ChrisW
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| posted on 25/4/10 at 11:17 PM |
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Shipping container - dealing with damp
Following on from my wanted thread...
http://www.locostbuilders.co.uk/viewthread.php?tid=134696
... thought I'd best stay on topic by starting a new discussion.
So, to recap, the scenario is that I want to use a shipping container to store some furniture. Things like sofas, bed, electrical items, etc that
would get ruined if they got damp. They're currently stored on one side of my garage, but I'd rather have the space to work on another
car at the house. 
I'm intending to buy a container and already have arranged a spot to keep it locally. There's the option of power if I want it, and
theres no indiviudal meter on my supply, so (within reason) power is included in the rent. The guy that's renting me the spot expects me to run
lights tho, so I can't go too mad with the power usage!
Storage time for the current contents is going to be at least a year, and I'm sure I'll have more stuff I'll want stored after that
time, so I can't see myself getting rid in the foreseeable future. I'm therefore happy to spend a reasonable sum to do this right the
first time and have a useful resource where I'm not having to worry about the state things will be in when they come out.
So, it's been suggested that I need to do two things to combat damp/condensation.
1. Line the walls (and roof?) with plywood so that any condensation that forms is in the air gap between it and the metal, keeping it away from the
items being stored
2. Come up with some kind of controlled ventilation/dehumidification system
Anyone got any thoughts or experience with either, in particular:
a) Do I need to line the roof as well as the sides?
b) What thickness ply should I use?
c) How to fix it to the metal panels?
d) What's the best way to control humidity - extractor fan(s)? Domestic type dehumidifier? Or would full on air con (eg
like this) be the best way to be absolutely sure items are safe?
Any other comments/pointers/etc?
Cheers, Chris
[Edited on 4/25/2010 by ChrisW]
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dhutch
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| posted on 25/4/10 at 11:25 PM |
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Im not sure on your budget, but another option might be to get it spray foam with some PU foam.
- It sticks to the inside, is insluative, and typically fairly closed cell. The use it on narrowboats, barns, fridges, etc.
- If you find somewhere local it might not be much more then the ply to have someone come and do it out to a thicknes of about 20mm or so.
Then i would just arrange decent ventilation for it.
Daniel
[Edited on 25/4/2010 by dhutch]
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ChrisW
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| posted on 25/4/10 at 11:28 PM |
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Thanks for the suggestion, Daniel. It's not something I've heard of, but will do some reading tomorrow.
It's more the ventilation I'm concerned about. My worry is that, if I just have a simple extract fan system, in the winter I'll
just be drawing more damp air in from outside than if the thing was sealed.... surely???
Chris
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mcerd1
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| posted on 25/4/10 at 11:47 PM |
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we've got one at work for all the old paper work
its lined with ~10mm ply on the floor, walls and roof (sorry - not sure how they fixed it on)
its got power in it - but all its got is a light and wee eletric heater - seems to work though
[Edited on 25/4/10 by mcerd1]
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indykid
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| posted on 26/4/10 at 12:36 AM |
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and you can get a plug in electric meter if you're going to be running heaters/air con in there too.
just plug in between the device and the supply, no quibbles about power consumption
tom
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skibikejohn
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| posted on 26/4/10 at 01:15 AM |
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We use a shipping container for storage and have never had any sign of condensation or seen ay of its effect. Our container is unlined but we are in
dry Alberta (relative humidity 40%) so it may not be applicable to the wet UK.
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clairetoo
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| posted on 26/4/10 at 05:37 AM |
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We often fit out containers as mobile workshops / offices at work - we buy them in fully lined and insulated , with extra doors or windows fitted .
The lining is attached to a welded in steel framework - we used to do this ourselves , but found it too time consuming as the whole container then
needed painting !
I could find out where we buy them from if needed - but I dont think they are cheap 
Its cuz I is blond , innit
Claire xx
Will weld for food......
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richardlee237
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| posted on 26/4/10 at 05:55 AM |
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We have around 100 containers we use for storage of spare parts and filters (mostly paper elements) .
When it rains here it comes down in truck loads.
The main thing is to ensure the container is watertight and that the doors close and seals work.
If you raise it off the ground on some blocks then this should keep it out of the way of rising damp.
Keep the boxes of the floor and you should have no problems.
The only filters we have lost was due to there being a rust hole in the container.
We only ever line out the container if we are going to air con it.
Quote Lord Kelvin
“Large increases in cost with questionable increases in performance can be tolerated only in race horses and women.”
Quote Richard Lee
"and cars"
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chrsgrain
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| posted on 26/4/10 at 06:01 AM |
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Hi Chris,
I use an X-Dry dehumidifier in my double garage and it is brilliant, about £200 and works by a dessicant rather than cooling, which most of them do -
it has an automatic setting so only comes on when its damp, and can be piped to continuous drainage. It keeps the place below 50% humidity all the
time. The garage is on a hill with soil banked up against one wall and the water used to pour in through the wall - I guess it still does but the
dehumidifier just sucks the water off the wall and out the pipe. All the cardboard boxes and everything in there is perfect...
Definitely get one, it will solve all your problems (absolutely no connection with them, justy very pleased!)
dehumidifier link
HTH
Chris
Spoing! - the sound of an irony meter breaking...
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Myke 2463
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| posted on 26/4/10 at 06:52 AM |
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Hi Chris.
At work we use a shipping container for storage of all sorts of electrical motors and have never had any sign of condensation or seen ay of its
effect. Our container is unlined and only has a small domestic wall mounted convector on all the time using the stat at max. Doors are opened 3 or 4
times a day / night. Everything is on racks so each item has air circulation and not stacked as items of furniture would be.
Mike.
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bigfoot4616
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| posted on 26/4/10 at 07:14 AM |
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i have one for storage for work.
ply on the floor and the roof is insulated with kingspan which is held in place by ply.
store plaster and cement in there without problems and obviously they don't like damp.
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ChrisW
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| posted on 26/4/10 at 07:41 AM |
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Thanks for the pointer about the dehumidifer. I've dropped the supplier and email asking whether they think it would be suitable. That sounds
best so far as it'll be entirely internal, meaning nobody is going to ask questions about how much power I'm using. With a big air con
unit bolted to the side I'm bound to raise suspisions that there are more than just lights inside! 
Chris
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Peteff
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| posted on 26/4/10 at 07:58 AM |
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You can get Isospray insulation for roofing and floors which sprays on and is polyurethane foam based or line the inside and get cavity wall
insulation from somewhere like Screwfix.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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Bluemoon
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| posted on 26/4/10 at 08:30 AM |
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I'd second chrsgrain dehumidifier if you go this route, as the non descant ones will not work at low temperatures...
I would insulate the container, and go for either:
1) Ventilate the container (lots of holes to let the wind blow in!).
This will cause dust build up though, no the container should not build up condensation as the draft will remove any water. Think barn car storage.
People could peak in though the holes to see what's inside.. (could be sorted with thought)
Rodents might get in (mesh over vents would sort)...
2) De-humidify, no drafts.
with either of these I would invest in a humidity and temperature loging instrument so you can keep an eye on the humidity (i.e <50% RH ideally to
stop mold etc, and the dew point temperature never less than the temperature to stop drips!), I have used the company Skyview Systems Ltd
(www.skyview.co.uk) for such things.. By monitoring the humidity you will know if you have a problem with damp...
Dan
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ChrisW
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| posted on 26/4/10 at 08:51 AM |
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I think I'd rather go down the 'no holes' route. Far more likely to be able to sell the container (if necessary) at the end of all
this.
Interesting about the data logging tho. Maybe I'll knock something up with a PIC. There are comms available (Internet connection) if I can be
bothered to hook them up. Guess I need to know the air pressure, temperature and humidity?
Dew point is calculated with pressure and humidity isn't it??
Chris
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Bluemoon
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| posted on 26/4/10 at 08:55 AM |
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quote:
Originally posted by ChrisW
Guess I need to know the air pressure, temperature and humidity?
Temperature and humidity only (RS sell humidity sensors that are calibrated and give a nice DC output voltage (0-5 or somthing) can find the part
numbers if you like.
quote:
Dew point is calculated with pressure and humidity isn't it??
Yes...
Also should add the de-humidifier should have a humidity stat (so it will turn off/control the humidity to your set point, say <50% RH).
Danh
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chrsgrain
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| posted on 26/4/10 at 09:03 AM |
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The X dry one has a humidstat, which works very well. The company claim that it uses about the same amount of energy as 100W old fashioned bulb...
you would have to make a hole to get the water pipe out of the container ...
Chris
Spoing! - the sound of an irony meter breaking...
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ChrisW
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| posted on 26/4/10 at 09:04 AM |
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Sounds like an interesting PIC project! I found
THIS on eBay, but it seems a bit expensive - it must be possible to get the sensor without the board (and Honeywell branding!)
Would you expect the sensor just to work in free air? Or need a small fan to blow air over it?
Re: the humidity stat in the dehumidifer, I guess I can always modify it to be controlled by the PIC. I'd probably do something to feed back
it's on/off status to the PIC anyway.
Finally, on dew point, doesn't the dew point increase as the pressure drops? Hence I need a pressure sensor? Or am I misunderstanding??
Chris
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Bluemoon
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| posted on 26/4/10 at 09:27 AM |
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The pressure dependence of the dew point will be small (well unimportant for this app).
The humidity sensor will work fine in free air.
That price is quite good, not sure if you can get a non Honeywell branded one they are still a new-ish thing (humidity sensors are difficult to make,
dew point thermometers are simple (two thermocouples (for PRT's ect) and a damp wick, you could then calculate the RH.....).
Remember you can by a suitable data logging instrument for about £45 from skyview..
Dan
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v8kid
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| posted on 26/4/10 at 09:42 AM |
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Its the relative humidity that causes the damage the condensation you see on the walls are only the visible signs of the RH. The RH is a measure of
the ammount of water vapour that is "dissolved" in the air and this water vapour has a weight which contributes to the pressure in the
air. The pressure due to the water vapour or partial pressure as it is sometimes referred to tends to equalise - think of water finding its own level
if you like. So this partial vapour pressure is very powerfull and trying to stop it is a bit like old king canute.
Unless you have an airtight container you will never keep this vapour pressure out - you may slow it down a bit but not exclude it.
The problem arises when the air is saturated and cannot hold any more water vapour and it condences out i.e. 100% humidity. Condensation on the walls
is ok at least as far as the contents are concerned it is the interstial condensation in the contents which causes the mould and damp.
Fortunately for us this process is highly temperature dependant. Doubly fortunate for us is the partial vapour pressure due to the water equalises
between inside and outside. So the ammount of water in a cubic foot is the same whether we are inside or outside but if we raise the temperature the
air can absorb more water. So whilst the cold air outside may be at 100% humidity the inside warm air may be at 50% humidity and there is no risk of
condensation unless the air comes in contact with a colder surface - either the walls or contents.
We are thirdly fortunate that it does not take a great temp rise to achieve this - it appears that the insulation effect of the ply is enough to
retain the solar gain during the day long enough overnight to prevent condensation. I would believe this for 90% of the time in the UK's damp
climate but will bet there are occasional lapses which may or may not be significant depending on the contents.
In short put a heater in.
The effects of various dehumidigiers are more due to the incidental waste heat than to the removal of water from the atmosphere.
If you are tight for energy check out beechgrove gargen web where they have reversed a beer cooler to act as a heat pump - cheap to run and buy.
cheers
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Bluemoon
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| posted on 26/4/10 at 10:06 AM |
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Only thing to note is that mold likes heat , so if you attempt this route, getting the RH down ~50% will be more important..
Just remember any thing you do will need to be kept an eye on somehow.. (musty smell is a give away that mold has stated, paper items not crisp,
newspaper is a good one to check with etc. ect..)....
So what ever you do measure the RH, and check the container from time to time.
Dan
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ChrisW
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| posted on 26/4/10 at 10:25 AM |
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Thanks for all the suggestions so far guys.
Plan at the moment is to line the container with ply. Thinnest I can get away with to keep the cost down.
Then to go for one of the dehumidifiers that Chris suggested.
Then use one of those PIC web boards with sensors for inside and outside temperature and relative humidity. I'll use the PIC as I can just hook
it straight up to the Internet connection in the main building and monitor it remotely. I'll also be able to put a cam on it, altho the site
has full CCTV anyway.
I am led to believe that, with the dehumidifier running, there would be no need to install any additional vents in the container. Anyone care to
comment on whether that's true?
Can anyone see any flaws in this plan?
Thanks, Chris
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stevebubs
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| posted on 26/4/10 at 10:40 AM |
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quote:
Originally posted by ChrisW
I think I'd rather go down the 'no holes' route. Far more likely to be able to sell the container (if necessary) at the end of all
this.
Interesting about the data logging tho. Maybe I'll knock something up with a PIC. There are comms available (Internet connection) if I can be
bothered to hook them up. Guess I need to know the air pressure, temperature and humidity?
Dew point is calculated with pressure and humidity isn't it??
Chris
Go Geeky Link
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ChrisW
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| posted on 26/4/10 at 12:35 PM |
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Used those before!! They're good, as is most APC kit, but not exactly 'locost'
Chris
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stevebubs
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| posted on 26/4/10 at 04:16 PM |
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quote:
Originally posted by ChrisW
Used those before!! They're good, as is most APC kit, but not exactly 'locost'
Chris
Not for a small business, no....but not as bad as I expected - that unit is between £120-200.
Small drop in the ocean on some of the Datacentre builds I do, though..
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