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2018-Apr-7 - Wooroloo - Windows #12
It seems that every aspect of house design has its own built in rules. You discover these rules as you work closely with a particular piece of construction.

For bay windows, I have found that most web sites talk about how to install a bay window purchased from a manufacturer but details on how you should construct a bay window are very thin on the ground.

If you are building a 45 degree bay then the external angle is 135 degrees.

You would expect the corners to be made up of a single 45 degree wedge.

However, when you look at the design closely you discover, that if working from 45 x 90 mm timber, you are best producing two pieces at 22.5 degrees and joining them face to face.

All the pine I am using is CCA treated.

First thing Saturday morning, I realised that I would have to do a lot of cutting to produce the 22.5 degree angle, and this would produce a lot of fine sawdust carrying a number of nasties.

I did not want to spread this all around the veranda area where I have the table saw so I decided to hang some plastic tarpaulins around the area to create a "cutting booth".

Up to this point I have been putting any jarrah sawdust in to the garden, but because this new waste has to be contained, this meant that I had empty out the dust extractor and shop vacuum cleaner before starting.

It took me a while to set up the cut correctly but once done I found the joined pieces formed a perfect corner and sat over the template base exactly as I wanted.

I am screwing most of the pieces together with galvanised wood screws so I had to make a few visits to the local hardware as I realised that I needed some 8 g x 35, 65 and 75 mm screws.

During the day I cut all the pieces to form the bottom central panel but could not join them as I had left my air compressor out on site (it is much easier to maintain the correct alignment of timbers by using a framing gun as opposed to hammering in nails).


I spent the early hours preparing our house for an AGM of our computer museum but before the meeting I managed to nip out to site and grab the compressor.


During breaks I screwed and nailed the components prepared so far.

I intend to support the bay windows on the veranda at two points - if they just sit on the veranda joists there is a risk that they will bounce as anyone walks over the veranda decking and cause cracking against the internal wall.

I realised that bottom frames will effectively need some form of lintel inside them to span the 1.8 metres between point bearings without sagging.

I was given some 6.6 m e-joists a couple of years ago and these are good candidates to use inside the bay window frames.

I pulled one out of storage and had a look at it but I cannot determine if they are CCA treated or not.

I will contact Midland Timber this morning and see if they can tell me - if they are not treated I will see if Midland Timber can sell me something similar that is CCA treated.

I would like to avoid using any tall LVL pieces as these would be quite heavy.The e-joists use a lighter construction that is just as strong.

Test pieces

Assembled front corners (lower panel)

With lintel installed