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]

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]

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

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]

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

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.

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

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.

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

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.

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.

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

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.

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

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

quote:

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Originally posted by ChrisW

Guess I need to know the air pressure, temperature and humidity?

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quote:

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Dew point is calculated with pressure and humidity isn't it??

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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

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

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

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

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

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

quote:

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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

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Used those before!! They're good, as is most APC kit, but not exactly 'locost'

Chris

quote:

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Originally posted by ChrisW
Used those before!! They're good, as is most APC kit, but not exactly 'locost'

Chris

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And small compared to some of the APC kit I've bought in the past. We've got more masterswitch units than I can count

Chris

I use a max/min hydrometer and thermometer combined that i got from aldi/liddle - can't remember which. Can't remember the price but I would not have paid more than a tenner.

Not sure where the necessity for 50% rh comes from sounds empirical to me but for sure you will be safe with it. my garage mostly stays around 50 to 60% rh with the occasional excursion to 70%rh whem it is raining and warmer outside than inside.

No deterioration of contents.

As an experiment put a hydrometer in your house I think you will get a shock!

Cheers

I have one (well, a mini 'weather station' that someone bought me years ago on the window sill in view of my PC. Never paid any attention to it before, but since this conversation I have kept an eye on it when I remember.

Currently showing 34% at 24'C, altho it does tend to get warm in here with two PC's and a server running constantly, especially first thing in the morning when the door has closed all night.

I don't *think* I've seen it go much over 40% tho.

Chris

I'm at 40% already this morning Chris ... room temp 21.8 .... window open, and only the lappy on ....

I keep a dehumidifier on at all times in the garage. Stu plumbed it in using a small diameter copper tube system leading to the outside where it drains into a gulley in front of the garage.

Lots of peeps think I spend ages cleaning my car, (ali) I don't.....it just looks that way because the garage is 'dry'....
However, my garage is integral, so therefore brick built.....

We do advise our customers to use this method when storing/over wintering their 'pride and joys' ... and all have been delighted with the results.....
How that would equate with a 'bare bones' metal storage container I really am unsure ....

I think I would be inclined to line it as you have proposed, and also install a dehumidifier....

HTH
Fozzie

Chris

I have a shipping container in which I've stored quality furniture for the last 3 years. Its as dry as a bone in there, no humidity, dampness or condensation issues at all.

It has no more added than a plywood floor and sprayed foam insulation overhead. Most important is no leaks and doors that clamp shut tightly on good seals.

Location is important too, mine is well protected, tucked in the bottom level in the middle of terraced two storey row.

D

Thanks David. Unfortunatly location isn't much of a choice. It'll go in the corner of the yard at some local offices that my mate owns!

Interesting that you've done (basically) nothing and still have no issues. Maybe I'm worrying over nothing!

Chris

I wouldn't say there's nothing to worry about...

I rent mine and the rent I've paid now exceeds the value of the contents

If they HAD been consumed by mould in the first year I'd have taken the lot to the tip by now and cut my losses.

Alternatively if I'd sold it all on ebay instead of storing it I'd be a happy chap.

Just something to think about before you commit.

Indeed, thanks for that David. I have thought a lot about it, and still think it's worth it. The furniture is the driving force, and is only supposed to be in there for a year, but I'm sure all sorts of other things will find a home in there too hence thinking I'll probably keep it on. The rent I've been offered, which is obviously significantly less than renting an all-in package as I'm buying the container outright, would (roughly) break even on the replacement cost of the (furniture) contents in two years.

Chris

How much does a typical container cost?

If you camo'ed it a bit (start off with a green one?) do you reckon you can get away with dropping one in your back garden if you're nice to your neighbours?

I'm thinking either additional workshop space or possibly long term storage in the future (as I may need it).

When we were renovating the house, we put all our stuff into a couple of containers.

Cost to buy was £1100, with a guaranteed 'buy-back' of 50%. Worked out far far cheaper than renting one!

They've seen two winters and we've had no problems with damp... just make sure nothing is resting on the metal surfaces of the interior.

Scootz,

Was that £1100 for the pair or each?

Do you get a choice of colour? Sounds ghey I know but a green ish colour would be preferable for stealth reasons! I have a mate who is a container spotter who knows the exact numbers of colours and shades they come in and which shipping company they belong to etc etc. Makes a long car journey on the motorway fly by "container spotting"... honest.

EDIT: Quick search on eBay reveals that ~£1k *each* with a 50% buy back within 5years is the going rate.

[Edited on 8/5/10 by hobbsy]

A company I dealt with recently offers the containers at about £700 - not silly money for what they offer.

Painting was extra £100, lock a further £50 and then delivery. Still a cheap secure space!