Condensation

[ikd]

Does any one have some good tips on trying to avoid condensation :?:

Last night was a sharp frost (down here). My garage/workshop has a metal sheet roof. By 9.00am this morning it had started raining inside the garage, where the outside temperature had risen and vapour in the air, which had frozen on the inside roof, melted.

Help or advise would be appreciated.

 

[PowerTool]

General tips would be 1)Insulation and 2)Ventilation

My workshop is brick-built (single skin),the roof is 18mm ply and 2 layers of felt.
I have a "frostwatcher" heater to keep the temperature above freezing (generally over 5c) and have had NO condensation whatsoever.

Tin sheets aren't the best material to have,unfortunately

Andrew

 

[syntec4]

I had the same problem with my new Workshop. It used to be a Barn. I lined the Underside of the Roof with Hardboard. Its added to the insulation factor and does not allow and condensation to form.
See the pictures here

http://theguitardoctor.blogspot.com/

Lee.

 

[ikd]

Syntec4 - I thought about hardboard. There is a gap between the cross beams and the roof at one end so I should be able to slide it through the gaps.

It might give it a go and see what happens.

Thanks for your help powertool and syntec4

 

[9fingers]

I had the same problem with my new Workshop. It used to be a Barn. I lined the Underside of the Roof with Hardboard. Its added to the insulation factor and does not allow and condensation to form.
See the pictures here

http://theguitardoctor.blogspot.com/

Lee.

Apologies for thread Hijacking everyone

Hi Lee,

Please could you give me some details of your workshop heater?

TIA

Bob

 

[syntec4]

Bob,
The heater is a 'Hotspot' Model R2. recommended here by a few people so I ordered one last week. It arrived the next day. It was £200 inc 3 metres of Flue, 2x 45 deg bends and a 'top hat'. Very solid and safe too. It was frosty Here in Manchester last night and once lit, the ttemperaturewas 15deg within about 1 hour in the workshop. It was 3 degC when I went in there. I also notice that it is burning less material than when I first tried it, for the same amount of heat output. It will burn sawdust and all the offcuts no problem.

http://www.thehotspot.co.uk/

Well worth money. As are most things recommended round here.

Lee.

 

[9fingers]

Thanks Lee,

I'll give them a look.

I was wondering if there was a single unit available that would run on gas or wood scrap.

If it burnt wood it would have to have an external flue and a gas appliance with an external flue would remove the risk of condensation inside the the workshop - a problem with the cheaper heaters.

Bob

 

[Losos]

Hi Lee - Glad your 'Hot Spot' is working well. My wood burner was operating when the outside temp. was minus 20 a few weeks ago It didn't quite get to plus 15 (More like plus 10) but it was enough for me to work comfortably, and now the outside temp. is around zero I can get up to plus 15 easily.

Bob - I would recommend something like the 'Hot Spot' rather than the gas type. Yes, you will need a flue to the outside but not so complicated as the gas ones. The heat is dry, so it tends to remove water vapour in the air. (I'm not sure if it'll remove as much as you are currently experiencing) The only things to remember are to *always* sweep up around the stove at night (The American regulations say 3 feet all round) and close any air inlet shutter / door etc.

Insulation is, of course, always advisable and anything you can do to create a gap between the metal roof anf the inside will help to prevent the condensation, remember that it's there even when you don't see it freezing on the metal. BTW on another thread someone was saying that a lot of the vapour in the air comes from your breathing, so if you don't breath while working in the 'shop, that will help also

 

[OLD]

The principal of insulation is to use a trapped layer of air or gas so i can not see hardboard providing much at all. Better to use try and tested products and make sure they do not get wet from the passage of water vapour through them . I notice there is a system of spray foam direct to under side of roofs which should work well.

 

[syntec4]

OLD- The Hardboard is about 6 inches below the Metal Sheets. I had to pull down one of the sheets to add some wiring yesterday, I can tell you that behind the hardboard it was freezing cold. It was dry on the underside of the metal too. No Condensation had formed up there, it was not damp at all. I am pretty happy that the hardboard is definitely keeping the heat in the workshop.

Lee.

 

[Steve Maskery]

I notice there is a system of spray foam direct to under side of roofs which should work well.

We looked into this for our house, which is a 1930s tile roof, no felt. One or two of our neighbours have had their roofs replaced, they are getting to that sort of age.

Anyway, we rang the company and the lady on the phone said the minimum price was 2K. OK, fair enough. The sales man came, look at the house and told us 2.5K. He didn't want to look in the loft. He didn't measure up. OK, so he does this every day, he must have a feel for it, right? During the course of the conversation, this job, which would cost us between 2.5 and 3K, wwould, we were told, be done in just two days, by two men, and they would fix the few loose tiles first before everything was stuck in place by this foam. And all for somewhere between 3 and 3.5K. Bargain. Whe he left he gave us his quote, for £3,700. In the course of half an hour, with no new information, the price had risen by 50%.

Can anyone tell me how two men for two days, and a big can of polyurethane comes to that much? Foam is 90% air by definition, isn't it? I really don't like people giving me bovine colonic waste. Needless to say, we didn't buy.

Still leaves us with the problem of what to do about the roof, though

Cheers
Steve

 

[9fingers]

Be very very careful before embarking on this foam treatment for an old roof.
Currently with no felt, your roof will have excellent ventilation and wirtually no condensation. Any water blown up under the tiles etc will soon dry out and leave the rafters dry.
Once this foam is sprayed on, the ventilation will drop and the rafters will be enveloped on the 'wet' side of the roof and tiles. Rot will almost certainly start and will eventually need a really expensive repair.

I think you have two options.
1 fix the broken tiles and stick with a 30's design well ventilated roof which will have served your house well for the last 70 years or so.

or

2 Have the lot off, put on a modern warm roof with all the right vapour barriers and semi permiable membranes in place to current building regs.

The latter will cost you plenty but save on heating bills in the long term even them payback will be in terms of 10s of years. The first one is cheap & cheerful and will maintain the status quo on heating costs.

hth

Bob

 

[OLD]

I think that ikd requires a cure for the steel roof on his workshop it would seem that foam is expensive and provided by cowboys so perhaps moisture barrier, expanded poly. ventilation ,then the steel roof. with perhaps hardboard on the room side of the v/b for looks.

 

[WoodPecker]

Does any one have some good tips on trying to avoid condensation

There is a type of nylon sacking material you can get which is designed to stop the condensation dripping down. I saw it recently in a tile warehouse the sacking was stretched out in a layer under the rafters and seemed to work very well. Unfortunately I don't know what the brand name is but it shouldn't be too hard to source.

For anyone thinking of putting an iron roof on a workshop in the future, there is a product available with a non drip coating, I think it's made by Kingspan.

 

[ikd]

OLD- The Hardboard is about 6 inches below the Metal Sheets. I had to pull down one of the sheets to add some wiring yesterday, I can tell you that behind the hardboard it was freezing cold. It was dry on the underside of the metal too. No Condensation had formed up there, it was not damp at all. I am pretty happy that the hardboard is definitely keeping the heat in the workshop.

Lee.

I have a 3 inch gap between the metal roof and the top side of the wooden beams. an 8'x4' sheet of 3mm hardbaord is about £3 (Wickes)and I will need 6 sheets. So I am working on the premise that if it doesnt work then I have wasted £18. Ive wasted more miscutting some maple before :wink:

 

[syntec4]

OLD- The Hardboard is about 6 inches below the Metal Sheets. I had to pull down one of the sheets to add some wiring yesterday, I can tell you that behind the hardboard it was freezing cold. It was dry on the underside of the metal too. No Condensation had formed up there, it was not damp at all. I am pretty happy that the hardboard is definitely keeping the heat in the workshop.

Lee.

I have a 3 inch gap between the metal roof and the top side of the wooden beams. an 8'x4' sheet of 3mm hardbaord is about £3 (Wickes)and I will need 6 sheets. So I am working on the premise that if it doesnt work then I have wasted £18. Ive wasted more miscutting some maple before :wink:

Its £2.58 at B&Q I bought 30 sheets :wink:
Lee.

I too have turned WAY more than that into firewood