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From frame to facade, WrightWall Light provides a slim and efficient wall build up, designed to accommodate multiple external finishes. WrightWall Light is designed to ensure a fully integrated process between frame and shell, using the same innovative software employed to design your oak frame. WrightWall Light is manufactured off site, reducing onsite time for you and our dedicated site team who will assemble the system; ensuring the highest level of quality control throughout the process.

WrightWall Light infill explained


0.16 W/m2K



0.14 W/m2K




Building on an island can sometimes be a challenge and it is for this exact reason that Mike and Ros chose to enhance the Oakwrights experience beyond the oak frame and utilise the advantages of enclosing their oak frame with WrightWall Light encapsulation system.

The advantages of using Wrightwall were two fold for Mike and Ros.
The oak frame designer works in the same office as the encapsulation designer and they are able to make sure that the encapsulation system will fit correctly around the bespoke oak frame. This integrated solution leads to a reduction of design time, simply achieved by a team who work closely together in the same office on a day to day basis. This co-ordinated design system leads to a seamless and more detailed production process.

From design through to encapsulation, Oakwrights provide the intelligent solution to your self-build project, using one team to provide the whole package. Designed using the same innovative software employed to design your oak frame, WrightWall Natural & WrightRoof Light provides a slim and efficient bespoke encapsulation system for your home. Prefabricating the Light System Panels in our Herefordshire workshops reduces on-site time and ensures precision, speed and quality control. Designed and detailed specifically to achieve high levels of insulation and airtightness, the Light System will reduce the energy consumption of your home and lower heating costs.

Not only do Oakwrights supply wall panels but also roof panels, pre manufactured in sizes up to 8m x 2.4m. The size of Oakwrights large format panels not only assists with speed on site but also helps with the air tightness of the shell due to reduced panel connections.

Onsite installation is carried out by our carpentry teams, who follow through from the erection of the oak frame to the installation of the wall and roof panel system. A lead carpenter will control the site process from erection of oak frame through to a dry shell and the on-site team will often be joined by the oak frame or panel designer.

Mike and Ros found that the WrightWall Light system allowed them to complete the complicated dry shell process around their oak frame in good time, allowing the general contractor to follow swiftly on to the standard build work – meaning that the house was built in just five months.

Mike and Ros chose to enhance the Oakwrights experience beyond the oak frame and utilise the advantages of enclosing their oak frame with WrightWall Light encapsulation system




Cost effective encapsulation system resulting in further energy efficiency.


Large format panels manufactured off site to maintain high quality.


Additional insulation upgrades available if required;
made possible by bespoke design.


Wall, floor and roof panel is designed to fit smoothly together creating a shell ready to be made air tight.


One build team look after your oak frame and the installation of your panel system generating close attention to detail and a seamless process.

One build team look after your oak frame and the installation of your panel system generating close attention to detail and a seamless process



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 leakage we think you will agree!!
Before the test is carried out, passive ventilation must be temporarily sealed. HVAC plant is switched of 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 relative 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 natural

3i infill panel system

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