The ‘Direct Glazing’ technique.
This article is hopefully a brief and simple explanation of the direct glazing system used on green oak frame buildings. Typically ‘green’ (fresh) timber will shrink, twist and move over a period of time, and hence it is unsuitable to use as a flat and consistent surface for fixing a vulnerable material such as glass.
The glazing system described here allows the glass to ‘float’ away from the slowly moving timber. Once the timber has dried it will become stable, but this process typically takes up to 5-8 years with green oak (or 1 year per inch of timber thickness). This is a very simple technique, not a dark art which I feel anybody should be able to do with the right tools and simple knowledge.
These illustrations shows a typical post and stud type construction, with glass applied to the outside.
In plan, the following drawing illustrates the cross section detail. We use EPX6 tape (not EPDM) compressed to its minimum thickness when installed. This will expand to take up any movement as the green oak shrinks and twists.
It is important that a stabilised cladding is used for the cover boards. These are typically a durable air-dried hardwood (correctly orientated to avoid outward cupping), such as oak. But it is possible to use other materials that will offer a better level of protection. Finally an exploded isometric view:
Please note that we no longer take on the glazing of green oak frames.
Update – October 2019. I thought it might be of use to share these section drawings, showing various combinations of opening window inserts: