Correct humidity level in the winter

Reply

  #1  
Old 01-26-15, 06:09 PM
D
Member
Thread Starter
Join Date: Aug 2014
Location: United States
Posts: 15
Received 0 Votes on 0 Posts
Correct humidity level in the winter

What is the correct humidity levels in the winter? I saw some people recommending around 30% when its below freezing out and others say that you can have it higher as long as your windows do not have condensation on them. What is the correct levels? I live in Michigan and its often 20 degrees in the Winter. I have been keeping my humidity around 40 to 45% and don't have any condensation on the windows. Is this too high? I would hate for it to get in my walls.
 
Sponsored Links
  #2  
Old 01-26-15, 06:54 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 59,061
Received 1,109 Votes on 1,029 Posts
Typically you should not need to use a humidifier in the winter because of the amount of moisture that is generated during your daily activities.

Outside Temperature ............. Inside Humidity
..... 20 to 40F ..................... Not over 40%
......10 to 20F ..................... Not over 35%
...... 0 to 10F ...................... Not over 30%
... -10 to. 0F ....................... Not over 25%
... -20 to 10F .................... Not over 20%
....-20F or below ................... Not over 15%

I'd say you are pushing the humidity level a bit. You are right to be concerned about sweating in the walls and mold growth.
 
  #3  
Old 01-26-15, 08:05 PM
XSleeper's Avatar
Group Moderator
Join Date: Dec 2004
Location: USA
Posts: 25,991
Received 667 Votes on 617 Posts
While PJ's chart is a good rule of thumb, I have a hard time saying that there is a "correct" amount of humidity that should be in a home, as if that is something that we always need to control. Nature usually does a fine job of regulating the humidity in a home. It doesn't sound like you HAVE a problem... it sounds like you are worried about the "possibilities" of having a problem.

Houses that have a humidifier on their furnace/forced air probably do need to be adjusted, or else they could be pumping too much moisture into the air and causing problems.

Since you said you don't have a problem with condensation on windows, my opinion would be that "there is no problem" with your current humidity. If you get moisture on the windows, you should probably try to lower the humidity. No moisture... no problem. If you aren't getting sweat on the interior surfaces of the walls you have no problems to worry about.

Now if the temperature dropped to 0F for a week, your current humidity would probably be too high... and your windows would probably start to sweat. Even then, would it create some unseen problem in your walls? not likely.

Mold needs humidity of 60% or higher, and mold favors warm temperatures, not cold winters.
 
  #4  
Old 01-26-15, 08:30 PM
Norm201's Avatar
Member
Join Date: Sep 2013
Location: United States
Posts: 8,991
Received 230 Votes on 205 Posts
Typically you should not need to use a humidifier in the winter because of the amount of moisture that is generated during your daily activities.
This statement flies in the face of reality. When does one need a humidifier? Assuming a forced hot air furnace, winter time humidity drops dramatically (you're adding lots of warm dry air). Furniture joints dry out and night time breathing is typically hampered. This especilly true in today's households because usually all adults work and the house has little or no activity. Upon installing my humidifier to the furnace my house is warmer, breathing is easier, less colds, and all furniture joints are intact (no more re-gluing). My humidistat is about 30% to 40% in winter. Yes I do get a bit of window moisture but that is mainly due to the need for new windows and lots of air exchange.

I regularly recommend a humidifier to customers that complain of loose chair joints and scratchy throats during winter. Many customer have come back to verify my suggestions by either doctors recommendations or no more loose furniture.

Now, hot water (steam) heat is another story and does not upset the natural moisture level of a home. The draw back of that is the lack of A/C in the summer.
 
  #5  
Old 01-26-15, 08:50 PM
B
Member
Join Date: Oct 2008
Location: New England
Posts: 10,514
Received 37 Votes on 34 Posts
Adding moisture in the winter is only necessary because the moisture being generated by people ad their activities is being lost through air leakage. Tight homes actually need help on the dehumidification side. A target number for air sealing is often 0.35 air changes per HOUR (ach) and yours is leaking more than that. If it were tighter your windows would be raining with the humidifier running.

So, yes you should be concerned about moisture in your walls as somewhere there are some significant leaks.

But the solution, along with turning that humidifier down, is to locate and seal some of the leaks. I'll attach a link on air sealing.

But there's the catch. In existing homes the leakage can rarely be reduced to below that 0.35 ach number so where does all of that moisture go? In the walls, yes, but a properly designed wall will be able to dry to the outside. Vapor barrier or vapor diffusion retarders on the inside and vapor open to the outside.

A quick example while I wait to get buried in 18" of snow, your 70 degree inside air at 40% RH will start condensing at 45, its dew point. Not hard to find inside a wall.

Here's my advice: Pick up a separate RH meter that gives you both temperature and humidity. This is always important air quality information beyond the setting of the humidifier.

Run the humidifier as low as you can and be comfortable. If 40 - 45% is the number, then you are probably not causing a problem.

Then, review that air sealing link from Efficiency Vermont and put some of that work at the top of your to-do list. It will not only help with the RH, it will reduce your heating costs.

Bud

http://www.efficiencyvermont.com/ste...ide_062507.pdf
 
  #6  
Old 01-26-15, 08:51 PM
D
Member
Thread Starter
Join Date: Aug 2014
Location: United States
Posts: 15
Received 0 Votes on 0 Posts
Thanks for all of your advise. I really enjoy the higher humidity as it just feels warmer plus my daughter seems to get bloody noises easy in the winter if it's too low.

Here is another question. I have only seen condensation on the windows once or twice when we forgot to turn on the bathroom fan and the humidity reaches 52 to 55 in that room. Is that normal? It sounds like others get it with humidity in the 30s. I do have a 3 year old house so maybe my windows are a little better?
 
  #7  
Old 01-26-15, 09:10 PM
B
Member
Join Date: Oct 2008
Location: New England
Posts: 10,514
Received 37 Votes on 34 Posts
All windows are terrible but yours must be a bit above the pack. Many factors involved like air circulation inside and wind outside the house. But yes, typically you want to run the exhaust fan for about 20 minutes after a shower. If that 3 year old is a daughter, then that time will increase as she grows up . To make it easier they make delayed off switches where the fan turns on normally but will remain on for a pre-set time when turned off.

Bud
 
Reply
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: