Metal Shed - Condensation

[^woody^]

The principles of condensation formation and evaporation in a metal shed, are totally different to what goes on in a masonry building or large warehouse.

Putting vents in the ridge or even adding more vents anywhere else won't help in the slightest. Leave the doors open, or put a sheet of the metal outside - you wont get more ventilation than that, and condensation will still form on the sheet

 

[coolcatkelso]

So there is no core at the end of the day?

Leaving door open isn't an option obviously for security issues at the least. How about that spray on foam insulation ,or foil bubble wrap, heard someone on here used that on a metal roof

 

[^woody^]

Err, I used the leave door open comment as an illustration of how ventilation won't prevent condensation in your shed.

The concept is to deny air a cold surface to condense on. The large metal clad buildings use insulated panels for this.

Spray foam would do the job, but as per posts right at the start of this thread, bubble wrap and the air gap it will leave won't help

The practicalities of using spray insulation are outweighed by just ripping the stupid thing off and constructing something more suitable for the use of the shed

 

[coolcatkelso]

Yeah I do agree that a brick building or timber building would have been alot better, but now the shed it kitted out etc and all landscaping outside is done ripping it down isn't going to be an option for a few years yet.

I still think replacing the metal roof with osb or ply and felt will be more than enough and like I said, there is no issues with the metal walls, lost insulation and plasterboard, so the walls are coping ok.

 

[Norcon]

So there is no core at the end of the day?

A sheet of polythene or clear reinforced felt will stop the drips.
Anti-drip corrugated tin would have been a good spec which is coated with a cloth like fabric which absorbs the condensation like a sponge which later evaporates back into the air.

 

[coolcatkelso]

Yeah that sounds good enough for now. If I take the roof off, install polythene from ridge to gutter, put roof back on. Insulate the inside roof and plyboard, that should make a big difference, and if it does still condensate then the drips should run down the poly into the gutter?

 

[Norcon]

and if it does still condensate then the drips should run down the poly into the gutter?

Yeah thats how it works.

 

[coolcatkelso]

Perfect, will get started next weekend.

Cheers for your help

 

[bhm1712]

The principles of condensation formation and evaporation in a metal shed, are totally different to what goes on in a masonry building or large warehouse.

I beg to differ, condensation forms for the same reason no matter where it is found. Moisture in the air condenses when the temperature of the air equals the dew point whether it is inside a building, or outside in a metal shed. However when outside, especially in the evenings, the dew point tends to be lower than the temperature of the air and so condensation will form on any surface. If you increase the moisture content and air temperature even more, by breathing and heating a space, the condensation problem willl be even more prominent and so keeping fresh air coming in will lessen the impact.

 

[coolcatkelso]

That makes sense actually coz if I put the heater on in the shed, the droplets are bigger and more frequent.

So how's out I install 2 vents in the apex frame and expose the holes in the ridge again this should create a constant fresh air source and extraction off warm air, install a vapour barrier and Wolly insulation and then 9mm ply witha couple of surface vents allowing everything to breathe?