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29th January 2015 / posted by BillKeir

The Proof is in the Panel

More and more we are finding that our encapsulation systems are being taken up as part of the overall products and services we have to offer Self Builders. When it comes to traditional oak frame homes - Village Homes to Country Homes – we are still the company way ahead of the field for the infill panel system. Our Award winning 3i Infill Panel System is innovatively designed to fit within and allow for movement of your traditional oak frame. Below, Oakwrights General Manager, Bill Keir explains just why 3i outperforms all similar solutions offered by our competitors and explains how we offer the best of modern solutions to an age old problem.

Oakwrights 3i Infill Panel System

Oakwrights 3i Infill Panel System

Panels in the Past

A little about wattle and daub - this is where the panels, those gaps between the Oak, or in other words, the white bits of a traditional black and white house, were filled in by a mixture of clay, cattle dung, sand, hair, lime or whatever else came to hand.  This is the daub, and was daubed onto (and into) wattles (sticks or split laths) woven between vertical staves (bigger bits of wood) set into the oak frame. 

Traditional Wattle and Daub

Traditional Wattle and Daub

Cheap and effective in its day, the daub would probably get a thin layer of lime-based render or plaster, and then be refinished annually with multiple layers of limewash, sometimes white, but often coloured in attractive yellows or reds using earth pigments.  (Multiple layers of lime wash are surprisingly effective at filling small gaps and cracks in the frame and panels).

Back then (before the days of glass fit for glazing windows) the windows (or more accurately ‘wind holes’) were covered over by simple wooden shutters, sometimes sliding in grooves formed into the frame timbers.  Given the quantity of water that could be blown in through these apertures, people were not remotely bothered by the smaller amounts of water leaking in through the panels, or even water driving through the joints or the gaps in the frame.

These days we are used to a more 21st Century level of comfort. This coupled with the ever more stringent requirements of building regulations, demands a similarly 21st Century approach to infilling panels between oak frames.

21st Century Panels

Our 3i Infill Panel system beat off stiff competition from multinational companies to win top place in the prestigious Home Building and Renovating magazine’s Self Build Product Innovation Award in 2010. We have been trumpeting the properties of this particular system for almost half a decade now. We have been further gratified to see our huge investment of faith, time and effort in this patented system not only recognised by an independent panel of industry experts, but still outperforming all similar solutions in the market some five years later.

Wealden Style Farmhouse

Oakwrights Wealden Style Farmhouse with 3i Infill Panel System

Building regulations-compliant panels

The Oakwrights Show Home easily meets code level 3, and would have met code level 4 if we had known about it 8 years ago when we started construction. Such things as the ecological survey simply did not exist back then.

What do exist now are Government targets for building houses that use less carbon, and the key to this is the SAP Calculation. SAP is the Government’s 'Standard Assessment Procedure' for energy rating of dwellings. Every new house has to have a SAP rating (similar to mpg tests for cars). It is a simple means of estimating the energy efficiency performance of buildings, and must be submitted for Building Regulations approval by the local Building Control department. 

Oakwrights 3i Panel On-Site

Oakwrights 3i Infill Panel System - External

Key to SAP calculations is estimating the heat loss through the fabric of the building. Individual building materials and composites of building materials like walls and roofs have a U-Value.

The U-value is a measure of the heat flow through a building. Generally in the UK this means heat transmitted through the walls, floors and roof from the inside to the outside. The higher the U-value the more heat is transmitted. The unit for U-values is W/ (m²K). The amount of heat (in Watts) that passes through a square metre of building (or building component) for a difference in temperature of one degree (one degree variance from one side to the other) the smaller the figure the better. A window should achieve less than 1.0 W/ (m²K), roofs - 0.15 W/ (m²K) or less and walls 0.25 W/ (m²K) or less.

Oakwrights 3i Panel On-Site

Oakwrights 3i Infill Panel System - Internal

The big disadvantage of a traditional oak frame, half-timbered with infill panels is that you can see the timbers from both the inside and the outside. This is both the charm and the Achilles’ heel of a traditional exposed oak frame. Those exposed oak timbers whose interior and exterior surfaces can both be seen, do actually conduct heat, and act as ‘cold bridges’.  In order to counteract these cold bridges we use high performance insulation integrated in a panel system that remains weather tight and allows for the inevitable movement of the frame both as it ‘matures’ and as it adjusts to the seasons.

Oakwrights 3i Infill Panel with Brick Slip

Oakwrights 3i Infill Panel System - Brick Slip Infill

The Oakwrights Type 3i Infill Panel successfully addresses air tightness and fire performance to meet the requirements of building regulations. Type 3i regularly achieves a U-value of 0.235 W/ (m²K) when accounting for and including for all the cold bridging, although it does vary wall to wall depending on the actual design of the house. This meets the building regulations and has been independently assessed and confirmed by various 3rd party consultants, including TRADA Technology.

Oakwrights 3i Infill Panel - The Lavington

Oakwrights 3i Infill Panel System - The Lavington

Non Functioning Panels

I was approached a couple of years ago (in my capacity as Chairman of the Carpenters Fellowship) to assist a couple who had a timber frame house built by somebody who had never done an infill panel house before. Sadly and rather predictably it leaked like the proverbial sieve and this before they had even started on interior work.  The builder washed his hands of the whole affair, and walked away. Eventually it was sorted out in the courts, which isn’t good for anybody as of course it costs a lot of money (even if you win) and distracts everyone from the task in hand – building the house.

How could this have been avoided? Well basically, by the clients doing their research beforehand.  ‘Caveat emptor’ – buyer beware is an important principle in this field.  Building a house is an expensive business, and people are naturally tempted to take what appears to be a saving. But before you sign on the dotted line, make sure that you do some research into your builder.  Have they done this before?  Do they have examples of previous houses you can visit? Past clients to whom you can talk?  Do they have a track record?  If the answer to any of these questions is no – then you are taking a major risk. Nobody ever wins in the courts. Caveat emptor as they say. Remember it all started with panels made of cattle dung, don't let it end up with your panels made from cattle dung.

Oakwrights 3i Infill Panel - A Modern Manor Approach

Oakwrights 3i Infill Panel System - A Modern Manor Approach




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