Humidity & Temperaturecontrol & condensation during winter in 100% wooden workshop

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Forum topic by Graem Lourens posted 09-28-2016 04:42 AM 2464 views 0 times favorited 15 replies Add to Favorites Watch
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Graem Lourens

36 posts in 869 days

09-28-2016 04:42 AM

Hi everybody.

I have treated myself to my first workshop.

A few infos first about it:

- Its a 7×5 meters (23 by 16 feet approx) 100% wooden garage, made out of approx 1.5” thick solid pine (general wall thickness).
- The roof is double insulated, the doors are insulated as well as possible, and the 2 windows are double glass.
- Its standing on a solid block of raised concrete, that has a vapour barrier underneath, and the slab is standing on an older slab of concrete that levels up with the soil.
- The concrete floor has been sealed with a double epoxy coating and does not let water through and is also chemical resistant.

Winter is approaching, and in Warsaw (Poland) we have extremes from 40 degrees (104F) in summer to -20 degrees (-4F) in winter.
My biggest concern since i decided to build the workshop was keeping the tons of tools that are inside, as safe as possible mostly concerning rust. There are several cast iron devices that will suffer if i do not have some kind of control.

Most people i talk to are saying that due to the fully wooden construction, and roof insulation, the temperature changes will not occur rapidly, and i’ll not have condensation problems. After lots of research i have come to the conclusion that either i don’t have to do anything, or at least have a fan running to circulate the air as well as possible.

I’d like to have your opinions though, as i’m not the first with this problem and i have read a lot of threads here, but i didn’t find any thread where there was a fully wooden workshop, and i do think that wooden construction changes the actions necessary to protect the inside devices.

Any insights warmly welcome.

Kind regards, Graem

-- Novice woodworker and passionate astrophotographer

15 replies so far

View mahdee's profile


4021 posts in 1969 days

#1 posted 09-28-2016 10:49 AM

Hi Graem,
I don’t think you have to worry about it. You can always get a small heater with a blower to dry the inside when needed. As it relates to your equipment, just give them a good waxing after you clean all the oil and dirt off of them.


View Graem Lourens's profile

Graem Lourens

36 posts in 869 days

#2 posted 09-28-2016 11:09 AM

Hi Mahdee.

Thank you for your reply. Thats pretty much what everybody else is telling me, so i’m starting to believe it :) (don’t want to suddenly have surprise-rust popping up everywhere!)

I’ll be building there also in winter, so i guess a small heater for keeping me warm will be a must, but i’d like to first see how warm it is in deep winter, so i know how powerful my heater has to be. I have a cheap small 1000 watt electric heater (20$?) and i doubt it will work much, but will give it a try and measure how fast/slow it heats up the workshop.

Kind regards, Graem

-- Novice woodworker and passionate astrophotographer

View bondogaposis's profile


5091 posts in 2553 days

#3 posted 09-28-2016 12:43 PM

Here is a way to calculate the size of heater that you will need. First calculate the cubic size of your shop. You said it is 23×16 x and I will assume an 8 ft ceiling. That gives you 2944 cu. ft multiply that times .133 gives you 392. Now you have to decide how many degrees above the outside temperature you want to have your shop on average, let’s say 50°F. That means that if the outside temperature is 0°F you will be able to heat your shop to 50°F. The chart I have shows you will need a heater rated 34,000 BTU’s. Here is the link to the calculater so you can play with the variables compare the prices of heaters on your own.

-- Bondo Gaposis

View Graem Lourens's profile

Graem Lourens

36 posts in 869 days

#4 posted 09-28-2016 01:51 PM

Hi Bondo.

Thank you very much for your very detailed answer and the link. I’ve snooped around and seen some devices that would match the requirements.

But this would more be for my comfort (to have an acceptable temperature) when i am there, and the time i’m not in she shop i will not be heating, correct? This on/off cycle will not cause problems due to that when you turn the heater off the air as able to absorb more moisture (taking it for example from the wooden walls), and when i turn the heater off, the temperate drops and relative humidity rises again.

I’m worried if this will not be a problem when only sometimes heating?

-- Novice woodworker and passionate astrophotographer

View richimage's profile


43 posts in 1932 days

#5 posted 09-28-2016 02:10 PM

Congratulations on your shop! I first learned about split AC/Heat pump systems stationed in Germany, and now own two of them – one for my office (over the garage room) and my woodshop. They are quite efficient, and easily keep the spaces at specified temps for the season. One big benefit I did not forsee is the drying effect the AC has in the summer… Here in Missouri, wet and hot seem to go together for months in the summer! Any wood I bring in just gets dryer! Modern split systems run at reduced rates when no heating or cooling is required, and just ramp up when needed.

-- "Women are like modern paintings. You can't enjoy them if you try to understand them." Farrokh Bulsara (Freddie Mercury)

View bondogaposis's profile


5091 posts in 2553 days

#6 posted 09-29-2016 01:50 AM

But this would more be for my comfort (to have an acceptable temperature) when i am there, and the time i’m not in she shop i will not be heating, correct?

Yes, that is what I did for many years. I live in a cold climate, Montana, I would turn on the heat about an hour before I went to work in the shop just to get the tools warmed up and make it more pleasant and so I wouldn’t need to work with a heavy coat. When I was done I would shut the heat off, unless it was to let a finish cure or let some glue dry, I might let it run for another hour. I never ran it all night though. It usually would not freeze out there unless we really had a big cold snap, below 0°F and such. I always had to bring the glues inside, ruined a few bottles if I forgot. Machinery doesn’t like to work real cold either, heat is essential in a cold climate.

-- Bondo Gaposis

View REO's profile


929 posts in 2276 days

#7 posted 09-29-2016 09:35 AM

as long as an electric heater is used no problem. if you go with a ventless space or gas heater you will add moisture to the air and could get a condensation problem. vented heater no problem as the by products are vented outside.

View rwe2156's profile


3171 posts in 1682 days

#8 posted 09-29-2016 01:33 PM

the temperature changes will not occur rapidly

This is the key. It all depends on the humidity and how fast it cools.

My shop is unheated and not insulated. Certain days in the fall and spring the water is literally dripping off the bottom of the metal roof. The machines will be cool to the touch and moist. I have the least amount of problem in the summer, even though the humidity is highest, because the temp drop is not that much.

In addition, machines used on a daily basis don’t get rusty.

Other machines used less frequently can be coated with oil, wax, or various other products.

You will need a heater anyway, so this should drop the humidity. You’ll be in good shape.

-- Everything is a prototype thats why its one of a kind!!

View REO's profile


929 posts in 2276 days

#9 posted 09-29-2016 09:37 PM

How fast or slow the temp or humidity changes makes no difference. If the equipment is at a temp below dew-point, humidity will condense.

View pontic's profile


650 posts in 810 days

#10 posted 09-29-2016 10:13 PM

I agree with Mahdee. Sounds like a typical Indiana weather cycle to me.

-- Illigitimii non carburundum sum

View Fresch's profile


360 posts in 2122 days

#11 posted 09-29-2016 11:21 PM

I use paddle fans. Keep the air moving; wax your tools! Yes I did just say that.

View NewfieDan's profile


50 posts in 2850 days

#12 posted 09-29-2016 11:34 PM

I had a similar issue when I was in northern Alberta, where we had winter temps of down to -45C and summer temps of 35C. To prevent rust I kept the temp about 5C when I was out in the shop working. When I was working i had the shop about 18C. To help prevent rust I kept a coating on my tools when not in use. After 10yrs there was no rust on my cast iron. To heat the shop I put in a natural gas heater. Can’t remember the btu rrating.

Now I am in eastern Canada with very high humidity and still do the same as when I was in Alberta. Been here in eastern Newfoundland for 6yrs and no rust here either. Here in NL I have an forced air electric heater mounted on the ceiling. It has a 4500W(?) rating (20A x 240V).

The only rust I have had on my TS was when somebody placed a cold beer bottle on it during a party. Can anyone say condensation? Cleaned it up with some 2000grit sandpaper and a sanding block.

View Kirk650's profile


576 posts in 950 days

#13 posted 09-30-2016 05:11 PM

NewlieDan just reminded me of the constant visitor I had for a long time (he finally died, not that it’s a good thing, and I miss him). He’d go into my little fridge, get a cold beer and sit next to my Jointer and put the cold beer can on the jointer table. Sandpaper and wax kept things under control.

I have a 20 by 20 workshop that’s separate from the house. In the summer I have a window A/C running, and in the winter I normally use a small electric heater. It works quite well. I also have the thing that some of you may fear – a propane gas heater for those really cold days. I only run it when I’m in the shop, and I really have had no condensation/rust issues in the last 3 or 4 years. I measure indoor and outdoor humidity, just to know what it is.

Many years ago I discovered (due to a slightly flooded house) that humidity isn’t just in the air. It’s in the carpet, the drapes, the couch, the clothes in your closet. Once a building reaches a certain humidity inside, it will tend to hold that humidity until it slowly equilibrates with the next weather change. So, back when I had a wet home, I decided to get a dehumidifier. I found a place that sold them and the sales guy wanted to know how big it needed to be. After much calculation, I finally just winged it and got the biggest non-commercial unit they had. I ran it day and night for over a month and it recovered an astounding amount of water.

View Graem Lourens's profile

Graem Lourens

36 posts in 869 days

#14 posted 09-30-2016 05:37 PM

Hi Everybody.

Thank you so much for your comments and suggestions. I have put in a small weather station to monitor humidity (so far its way below what i thought it is, at 60% pretty much constant) and will see how it turns out during winter.

Before i go and buy anything expensive i first want to get a feeling on how cold it is really, to see what kind of heating i’ll need. But the general consensus seems to be that in a wooden shop like mine, i’ll not have to go to tremendous efforts to keep everything safe. I’ll probably be starting with a small heater+fan that i turn on a while before i want to start working.

Kind regards, Graem

-- Novice woodworker and passionate astrophotographer

View Dustin's profile


597 posts in 942 days

#15 posted 09-30-2016 07:14 PM

I agree with Mahdee. Sounds like a typical Indiana weather cycle to me.

- pontic

Ditto for Kentucky. Never would have guessed that Poland’s climate was so similar to the Midwest…my condolences!

And congratulations on the new shop!

-- "Ladies, if your husband says he'll get to it, he'll get to it. No need to remind him about it every 6 months."

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