Top-up insulation
Add compatible material where the existing layer is sound.
FABRIC FIRST
Plan loft insulation and reduce home heat loss
Insulation should reduce unwanted heat flow without trapping moisture or blocking required ventilation. Survey the loft before adding material or boarding.
Decision routes
Start with the outcome, not the advert
Loft boarding
Raise the deck rather than compressing insulation.
Room-in-roof
Sloping ceilings and dwarf walls need a tailored approach.
The CoolCompare check
Four things to compare before committing
Understand loft-insulation depth, access, ventilation, storage, moisture and installer scope before improving a UK roof space.
Existing materialIdentify type, condition, coverage and approximate depth.
VentilationKeep eaves and designed airflow paths clear.
Storage and accessRaised boarding and safe access need a deliberate solution.
Moisture and servicesAddress leaks, tanks, wiring and downlights before covering them.
Loft insulation products
Compare material—and protect ventilation
Thermal conductivity, fire class, handling, installed depth and complete coverage determine performance.
A common A1-rated route where depth is available.
A1 stone wool with acoustic benefits.
A non-combustible alternative for between and over joists.
Loft Roll 44
- Conductivity
- 0.044W/mK
- Fire class
- Euroclass A1
- Thicknesses
- 100 / 150 / 200mm
- Formats
- Ready-cut and uncut
A practical value route for accessible cold lofts when installed without gaps or compression.
+ Pros
- A1 fire class
- Multiple formats
- Cold-loft value
− Cons
- Needs depth
- Handling protection
- Compression harms performance
! Complaints & watch-outs
- Gaps, blocked eaves and compression are workmanship issues often mistaken for product failure.
- Photograph ventilation and coverage before boarding.
Thermal Insulation Roll
- Conductivity
- 0.044W/mK
- Fire class
- Euroclass A1
- Format
- Pre-split twin roll
- Added property
- Acoustic absorption
Compare where non-combustibility, robustness and acoustic performance matter.
+ Pros
- A1 stone wool
- Acoustic benefit
- Robust material
− Cons
- Heavier handling
- Pack economics vary
- Careful cutting needed
! Complaints & watch-outs
- Cold spots usually follow gaps, displacement or hatch omissions.
- Fix damp and roof leaks first.
Multi-Roll 44
- Conductivity class
- 0.044 family
- Fire
- Non-combustible
- Application
- Between and over joists
- Build type
- Cold loft
Use as a like-for-like quote with identical depth, area, access and boarding assumptions.
+ Pros
- Non-combustible
- Made for joists
- Value alternative
− Cons
- Handling protection
- Storage headroom loss
- Raised boarding extra
! Complaints & watch-outs
- Quotes can omit hatch, pipe protection or raised access.
- Require area, thickness and exclusions in writing.
READ BEFORE SHORTLISTING
Do not block eaves ventilation, cover unsafe downlights, compress insulation under boards or proceed over active damp. The familiar 270mm figure is material-dependent, not universal.
Side-by-side
Compare the main routes
A quick orientation before you request prices or commit to a contract.
| Decision | Top-up rolls | Blown insulation | Room-in-roof |
|---|---|---|---|
| Typical area | Accessible loft floor | Awkward voids | Slopes and dwarf walls |
| Access | Clear working area | Specialist installation | Detailed construction access |
| Main risk | Compression and blocked eaves | Uneven fill or unsuitable void | Thermal bridges and moisture |
| Quote focus | Coverage, depth and boarding | Material, density and ventilation | Continuous layer and junctions |
Before you buy
Your quote and contract checklist
Save this list and use the same questions with every provider. Comparable inputs produce a more useful comparison.
- 01
Survey firstRecord moisture, leaks, ventilation, wiring, tanks and existing material.
- 02
Do not compressRaised storage should preserve the intended insulation thickness.
- 03
Protect ventilationKeep eaves and other designed airflow paths open.
- 04
Safe servicesTreat downlights, cables, flues and water tanks appropriately.
Start here
Essential loft insulation guides
Three practical reads that frame the decision without sales pressure.
DEPTH01
How much loft insulation?
Understand depth without ignoring material and installation quality.
Read the key answers ↓STORAGE02
Insulation and loft boarding
Keep storage without crushing the thermal layer.
Read the key answers ↓MOISTURE03
Ventilation and condensation
Improve heat retention while managing moisture safely.
Read the key answers ↓Plain-English answers
Frequently asked questions
General UK guidance. Product, property, tariff and policy details still need individual verification.
Can new insulation go over old insulation?+
Often, if the existing material is dry, compatible and in reasonable condition. Problems should be corrected before covering it.
Can I board directly over insulation?+
Boarding should not compress insulation. A suitable raised structure and safe access plan may be needed.
Should eaves vents be covered?+
Designed ventilation paths should remain clear. Blocking them can increase moisture risk.
Does loft insulation help in summer?+
It can slow heat transfer through the roof, although shading, ventilation and internal gains also shape overheating.
Connected decisions