How do I stop condensation on inside of garage roof

Question

Every cold morning there’s water droplets on the underside of the roof, and it’s starting to drip onto things stored inside. Is there a way to fix this cheaply or is there a bigger issue that I just can't see?

James · Answer

Make sure it’s properly ventilated. If it’s tiled then maybe put some ventilated tiles in, or if it’s felted then maybe consider putting some felt attachments you can buy from amazon which work as vents

Jackson · Answer

It sounds like your roof is a none sheet insulated profile metal roof, the only method is to install insulated profile sheets, there is another cheaper option to remove sheets and line with breathable roofing felt, And refix sheets. New insulated sheets is the way to go.

Liviu Adrian · Answer

Improve ventilation (biggest impact) 
2. Add anti-condensation layer (especially metal roofs

Benjamin · Answer

It is dependent on what material is used on the roof i am geussing it is a tiled roof with the old bitumen felt if it is this they are known for sweating so if it is this it would need a refelt with the new breathable membrane /felt this will stop this issue

Daniel · Answer

Hi Patrick, it looks like it could be a lack of ventilation. 
In regards of how expensive it could be if all depends on the situation and to give an accurate diagnosis and estimate would require a survey.
Hope it helps.

Anthony · Answer

Install vent tiles , maintenance free dry ridge system and over fascia vents . This will allow airflow  to run from the bottom of your roof and out the the dry ridge system at the top

Connor · Answer

Depends on the level of insulation currently in the roof space, is there a habitable room above? On a basic level you can look at a cheap heating option, bringing the temperature inside the garage up will eliminate condensation, however this may not be practicable or desirable.  If the roof is plasterboard and there is a room above then there are different resolutions from a standard up and over garage with a corrugated roof or similar. Please let me know, pics would be useful.

Kyle · Answer

Condensation on a garage roof is really common in the UK — it’s just warm, moist air hitting a cold surface and turning to water. To stop it properly, you need to control moisture + improve ventilation + (ideally) add insulation.

Here’s how to sort it 👇

⸻

🔧 1. Improve ventilation (most important)

You’ve got to let moist air escape, otherwise it’ll always come back.
	•	Add air vents on opposite sides of the garage (cross ventilation)
	•	Fit soffit vents if it’s a pitched roof
	•	Even leaving small gaps at eaves helps

👉 No airflow = guaranteed condensation

⸻

🧱 2. Add insulation (big improvement)

This stops the roof surface getting freezing cold.

If it’s a pitched roof:
	•	Fit PIR boards (Celotex/Kingspan) between rafters
	•	Leave a 25–50mm air gap above for airflow
	•	Board over with plasterboard if needed

If it’s a flat roof:
	•	Best: Warm roof (insulation on top)
	•	Easier: insulate between joists underneath (still helps a lot)

⸻

🚫 3. Stop moisture getting in

Look at what’s causing the damp air:
	•	Wet car parked inside 🚗💧
	•	Tumble dryer or washing
	•	Storing damp tools/materials
	•	No damp proofing in floor/walls

👉 If you’re bringing water in, ventilation alone won’t fully fix it.

⸻

🧴 4. Anti-condensation coatings (quick fix)
	•	Special anti-condensation paint or felt backing
	•	Works okay on metal or sheet roofs
	•	But this is more of a temporary/secondary fix, not the main solution

⸻

⚠️ Common mistakes
	•	❌ Blocking all airflow when insulating
	•	❌ Using just loft roll with no vapour barrier
	•	❌ Thinking a dehumidifier alone will solve it
	•	❌ Ignoring it (can lead to rust, mould, timber rot)

⸻

💡 Straight answer (what I’d do as a tradesman)

If it were mine:
	1.	Add vents front & back
	2.	Insulate between rafters with PIR + air gap
	3.	Board it and seal it properly

That pretty much eliminates condensation long-term.

Samuel · Answer

Hello, it sounds like condensation is more likely to be the cause than a roof leak, which is very common in garages, especially on winter mornings. When the warm, moist air inside the garage rises and hits the cold roof, it turns into water droplets and can drip down.
The good news is that the solution is usually quite simple and inexpensive. In most cases, improving ventilation (such as by adding vents) and installing a condensation-proof layer or insulation under the roof will solve the problem.
If the problem is all over the garage, it is almost certainly condensation. However, if it is only in one specific area, it can be checked for small leaks. I will be happy to take a look and advise you on the best and most cost-effective solution for you.

Chris · Answer

You need to improve ventilation via roof vents or extractor fans

How do I stop condensation on inside of garage roof

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