Glazing

Glazing Green Oak frames.

There are three methods of glazing green oak frames :-

Directly - this involves seating the units either within the envelope of the frame, or on the external face of the frame.
Secondary - which involves securing the units in a separate frame on the external face of the frame.
Casement - where units are within a separate window frame, like normal windows.

Direct Glazing
Glazing can be either directly onto the external face, or within the oak frame. These methods often work out to be the cheaper options, but some methods can be more effective than others, especially on a 'green' oak frame. The main consideration with all these methods needs to be requirements for opening windows. There are four methods for direct glazing:

Quadrant

Glazing (see Fig. 1)

Glass units are seated with the posts of each section of the frame (fig 1), held in place with quadrant beading, made from air dried oak. EPDM tape creates the weather seal. This method requires special consideration given to the movement and shrinkage of the oak frame. If this is not duly considered, then failure of the glazing with occur, resulting in rain ingress, and remedial work to correct.

If this is not duly considered, then failure of the glazing with occur, resulting in rain ingress, and remedial work to correct. Elevations prone to weather extremes can benefit from improved sealing, by using a 'wrap around' quadrant.

This method generally proves to be the quickest, and least expensive, but runs the highest risk of failure.

Rebate

Glazing (See Fig. 2)

The glass is seated in a rebate, which is cut into the arris on the exterior face of the frame, in each frame section. The units are then held in situ with quadrant beading, and sealed with EPDM tape, as in fig 1.

Inside, the visual effect is less imposing, as the glass blends into the frame. This method requires a greater detail of planning during the frame machining process, to allow for the rebating. Hence this will be more costly.

Rebate Fascia

Glazing (See Fig. 3)

Here, the rebate cut into the exterior frame arris is shallower, allowing a fuller post depth view internally. The unit is held in position with an exterior elevation air dried fascia board, and is sealed as previous, with EPDM tape.

A greater seal against the elements, and allowance for shrinkage in the frame, is achieved by this method. From the outside, the appearance is off a full oak frame, as the fascia's are the width of each post.

Direct Fascia Glazing

This method is our preferred way of glazing our frames and sees the glazing units seated on the exterior elevation of the frame, and as with rebate fascia glazing, secured in place with an air dried fascia. This method requires softwood spacer (we like to use 25mm Ply) to be fixed to the exterior face of the frame, the same depth as the glazing unit and EPDM tape combined. The glazing unit is seated on a similar depth piece of wood, which is either softwood, or air dried oak, dependant on the method used on the bottom edge of the glass. (See Fig. 4)

Advantages:

This method allows for a greater seal against the weather and a greater tolerance for movement and shrinkage in the green oak frame, which in the previous methods, could mean damage to the glass units. This is because the glass unit is in effect 'floating' on the exterior face. It gives a 'full' oak frame perception from inside and out.

With the use of Compriband, the glazing boards and glass provide a full seal around the building. Compriband is an expanding, polyurethane foam which comes in tape form. Placed between the glass and the oak frame and then the glass and the glazing boards, it expands to fill and seal the gap, providing a fully weather proof, water tight barrier.

In terms of difficulty and labour time, this method is the most straight-forward and efficient. The Glazing boards are ordered to the required width and thickness and only need cutting on the length. The softwood spacers/ border can be cut to size in our workshop and then screwed onto the exterior of the frame. Each glass unit can be fitted within a matter of minutes and then all that's left to do is screw the glazing boards to the softwood, making sure that where each board meets another, the join is nice and neat. We then plug the screw holes to provide a seamless oak finish.

Secondary Glazing

Casement Windows & Doors.

This final method is as simple as it sounds. Separate 'casement' windows and doors, as you would find in any home, can be manufactured, and installed within the frame. There is no rebating or fascia boards, but a larger section quadrant beading is used, and pinned to ONE face only (usually the oak frame). This allows for the shrinkage in the frame, as the quadrant moves with the frame. Compriband foam tape is used around the edges of the casement frames, which continues to expand as the frame shrinks, giving a full weather tight seal.

This method is expensive, especially if the doors and windows are manufactured from kiln dried oak, and can be the most ineffective method (if done wrong), to combat the frame shrinkage and warping.

Extreme pressures from the frame movement can be exerted on the windows and doors, and in turn damage the actual casement frames. The process of installation requires the casements to be 'floating' inside the oak frame, and all gaps are sealed with compriband expanding foam tape. These gaps are then covered with quadrant beading, both internally, and externally.

This method also allows for windows and doors to be a material other than wood, such as:

pvcU
Aluminium
Alu-timber (ppc)

It is worth noting, that any doors or windows manufactured out of a kiln dried 'joinery grade' timber, will need treating, and this needs doing annually. The failure to do this, will lead to the wood absorbing moisture from the air, and starting to swell. This action will result in the casement frames twisting, as the pressure from the swelling has to be diverted somewhere, and then glazing units will 'pop'. Once this process starts, it is very difficult to stop, without removing the casement frames, allowing them to dry out, tending to any remedial work, resealing and refitting.

One final point to note is, with ALL these methods described, if undertaken by a competent person, with knowledge of the required processes, you can achieve a weather tight seal, and there should NEVER be the need to use silicone sealants. No matter if it is low modulus, or hard setting, IT IS NOT NEEDED!