What the heck is this moisture under my hearth pad?!?!

[KennyK]

Yesterday, I removed my hearth extension pad for the first time since installing my stove almost two months ago. I was surprised to see a bunch of moisture under parts of the pad, to the extent that there were drops of water, some about the size of a quarter. I thought maybe something had spilled and just got trapped under there. I cleaned up the floor and the bottom of the pad, and put everything back. Just now, about 30 hours later, with the stove running basically non-stop since, I removed the hearth pad and again there are drops of water under it! What gives? The water is cool, the hearth pad is warm to touch and so is the wood floor underneath (not excessively, just a nice radiant warmth). I can't figure this out, and it's clearly not good for the wood floor.

I bought this hearth extension pad used, so I don't know much about it, but I believe it had been stored in a garage for some time before I bought it. Here attached are pics of the beads of wood (hard to get a good pic of this), the hearth pad top and bottom (the bottom has some sort of dull aluminum foil looking material and was discolored and scratched/rusty looking on parts when I bought it), and the label on the hearth pad. Any thoughts of what this might be? Could this be coming from the pad, the floor (white oak, with polyurethane coats I believe), the air...? Any thoughts on what I should do about this? Should I put some very thin plywood below it to protect my hardwood floor?

Any help is appreciated!

 

[Eureka]

What is below your stove area? Basement or crawl space? It’s odd but might be condensation from cold basement air meeting warm upstairs air. Same effect that you’ll get on windows when it’s very cold outside. Moisture in the warm space condenses where it meets cold air. You might be seeing it under the hearth pad due to the lack of airflow there.

 

[coutufr]

Condensation is from warm humid air getting in contact with a cold surface. Is the floor cold and what is the humidity within that room? You may need to isolate the floor from underneath. The reason is that the hearth is preventing warm air from the room to heat the floor under it making it colder that the rest of the floor area.

 

[coutufr]

You could try to put the hearth on shims and see if it solves the problem

 

[KindredSpiritzz]

yeah, whats underneath that flooring??

 

[KennyK]

What is below your stove area? Basement or crawl space? It’s odd but might be condensation from cold basement air meeting warm upstairs air. Same effect that you’ll get on windows when it’s very cold outside. Moisture in the warm space condenses where it meets cold air. You might be seeing it under the hearth pad due to the lack of airflow there.

Condensation is from warm humid air getting in contact with a cold surface. Is the floor cold and what is the humidity within that room? You may need to isolate the floor from underneath. The reason is that the hearth is preventing warm air from the room to heat the floor under it making it colder that the rest of the floor area.

yeah, whats underneath that flooring??

Thanks! I hadn't thought of this, but it makes sense and might be the case. Underneath the stove is an unfinished basement which is partially below ground, pretty humid (not sure of the humidity level in the basement nor the rest of the house - I'll have to look into that - but any paper/cardboard left in the basement quickly gets destroyed by moisture) and probably pretty cold when I have the stove running as my forced hot air system isn't running (the forced hot air system doesn't blow air into the basement, but when it runs, it keeps the basement warmer due to the hot air going through the ducts throughout the basement). Directly below the hearth extension pad is the wood floor and under that a subfloor and joists, however a few years back I had pink fiberglass insulation put in all the bays between the joists of the basement ceiling. I got this done as part of a free green energy program, and honestly I don't think it does much to keep the house warmer, and I wonder if somehow it's adding to trapping moisture. In any case, over the weekend I could pull some of the fiberglass batts from between the joists and look to see if I find any moisture on the ceiling on the joists or subfloor below the hearth pad. Thoughts?

You could try to put the hearth on shims and see if it solves the problem

Shims would be easy to do and in general this isn't a huge issue now as there is nothing on top of the hearth extension so I can easily remove it. However, this could become a much bigger issue very soon as I plan on putting in a new stove soon, which will likely sit on top of the hearth extension making it impossible to pull it up to check, clean moisture and figure out if there is a problem. I'm actually glad this is happening now so, with the help of all of you, I can hopefully figure it out before I have a new stove and hearth pad I can't remove. Thanks!

 

[Hogwildz]

Is the hearth extension made of micore? Id the extension warm on the bottom side?

 

[KennyK]

Is the hearth extension made of micore? Id the extension warm on the bottom side?

I'm not sure what it's made of as I bought it used and all it says is what I showed in the picture of the label. I do think it is a bit warm on the bottom side, but I'm not at home now and will have to double check. Would micore be stay cool on the bottom or warm? Would it make a difference? I'm thinking to use micore 300 for the new hearth extension with the new stove.

 

[begreen]

It may have sat outside and soaked up moisture. Elevate it so that air can get below it and see if the stove heat will eventually dry it out.

 

[webby3650]

This is not a hearth board issue. The problem is the moisture level in the basement. You really need to address this problem from below, excessive moisture like this is damaging to the entire home. I’ve seen mildew under hearth pads before, but never water droplets, it looks you have a pretty severe case on your hands. Unless of course that hearth pad is saturated with water from the previous owner...

 

[armanidog]

I would buy a roll of 6 mil plastic and lay it on the ground under the house, overlapping about a foot. My problem was drainage from rainwater soaking in and a layer of clay was directing the water to drain under the house under the foundation. I put in a french drain but also covered the crawl space under the house with plastic. A lot drier under my house now.

 

[KennyK]

This is not a hearth board issue. The problem is the moisture level in the basement. You really need to address this problem from below, excessive moisture like this is damaging to the entire home. I’ve seen mildew under hearth pads before, but never water droplets, it looks you have a pretty severe case on your hands. Unless of course that hearth pad is saturated with water from the previous owner...

My basement is on the humid side, it's fieldstone walls and a concrete foundation, partially below ground, partially above, but I don't think it's extremely wet. I could be wrong about this, but my house is on a hill, and the basement has never flooded when others in the neighborhood do during big storms (maybe that's different than humidity). Also,I mentioned that paper and cardboard get eaten in my basement, but it takes a little time. I just noticed I have a piece of cardboard that's been sitting on the floor of the basement for two months and it's fine. All of this said, I'm here to learn and fix whatever problem I may have. For years I've been meaning to get a dehumidifier for the basement, so maybe it's time to do that. Seems like I should get a humidity reader too, to see what it really is down there. Any other thoughts on how to asses and address?

 

[KennyK]

I would buy a roll of 6 mil plastic and lay it on the ground under the house, overlapping about a foot. My problem was drainage from rainwater soaking in and a layer of clay was directing the water to drain under the house under the foundation. I put in a french drain but also covered the crawl space under the house with plastic. A lot drier under my house now.

Do you mean put the plastic under the house itself or on the floor of the basement? There is no space under my basement to get to, such as a crawl space like you have. It's just concrete foundation and fieldstone walls built on top of the earth, partially underground and partially at ground level due to my house being built on a hill.

 

[begreen]

I think folks were assuming crawlspace. I'm still going with the hearth pad sat outdoors theory.

 

[mountain man 2]

Why not put a dehumidifier in the basement.....one of the best things we have bought is temp/humidity monitor. It cacame with 4 sensors and main readout/sensor so you can read temp n humidity in 5 different locations. We have in living room...crawl space...detached garage....outside. I feel it really pays for itself.
https://www.amazon.com/gp/product/B00FX8ZGOO/?tag=hearthamazon-20

 

[coutufr]

If it is not a conditionned space in your basement the humidity level most be around 80 % humidity. Using a dehumidifier is expensive and you need to make sure you by one that works under cold conditions. I would try to aerate the basement to get rid of the humidity. You need more that one humidity / temperature reader. If the water is condensation the humidity level in the main house must be well above 50%.

 

[KennyK]

Why not put a dehumidifier in the basement.....one of the best things we have bought is temp/humidity monitor. It cacame with 4 sensors and main readout/sensor so you can read temp n humidity in 5 different locations. We have in living room...crawl space...detached garage....outside. I feel it really pays for itself.
https://www.amazon.com/gp/product/B00FX8ZGOO/?tag=hearthamazon-20

This temp/humidity sensor looks great! I've been wanting to know this info in multiple areas of my house. Amongst other things, not that I'm turning off my heating system for much longer periods of time, I want to make sure my basement doesn't get so cold that pipes burst. I think I'm going to order one of these. And, I'm thinking about a dehumidifier for the basement regardless of if that's the cause for the water under the hearth pad.

If it is not a conditionned space in your basement the humidity level most be around 80 % humidity. Using a dehumidifier is expensive and you need to make sure you by one that works under cold conditions. I would try to aerate the basement to get rid of the humidity. You need more that one humidity / temperature reader. If the water is condensation the humidity level in the main house must be well above 50%.

The basement is unfinished and the only heat in there comes from the ducts for the forced air system bringing heat upstairs and I suppose some heat off the furnace just being there. While I don't know for sure, and need to get a meter to find the humidity level in multiple areas of my house, I can't imagine the humidity is above 50% in the main house. In fact, when I first moved in, I found the house to be very dry feeling in the winters (still do, but I've gotten more used to it). I will definitely be getting some sensors soon to check the humidity in multiple areas of the house.

What do you mean by aerate the basement? In the warmer weather, I try to leave the basement door open as much as possible, but are you talking about more than that?

Good tip to look for a dehumidifier that works under cold conditions. What makes using a dehumidifier expensive, the electricity bill? I would think nowadays there are fairly energy efficient models.

 

[coutufr]

The challenge to understand your situation is that we do not know where the water comes from. We believe that it is comming from the humidity in the air since there’s no other logical explanation to it. If your house is dry and the basement is part of your conditioned space I don’t understand what is going on. If you have other observations or pictures it will help but at this point I do not believe this is condensation. I found using a dehumidifier relatively expensive to use during the summer, mine is a very basic one. Cold outside air in winter is relatively dry. If you exchange internal air with outside air it will dry the air inside your house.

 

[begreen]

We believe that it is comming from the humidity in the air since there’s no other logical explanation to it.

Unless the hearth pad sat outdoors in the rain and the micore in it soaked up a lot of moisture.

 

[mountain man 2]

One of the main reasons we have a dehumidifier in our crawl space (in which is really not that small) is when we bought our home there was a small problem with mold on the floor joist. Had it removed n decided to run a dehumidifier.
As far as cost...I have central air in home...l.p. heat n central air in my 30x40 detached garage (insulated)...keep at 70* in summer. Dehumidifier in crawl space n garage, 3) 8 cu.ft.chest freezers...2)refrigs..etc.
Eletric bill never over 200.00.
Our house is only 1300 sq.ft. n its 80% hardwood floors (the rest is stone n tile)
I try n keep the humidity at 45 to 50% year round (humidifier in winter).
Like begreen stated...it is puzzling why there is condensation under your extention.
Maybe is was wet at one time kinda make sense.
GOOD LUCK

 

[coutufr]

My electric bill was on average below 80$ a month last year so yes I found it expensive relatively speaking. it was costing me almost 5$ per day to run a humidifier non stop during the summer.

 

[mountain man 2]

My electric bill was on average below 80$ a month last year so yes I found it expensive relatively speaking. it was costing me almost 5$ per day to run a humidifier non stop during the summer.

Nothins cheap in canada

 

[coutufr]

We live well but for some reason everytime we buy something it is expensive. The taxes are brutal here.

 

[sportbikerider78]

I'd put a dehumidifier in the basement as well. 80% humidity isn't healthy! I'm surprised you haven't seen mold under the floor. That type of moisture and a wood floor is not a great idea. The typical max for humidity is around the 60-70% range. You might have to run it full time to get it down to 60, but then not that much to maintain.

I'd also put a vapor barrier insulation like XPS under the floor where the stove and pad is.

 

[peakbagger]

I would be curious if you picked a similar stretch of floor and laid down a piece of tin foil on the floor weighed down by books if you would experience a similar issue. That would rule out the micore.

I have seen homes with wet basements that can create mold under anything watertight left on the floor. I have seen that with wood boxes set directly on the floor with no legs. The house is much drier and warmer than the basement so the water vapor in the basement air will naturally get driven towards the heated drier portion of the house. This is not an issue unless the moisture is stopped by a waterproof object. I also could speculate that the Micore is acting to insulate the floor from heat in the house so the lower surface is cooler than the rest of the space which could cause the vapor from the basement to condense. The obvious quick fix is put in an air gap under the pad so that air can get into that space.