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WrightWall Natural provides a full encapsulation package that will meet the building regulations of the future.
Your oak frame, wrapped naturally. WrightWall Natural provides your home with an exceptional thermal performance, ensuring a healthy, warm home. Using 100% recycled materials, WrightWall Natural brings you an airtight encapsulation system using breathable cellulose insulation. WrightWall Natural is manufactured off-site, reducing on-site time and ensuring the highest level of quality control throughout the process.

wrightwall natural encapsulation explained


0.15 W/m2K



0.12 W/m2K




When the time came for Lisa & Ian Milne to choose an encapsulation system for their new Oakwrights oak frame home, they were not just looking for an environmentally friendly solution. Lisa & Ian also required a solution that would meet the highest standards of insulation, breathability, and airtightness.

The couple did not have to look any further than the team they were already dealing with to design their oak frame; Oakwrights Design Department is an integrated team of oak frame designers and panel designers. Our design team works together seamlessly to provide encapsulation of oak frames with our Natural Wall and Roof panel systems.

Lisa & Ian’s specifications for encapsulation were to create an air tight shell using natural materials, with the ultimate aim of creating the healthiest of living environments. It was felt that WrightWall Natural was the best option to encapsulate their home, as this would also provide a low environmental impact whilst creating a breathing wall.

The main advantage of the Natural WrightWall system is that it uses Warmcel recycled cellulose. This along with a highly engineered panel system, create a breathing wall and roof envelope that create a healthy living environment along with very low u value levels and an ability to achieve airtightness.

The density of the Warmcel insulation creates a decrement delay that will keep your home’s temperature at a steady state of equilibrium throughout the year. This, in itself, leads to a more comfortable and healthy living environment.

The highly engineered panel system is designed to give high levels of structure along with top level insulation and an encapsulation that will match the lifespan of your oak frame.

As part of the Natural panel system, Oakwrights supply a fully designed gable ladder system and sprocket and closure board system for the verge and eaves. This system is specially designed to create the traditional fine line of exposed rafter feet, which masks the full depth of insulation build up in the roof to give a traditional look to your design.

an environmentally friendly solution to oak frame infill panels
oakwrights infill panel systems




Passivhaus levels of insulation 0.15W/m²K for walls and 0.12W/m²K for roofs.
WrightWall Natural has a ‘Better than Carbon Zero’ status making it ideal for those targeting the Code for Sustainable Homes(CfSH); combining ease of installation with its other sustainable benefits (airtightness, fire resistance, acoustic insulation, complete void fill etc) what we have here is the best value, best choice insulation on the market. An encapsulation system that will meet the demands of the future.

Quality integrated design. The same team who design your oak frame will design your panel system.

Oakwrights precision manufacturing, using the most advanced technology available, will make your jumbo panel system to the highest tolerances possible.

Reduced site time. Panels built up to 8m x 2.4m to save time on-site and reduce the amount of panel connections.

Site ready. All vapour control layers and counter batten systems are workshop fitted giving a complete panel ready for fit out on site.

Natural recycled materials. Healthy living environment.

Integrated floor systems. Floors can be installed as cassettes, integrating with the panel system, to help save further time on site.

One team, total encapsulation. Your site team will follow through from the erection of your oak frame to carry out the total encapsulation of your frame.

oakwrights team of encapsulation specialists



What are U-values
A U-value is a measurement that describes how much heat is lost from a particular building material, such as a wall, window or roof. A low U-value means that the material is good at retaining heat, a high U-value means that it loses a lot of heat. As far as your home is concerned, the lower the U-value, the better.

What are Psi-values
In a similar way to a U-value, a Psi-value is a measurement that describes how much heat is lost along a linear junction between two surfaces, for example, two walls, the wall and roof or floor and all around windows and doors. The same principal is true of Psi-values in that the lower the value, the better the heat retention.

The scientific bit
U-value is measured in watts per metre-squared kelvin, or W/m2K. In other words, it is the amount of energy (in Watts, or W) that travels through one square metre of a material (m2) per every 1 degree of temperature difference between inside and outside (K).

U-values can apply to single materials (e.g. a metal sheet) or a composite building element (e.g. a softwood encapsulation system).

Psi-values are measured in watts per metre kelvin, or W/mK. In other words, it is the amount of energy (in Watts, or W) that travels through one linear metre of a junction (m) per every 1 degree of temperature difference between inside and outside (K).

Building regulations
The government have set out minimum U-values that are allowed when constructing a new building. Different U-values are required for different building codes. Although to get the final U-value calculation for a house is a very complex set of equations and is dependent on a lot of different factors.

We have had our junctions for both WrightWall Light and WrightWall Natural modelled to calculate the Psi-values which in turn can be inputted into a SAP calculation which is required on all new properties to predict the energy requirements and CO2 production of the proposed building. This will give a significant energy saving instead of using the default values which otherwise have to be used.

U-values of the different Wrightwall Systems.
The table below shows the typical U-values of Oakwrights Wrightwall Systems with different external finishes. Oakwrights Wrightwall Light can be used to build up to and over Code 4 & our Natural System can be used to build up to Passivhaus Standards.



Lightwall - Weatherboarding


U-Value 0.17 W/m2K

 Lightwall - Rendered

 258mm (depends on exact render) 

 U-Value 0.17 W/m2K

 Lightwall - Brickwork


 U-Value 0.16 W/m2K

 Lightwall - Stonework

388mm (150mm stone) 

 U-Value 0.16 W/m2K

 Lightwall - Roof 

 283mm (plus battens and slates/tiles)

 U-Value 0.14 W/m2K

 Natural - Weatherboarding


 U-Value 0.15 W/m2K

 Natural - Rendered

 398mm (depends on exact render detail)

 U-Value 0.15 W/m2K

Natural - Brickwork 


 U-Value 0.15 W/m2K

 Natural - Stonework


 U-Value 0.15 W/m2K

 Natural - Roof

421mm (plus battens and slates/tiles)

 U-Value 0.12 W/m2K


The Passivhaus standard was developed in Germany in the early 1990s and, supported by the European Commission, is rapidly becoming a pan-European standard for low carbon dwellings. The standard is performance based and at its heart are requirements that annual space heating demand does not exceed 15 kWh/m2/yr and that primary energy use (for all purposes) does not exceed 120 kWh/m2/yr.

The standard also requires:

  • Fabric U values not exceeding 0.15 W/m2K.

  • Window U values not exceeding 0.8 W/m2K.

  • Air permeability not exceeding 0.6 air changes per hour at 50 Pa (demonstrated by a pressure test of the completed building).

  • Advanced whole-house mechanical ventilation with heat recovery with at least 75% heat recovery efficiency and electricity use no greater than 0.4 W/m3 of supply air.

Breathability in an Air Tight House!
Breathability or Vapour Permeability – using the term breathable - has caused a lot of misunderstanding across the industry.

The wall construction should be vapour permeable, but can still be made airtight. On Wrightwall Natural the inner Airtightness Membrane is sealed between the panel junctions as the panels slot together, this layer also doubles as vapour control were required (kitchens, bathrooms etc.).
The most important factor in the design of the panel is that the outer layers (cold side) are five times more vapour permeable than the inner layer (warm side of the wall). This means that any moisture that gets into the envelope either during manufacture or on site will be able to move from the inner layers of the walls out through the outer layers and evaporate into the outside environment or not stay trapped in the wall panel itself.

Airtightness is important in such constructions and is achieved by sealing the joints between panels, as air leakage will allow moisture into the structure, increasing relative humidity and the risk of rot. An advantage of vapour permeable construction is that moisture settling within the structure under certain conditions will usually escape later on, as temperature and relative humidity change.
So just call it vapour permeable, and make it airtight and it should be fine in a pressure test.

What is air tightness?
Air tightness refers to the infiltration of cold/hot air into the building and/or the loss of heated/cooled air from inside through gaps, cracks, holes, etc in the building fabric.

By limiting the leakage of heated/conditioned air from buildings, it is possible to reduce energy consumption and costs.

Too much air leakage leads to unnecessary heat loss and discomfort for the occupants. As the Government strives to reduce CO2 emissions from new buildings, building regulations now place greater emphasis on the quality of the fabric of the building.
At Oakwrights we have developed our Wrightwall Systems for a high level of airtightness. Our systems differ in that we allow for the movement of the oak frame & also sealing the hard to get to areas of the encapsulation system behind the oak frame! We have had test results back for our Wrightwall Natural as low as 0.3 air changes per hour at 50 Pa.

How is the Air Tightness Testing done?
In a nutshell, a fan or a number of fans are installed to a suitable external opening and the entire building is pressurised over a range of pressure difference.

The testing is measured in air flow m3 over an average hour period at an average of 50Pascal for every m2 of building fabric. A typical large detached house would have around 400m2 of exposed fabric on the floor, walls and roof. A test figure of 10 would give 4000m3 of leakage at 50Pa over an hour period or as an equation 10 m3.hr.m2@50Pa. Quite a lot of leakages we think you will agree!!
Before the test is carried out, passive ventilation must be temporarily sealed. HVAC plant is switched off and temporarily sealed. The exterior envelope and all its openings are closed.

When is the Air Tightness Testing done?
Testing is carried out when the envelope is complete. If possible, it is wise to test twice - once before the covering-up of the membrane when remedial work can easily be carried out, and again at completion.

Decrement delay
Anyone familiar with spending a hot summer's day in a caravan and then another in a stone house with closed shutters will understand decrement delay. The inside of the caravan closely maps the rise and fall in external temperature to provide the familiar stifling effect on the occupants. In the stone house, the internal air temperature, staying well below the midday heat, barely varies throughout the day and so provides relative comfort to those sheltering from the sun.

Different materials, allow the passage of heat at different rates. The time it takes the peak temperature on the outside of a material, such as a wall or a roof, to make its way to a peak temperature on the inside face, is called 'time lag' or, more commonly, 'decrement delay'.

By controlling decrement delay it is often possible to control and prevent the overheating of a building. Denser Insulations have greater ‘thermal mass’ and heat takes longer to travel through such insulation. Therefore a building wrapped in a relatively dense insulation will have a longer delay in the transfer of the heat through the wall. In the summer this keeps the inside of the house cooler for longer & in the winter keeps the heat in the house for longer!

By using Wrightwall Natural with Weatherboarding the system has a Decrement Delay of 6 hours, this is in comparison to a SIP’s panel of 5 hours and a non-insulated wall of 1 hour!

encapsulation systems

wrightwall light infill panels

3i infill panels

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