80% - 50% humidity. should i be worried

[tyler mckenzie]

Just moved to a new town (kelowna B.C.). I was shocked to find out the humidity is 80% (32 f) in the winter and 50% (80 f) in the summer. Anyone else having to deal with a simular climate? Any advice would be highly appreciated. I am novice furniture builder. thanks

[John Thompson]

When the humidity is high... tighten up on joints.. When low.. loosen up. Observe.. evaluate.. and adapt!

Sarge..

[Sean Troy]

When the humidity is high... tighten up on joints.. When low.. loosen up. Observe.. evaluate.. and adapt!

Sarge..
Wouldn't it be the opposite? If not, why? Thanks, Sean

[Heather Thompson]

Wouldn't it be the opposite? If not, why? Thanks, Sean

Sean,

When the humidity is low, wood is smaller, when it is high the wood is at its largest point.

Heather

[Joe Chritz]

Check the shrinkulator online. You can get exact wood movement figures. At least, as exact as can be expected.

If you house is conditioned, AC and/or heat the humidity won't change as much as the ambient air normally.

Joe

[Jason Beam]

I have a similar climate here ... it's the opposite of everyone else - my humidity goes UP in the winter, not down like everyone else. But I don't really do anything special - I apply basic "wood movement" rules no matter what.

[Marcus Isaacson]

Remember that humidity % is related to temperature. Given the same amount of moisture in the air, as the temperature decreases, the humidity % increases. Right now it is 76% humidity outside at 30 degrees and inside it is only 35% humid at 65 degrees. Like others have mentioned, the humidity swings should not be extreme inside your house.

[John Thompson]

Miss Heather pretty much nailed it, Sean. More moisture in the air, the amount likely to be absorbed by the stock will increase and decrease as humidity falls. And I wouldn't judge it by the seasons as local climates can vary all over the world as to how it will affect wood.

Then you have outside humidity.. shop humidity and inside humidity where the project ends up. And that's why what I stated is nothing more than an old rule of thumb I learned years ago. It comes into play, but I personally don't feel you can go by a chart as the chart cannot reflect all conditions that might exist.

Therefore... Observe.. Evaluate.. and Adapt takes a deeper meaning with the tight when high.. loose when low being a mere indicator of what is most likely to happen.

Thanks all that clarified to Sean as am up to my neck in drawers for a chest at the moment and just glance here on coffee break.

Sarge..

[tyler mckenzie]

thanks everyone,
marcus i think you're confussed, in my location the humidity drops to 50% during the summer.

[Clay Crocker]

Just moved to a new town (kelowna B.C.). I was shocked to find out the humidity is 80% (32 f) in the winter and 50% (80 f) in the summer. Anyone else having to deal with a simular climate? Any advice would be highly appreciated. I am novice furniture builder. thanks

You will find some interesting information on humidity and wood here:

http://www.umass.edu/bmatwt/publications/articles/humidity_tempature_wood_moisture_content.html

I think that your local ambient relative humidity would be an advantage because the absolute humidity does not change much from season to season.

Clay

[Russ Filtz]

You pretty much get high humidity always in cold weather. The air can't hold much moisture. It feels dry since there's not much there, but the RH can be 100%!

Try living in FLorida, I'd take 50% humidity in summer any day!

[Sean Troy]

Miss Heather pretty much nailed it, Sean. More moisture in the air, the amount likely to be absorbed by the stock will increase and decrease as humidity falls. And I wouldn't judge it by the seasons as local climates can vary all over the world as to how it will affect wood.

Then you have outside humidity.. shop humidity and inside humidity where the project ends up. And that's why what I stated is nothing more than an old rule of thumb I learned years ago. It comes into play, but I personally don't feel you can go by a chart as the chart cannot reflect all conditions that might exist.

Therefore... Observe.. Evaluate.. and Adapt takes a deeper meaning with the tight when high.. loose when low being a mere indicator of what is most likely to happen.

Thanks all that clarified to Sean as am up to my neck in drawers for a chest at the moment and just glance here on coffee break.

Sarge..
Man, I can confuse myself so easily. My end thought was the same as yours but how I got there wasn't. LOL

[alex grams]

Welcome to Houston, the land of 90/90 summers.

90 degrees and 90% humidity, where you sweat even just thinking about going into the garage and working!

I think for the most part, as long as each piece of lumber has been acclimated to where you are working, you should be fine. But if you take some wood you had in a closet in the house and take it into your garage to start working on it when it is 90% relative humidity and use them both on what you are building, they will move differently. But if both have been stored in the same area,they should move relatively more closely to one another.

[Will Blick]

Alex, 90/90 is brutal, I have experienced your weather... lots of sweat on your wood :-(

This RH humidity issues comes up all the time. It is very important.... what ww's should be really concerned with is, grains of moisture in the air.... as this indicator levels the playing field and you can do an apples to apples comparison between two different temp/RH. For some reason, this isn't promoted though, but is easy to look-up on a psychometric chart.

As mentioned earlier, your wood will acclimate in a short period of time to your work space. But the other part of the equation is, where does the final work piece find its home? If that differs radically from the humidity level in your shop, then you really might have a problem.

Alex, have you ever built something in 90/90 with wood acclimated to such, then kept it inside an AC home? Any catastrophe's?

Here is a table of Grains of Moisture, per lb of dry air.

30/25
(30 deg F dry air can hold 25 grains of water vapor)

40/38
50/54
60/80
70/110
80/156
90/215


So, 50 deg F air, at 100% RH has the same moisture content as 70 deg. F air at 50% RH. This is why RH is so confusing, and IMO should have never surfaced as a yard stick to express moisture content of air. But, too late now...


If you build something in 90F/90RH, and move it to an AC space, you have taken wood that has acclimated to 210 grains of moisture, to the AC space, assuming 70 deg at 30% RH, or 34 grains of moisture in the air. So 210/34 = 6.2x the water content in the shop air vs. the indoor air. I would consider this difference quite extreme. Of course, some wood is more sensitive than others for movement, and not only is the wood type significant, but also the the cut of the wood.

[Al Willits]

Tyler, I'm assuming your weather is close to what ours is in Minn, and with that and considering I'm a newbie at this, I'd think you'd be more concerned with inside humidity than outside, least for furniture building.
Considering we run from -30 to 100+degrees F in temps and humidity swings just from one end of the scale to the other outside, I think you'd go crazy trying to work with that.

Inside temps and humidities are far more stable and that's the swings I would deal with..imho

Al