condensation

[neilyweely]

Folks - I put the last bit of insulation into the workshop last night, and I think I can tell the difference already. Basically I insulated the door, and put insulation into all the cracks in the chipboard. I think I can feel the difference.

But what is worrying me is that just now, even though the heating has not been on, there is a film of condensation on the inside of the windows (which are not double glazed).

Will this contribute to a damp problem? I worry about the floor, which is concrete, causing problems. But this is the first time I have noticed any condensation.

Any thoughts?

Any help appreciated.

Neil

 

[Vann]

If you're getting condesation on the window, that means there's moisture in the air INSIDE your workshop. Double glazing would stop it condensing on the window, but would not reduce the moisture content in the air - so it can still rust your tools (if anything, the single glazed window collects moisture, so that if you mop the window every hour or so, and wring it out outside, you'd reduce the moisture content a little).

By blocking off all the drafts, you've also cut off the airflow that might dry out the shop in some circumstances.

Heating the air in the workshop will reduce its ability to hold moisture, but at a financial cost to you.

I'm sorry I don't know the answer to this one. Maybe painting or otherwise covering the floor so that no moisture can get in that way. Then ventilate as much as possible next summer to dry out the air. Then seal it up again so that it contains less moisture next winter....

Good luck,

Vann.

 

[Lee Brubaker]

Sorry Vaan....can't agree with you because actually heating air increases it's ability to hold moisture...not the opposite. Don't know about your side of the ocean but here in Canada we can purchase shrink wrap for windows which can be a big help for older homes that do not have double glazing. Anyhow, the colder it gets here the lower we set our humidifiers or frost will soon build-up on double glazed windows(inside). For example when we are running -15C temps or so I do not let humidity in the house exceed 30%.

Lee

 

[Vann]

Err, yeah, sorry. Wrong about the warm air. As it cools in dumps moisture (hence my ****-up about cold air and more moisture) But still correct about condesation indicating moisture inside the room. Water doesn't pass through glass (heat does), water that's already inside condenses on the cooled inside surface of the glass.

Cheers, Vann.

 

[Lee Brubaker]

Yup...that part is correct Vann....when the warm air hits the cold glass it loses heat hence condensate on the glass. My shop is my double garage. The shop is insulated as is the overhead door which is weather stripped. I have a ceiling mounted gas fired 25,000 BTU heater. I have never had a problem of condensate on equipment because I leave the thermostat set at 10C for those periods that I'm not working in the shop. Hence, the air is always warm enough that it continues to hold what moisture is there & the equipment is warm enough that condensate does not occur.

Lee

 

[sawdustmonkey]

A small de-humidifier may help remove moisture in the air.

 

[PowerTool]

I've read before,from people who understand it better than I do,that it is a balance between temperature,ambient humidity and relative humidity.
Similar to Lee,I find keeping the workshop above 5C means I never get any condensation or rust.

Andrew

 

[filsgreen]

Like many Neil I have an oil filled 2Kw radiator set on 3 and have had no problems with damp, the heater keeps the temp at about 45F.

Phil

 

[adzeman]

Hi Neil, as I deal with condensation for a living and without getting too involved I thought I could give you a few pointers.
1. Condensation is caused by a temperature difference (there things called dew point etc)
2. All air contains water and in this country we like it to be 50% of the airs weight (quite a lot really) and we call this humidity. below 40% is towards arid. Makes your throat sore. above 60% is humid affects your asthma.
3 Applying heat aggravates the situation not solve it.
4. Humidifiers are only any good if you air lock the area otherwise you will be dehumidifying the outside as well.

The bottom line is condensation is cured by good air circulation keep the air moving. When your in the shop your movement moves some of the air but when you leave everything becomes still. If you have an electric supply fit a bathroom fan with a de-humidi stat. (these are cheap to run)
If its just the windows showing condensation you dent have much of a problem.
We have a saying in the industry, "we only get condensation when we put people into our buildings our empty buildings just dent have it"

If the temp on the inside of the glass is the same as that on the outside, no condensation.

 

[neilyweely]

Filsgreen, adzeman, powertool, sawdust, lee and vann.
Thanks a lot folks. I think the problem may be the air circulation.
I was told to use the halogen bar heaters as they are cheaper to run (best mate is a plumber). So thats what I have ATM.

I do keep most of the expensive tools (the ones I can move) in the house, but obviously this is impractical at times.

Adzeman - so my learn-ed friend, what should I do? I am a pauper ATM, and need a good solution that doesn't cost the earth. Any ideas?

Thanks all, again.

Neil

 

[MikeG.]

Neil,

this:

http://cgi.ebay.co.uk/ws/eBayISAPI....8&category=122909&ssPageName=mem_guide:5&rd=1

is the sort of thing.....£17 plus P&P.

I am not familiar with this particular one, but its the right sort of product.

It should soon sort your problem out.

Mike

 

[adzeman]

Hi Neil, Mike could not read your suggestion due to security protocol but the cheapest method is leaving the window open by about an inch. Security is an issue its OK when your there but could mean internal grills.
Vent Axia do a good fan at a reasonable cost as do a firm called Airtech base in Walton on Thames.

The basic principle of leaving a window ajar is the Victorian sliding box sash window. In my opinion the best window ever invented. The problems I have to attend where old properties have had these removed and PVCu double glazed fitted are Legion. Chimney blocked up and central heating installed and they wonder why they have mould growth!

What I did in my own workshop was fit an Airvac air management system using 4" PVCu R.wy.P. drainage as ducts. To install from new well over a thousand pounda BUT I kept my eyes open for Industrial unit being refurbished, business gone bust, or new tenant and picked one for free just before it was thrown in the skip. I put an outlet above every machine position and when its on keeps dust levels down to a minimum. The exhaust goes out at the back of the workshop where there are some holly trees and know one knows its there. If you go to the back of the shop though the leaves are covered in sawdust, but not that bad and the rain does wash them down now and then.

keeps the shop free from condensation even in winter when I have a bit of heat on.

Oh by the way the roof has developed a leak which I am chasing (cant find the source and not strong enough to stand on. Nothing to do with my air management system though.

Best of luck (try some skip diving)

 

[MikeG.]

Mike,

If you were to trawl through some of the old postings on here, you will see that I am a strong advocate of proper ventilation. I have recommended whole house ventilation systems on here, as well as DIY forced ventilation using extractor fans. I hate dehumidifiers with a passion and will immediately answer any thread where they are suggested. I think they are the spawn of satan..........

With workshops I don't think leaving a window open is an option. Too tempting for the local thieves.

Mike

 

[9fingers]

Neil,

I don't think the source of the condensation is very clear. Do you have a damp proof membrane in the floor? If not then potentially the inside volume of the workshop is connected to a near infinite supply of moisture.

A few coats of floor paint would help control this or better still lay a wooden floor on heavy polythene sheeting which will be dampproof and more comfortable to stand on.

hth

Bob

 

[MikeG.]

If you suspect the floor, Neil, lay a piece of plastic down on the floor for a few days, weighted down at the edges. When you remove it you will see clearly if the underside is damp, or the concrete is darker.

Mike

 

[neilyweely]

Mike and 9 fingers
I do suspect the floor. It is about a foot of concrete raised up from the ground level, but there is a huge crack that runs down the middle of the WS. This makes me think there are problems here. I wonder if painting it with some sort of floor paint would help?

I have been waiting for you Mike, Hhhhhheeeelllppp!!!!!!

This is worrying me, but soon I will be starting the new WS and need to be SURE it is all done perfectly, as I do not want to ever worry about any aspect of it.

What can I do guys? I think the floor is the weak point, for sure.

Neil
(although, because the floor is raised from ground level a foot or so, surely this is good??)

 

[MikeG.]

Try the plastic trick, Neil.........let us know on Sunday or Monday.

Don't worry about the crack........it is a very English obsession, worrying about cracks!

Mike

 

[johnnyb]

run a dehumidifier on low. despite some peoples objections it will work. ventilation is not usually an issue in most workshops (ive worked in). but the dehumidifier will keep the ambient temperature higher anyway. this will always be a problem in an unheated shop. the temp drops to minus 1 a little bit of condensation forms on the c i bang instant rust. trust me despite what anybody says subsequently de humidification will work, excessive ventilation will be a risk of rust. the ideal de hum would be a small dessicant(such as an amberdry) run on low. to have intermittant heating could well make condensation problems worse. c i is very slow to warm and warmer air holds more water. patently attempt to block obvious damp sources. my shop is absolute proof this works.

 

[MikeG.]

despite some peoples objections it will work.
despite what anybody says subsequently de humidification will work

excessive ventilation will be a risk of rust

I guess you mean me!!

I haven't ever said that de-humidifiers don't work. Given a sealed room, they will, of course, work perfectly well. But you miss the point. The point is that they are consuming quite a lot of energy to do an unnecessary job. A properly ventilated shed will not require de-humidifying.......end of story.

"Excessive ventilation will risk rust" is simply not true. Not true at all.

When Neil said "I'm a pauper at the moment" and I suggested a £17 solution I am really struggling to see why he should go out and spend many times that on a de-humidifier.

Mike

 

[neilyweely]

Mike - 17quid sounds great, and I will of course give it a go. Cheers mate.

Jonnyb - I hear what you are saying mate; how much does it cost to run your de hum? My mum says she's got one that doesn't require power!! Surely this is not gonna work?

Mike - 9fingers is saying to put down the sheet, permanently, and lay boards on top of that, whaddya reckon. It kinda makes sense to me, but can it be this easy? I do not think there is a dpm in the floor at all as it was always used as a bit of a bike shed/junk store. Now it has all my tools in it and I am panicking!!!

So, try the sheet, then if that shows damp coming from floor then I guess I cover floor in paint/plastic. Yes?

Thanking you all again.

Neil