More insulation depth
Explore the deepest of these three options and the space needed to fit it properly.
Explore 145mm IsothermCape Ceilings & Drywalling
Isotherm Insulation in Cape Town.
Explore 145mm, 135mm and 100mm Isotherm insulation for your ceiling. Get practical advice on thickness, coverage and the specification your project needs.
Available on request. We confirm the product and project requirements before quoting.
A considered choice
for your ceiling.
for your ceiling.
36+ yearsOf insulation industry experience
Three thicknesses145mm · 135mm · 100mm
Local project adviceCape Town & selected West Coast areas
Find your starting point
Which Isotherm thickness are you considering?
Start with the thickness you have been quoted or specified. Then check the product grade, available ceiling depth and required performance before choosing.
Compare the specification
Check the declared performance and roof arrangement rather than choosing by appearance alone.
Explore 135mm IsothermConfirm the exact grade
Thickness alone does not tell the whole story. Make sure the quoted grade is clearly identified.
Explore 100mm IsothermAlready have a specification? Send it with your plans or roof photographs. We can discuss the requested material and confirm availability before you commit to an order.
Know the material
What is Isotherm insulation?
Isotherm is a polyester bulk-insulation material. The manufacturer describes thermally bonded fibres made using recycled PET, supplied in a flexible form for suitable roof and wall applications.
For a ceiling upgrade, the product is only part of the decision. The roof condition, fitting method, coverage and available depth affect the finished result. Cape Ceilings & Drywalling helps you assess those practical details alongside the requested thickness.
Thermal comfort
A suitable insulation layer helps limit heat transfer through the ceiling. It works alongside roof design, glazing, draught control and ventilation as part of the building’s overall comfort.
Flexible polyester
The soft blanket format can be fitted around a planned ceiling layout. Handling comfort does not remove the need for safe access, appropriate equipment and correct installation details.
A specification you can compare
Ask which product is included, how much area each roll covers and what work is allowed for. A clear quote is more useful than a thickness or roll price on its own.
Option 01 / Greater depth
145mm Isotherm Insulation
145mm Isotherm insulation is worth investigating when your project calls for a deeper polyester layer. The key question is whether the chosen product suits the required performance and can be accommodated at its intended thickness.
Before selecting it, check the space around roof members, changes in ceiling level and existing services. Storage boards or other items resting on the insulation can compress it, so the usable roof space should be considered as part of the plan.
For an existing home, photographs and a description of the current insulation help us understand whether the request is for a new layer, a replacement or an assessment of an earlier installation. A new build should follow the agreed roof specification.
When asking for a quote: include the ceiling area, roof access and any document specifying the required product. We will confirm the available material and scope.
Ask about 145mm Isotherm insulation ↗
Option 02 / Compare the build-up
135mm Isotherm Insulation
135mm Isotherm insulation is another option to compare when specifying a polyester ceiling blanket. A small difference in thickness can still matter, so it should not be treated as an automatic replacement for a different specified product.
Pay attention to the complete quotation: the product grade, declared thermal performance, quantity and fitting arrangement. Products with similar dimensions can have different specifications, and an attractive roll price does not necessarily mean a lower cost for the required result.
Stepped ceilings, roof edges and awkward service routes deserve particular attention. The layout needs to allow the chosen material to be fitted in the intended position without leaving avoidable gaps or forcing it into restricted spaces.
Replacing an existing layer? Tell us what is already in the roof, whether it is dry and whether the project specification calls for removal or an additional layer.
Ask about 135mm Isotherm insulation ↗Option 03 / Identify the grade
100mm Isotherm Insulation
When comparing 100mm Isotherm insulation, ask for more than the thickness. Published literature distinguishes different densities at this depth, which is why two listings can show different thermal figures.
The current pack label and supporting product documentation should identify what is being supplied. This matters when comparing prices, replacing an existing material or checking whether a proposed layer matches a specification.
A shallower blanket may fit a particular space, but available space alone does not establish suitability. An additional layer is also a separate design decision: existing insulation, ventilation, service clearances and the intended roof arrangement must be considered.
For a useful comparison: send us the quoted product name, thickness, density if stated, roll size and the project requirement.
Ask about 100mm Isotherm insulation ↗Make an informed comparison
Compare Isotherm
insulation specifications.
Compare thickness, density and thermal performance using the manufacturer’s published reference figures. We confirm the supplied product and current specification with your quotation.
Swipe the table to view all columns.
| Nominal thickness | Published density | Product R-value* | Published length |
|---|---|---|---|
| 145mm Isotherm | 11.5 kg/m³ | 3.37 | 5 m |
| 135mm Isotherm | 11.5 kg/m³ | 3.14 | 5 m |
| 100mm Isotherm10 kg/m³ reference grade | 10 kg/m³ | 2.04 | 6 m |
| 100mm Isotherm11.5 kg/m³ reference grade | 11.5 kg/m³ | 2.33 | 6 m |
*R-values in m²·K/W. Source: manufacturer’s published Isotherm brochure (PDF). The document also lists different roll widths; confirm the pack dimensions, grade and current technical data. Reference figures do not guarantee a particular roof’s performance or compliance.
Product R-value
This describes the material’s resistance to heat flow at the stated specification. Compare like-for-like figures when evaluating insulation products.
Whole-roof performance
A roof or ceiling assembly includes more than its insulation. Figures that include other construction layers should not be presented as the insulation product’s own rating. Have the applicable project requirements checked separately.
How to calculate roll coverage
Roll length × roll width = coverage per roll.
For example, a roll labelled 5 m × 1.2 m covers 6 m² before cutting and layout allowances. A 60 m² area would therefore use 10 such rolls before those allowances. Confirm the dimensions on the actual quoted pack, then allow for the roof layout and round the final order to whole rolls.
Plan for the whole ceiling
Comfort depends on more
than the material.
A sound roof, a suitable specification and a properly planned installation all contribute to the result.
Limit unwanted heat flow.
Insulation can support a more comfortable indoor environment and reduce heating or cooling demand. Results vary with the building, weather and how the rooms are used.
Windows, draughts and ventilation can still influence comfort after a ceiling upgrade.
Describe the noise problem.
Sound absorption within a construction is different from making a room soundproof. Rain, traffic, equipment and noise between rooms can need different solutions.
Tell us what you hear and where it comes from before choosing a product.
Check before fitting.
Repair roof leaks, assess existing insulation and identify equipment that requires clearance. Follow the current product and equipment instructions.
Commercial, institutional and specialist projects need their own specification checks.
From enquiry to project plan
Planning an Isotherm ceiling installation.
Start with the actual ceiling and the intended result. We confirm the requested product and what can be offered for your project before agreeing the scope.
Watch the Isotherm installation video ↗Use the current product instructions when planning your own installation.
Understand the ceiling
Start with the property location, approximate area, roof photographs and access. Discuss how the rooms are used and whether heat gain, heat loss or a specific noise issue is the priority.
Inspect the existing conditions
Check for active leaks, damp material, damaged ceilings and access restrictions. Identify the existing insulation and any work that needs to happen before a new layer is considered.
Confirm the product & scope
Identify the proposed grade, thickness and documentation. Agree whether the request is for supply or additional site work, and confirm what the quotation includes.
Plan the fitting details
Allow for roof members, changes in ceiling level, access hatches, ventilation and service routes. The selected material must fit the intended arrangement without being forced into place.
Follow the installation instructions
Where installation proceeds, fit the material using the specified method. Keep the designed coverage and loft, and follow equipment requirements around electrical and heat-producing components.
Check the completed work
Review the agreed coverage, edges and access details. Keep the product information and record what was supplied so future roof or electrical work can take the insulation into account.
Prices & project scope
What affects Isotherm insulation prices?
Compare the cost of the required coverage and work, as well as the price of an individual roll. A useful quotation makes the material and scope clear.
Thickness & grade
The specified product, nominal depth and declared performance form the starting point for a fair comparison.
Quantity & coverage
Confirm pack dimensions and the area to be insulated, including the fitting allowances needed for the layout.
Access & existing conditions
Restricted roof space, old insulation and preparatory work can change the scope of an installation enquiry.
Delivery & agreed work
Ask what is included in the quoted total, with delivery, installation work where applicable and VAT clearly identified.
Working out the area? Add the ceiling areas of the rooms being considered. A simple sketch is useful where the layout includes extensions, different ceiling heights or areas already insulated. The final quantity should follow the agreed installation plan.
Cape Ceilings & Drywalling
Advice grounded in
the work above your ceiling.
36+ years of experience
Experience with ceiling insulation and interior building systems helps us ask the practical questions that matter.
Product comparisons
We can discuss the specified material alongside other insulation options when the project calls for a different approach.
Clear project scope
Material, quantity, access and the agreed work should be understood before ordering or arranging a site visit.
Local knowledge
We work with enquiries from Cape Town and selected surrounding and West Coast areas, according to the project.
Cape Town & the West Coast
Tell us where
your project is.
Include the suburb or town in your enquiry so we can confirm availability and any location-related requirements.
Cape Town & Northern Suburbs
Cape Town, Century City, Bellville, Durbanville, Brackenfell, Parow and Goodwood.
Western Seaboard
Milnerton, Table View, Blouberg and surrounding areas.
Selected West Coast projects
Malmesbury, Yzerfontein, Langebaan, Saldanha, Vredenburg, Hopefield and Velddrif.
Other Western Cape locations can be discussed according to project scope and scheduling.
Your questions answered
Isotherm insulation FAQs.
Thickness, prices, coverage and the practical details to consider before choosing a ceiling insulation product.
What is Isotherm insulation?
Isotherm is a flexible polyester bulk-insulation product used in suitable building applications. It is supplied as a blanket or roll and fitted to the intended construction. The exact product specification, application and installation method should be checked before ordering.
What is the difference between 145mm and 135mm Isotherm insulation?
The nominal thickness differs by 10mm. Compare the declared product performance as well as thickness, and check whether the chosen material can fit at its intended depth. The deeper option should not be squeezed into a space that requires a different construction.
Is 145mm Isotherm insulation the right choice for Cape Town?
It is one of the thicknesses worth assessing for a Cape Town ceiling, but suitability is specific to the project. Check the supplied product, available depth, roof arrangement, installation details and required performance. A thickness label by itself does not establish that a building meets its requirements.
Can I use 135mm Isotherm insulation instead of 145mm?
Only where the selected product meets the project specification. A thinner roll is not automatically interchangeable because its price or appearance is similar. If a drawing, quotation or specification calls for a particular product, confirm the change before ordering.
Why do 100mm Isotherm insulation R-values differ online?
Different product grades and product-versus-system figures can produce different listings. Check which specification the supplier is quoting, and ask for the current product label or technical documentation. Comparing only the number of millimetres can hide an important difference.
Is 100mm Isotherm insulation enough on its own?
That depends on the supplied grade, the building and the project requirement. Do not choose it solely because the roof has limited space or because a thicker roll costs more. Assess the installation arrangement and required performance before treating it as a complete solution.
How many rolls will I need?
Start with the measured area and the coverage stated on the quoted roll, then account for the layout, cutting and required detailing. Round up to whole rolls. Existing insulation and any planned extra layer should be assessed separately, rather than assuming every ceiling needs the same order.
How much does Isotherm insulation cost?
A useful quotation identifies the grade, thickness, roll coverage and required quantity, plus delivery and installation work where applicable. Access, existing insulation, roof condition and the project location can affect the total. Ask for the full scope and VAT treatment in writing.
Can Isotherm be fitted above an existing ceiling?
Sometimes, where there is safe roof access and enough working space. The ceiling condition, roof structure, services and existing insulation need to be assessed. The practical installation route should be agreed before any material is ordered.
Can new insulation go over old insulation?
An additional layer may be considered after checking the existing material, its condition and the proposed roof build-up. Wet, contaminated, damaged or heavily compressed insulation needs attention first. Extra insulation must not obstruct ventilation or conflict with equipment clearances.
Will ceiling insulation reduce electricity costs?
Insulation can reduce unwanted heat flow and therefore the heating or cooling needed to maintain comfort. Actual electricity use also depends on weather, windows, draughts, equipment settings and occupancy. A fixed saving percentage or payback period should not be assumed for every property.
Does Isotherm make a room soundproof?
No. A ceiling insulation layer may help with some sound absorption, but acoustic performance depends on the complete construction and the type of noise. Roof structure, ceilings, openings and adjoining rooms all matter. Explain the noise problem before choosing an insulation product.
Can Isotherm go near downlights or electrical equipment?
Only with the installation details and clearances required for the specific insulation and equipment. Do not assume an LED fitting or a driver can be covered. Electrical concerns should be assessed by a qualified electrician before the insulation work proceeds.
Is Isotherm fireproof or suitable for every commercial building?
Do not treat polyester insulation as fireproof or assume one approval applies to every building. Fire requirements depend on the application, building and specified material. For commercial, institutional or specialist projects, confirm the relevant specification and current product documentation first.
What should happen if the roof leaks?
Repair active leaks and investigate damp or damaged materials before installing new insulation. The roof, ventilation and ceiling must be suitable for the work. New material should be kept dry and fitted according to the product instructions.
Do you offer Isotherm in my area?
Contact Cape Ceilings & Drywalling with your location and requirements. We handle Isotherm enquiries on request and will confirm availability, the appropriate specification and what can be offered for your project. Cape Town and selected West Coast projects can be discussed.
Explore the options
Considering another insulation?
The right comparison starts with the required performance and the application. These pages explain other ceiling insulation services offered by CCDW.
Let’s look at your ceiling
Ask us about
Isotherm insulation.
Send your location, approximate area and the thickness you are considering. We will confirm availability and the appropriate next step for your project.
145mm · 135mm · 100mm
Have a quote or specification already? Include it with your photographs so we can discuss the exact product you need.
Not sure which thickness to request? Start with your project details.