Draughts and condensation often show up together, but they are not the same problem.

• Draughts usually mean air is leaking through gaps.

• Condensation is warm, moist indoor air hitting a cold surface (often glass or cold wall corners).

This guide helps you work out what’s actually happening, do the quick wins first, and then know when it’s time for proper sealing, repairs, or ventilation upgrades.

Quick answer: what to do in the next 30 minutes

If your windows are wet most mornings

1. Wipe the glass and the frame dry (especially the bottom corners).

2. Use extraction properly:

   • Bathroom: fan on during showers and keep it running after.

   • Kitchen: extractor on while cooking, lids on pans.

3. Open trickle vents if you have them (they exist for a reason).

4. Vent briefly after moisture-heavy moments (showering, cooking, indoor drying).

Building Regulations guidance for ventilation in homes is laid out in Approved Document F, and it’s a useful reference for why background ventilation and extraction matter in real-life homes.

If mould or condensation is an ongoing battle in your home, the most practical starting point is our checklist: Awaab’s Law and Damp/Mould: The 2026 Ventilation Checklist Homeowners Can Use Today.

If you can feel a cold draught around the sash or frame

1. Find the exact leak point using the 10-minute window check below.

2. Use draught proofing designed for windows (not random tape that gums up the seals).

3. If gaps are bigger, seals are perished, or the window is misaligned, plan on proper repair and sealing.

The Energy Saving Trust has a simple point that matters: the strip needs to match the gap. Too big and the window won’t close properly. Too small and it won’t stop the draught.

First: work out what you’re dealing with

Where is the moisture showing up?

• Only on the glass, mainly in the morning
  Likely condensation from indoor humidity and cold glass.

• On the wall or plaster around the window (reveals and corners)
  Often a cold-spot issue, sometimes made worse by draughts cooling the surface.

• A patch that gets worse after rain on one wall
  More likely penetrating damp (external defects can let rain in, including around window frames).

• A patch that changes when plumbing is used
  Possible leak.

BRE highlights that condensation can be mistaken for other dampness problems, especially where cold surfaces create local moisture.

Is it local or whole-house?

• One room (often bathroom, kitchen, or a bedroom with laundry drying) suggests moisture sources and weak extraction.

• Several rooms suggests a broader ventilation pattern issue, plus cold surfaces.

The 10-minute window check

Grab a torch. You’re looking for air leaks, failed seals, and water pathways.

1) Hand test

On a breezy day, slowly run your hand around:

• opening edge

• hinge side

• bottom corners

• meeting rail (sash windows)

• where the frame meets the wall

A steady cold stream is a draught gap, not “normal airflow”.

2) Paper test (for opening windows)

Close the window on a sheet of paper.

• If it slips out easily, the seal is not biting properly.

• If it grips firmly, the closing pressure is doing its job.

3) Seal and frame check

Look for:

• cracked, flattened, or missing rubber gaskets

• gaps in sealant around the frame

• staining on the plaster return

• mould forming in the same bottom corner repeatedly

4) Double glazing red flag

If you get condensation between the panes, that is typically a failed unit seal. That needs repair or replacement, not a DIY hack.

Quick fixes that genuinely help

A) Draughts: fix small gaps properly

Use proper draught-proofing products made for moving parts, so the window still closes and locks correctly. The Energy Saving Trust specifically flags that foam strips do not work well on sliding sash windows, and that brush strips are usually the better option.

Draught-proofing materials and how to choose the right one

This is where most DIY goes wrong: people pick a material first, then try to force it to work. Better way is to match the product to the window type and gap shape.

Here are the main materials you’ll see, and when they actually make sense.

1) Self-adhesive foam strips (compressible foam)

• Best for: small, uneven gaps on casement-style opening windows where the foam compresses when you close the sash.

• Avoid when: the window is already stiff, misaligned, or it’s a sliding sash (it tends to drag, peel, and jam).

2) Brush strips (pile strips / brush seals)

• Best for: sliding sash windows and anywhere something needs to slide past the seal without sticking.

• Why it works: brush seals reduce air leakage while still letting the window move smoothly.

3) V-strip (also called V-seal, tension strip)

• Best for: the edges of opening windows where you need a springy seal along a long straight gap.

• Good for: tidy, consistent gaps, especially where foam would look bulky.

4) Rubber or plastic compression seals (gaskets)

• Best for: uPVC and modern frames where a gasket system is part of the window design.

• If yours are split, flattened, or missing, replacement is usually more effective than adding extra layers on top.

5) Silicone sealant or frame sealant (for non-opening gaps)

• Best for: fixed gaps where the window does not need to move, such as around a fixed pane or around the frame to wall junction.

• Energy Saving Trust specifically notes sealant is suitable for windows that do not open.

6) Temporary measures (good as a short stopgap)

• Things like temporary draught films or temporary strips can help for a short period, but they often fail on moving parts. If you find yourself replacing the same temporary fix repeatedly, that’s your sign to do it properly.

The UK Government energy factsheet sums up the main categories you’ll come across: brushes, foams, sealants, strips, and shaped rubber or plastic.

How to fit draught proofing so it actually works

A simple sequence that avoids the common mistakes:

1. Clean the surface first
   Dust and polish residue are why adhesives fail. Clean and dry the frame so the strip sticks properly.

2. Measure the gap, then choose the strip
   Do not guess. Too thick and the window won’t close. Too thin and you still get a draught.

3. Start small and test the close
   Fit a short section, close and lock the window, then adjust before you commit to the whole perimeter.

4. Do not block drainage routes
   Many modern frames have drainage paths. If you cover them, you can create water problems.

5. Do not seal deliberate ventilation
   If you have trickle vents, keep them functional. Ventilation guidance exists for a reason.

Special note for older timber and sash windows

If you’re in a period property, a heavy-handed approach can cause more problems than it fixes.

• Historic England notes that draught-proofing can significantly reduce air infiltration through sash windows in good condition.

• If you have (or plan to install) secondary glazing, both Historic England and SPAB flag an important detail: you often should not draught-proof the original window, because some airflow helps ventilate the cavity and reduce condensation risk between layers.

If any of that sounds like your setup, it’s worth getting it assessed rather than trial-and-erroring your way into stuck sashes and new condensation.

B) Condensation: reduce moisture at the source

Moisture is created by normal living: showers, cooking, indoor laundry drying.

A simple approach that works:

• extract air at source (bathroom, kitchen)

• keep background ventilation open (trickle vents where fitted)

• ventilate briefly after moisture-heavy moments

NHS Inform explains that damp and mould come from excess moisture and lists common causes, including condensation and leaks.

C) Dry the frame, not just the glass

If water sits in the bottom corners of frames, mould can start there first. Wipe and dry the frame edges too.

When proper sealing or repair is the right move

Quick fixes are great for minor gaps. Proper sealing and repairs are the right move when the problem is structural, persistent, or tied to failed components.

Signs you probably need repair and sealing

• Paper test fails in multiple spots

• You can feel draughts even when the window is fully locked

• The window is hard to close or looks slightly dropped

• Seals are visibly split, brittle, or missing

• Frame-to-wall sealant is cracked or pulling away

• Condensation is happening between panes

• Mould returns in the same corner even after consistent ventilation changes

If you want us to check the windows properly and stop the draughts at the source, see Window Repair and Sealing Services.

Ventilation checks that stop condensation coming back

Sealing draughts helps comfort, but a home still needs controlled ventilation. Approved Document F is the core guidance for ventilation requirements and principles in England.

Bathroom

• Does the fan actually clear steam, or does the mirror stay fogged long after?

• Is it vented outside (not into a loft void)?

• Are you leaving it on after showers?

Kitchen

• Extract when cooking, especially boiling and frying.

• Lids on pans reduce moisture release fast.

Trickle vents and background ventilation

If your windows have trickle vents, keep them open as part of normal background ventilation.

If you still get damp patches on the wall

If you have done the basics and the wall still gets wet, do not assume it is “just condensation”. Two common reasons:

1. Cold spots around openings
   Corners and window reveals can be colder than the rest of the room, so moisture forms there first. Historic England and BRE both discuss how air leakage and cold surfaces link to comfort and moisture patterns.

2. Leaks or rain ingress
   NHS Inform includes rain seeping in around window frames and leaking pipes as common moisture causes.

A quick note if you’re decorating

If condensation or damp is part of the story, do not paint as a “cover up”. It tends to fail fast and you end up doing the job twice. This is exactly why we built the prep around fixing the cause first in Painting a Room Properly: The Prep Sequence Most DIY Guides Skip.

Shareable checklist

Today

• Wipe glass and frames dry

• Use extraction during and after showers and cooking

• Keep trickle vents open if fitted

• Do the paper test on any draughty window

• Check seals for splits and flattened sections

This week

• Fit appropriate draught-proofing to minor moving-part gaps

• Stop drying laundry in the coldest room, or only do it with good extraction

• Monitor one room’s pattern for 7 days (glass only vs wall patches)

Book a check if

• The same window corner keeps moulding

• The window will not close square

• You have condensation between panes

• Damp patches track with rain or plumbing use

FAQs

Why do I get condensation even with windows shut?

Because the moisture is already inside the home. Warm moist air hits a cold surface and condenses. Closing the window reduces draughts but does not remove humidity.

Is condensation a health concern?

It can be, especially when it leads to damp and mould. NHS Inform explains how damp and mould relate to excess moisture and why identifying the cause matters.

Can draught-proofing make condensation worse?

Yes, if you seal gaps but do not improve extraction and background ventilation. The best outcome is usually controlled ventilation plus sealing the unwanted leaks.

Why did my draught strip fall off after a week?

Usually one of three reasons: the surface was dusty or damp, the strip was the wrong thickness, or it was fitted where friction is too high (common on sliding sashes). The Energy Saving Trust points out how important it is to match strip size and type to the window.

Want a proper diagnosis rather than guessing?

If you want us to identify the cause and fix it properly, here are the most relevant next steps:

• Window Repair and Sealing Services

• Contact