Condensation is a common winter problem. You might see it on windows, walls, roofs and even door handles.
It can be a particular issue in sheds, garages and garden rooms with single skin steel roofs. Once the weather warms up, it’s easy to forget about it. But if you had condensation problems last winter, now’s a good time to act.
Sorting it early can help protect your building and stop tools, furniture and stored materials from getting damp, mouldy or rusty.
Why condensation happens.
Condensation happens when warm, moist air hits a cold surface and turns into water droplets.
In a shed, garage or garden room, the warm air inside can hit the cold metal roof sheet. Water then forms on the underside of the roof and can drip into the building.
That moisture can damage the structure and anything stored inside.
Here are some practical ways to reduce condensation.
Choose the right roof sheets
If you need dry storage all year round, single skin steel sheeting may not be the best option on its own.
You could look at these alternatives.
Anti-condensation steel sheets
These sheets come with a non-drip woven fabric liner already attached. The liner holds moisture on the underside of the sheet until it dries out through ventilation. It also helps stop water dripping into the building
Insulated composite panels
These panels have insulation between two steel sheets. They can help reduce condensation and keep the building warmer.
Fibre cement or bituminous sheets
If you want to move away from steel, fibre cement profiled sheets or Onduline bituminous sheets may be worth considering. They are less prone to condensation than single skin steel sheets.
Apply an anti-condensation coating
GrafoTherm is a spray-on coating made for the underside of metal roofing and cladding sheets.
It absorbs moisture and helps stop walls and ceilings from dripping. It can be a cost-effective way to keep sheds, garages, garden rooms, warehouses and shipping containers drier in colder months.
It also has a Class A fire rating.
Be careful with insulation boards
Some people try to insulate the underside of roof sheets with boards. We’ve even heard of polystyrene being glued straight to the underside of sheets.
This can help in some cases, but it is not always the best answer.
In our experience, retrofit insulation boards rarely give a fully drip-proof result. That’s because cold spots can still form.
Think carefully before using spray foam
Spray insulation foam can reduce condensation and add insulation.
The downside is that it can be messy and difficult to apply. It is also hard to remove if you ever need to take it off.
It’s worth checking the fire rating too, as many spray insulation products do not have a strong fire rating.
Improve ventilation
Better airflow can help reduce condensation.
Simple steps can make a difference, such as opening windows or creating vented eaves by removing profiled foam fillers.
For more serious condensation problems, ventilation alone may not be enough. You may need to combine it with one of the other options above.
Check the floor
Many sheds are built on concrete slabs with no extra flooring.
Cold, damp concrete can add moisture to the air inside the building. A floating floor with timber, insulation and a vapour barrier can help improve the issue.
Use a dehumidifier with care
A dehumidifier can dry the air inside the building.
But it can be expensive to run, especially with higher energy costs. We also would not recommend leaving one running for long periods while unattended.
Need help choosing the right option?
There is no single fix for every building. The right answer depends on the roof, the floor, the ventilation and how you use the space.
At Southern Sheeting, we help customers choose the right materials for the job. Whether you’re improving a shed, garage, garden room or commercial building, our team can talk you through the options.
Get in touch or visit our help and advice section for more practical guidance this winter.
