How to Achieve a 0.15 U-value for Pitched Roof Insulation Applications

Achieving a specific U-value for building control can be difficult to understand. Especially when you’re up against constantly rising costs of materials and head-height restrictions.

What is a U-value?

A U-value is a measurement of heat loss and can explain the energy efficiency of an area like roofs, walls, floors, as well as windows. The U-value is calculated by a sum of all the thermal resistance of each layer that makes up the structure. Within a roof, you would generally find the structure is made from tiles, membranes, air gaps, and timber. All these factors can impact the U-value in either a positive or negative way.

The lower the U-value, the less heat will escape from that area, due to rising energy costs, a lower U-value will result in lower energy bills. If you are building an entirely new structure or renovating a property, it’s also essential to ensure the property is achieving the specific U-value you’re required to meet.

2023 U-values for Building Regulations

The government-approved Document Part L has recently been updated about U-values, heat gain, and heat loss. The updated rules came to fruition in June 2022. On the UK government website, you can find more information on Part L See Data Source Here. In a Nutshell, the lower the number of the U-value required, the more insulation is required for the project.

New for 2023 – U-value requirements for existing dwellings
Application	Current U-value
Roof (Pitched & Flat Roof)	0.15
Wall	0.18
Floor	0.18

 

Products Recommended by Ecohome Insulation

Here at Ecohome Insulation, we distribute a wide variety of Multifoil Insulation including SuperQuilt as well as BreatherQuilt. Both these products are multi-layered blankets consisting of reflective foils, PE foams and recycled waddings. Due to their slim profiles, both of these products are proven space savers allowing you to retain as much space as possible inside the property. Not only are they space-saving they also have superior R-value ratings. Below you’ll find our recommended insulation systems to meet specific U-values. You’ll also find details including SuperQuilt and BreatherQuilt as well as SuperQuilt with additional insulation materials.

SuperQuilt For Pitched Roofs

SuperQuilt Available HERE

• 40mm multifoil insulation with 19 layers
• Compresses down to just 7mm
• BDA and BBA Agremont Certified
• Built-in Vapour Control Layer
• Made from 83% recycled materials
• Manufactured in the UK

BreatherQuilt For Pitched Roofs

BreatherQuilt Available HERE

• 11 layer 2 1 insulating breather membrane
• 40mm thick
• Compresses down to just 7mm
• BDA Agremont Certified
• Waterproof protects your home from all weather conditions
• Made from 72% recycled materials
• Manufactured in the UK

Systems to Achieve a 0.15 U-Value

Here at Ecohome Insulation, we have a variety of methods and systems to achieve current U-value regulations, for pitched roof insulation. Depending on whether you are installing insulation under the roofing rafters, over the rafters, or a combination of both these details can vary. Below each image, you will also find the minimum rafter depth required for the project.

Option A – Insulating Under Rafter – 3 layers of SuperQuilt, Standard Plasterboard

Method to achieve 0.15 on a pitched roof. Minimum rafter depth 100mm @ 400mm Centres.

Option B – Insulating Under Rafter – 2 layers of SuperQuilt, 52.5mm insulated PlasterBoard

 

Method to achieve 0.15 on a pitched roof. Minimum rafter depth 100mm @ 400mm Centres

Option C – Insulating Under Rafter – 1 layer of SuperQuilt, 110mm PIR Insulation, Standard Plasterboard

Method to achieve 0.15 on a pitched roof. Minimum rafter depth 160mm @ 400mm Centres.

Option D – Insulating Under Rafter – 1 layer of SuperQuilt, 100mm Phenolic Insulation, Standard Plasterboard

Method to achieve 0.15 on a pitched roof. Minimum rafter depth 150mm @ 400mm Centres.

Option E – Insulating Under Rafter – 2 layers of SuperQuilt, 100mm EcoLoft Non-Itch, Standard Plasterboard

Method to achieve 0.15 on a pitched roof. Minimum rafter depth 100mm @ 600mm Centres.

Option F – Insulating Under Rafter – 2 layers of SuperQuilt, 50mm PIR Insulation, Standard Plasterboard

Method to achieve 0.15 on a pitched roof. Minimum rafter depth 100mm @ 600mm Centres.

Option G – Insulating Over and Under Rafters – 1 layer of SuperQuilt, 70mm PIR Insulation, 1 layer of BreatherQuilt, Standard Plasterboard

Method to achieve 0.15 on a pitched roof. Minimum rafter depth 125mm @ 400mm Centres.

Option H – Insulating Over & Under Rafter – 1 layer of SuperQuilt, 140mm Rockwool, 1 layer of BreatherQuilt, Standard Plasterboard

Method to achieve 0.15 on a pitched roof. Minimum rafter depth 100mm @ 600mm Centres.

Option I – Insulating Over Rafter only – 1 layer of SuperQuilt, 75mm PIR Insulation, 1 layer of BreatherQuilt, Standard Plasterboard

Method to achieve 0.15 on a pitched roof. Minimum rafter depth 100mm @ 600mm Centres.

Require a Certificate for Building Control?

If you’re going though Building Control, it is likely they will want to see a document displaying the achieved U-value. You can download these from our Online U-Value Calculator. Once you have filled out our form, our system will email your bespoke calculation in PDF form.

Are you struggling to find the correct calculation? If so, please request a U-value on our Contact Form. On our  contact form please mention which method you’d prefer (for example Option C, or Option D) as well as the m² coverage, we will email a bespoke U-value Calculation and Quote.

Delivery Schedule

Ecohome Insulation offer SuperQuilt and BreatherQuilt with FREE next-working day delivery!

You can purchase these as loose rolls, or save cost with our Trade Pallet Deals!

See below links to order both online with next-working day delivery;

SuperQuilt Loose Rolls – Click Here!
SuperQuilt Trade Pallet – Click Here!
BreatherQuilt Loose Rolls – Click Here!
BreatherQuilt Trade Pallet – Click Here!

Disclaimer

All build-ups and suggestions are provided in good faith. Our recommended details should be double-checked with building control before committing to a purchase. The U-value table is a guide, and your desired target U-value is to be advised by your building inspector. Please check the calculations for correct air gaps and battens, battens may be required to be installed perpendicular to how they are supplied in the image. 2D images are not to scale and are for illustrational purposes only. Multifoils-Direct cannot be held responsible for any losses financially or physically from advice provided on this webpage.

Achieve a 0.15 U-Value – Pitched Roof Insulation