stays colder all of the time as sun never shines on it.
Base of trailer get cold and wet.

In winter the ground under the trailer gets colder overnight.
The air outside warms quickly in the sun and the moisture dives under the trailer and settles on the ground and trailer making everything wet = condensation, dew or frost in the open!
Wood, leather, fabrics all absorb water and start to go mouldy.

The solution is to keep things warmer than the dew point
As always, keep the heating on and insulate. (Insulation means the floor will stay warmer longer = the polystyrene will keep the wind off the floor, result it costs less to run.)
A trailer being so high off the ground is more prone to chill with the wind blowing under.
Fix two inches or more of polystyrene under whole floor.

Buy a compensating thermostat to run your heating, this has an external sensor, that reads the outside weather conditions and turns the heating on and off earlier as required.

[luckydriver]

am i reading that chart correctly that at 95% RH and 68F (let's round it to 90RH and 70F for ease) means that at 67F the joists WILL get moldy? If so them bumping that up to the real life and true 95% RH and lower the temp down to the mid to lower 60s F - which is where it is most of the time - means you've just proven that my 95% RH in the crawl IS causing mold on the joists

So how do i lower this from 95% on an ongoing basis? I do have to disagree that a single dehumidifier cant lower the crawl. In my house when i got my santa fe i did run it in the dining room and it did lower the RH throughout the house, though lesser amounts farther away. I was told RH equalizes throughout the house and it's relatively true.

while i cant know what went on every year for the 50 years before i owned the house, i do know what happened the past 15 years. But I dont remember the mold being that bad in the earlier years that i owned the home when i went down there to run new phone wires in 1994. Now just sticking your head in there makes you gag where before i was down crawling around no issues. Also ran new RG6 in the early 00s with no bad issues. So i'm positive it's gotten worse since then but cant say when it started.

Also the other thing i'm positive of is that in the early 00s I cleaned the mold off the cabinets upstairs and it came back. But perhaps this is the 'wall/concrete wicking we've been discussing and it's picking up the high stuff down in the crawl and coming up thru the walls. I hope so because i cant figure out any other reason.

And we are back to the same old broken record where i still have my 95% RH but if the 'cold joist' theory is to be believed we need to monitor the temps and RH in fall and winter upcoming. If that wood gets colder then I will really have worse mold issues down there. But i see all this coming back as i need this RH lower than 95%. There's no scenario where i can see 95% as 'not' causing my issues.

and you keep saying the house may have been flooded at sometime. And i've told you yes for the past 15 years it's flooded every year in the crawl so we know there has been a lake of water up to 6 inches deep which slowly drains then fills back up when it rains. So it seems like the lakes have contributed to the 95% reading, correct? Unless you dont mean the crawlspace and you mean the 1st floor flooding? In that case I can virtually assure you that didnt happen. the very old carpet has been pulled up in my hallwayand i can see the hardwood floors and they are in great shape. I'm guessing if the 1st floor flooded, the hardwood would show extreme damage in many ways (stains etc etc). Now i didnt do the living room and dining room but my guess is water wouldnt just stop at the edge of the hall, it would have flooded the hallway too.

edit: just saw on the meter that the house is down to 41%...sure wish i could move all that downstairs lol

[airman.1994]

Again temp has nothing to do with mold growth in the crawl. Anything above 60% RH will be enough moisture in the air to promote mold growth. Your Santa Fe should be enough to keep RH under 55% but you will have to stop the water infiltration and seal the crawl.

[ecman51`]

So who is right? Perry or airman?

So what happens in the tropics? More fungal growth in shady areas? - or not? Never been there, so do not know.

I think I have heard that people in Florida can have mildew growing in their closets. Is that true? I doubt water drops are actually forming on the walls.

And is there a more likelihood that mildew can form - that black speckled stuff - without that white frothy mold forming? It seems to me that it is the white frothy mold, not just mildew only, that seems to hasten rot more. Or am I wrong about that?

Or how to explain why mushrooms grew in a bathroom along tiled floor when water got outside the tub.

Is the bottom line that you actually need physical water present to cause mold growth? Or is high humidity(suspended water vapors) alone, enough, even if dew point and water droplets are not forming on the surface? Can it just be from moister air contacting the surfaces, without necessarily condensing?

Is Perry sidetracked too much on the theory of what makes dewpoints/condensation occur? Will or will not molds form in humid environment without actual fallout of water droplets?

[luckydriver]

Originally Posted by ecman51`

So who is right? Perry or airman?

we could always do a cage match on WWE i guess. But at this point i'm ready to call in Dateline NBC and maybe get a free remediation out of it Or maybe the weather channel can do a remote from my house.

it's fun watching the dials though.... even yesterday with all the windows open ( a theoretical equalizer) the bathroom remained 10% higher than the living room.

I think each of them may be right actually..that's how messed up the house is But based on even that latest chart i think it's pretty clear 95% does cause mold at the temps in my crawlspace. Maybe they can both agree on that at least.

Then in winter with my infrared i can take the temps of the insides of my cabinets and bottoms of my closet doors, joists etc and see how cold things really get

it's looking more and more like i need a year of data before i can do anything to remediate this issue.

[airman.1994]

Can't remember if you have looked at this. Building Science Corporation

[Gunguy45]

Well, I'm no expert but this has been an interesting discussion. IMO condensation is not the issue. Just as you need to leave wood flooring in the room to allow its moisture content to acclimate, I would believe that wood left exposed in an area of 95% humidity would naturally have an increased moisture content over time.

A little bit of searching for "mold growth conditions" seems to agree. Of course condensation of warm humid air on a cold surface will produce moisture on that surface, but you are talking about humidity (very basically water vapor suspended in the air), since wood is a permeable material that humidity is inside the very fibers/cells of the wood.

Heres something to read..there's lots more out there...Conditions That Promote Mold Growth.

Most places I found state 70% is the threshold, but I'm sure that is somewhat temperature dependent.


EDIT...just to add to Airmans link....Welcome to building science.com —

[luckydriver]

just a quick read found these quotes

Conditions That Promote Mold Growth

In buildings that have slab construction, water can seep or wick up through the cement floor causing mold to grow on carpet pads or carpet backing

seems to likely apply to my house since i know i had a lake under it and that water would wick up the block. However strangely i dont have mold on any walls! why is that? It's just on cabinets/doors or maybe even clothes that have been left in a pile on a closet floor

If there are no cold condensing surfaces and the relative humidity (RH) is maintained below 60 percent indoors, there will not be enough water in those materials for mold to grow. However, if the RH stays above 70 percent indoors for extended periods of time, mold will almost certainly grow.

seems to indicate my crawl will have mold at 95% RH regardless of temp and the other rooms have definitely been pushing 70+

In the winter, when buildings are heated, mold often grows in cold, uninsulated exterior windows and walls, including uninsulated closets along exterior walls where building surfaces are generally cold relative to the indoor air temperature.

i've never seen mold on any exterior walls and all my closets are on interior walls. So this perplexes me and is one reasoning against the theory water wicks up my uninsulated walls. Of course my kitchen cabinets are all exterior walls so i can understand why they got mold but the bathroom ones are interior and got it anyway. As are interior doors which, i'd think, would be pretty darn warm even in winter.


RR-0208: What You Need to Know About Mold —

Mold needs water to grow; without water mold cannot
grow. Mold also needs food, oxygen and a temperature
between 40 degrees and 100 degrees F.

hmmm maybe once the crawl is dry, the mold will stop growing!

no time to read more now but at least it's some new reading material and maybe I'm closer than i thought to a solution.

[Gunguy45]

lucky...plenty of places for sale out here in AZ...mold isn't an issue. Coyotes eating your pets, 110 degree heat, and high winds..yes...mold...no...lol

[ecman51`]

Originally Posted by luckydriver

....with my infrared i can take the temps .....

I did that to the mobile home rental crawl space this weekend, due to this discussion! I got 58 degrees ground, 60 degree underbelly on one side of the trailer, and on the other side I got 60 degree ground and 62 degree underbelly.

Remember, I said this trailer has particle board flooring, and is swagging in areas between the joists, and black splotching is showing on certain areas on the sheets on the inside of the trailer, after the carpet was pulled back. And an area down the hall had deteriorated to the point where someone could have fallen right out the bottom of the trailer onto the ground if I hadn't fixed it.

Even though I have left open quite a few skirting sections, the ground is still moist under there. I mean real moist. We are downstream of natural springs in this lush area. This site is even on the highland of the property which makes it a little more surprising to find that moistness. But not too surprising. Grass grows great in this area - I do have to say. I could mow grass every day. I also planted some white pine trees, and they grew like weeds.

[ecman51`]

Thanks go to Gunguy for finding that site. A good read.

[ecman51`]

And I honed into airman's site. If you go there, you can click onto each subtitle to learn more.

More about Mold —

Yet, the subtext found in the article I posted above, seems to agree with what Perry has been saying!

BSI-009: New Light In Crawlspaces —

Now I have yet a new reason to consider as to the real cause of why the ground is really moist under there! I am going to find out what some of our dewpoints have been lately. This subject I have to agree, with Gg, is truly fascinating.

[Perry525]

I had thought that with the printing of my relationship between temperature and humidity that would bring the thread to an end.
Working backwards, as I wrote earlier, the humidity in a space isn't the same everywhere - its like the clouds in the sky many shapes humidity's and temperatures.
When I record the temperature and humidity's in and around my home they vary from room to room wall to wall.
On one side a window can be in the lower hundred the other mid sixties.
The humidity near the dehumidifier is around 65%, in the sun it can be 15% outside 90%.
My trailer has a waterproof plywood floor and the underneath is covered in waterproof paint, its nine years old and as good as new.
Where you have wet ground every time the sun shines or the wind blows the top molecules are going to break free and add themselves to the humidity.
Where you have an open surface, like sawn untreated wood, the very tiny molecules of water vapour can slide in and out, between the wood molecules, very easy. This is why it is important that wood is kept warm, the warmth dries the wood and stops it from reaching the point where rot sets in.

I wrote some while back that moisture can and does climb as high as four feet through concrete.
And that Lucky should dig up his concrete to a depth of four feet, line the walls with plastic sheet or paint them with waterproof paint, then refill the trench with clean stones to make a French drain.

The mould is already there. As I wrote.... as long as there is cellulose in the wood and humidity in the air it will grow! Take away the moisture and it dies.

Th mould is encouraged by the cold of the concrete and the rising damp therein......It doesn't grow on the outside as the passing warm air raises the temperature......but, it does grow inside the wall where the air is stagnant...and you can't see it!

The crawl will never be that dry....as the water vapour in the air makes it way in through the very fabric of the building. The wood needs to be cleaned and treated.

[luckydriver]

Originally Posted by Perry525

And that Lucky should dig up his concrete to a depth of four feet, line the walls with plastic sheet or paint them with waterproof paint, then refill the trench with clean stones to make a French drain.

you keep saying that...do you mean in addition to the 3 drainage systems I had put in outside already (and enumerated details of in many places so i wont repeat it here)? the only reason i can think you keep saying about french drains is you mean inside the crawl. If so, then i can tell you digging up my crawl will 100% never happen. And there's no reason it should be dug up. With the 12K i spent outside the house if water ever gets in after this, the contractor will be called back to fix the leak!

so can you clarify if you mean dig up inside or outside the house. Either way, nothing will be dug up anymore, that ship has sailed. If waterproofing the outside of the house doesnt stop water from getting in, then ill be living in a lake of water because i'm out of money for that kind of thing to be done inside a 3ft crawlspace.

Plus as i've countered before, you said getting rid of the lake has nothing to do with my mold and i shouldnt worry about it. But now you say install drains. The 2 points are at odds with each other so you need to decide if the water is a problem or it isnt. You cant say water under the house doesnt matter (though you did) then say install drains

[Perry525]

Quote:

In the winter, when buildings are heated, mold often grows in cold, uninsulated exterior windows and walls, including uninsulated closets along exterior walls where building surfaces are generally cold relative to the indoor air temperature.
------------Your reply:-
I've never seen mold on any exterior walls and all my closets are on interior walls. So this perplexes me and is one reasoning against the theory water wicks up my uninsulated walls. Of course my kitchen cabinets are all exterior walls so i can understand why they got mold but the bathroom ones are interior and got it anyway. As are interior doors which, I'd think, would be pretty darn warm even in winter.
========I was replying to the the above.
I accept you have had a French drain installed!
But do you know how deep they went, if they did or did not exceed four feet from the bottom of the French drain to bottom of the house on the outside?
Did they dig down on the inside of the walls to separate them and the floor above from the clay to a depth of four feet or more?
You write that they installed a plastic membrane along the wall to stop the water standing alongside it, did that cover the wall in total?
You see, if they did not do these things properly, then while the rain and surface water will take the easy routs round the house and into your lawn, and the lake under your home may shrink over the next three to five years, the remaining damp in the ground under the house will continue to rise through the walls and keep the house walls damp, this usually happens inside the wall, where the air is stagnant. Not on the outside where the passing air dries and warms.
I am not asking you to do anything, I am merely commenting on your situation and drawing your attention (and others who may read this blog)to the possibilities and the relationship between temperature/humidity/water vapour/damp/mould/waterproof membranes/paint etc;
I do say that water under a house is of no importance (if the design, building, foundation, ground and wood work have been done correctly.)
From the point that you believe that the water is somehow causing the mould. I write that the damage is done already.
The mould is in place and it gets its moisture to keep alive from the water vapour coming into the crawl space from outside.

Perhaps you would like to conduct an experiment?
Take several glass tumblers and put an equal amount of water in each and mark the level on each. Then place one in full sun in the yard, cover the top to stop the rain getting in but loose enough to let the water vapour out.
Place another on a south facing window cill, perhaps another on a north facing window cill.
And the last in the lake in your crawl space, placing it so that the top of the water in the tumbler is level with the surface of the lake.
Then when the tumbler in the yard is empty, or the one on the south facing window cill take a look at the others and see what's happened.

In a earlier blog you wrote that the average indoor temperature of your home during the winter was probably 65 degrees f.
When you consider the temperature loss through the floor the temperature of the lower parts of the joists will be lower.
The dew point of 60f is between 36f and 60f so there is little margin of error. But, the ground/lake temperature will continue at 40f most of the time the ground and lake will attract the water vapour in the air as it is attracted to the coldest surfaces.
You could consider raising the indoor temperature to 70f this will widen the margin.

[luckydriver]

Originally Posted by Perry525

I accept you have had a French drain installed!
But do you know how deep they went, if they did or did not exceed four feet from the bottom of the French drain to bottom of the house on the outside?

I think we have different ideas of french drains. I always believed a french drain just was a hole in the basement floor that led down into the earth..period. If you have a different definition, we arent talking the same language. When you talk about bottom of drain to outside of the house it makes no sense based on my definition. But regardless, no one will, or ever has, done anything inside the crawl itself. And there's no reason to since the outside is supposed to prevent water from getting in. I firmly believe in dealing with water before it gets through your walls, not after. Thats why i did all this and dont understand why people put in sumps etc.

Originally Posted by Perry525

Did they dig down on the inside of the walls to separate them and the floor above from the clay to a depth of four feet or more?
You write that they installed a plastic membrane along the wall to stop the water standing alongside it, did that cover the wall in total?

so we are on the same page, what do you mean inside of the wall? To me you mean the inside of the crawl because inside is..well..inside.

However as i said above, theres no way anyone is digging inside the crawl, that would be pointlessly disturbing the earth and very difficult. What they did is dig down to the bottom of the foundation outside and then installed the rubber like membrane that will start at the topsoil (still waiting for the dirt job to be completed lol) and goes down the entire outside of the foundation and then bends outward in a "L" shape into the ditch. then of course i have tons of big stone and 3 four inch pvc pipes for my drainage systems on top of that.

So any water that does not get taken away by the yard drains or the gutter drain will soak down through the grass and stones to the bottom of that stone pit, settle on the membrane and either go away from the house or else get picked up by the bottom pvc pipe which has holes at 4 and 8 oclock. When i asked why the holes face down instead of up he told me that way they wont ever clog and i think they also said the water drains into the pipe easier from the bottom but i forget the exact explanation. Oh and they also put a porous mat on top of all this stone to help the dirt not clog up all the stone over time. This is what my yard looks like now...the mat over the stone and a shallow pit..i cant wait for my soil and grass!. They also tarred the heck out of all surfaces too so that will help a bit i'd imagine.

Originally Posted by Perry525

I do say that water under a house is of no importance (if the design, building, foundation, ground and wood work have been done correctly.)

From the point that you believe that the water is somehow causing the mould. I write that the damage is done already.
The mould is in place and it gets its moisture to keep alive from the water vapour coming into the crawl space from outside.

well thats one thing we will never agree on. You say the damage is done and i agree, happened because of water down there. I do believe decades of clogged gutters and downspouts and the water that then went into the crawl was absolutely the cause of the mold. Both my home inspector and the contractor i hired said so. If water intrusion wasnt a big deal, then why do people even bother with sump pumps and waterproofing in general? they'd be content with puddles etc under there house and be happy fluffy has a new drinking source

And in every article i've read, including those posted in this thread, it says if you have a water leak fix it asap because your place may get moldy in as little as 24 hours. And you yourself even said you think years ago some pipe burst or something and caused this mold (which for the reasons i posted before seems very unlikely). Whats the difference between a pipe bursting and flooding everything and causing mold vs having all my outside drains emptying in the the crawl? i cant see that distinction at all. Either way tons of water got in the crawl for sure. Do you agree with that?

And one thing i'm positive of is that standing water breeds mosquitos though i'm not sure why i dont have that problem in the crawl. they actually fly over my township and spray for the problem every year it gets so bad in places.

Im also unsure what you mean about moisture coming in from the outside keeping the mold alive. I believe i get "ZERO" infiltration from outside air. How do you explain a 95% reading that's just a few feet from a screened in window when the RH has been well below 60 outside for the past week? Unless of course i have my fan running then it comes down

I believe moisture seeks dry air and i think thats evidenced by my test of using the dehumidifier in the house. If it's on in one room, that room gets very low RH but the rest of the house only comes down a bit becasue it's farther from the machine. But it does come down. The sales rep from santa fe told me the house will equalize and that putting the unit it one room would help all the other rooms, just maybe not as quickly. I saw this first hand last fall when i first bought the machine and ran it a few days.

also if i open a window in my bathroom, the RH drops significantly. But yet my open window in my crawl produces zero drop in RH.

Originally Posted by Perry525

Perhaps you would like to conduct an experiment?

well now that the lake is down to less than an inch (all the sump would do for me) i dont know how effective that would be. But now you got me thinking, why dont you flood a basement with water and see if you grow any mold on any surfaces? It would beyond a doubt prove me right or wrong lol. or even just take a cabinet of yours and make a sealed in 'pool' on the bottom of it, close it, and let a few inches of water in there a few months. I'm pretty sure it wouldnt look so nice.

speaking of mold, i actually had to go to the bottom of my pantry to look for something and saw some there last night! I had totally cleaned my kitchen just last month..top to bottom in every cabinet... but skipped the pantry because i knew i just cleaned it last summer in its entirety. But in that year, mold grew from the bottom up a few inches. And this cabinet actually is about 8 feet from any exterior wall and only about 9 feet from the utility room (ie heat source), where my boiler is. But i guess it was cold enough in the bottom of the cabinet for the mold to grow. Sigh. I had forgotten about those cabinets being on the interior wall in earlier explanations.

Originally Posted by Perry525

In a earlier blog you wrote that the average indoor temperature of your home during the winter was probably 65 degrees f.
When you consider the temperature loss through the floor the temperature of the lower parts of the joists will be lower.
The dew point of 60f is between 36f and 60f so there is little margin of error. But, the ground/lake temperature will continue at 40f most of the time the ground and lake will attract the water vapour in the air as it is attracted to the coldest surfaces.
You could consider raising the indoor temperature to 70f this will widen the margin.

I understand the theory you are talking about (though dont necessarily agree with it all). But if this lake in the crawl is always the coldest surface in the crawl (i think you are saying that) and drawing all the moisture to it, then why is it even necessary to raise the temp in the house? And if the water always is pulling down the moisture, why is the mold even still growing on the joists? My position is that any water in the crawl contributes and causes mold. Period.

and i have the feeling we are really not even touching the most serious issue here. Even with my 1 inch of water over perhaps 25% of my one room in my crawl, vs several inches in the past), i still have 95% RH. I fear that even once the crawl is dry ill still have that high RH but i guess thats when we put the dehumidifier down there and pay the electric man to see how dry i can get it.

[ecman51`]

Have you tried to use a different humidity gauge? (95% sounds awfully high. You'd think you'd practically be seeing fog at that amount.)

The reason he thought raising your inside temp to 70 would be so that you'd widen the temp gap between the underside of the joists and the top of the ground, lessening any chance at all of mold formation, just in case there are times where the temps popssibly equalize or invert between the lake and joists. It be like if you were into trying to jump over a bed of nails -and more often than not, you cleared the nails - but once in a while you did not. Why not move the nails bed or jump further to reduce any possible risk?

I think according to those links that got posted on this thread, and I honed into specific things - I think that there can be problems if the humidity is over 75% - even without condensation if I remember what I read right.

I haven't put a humidity gauge under the mobile home crawl space yet. I will try that and come back here and let you know what I have. I have 2 gauges, by different manufacturers, and will use them both. I wil try to lay them on the damp ground, and then tape them to the underbelly of the trailer, to see if it is lower or substantially lower on the ground.

[luckydriver]

when i got my sensors a few months ago, i lined them up next to each other and they all read the same thing so i know they were good. It's a PITA to get the sensor that's under the house the way i have it

and i do have a small update...yesterday when i got home it was down to 82 in there...and this morning it popped up to 89 lol. It's 65 degrees. I did confirm it's now dry under there but i havent looked under there in weeks so dont know if it just dried out recently or a month ago. At least now ill know for sure if the waterproofing worked. Except now we have a dry summer!

oh and for the record, if i had 70 in my house in winter i'd need to be naked..thats too hot lol. 65 is a tad chilly but the 67 i have in the evenings was always just right for me. But i still havent been able to fill my oil tanks since february so i dont know how much money i saved with my new boiler so maybe if it's a lot i can crank it up and be summer like all winter lol

[ecman51`]

I'm not going to enjoy trying to place gauges under the trailer since it is low, and I have to crawl under the main beam, that is inward from the skirting a couple of feet, which is even lower to the ground. You have to belly it. I'll lay down some cardboard sheets though, I have for this type of work, when I do that.

I can't wait to see what my readings are. Also I want to inspect where that rot is, in the area of the washer/dryer, to see if underbelly is gone and maybe this has contributed to the humidity damage, especially if the crawl space readings up at that joist level are real high, like yours.

[luckydriver]

what i did was take a tomato cage and tie the meter so it's suspended in the air a few inches off the ground. Then i tied a rope to the cage and used a long pole to push the entire contraption in about 10 ft into the crawl thru my window. Then kept the rope so i can easily pull it out when need be. Easily being a relative term lol. This way i dont have to climb in. Of course with a 3000 sq ft crawl it's only getting a small spot but i'd have to assume it's relatively consistent throughout.

got some pics

[Perry525]

The French drain was invented over 2000 years ago by the Romans, many of the original drains are still working today in many places in Europe.

The French drain, was re-invented by a farmer called French, who realised that it was the ideal solution for his fields, in as much as once installed it is not effected by frost and ice and cannot be damaged by driving over it. The top being level with the surface avoids accidents, children and animals cannot fall in. French drains are now in use all over the world.

A French drain is a trench that is filled with clean stones, it crosses a field and collects the water coming down or goes along side a house or barn and collects the water and redirects it downhill and away from the structure.

The water moving through the soil is clean and remains so while it travels through the drain.
Surface water does pick up dirt, from a point of longevity it helps if this is filtered out before the water enters the drain.

[Gunguy45]

lucky ack! what a mess under there..don't let any of the electrical guys see those pics...lol.

[airman.1994]

Lucky looks like all you need now is a VB and some mold remediation.

[ecman51`]

Look at how the light wire staples rusted. Also interestingly, unless I am being fooled by some effect of the flash, the mold looks worse on the joist that has the light. It almost looks like someone started to experiment with spraying something out of a hopper.

[luckydriver]

Originally Posted by ecman51`

Look at how the light wire staples rusted. Also interestingly, unless I am being fooled by some effect of the flash, the mold looks worse on the joist that has the light. It almost looks like someone started to experiment with spraying something out of a hopper.

id say the light is irrelevant unless you mean there is heat generated even while it's off. I have no reason to ever turn it on except rigging cable and that's once every 5-10 years lol. so 99.99999 percent of the time it's off.

[ecman51`]

Well, I was jsus sayin.

I do not know why(cause). Just stated what the picture shows. I just looked at that one photo again. There is definitely something along that joist and plywwod, to it's top left, more than the joist next to it. Coincidence? Or, is there a switch where the light was left on by msitake and heat caused steam and vapors to rise due to bulb heat?

[Perry525]

Writing about humidity.

When you have a relative humidity of 90% to 68 degrees fahrenheit a cubic metre of air holds 20.7 grams of water vapour.
If you put 20.7 grams of water in a whiskey glass it covers the bottom of the glass to a depth of roughly 1/4 of an inch.

When you have a relative humidity of 90% to 60 degrees fahrenheit a cubic metre of air holds 11.5 grams of water vapour.
Enough to cover the bottom of that glass to a depth of roughly a little over 1/8 of an inch.

So when the air in a room with a relative air humidity of 90% and a temperature of 68f comes alongside a colder object with a temperature of 60f, the air chills to to 60f and 9.2 grams of water vapour move into the fabric of /or onto the surface of the colder object. ( Of course one may expect the surface to warm during the process)
Or to visualise it that amount of water in roughly a 1/16th of an inch of whiskey glass moves. Not a lot of water?

But, the key question is how many metres of air are in the room, how many glasses of water are deposited on the surface?
This depends on the shape of the room and its many surfaces.
If you open the door and allow all the water vapour outside to come in, it can be a lot.

Once you get below 90% humidity and 50f the amount of water vapour in the air is very low, below 5 grams per cubic metre.
And of course humidity is rarely as high as 90% at 50f.

When you look at a piece of timber as used in the open in a house its water content is between 6 to 12%. Over time it adjusts to the average humidity of its location.
A cubic metre of wood will hold 60 to 120 litres of water. That's 60,000 to 120,000 grams.
From this you can see that a very long time needs to pass with water vapour transferring from the air into the wood before it makes a difference.
Below 16% water content and there is no mould.
Below 19% water content and there is no rot.
Keeping the woods temperature up makes sense.