New windows can completely transform a property.
They can improve energy efficiency, reduce draughts, modernise the appearance of a building and replace old frames that have reached the end of their useful life.
But in older UK properties, removing windows can sometimes uncover something considerably less welcome.
Asbestos-containing materials.
The glass and window frame themselves aren’t necessarily the problem. It’s often the materials around, above or below the window that can catch property owners and contractors by surprise.
Older boards, infill panels, linings and surrounding building materials may have remained hidden or untouched for decades.
Once a window replacement or refurbishment project begins, those materials can suddenly be drilled, broken or removed.
So if your property was built or refurbished before 2000, here’s what you need to know before the old windows start coming out.
Why Can Asbestos Be Found Around Windows?
Asbestos was historically used throughout UK construction because of its:
- Fire resistance
- Durability
- Insulating properties
- Strength
- Versatility
It wasn’t restricted to obvious applications such as corrugated garage roofs or pipe lagging.
Asbestos-containing boards and cement products were also incorporated into building fabric in places that modern property owners might never think to check.
That can include areas associated with window openings and external façades.
The exact construction varies enormously between properties, which is why understanding what’s present before intrusive work begins is important.
Where Could Asbestos Be Hidden Around a Window?
There isn’t one universal “asbestos window”.
Instead, asbestos-containing materials may be present in different components surrounding the opening.
Potential locations can include:
Infill Panels
Older buildings sometimes have solid panels positioned below or alongside windows.
Depending on the building’s age and construction, some may incorporate asbestos-containing materials.
Internal Linings
Boards used around window reveals or adjacent walls may contain asbestos.
External Cladding
Some older façade and cladding systems incorporated asbestos cement sheets or other asbestos-containing panels.
Window Surrounds
Materials concealed behind trims, finishes or newer installations may only become visible when an old window is removed.
Panels Beneath Windows
These are particularly worth considering in older commercial, public-sector and residential buildings where repeated window-and-panel systems were used across façades.
The important point is that the potential asbestos may not become apparent until the replacement project becomes intrusive.
Can Window Sills Contain Asbestos?
This is something people frequently search.
A window sill that merely looks old cannot automatically be assumed to contain asbestos.
Different materials have been used for sills and surrounding boards over the years, and appearance alone isn’t a reliable way to identify asbestos.
If a suspect material will be drilled, cut, broken or removed as part of the project, professional assessment can establish whether asbestos is present.
Can You Tell If a Window Panel Contains Asbestos by Looking?
Not reliably.
This is one of the recurring problems with asbestos.
Some asbestos-containing boards and cement products look very similar to non-asbestos alternatives.
You generally can’t confirm asbestos because something is:
- Grey
- Fibrous-looking
- Hard
- Old
- Cement-like
Likewise, photographs alone may not provide a definitive answer.
Where confirmation is necessary, appropriate sampling and laboratory analysis can establish whether asbestos fibres are present.
Why Window Replacement Can Cause a Problem
Asbestos-containing materials may remain safely undisturbed for decades.
Then the windows are replaced.
Installation work can involve:
- Removing old frames
- Taking off trims
- Drilling new fixing points
- Cutting surrounding materials
- Removing infill panels
- Altering reveals
- Repairing damaged openings
- Installing new insulation
If an asbestos-containing material sits within that work area, it could be disturbed accidentally.
That’s why identifying potential asbestos before the installers arrive is considerably easier than discovering it once half the old window is already out.
What Happens If a Window Installer Finds Suspected Asbestos?
If a contractor encounters a material they suspect contains asbestos, work that could disturb it should stop.
The next step is to establish what the material actually is.
Depending on the circumstances, this may involve:
- Assessing the suspect material.
- Arranging sampling where appropriate.
- Laboratory analysis.
- Determining the type and condition of any asbestos-containing material.
- Deciding whether it can remain safely in place or needs to be removed.
- Planning the window works accordingly.
What started as a straightforward installation may temporarily pause—but that’s far preferable to continuing and unnecessarily disturbing an unknown material.
What If the Old Windows Have Already Been Removed?
Sometimes the suspect material isn’t discovered until removal has begun.
If a surrounding board or panel has already been damaged:
Stop further disturbance.
Avoid:
- Breaking additional pieces away
- Sweeping up dust
- Using a normal household vacuum
- Drilling further fixings
- Sanding the material
- Carrying loose debris through the building
Professional advice can then determine the appropriate next steps based on what has happened.
Window Replacement in Homes
For homeowners, window replacement is often part of a larger renovation.
Perhaps you’ve bought a 1960s or 1970s property and you’re replacing:
- Old timber frames
- Early double glazing
- Patio doors
- Bay windows
- External cladding
If other building materials surrounding those installations are also being removed, asbestos should be considered before intrusive work starts.
This doesn’t mean every older home needs a full asbestos survey simply because you’re changing a window.
It means the scope and age of the building work should be considered, particularly where suspect materials will be disturbed.
Flats & Residential Blocks Can Be Different
Window replacement becomes particularly interesting in older blocks of flats.
Large residential buildings may have repetitive façade systems incorporating:
- Windows
- Infill panels
- External boards
- Cladding
- Fire-resistant materials
Replacing hundreds of windows across an occupied residential block is very different from changing one bedroom window in a house.
If asbestos-containing materials are identified, the programme may need to consider:
- Residents
- Access
- Phasing
- Segregation
- Waste routes
- Other contractors
- Maintaining secure and weatherproof properties
This is where early asbestos planning can make an enormous difference.
Schools & Public Buildings
Older schools and public-sector buildings can also contain asbestos-containing panels and boards associated with window systems and surrounding building fabric.
Window replacement programmes often take place during:
- Summer holidays
- Half-term closures
- Planned maintenance periods
Discovering asbestos after the programme has begun can put already tight completion dates under pressure.
Appropriate surveys before work begins allow asbestos removal, where required, to be programmed alongside the window installation.
Commercial Properties
Offices, factories, warehouses and other commercial buildings can present similar challenges.
Older façades may have undergone several refurbishments over the decades.
A modern-looking window doesn’t necessarily mean everything behind it is modern.
Previous contractors may simply have installed new components around older building materials.
When refurbishment becomes more intrusive, those hidden layers can finally be exposed.
What About Shopfronts?
Shop and commercial unit refurbishments often involve:
- Removing old shopfronts
- Altering entrances
- Replacing glazing
- Changing signage
- Opening up internal walls
Older materials concealed around these areas may become disturbed during strip-out.
Where the building predates 2000 and significant intrusive works are planned, asbestos information should form part of the project planning process.
Can Asbestos Around Windows Be Left in Place?
Potentially.
Finding asbestos doesn’t automatically mean it must all be removed.
If an asbestos-containing material is:
- In good condition
- Secure
- Unlikely to be disturbed
- Outside the scope of the proposed works
it may sometimes remain safely managed.
But if the new window installation requires contractors to drill through, remove or substantially alter the material, leaving it untouched may no longer be practical.
That’s where the planned works become just as important as the condition of the asbestos itself.
Could It Be Encapsulated Instead?
In some circumstances, appropriate asbestos-containing materials can be encapsulated rather than removed.
However, encapsulation shouldn’t simply mean:
“Put something over it and forget it’s there.”
If asbestos remains within the building, it should continue to be appropriately managed and recorded where applicable.
Future contractors need to know what’s behind that lovely new window finish before somebody drills through it ten years later.
Do I Need an Asbestos Survey Before Replacing Windows?
It depends on the property and the extent of the proposed works.
If you’re replacing windows in an older building and the project will disturb surrounding materials that haven’t been assessed, appropriate asbestos investigation may be necessary before work begins.
For larger refurbishment programmes, the survey should cover the areas that will actually be disturbed.
That’s important.
A previous general asbestos survey doesn’t necessarily mean every hidden material within a window opening has been inspected.
The survey needs to be appropriate for the planned work.
Housing Associations & Large Window Replacement Programmes
This is where asbestos planning becomes particularly valuable.
Imagine a housing provider replacing windows across:
- 50 flats
- 100 properties
- An entire estate
Discovering an unexpected asbestos-containing panel after the programme begins can affect:
- Residents
- Installation teams
- Project schedules
- Budgets
- Access arrangements
Identifying the construction type and asbestos risks at the planning stage allows the programme to be designed around them.
For large-scale refurbishment, that can save significant disruption.
Energy-Efficiency Improvements Are Increasing Window Replacement
There’s another reason this subject is increasingly relevant.
Property owners are investing heavily in:
- Better insulation
- Double and triple glazing
- Draught reduction
- Energy-efficiency improvements
- Wider retrofit programmes
That means older buildings are being opened up and upgraded.
And just like solar panels, heat pumps and insulation projects, modern energy improvements can sometimes encounter historic asbestos-containing materials.
Improving an old building doesn’t make its original construction materials disappear.
A Little Investigation Can Prevent a Big Delay
Picture two window replacement projects.
Project One
Potential asbestos-containing panels are identified before installation.
Sampling is arranged.
Any required removal is programmed.
Window contractors know exactly what they’re working around.
The project proceeds.
Project Two
Nobody checks.
Installers arrive.
The first window comes out.
A suspect board is uncovered.
Work stops.
Now you potentially have:
- An open window
- Contractors waiting
- Additional testing
- Removal works
- Revised schedules
- An increasingly unimpressed property owner
Same building.
Same asbestos.
Very different project experience.
Frequently Asked Questions
Can asbestos be found around window frames?
Yes. Older buildings can contain asbestos-containing boards, panels or other materials around window openings, although the window frame itself isn’t automatically asbestos-containing.
Can window sills contain asbestos?
Some older materials used around windows may contain asbestos, but appearance alone isn’t enough to confirm this. Testing may be required where suspect materials will be disturbed.
Do asbestos panels beneath windows need removing?
Not automatically. Their condition, location and whether planned works will disturb them determine the appropriate approach.
Should I have an asbestos survey before replacing my windows?
Where an older building may contain asbestos and replacement works will disturb surrounding materials, appropriate asbestos information should be obtained before intrusive work begins.
What should I do if my window installer finds suspected asbestos?
Work affecting the suspect material should stop and the material should be professionally assessed before further disturbance.
Can asbestos panels be covered instead of removed?
In some circumstances, suitable asbestos-containing materials may remain managed or encapsulated. However, future disturbance and ongoing management requirements must be considered.
Are asbestos window panels common in blocks of flats?
Asbestos-containing panels and boards can be found in some older residential blocks, particularly within historic façade and building systems. Each property should be assessed individually.
Can modern windows hide older asbestos materials?
Yes. Previous replacement windows may have been installed while older surrounding materials remained in place, meaning asbestos can sometimes be uncovered during later refurbishment.
Replacing Windows in an Older Property? Check Before Work Begins
Whether you’re replacing one window at home or managing a major window replacement programme across a residential estate, school or commercial property, identifying asbestos before work begins can prevent unnecessary delays and accidental disturbance.
At MD Environmental, we support homeowners, contractors, housing providers and commercial organisations with:
- Asbestos Surveys & Sampling
- Refurbishment & Demolition Surveys
- Licensed Asbestos Removal
- Asbestos Encapsulation
- Residential Block Asbestos Projects
- Commercial & Public Sector Asbestos Solutions
If you’re planning window replacement or façade refurbishment within an older property, our experienced team can help identify potential asbestos risks and determine the appropriate next steps.
Call: 0330 043 8778
Email: hello@md-env.com
Contact MD Environmental today for expert advice and a no-obligation quote.
