Thanks Nathan. I've been doing some reading since I posted here and WOW is there lots of info out there. Although i'm now thoroughly confused. Relative humidity, constant humidity, venting, etc. etc. My heads spinning .
I have a shop heater in there that I use in the winter. It sounds like I should continue to use the heater in the shop to maintain a constant temp? I thought that if I ventilated it would help with the moisture but it looks like I was wrong on that one. The shop is about 13x23 and it's insulated. Concrete slab floor. Essentially its the back part of the garage which is not insulated. IT has a roll up door to the outside and a man door which leads into the main un insulated garage. The man door is not insulated and I plan to replace it in the near future. Should I install a small air conditioner as well so I can control temp in summer and winter. We moved in lat year so i'd have to open a bit up to check for vapor barrier.
Oh okay I misunderstood.
Trying to read it on my damn phone lol
Well where's the moisture coming from?
How are you heating it?
Burning fossil fuels (furnace oil, keroscene etc) releases moisture into the air as a by product.
If you're only heating it once a week big temperature swings can cause humidity. I try to keep my shop at a constant 10 degrees and only turn it higher when I'm actually working in there.
Concrete is porous, if you're in a wet area it could actually be coming up through the floor.
My last shop was really damp, water coming up through the floor. Cant really do much except for running the dehumidifier. I usually only ran it in the spring & summer.
Steel doors actually have very low r value, a solid wood door is probably fine.
Getting it sealed from the outside air is usually the way to do, is the door leaky? Wood door I assume? Hows the weather stripping?
Here in Thunder Bay, my well insulated heated shop with a concrete slab floor will have a humidity level of about 12-15% during the cold dry winter period. This will rise to 50-60% during the hot summer period. I do not try to control the shop humidity, but have 2 hygrometers in the shop and do cross-grain work with the humidity in mind. Roy
Are you solving the problem, or becoming part of it?
Jerome 30% humidity is just a little above semi arid desert conditions which is terrible for wood in southern Ontario. Most good wood flooring manufactures/installers recommend a moisture level/RH of between 40 and 45%. This range also is good for helping with dry eyes nose and throat. I've heard your rec before and from HVAC people but no one can really explain where it originated or why. Our western friends are plagued by the conditions constantly and we have many issues transporting finished wood products across to them because of it. Just using a little logic, if 30% was the limit, this whole part of the world would be one big mouldy growth in from April to November.
35 percent anything from Gery Metz in the past will have a range ive forgotten but could look it up, he consulted to furntiure factories for years in Wood Magazine and was the guy they all turned to with problems when suppliers didnt know or to prevent problems ahead of time. I go from not registering when the woodstove is honking to one personal best of 94 percent. at that I say I had clouds forming. I pay attention to shop fitting depending on time of year and humidity and also where its going.
looking up notes he said temp 65-80 temp and humidity at 30-40 percent not less than 30. in low humidity areas place 55 gallon drums of water in the corners if that doesnt do the trick then you have to use industrial humidifiers. His notes are for people in the big leagues where runs could be 1000 pcs at a time of different pieces.
You have to realize we measure RELATIVE humidity, and that means you can have a low RH at 30 degrees and the same air will be at dew point (100%) when the temp drops near freezing. Heating with electricity means no dry winter air enters the building to replace flue gasses, so humidity builds from respiration etc.
Curious to know optimal humidity levels for wood shop.
Why exactly the same as the environment where the furniture will reside of course
That's the issue, it doesn't matter if your shop is 10 or 50% relative humidity, what matters is that if it'd substantially different from the location the furniture will be in, you have to take care of that by design and manufacture.
My shop conveniently is in the basement of my house so it's perfectly acclimatized for the final location of my furniture........regards, Rod.
John JMK if you look at a psychrometric chart and find the common room temp of 70* and then find where that line meets the 30% RH line and then go to the left in a straight line to the 100% RH line you will find that by cooling that air with an RH of 30% to just 40* (which is easy for walls with insulation gaps, or bad air circulation or around windows) it will condense. Mould need 3 things to grow food it loves cellulose (wood dust or drywall paper) Moisture (from the condensation) and warmth 40* is perfect.
That is where the recommendation comes from.
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Thanx Jerome for the info. I realize that HVAC recommend this also to try and keep condensation off of windows. The unfortunate part is its spells disaster for woodworking projects made in the warmer more humid part of the year, since it much easier to stress the wood to cracking and splitting. Personally I try to maintain minimum of 40 to 45% in the house and shop year round. I was called to a womens new house one time in early January and she was complaining that floors gaps were openings up, trim gaps were cracking and her wooden table had developed a crack. Through the conversation while I was waiting for my RH meter to register she also said since moving she always had a dry throat and eyes. The meter had drop to about 29% percent in the 20 minutes I was talking to her which also coincided with what the heating and air conditioning was set for.
The humidity right now , in my shop at 68°F is 31% the humidity in my house at 70°F is 41%.
in the winter months I am usually still at 64-70F in the shop depending if I am in there or not and I've seen 18% humidity .
in the summer months as I am not air-conditioned, I can hit 90F, but I have an attached garage shop with a dehumidifier and I can hit 52% humidity. In my house the lowest I've ever seen it was 22% humidity and I am usually running the humidifier (winter months).
ideally, anything you make should be climatised to an average of it's install. I'm guessing most installs will be within the home, so an ideal moisture level percentage for your shot should be 25 to 45%.
my location is extremely dry. I do not have sub pumps, (water just wants to run away from my home as fast as it can). In the summer I have no protection from direct sun heat. My Central air conditioner probably runs 18-20 hours a day. Adding air conditioning to my future shop is a must.
A few summers ago I had a pond it in my basement because of sawdust clogging one of the drains that the AC dumped into. But I think that's another story. I have a basement wood workshop too.
For every action there is an equal and opposite reaction.
Sir Isaac Newton.