Pitched Roof Insulation helps UK homeowners improve thermal performance, reduce heat loss, and make loft conversions or room-in-roof spaces more comfortable. LAMTANS Engineering provides PAS2035-compliant insulation solutions from our Manchester base, delivering professional roof upgrades across the UK.
Pitched roof insulation — also known as rafter insulation — is insulation installed between (and sometimes over) the sloping timber rafters of your roof. It is the correct insulation approach for loft conversions, room-in-roof spaces, and any property where the living space extends into the roof structure.
Unlike standard loft insulation, which sits on the loft floor between joists, pitched roof insulation follows the slope of the roof — keeping the rafter space warm, reducing heat loss through the roof covering, and preventing condensation in the roof structure. Building regulations require adequate insulation for loft conversions, and PAS2035 sets the standard for retrofit installations.
Loft Conversions
Any loft converted into habitable living space requires insulation between the rafters to meet building regulations and achieve an acceptable thermal standard. We install to PAS2035 for maximum performance and compliance.
Room in Roof
Properties built with a room-in-roof configuration — where the roof space is part of the original living area — often have inadequate or deteriorating insulation. We assess and upgrade to current standards.
Sloping Ceiling Spaces
Rooms with sloping ceilings — whether part of a dormer conversion or a property with a low-pitch roofline — benefit from rafter insulation to eliminate cold spots, draughts, and condensation issues.
Pitched Roof vs Loft Floor Insulation — Which Do You Need?
Loft floor insulation (between joists on the loft floor) is suitable if you use your loft only for storage and do not heat the space. Pitched roof insulation (between the rafters) is required when the loft is converted into a living space — the insulation must follow the roof slope, not the floor. We confirm the right approach at the free survey.
Pitched roof insulation can be installed in two main ways — between the rafters only, or between and over the rafters. The right approach depends on your rafter depth, performance requirements, and budget. We confirm the correct system at the free survey.
Between Rafters Only
StandardInsulation is cut and fitted tightly between the rafter timbers, with a ventilation gap maintained above the insulation for airflow and moisture control. A vapour control layer is applied to prevent condensation.
Between & Over Rafters
RecommendedInsulation is fitted between the rafters AND a continuous layer is added over the top. This eliminates thermal bridging through the timber and delivers significantly better overall energy performance.
We recommend between and over rafter insulation for most loft conversions and room-in-roof applications. At your free survey we check rafter depth, existing insulation, and ventilation — then confirm the most suitable system for your specific roof.
Get a Free SurveyInsulating your pitched roof transforms the comfort, energy efficiency, and moisture performance of your loft conversion or roof space — making it genuinely liveable all year round, not just tolerable in mild weather.
Keep Your Loft Conversion Warm
Proper rafter insulation prevents heat escaping through the roof covering and eliminates the cold ceiling effect common in poorly insulated loft rooms. A warm, comfortable room all year — regardless of weather.
Lower Energy Bills
Reducing heat loss through an uninsulated or under-insulated pitched roof directly reduces your heating demand — and your bills. Well-specified rafter insulation can deliver meaningful savings year on year.
Typical saving: £200–£500/yrPrevent Condensation
A correctly installed vapour control layer prevents warm moist air from reaching cold rafter surfaces and condensing — stopping the damp, mould, and structural timber damage that poorly detailed rafter insulation can cause.
Eliminate Cold Draughts
Sloping ceilings are a common source of cold draughts in loft conversions — caused by gaps between rafter bays, inadequate insulation depth, or missing vapour control. Correctly fitted rafter insulation seals these issues permanently.
Planning a loft conversion and need pitched roof insulation specified from the start? We work with loft conversion projects from initial survey through to PAS2035-compliant installation.
Learn more about room in roof conversions →Pitched roof insulation costs depend on your roof area and which installation method is used. Between and over rafter installation costs more upfront but delivers better long-term thermal performance. All prices include supply and installation — confirmed at the free survey.
| Roof Area | Between & Over Rafters (Recommended) | Between Rafters Only |
|---|---|---|
| 20m² — small loft | £1,500 – £2,500 | £800 – £1,500 |
| 30m² — medium loft | £2,000 – £3,000 | £1,200 – £2,000 |
| 40m² — large loft | £2,500 – £3,500 | £1,600 – £2,500 |
All figures are indicative estimates including supply and installation. Final price confirmed at your free survey based on roof area, rafter depth, access, and insulation specification.
Our installation process covers everything from the initial survey through to a finished, plastered ceiling ready for decoration — managed in sequence with no missed stages, no condensation risks, and no surprises.
Free Survey
We visit to check rafter depth, timber condition, existing insulation, and ventilation — confirming the correct insulation method, specification, and vapour control approach before any work is agreed.
Clear the Roof Space
Any stored items are removed from the loft space to give full access to the rafters. The existing condition is inspected before insulation work begins.
Install Insulation Between Rafters
Insulation is precision-cut and fitted tightly between each rafter bay with no gaps. Where between-only installation is specified, a ventilation gap is maintained above the insulation for airflow and moisture management.
Install Vapour Control Layer
A correctly detailed vapour control layer is applied across the insulated surface — the critical stage that prevents warm moist air reaching cold surfaces and condensing, protecting the roof structure long-term.
Install Insulation Over Rafters (where specified)
Where the between-and-over specification is required, a continuous layer of rigid insulation board is fixed over the rafters — eliminating thermal bridging through the timber and achieving optimal thermal performance.
Install Plasterboard & Finish
Plasterboard is fixed and skimmed to provide a clean, finished ceiling surface — ready for decorating. The installation is handed over complete and fully compliant.
A typical pitched roof insulation installation is completed in two to three days for a standard loft conversion. You can remain in your home throughout — works are confined to the roof space.
PAS2035 Compliant
We install pitched roof insulation to PAS2035 — the latest UK retrofit standard — ensuring every installation is assessed, specified, and installed to recognised best practice for safety and energy performance.
TrustMark Registered
TrustMark is the government-endorsed quality mark for home improvement work. All our pitched roof insulation installations meet TrustMark quality and compliance standards.
Vapour Control Expertise
Correct vapour control detailing is the most critical — and most commonly overlooked — element of rafter insulation. We design and install vapour control layers to prevent condensation, damp, and structural timber damage.
Free Surveys
No-obligation roof assessment before any work begins. We check rafter depth, existing insulation, ventilation, and condition — and confirm the right specification for your roof before you commit.
RECC Accredited
We hold RECC (Renewable Energy Consumer Code) accreditation — a recognised mark of professional standards and consumer protection for retrofit and energy improvement work.
Local UK-Wide Installer
Based in Manchester, we serve homes across the UK. A local team with deep knowledge of UK housing stock — from Edwardian terraces to modern loft conversions — with nationwide reach.
LAMTANS Engineering — Retrofit & Insulation Specialists
LAMTANS Engineering is a Manchester-based retrofit specialist delivering pitched roof insulation, loft insulation, flat roof insulation, cavity wall insulation, external wall insulation, solar panels, battery storage, and heating upgrades across the UK. We combine industry accreditations with thorough pre-installation surveys to deliver safe, effective, and compliant installations — from free survey to final sign-off.
📍 Based in Manchester — serving Stockport, Oldham, Droylsden, Ashton-under-Lyne, Tameside, and across Greater Manchester, with nationwide coverage.
Loft insulation goes on the floor of your loft space — between the joists — and is used when the loft is unoccupied and you want to keep heat in the rooms below. Pitched roof insulation goes between the rafters (the sloping roof timbers) and is used for loft conversions where the space is lived in. If you use the loft as a room, you need rafter insulation, not loft floor insulation.
Yes. Building regulations require insulation in the roof of a habitable loft conversion to meet minimum thermal performance standards. We install pitched roof insulation to PAS2035 — the current UK retrofit standard — ensuring the specification, installation, and vapour control all meet recognised best practice. We confirm the correct system at the free survey.
Not if installed correctly. A properly detailed vapour control layer — fitted on the warm side of the insulation — prevents warm moist air from reaching cold rafter surfaces and condensing. Poorly installed rafter insulation that omits or incorrectly details the vapour control layer is the single most common cause of condensation, damp, and structural timber damage in loft conversions. Getting this stage right is a core part of how we work.
Building regulations typically require 100–150mm of insulation between the rafters, depending on the insulation product's thermal conductivity and the rafter depth available. For optimal thermal performance, we recommend adding a continuous layer of rigid insulation board over the rafters — eliminating thermal bridging through the timber and achieving better overall U-values than between-only installation can reach. We specify the correct depths at the free survey based on your rafter depth and target performance.
We strongly recommend professional installation. Getting the vapour control layer correctly detailed — with sealed laps, properly treated junctions at walls, windows, and roof penetrations — is technically demanding. Errors in the vapour control layer lead to condensation, damp, and structural timber damage that can be costly to identify and rectify. Professional installation also ensures the work is PAS2035 compliant and meets building regulations.
LAMTANS Engineering is TrustMark Registered, RECC Accredited, and PAS2035 Compliant — along with a range of further industry accreditations covering retrofit, insulation, and energy improvement work. Our full accreditation list is on our accreditations page.
Book your free roof survey and we'll check rafter depth, existing insulation, and ventilation — then confirm the right insulation system and provide a fixed-price quote. You'll receive your quote within 72 hours following your free survey.