Dehumidifier or Heater for Workshop

[rjb]

Hi,

My workshop is a double garage about 20ft square (on 2 floors) and I’m having trouble with damp, particularly storing MDF as it quickly deteriorates in the cold damp environment i.e. swells and goes soft. The building does have insulation, but it’s not brilliant. I use a 3kw fan heater when I’m working, but the temperature quickly drops overnight. I’m looking at buying a new heater to provide a constant low level background heat or a dehumidifier, but I’m not sure which would work best. I’d appreciate some advice on the most effective and economical solution.

Thanks.

 

[neilyweely]

Hi
I would imagine most folk will agree with me when I suggest improving your insulation first; heating a poorly insulated WS is a bit of a no no. My garage/ws is insulated with kingspan-a-like and then heated, permanently, with one of those oil filled rads. I have it set on absolutely the lowest stting (frost setting) which keeps it about one degree or so warmer than outside. As far as I am aware this is enough to stop condensation/damp etc from forming on the machines and surfaces. You can feel the difference in the air (I do mean the air, not the temperature, it just feels drier) and the temp when you go into the workshop.
All that being said, last year I had no heating - just the insulation, which is fairly thorough, and I still had no real problems with the damp. I read, here I think, that a 5% lack of insulation equates to a 50% drop in efficiency. In other words if you fail to insulate the walls then you may as well not bother insulating at all. With that in mind I went to town with the insulation and I think my body temp once a day keeps it that one degree necessary to cease the damp sitting down.
I may be wrong with all this, but if I am then someone else is too - 'cos I read it somewhere! So, don't blame me for my stupidity.
To be honest this is all fairly basic stuff da da da........ #-o
Hope this helps

Neil

 

[kostello]

I don't think a dehumidifier will work at the low temperatures you are talking about as it cools the air to remove the water vapour...........



More insulation and low background heat......

Sent from my Nexus 7 using Tapatalk 2

 

[dickm]

Possibly also need to check that the floor has a damp proof layer. Often omitted from older garage floors.

 

[Matt@]

I've used a dehumidifier in a workshop and the results have been very noticable. In below zero temps though I think you ned some heat as well or the thing will freeze up!

If damp I would always go the dehumidifier as opposed to heat route before heating route as damp is caused by humidity not cold....

 

[rjb]

Thank you for all replies. I think I'll try an oil filled radiator first and see how effective that is. Although my workshop is already insulated I can also look at improving it if necessary.

 

[Matt@]

Thank you for all replies. I think I'll try an oil filled radiator first and see how effective that is. Although my workshop is already insulated I can also look at improving it if necessary.

if you have a damp problem, you need a dehumidifier.

Try hiring one and seeing how it goes?

An oil filled rad will make totally no difference to humidity in that area of space imo

 

[Lord Kitchener]

You need to follow the excellent advice given re insulation first. Floor can be done with a layer of dpm beneath a layer of t&g MR chipboard floor panels. Walls and ceiling can be done with celotex etc, even 25mm will be way better than nothing.

If you don't insulate it first then any other measures you take will be much less effective than they would otherwise be

 

[eribaMotters]

I would be looking at the concrete floor before you think about any other action. I base this on the condensation I experienced in my own workshop. This is a 26' x 16', 4"x2" stud work construction that sits on a three high brick wall, felted and feather edged with man made slate roof. 4" rock wool insulation in ceiling and walls and lined out in 3/8th ply. Windows are double glazed.
About a year after I built the workshop I was getting condensation and a musky smell. The one part of the job I had not done was laying the concrete base. This is [supposed] to be a 6" raft on top of strip footings [no insulation due to building dept wanting slab and strip foundations cast in one go hit, 180' from the road]. The raft was in fact thin, and the mix blind [low on cement content]
My remedy was to strip floor of paint, unibond surface, apply two coats of a DPC bitumous paint with a blinding finish of sharp sand whilst still wet. I then laid a row of flags down centre and along sides and screeded in between. When dry I unibonded the floor and applied two coats of floor paint. The later I repeat every couple of years as it chips. I also added trinkle vents to the windows.
Heating has always been a 3Kw convection heater. I was advised against a heater in such a large space as the blow facility will not push the air far.
I have since, over the last 15yrs experienced no problems.

Colin

 

[rjb]

Thanks for the advice re insulation and damp proofing. The walls, floor and roof of the building are in fact reasonably well insulated already with rockwool, kingspan plus dpm, but I think there is still room for improvement. Regardless of how good the insulation is though, the temperature will eventually drop when the heating is off and I think this must be what is causing the mdf stored in there to become slightly damp. I'm not talking about condensation or a serious damp problem, but I have noticed that after mdf has been stored in there for more than a few weeks it doesn't cut as cleanly as when it's first delivered and I can only assume that this is being caused by damp being absorbed by the boards. I was hoping that a constant background heat to raise the temp by just a few degrees may help to prevent this.

 

[morfa]

It's worth looking at a heat (energy) recovery system, as these are supposed to control the climate in a room/house quite well. I've no personal experience with them, but I'm researching one for my house.

http://en.wikipedia.org/wiki/Heat_recovery_ventilation

 

[dickm]

We have a heat recovery/forced ventilation system in the house, and it works very well. But pricey for a workshop. My suspicion is still that damp is getting in through the floor of the OP's shop. Damp proofing and an insulated suspended floor would make a big difference.