National Brood Box

Enough is enough! I cannot be trawling the web looking for COMPLETE metric national brood box dimensions ever again.

If you want to build your own National Brood Box and are looking for brood box dimensions then you need to look no further! The metric dimensions are credit Dave Cushman’s website. The design should work with either castellations or rails.

Cutting List

ItemQTYLength (mm)Width (MM)Thickness(MM)
Top Rails24244425
Bottom Rails24244425


  • To cut the angle on the Bottom Rails I set my table saw to 30° and use a measure of 29.5mm (see photo for orientation of timber if you are unsure).
  • If you want to add joints for the rails into the sides increase the length to 460mm.

Build Guide

Get prepped.

Once you have completed the cutting list you should have a pile of wood like on the left. Although I have a access to a brad nailer as there are no joints I prefer to use more substantial nails to hold the sides and ends together.

You will also need smaller tacks for fitting the rails and wood glue.

Build the ends.

Due to the lack of joints you can completely construct the ends with their rails before introducing the sides. This has the added benefit of making it easier to hold the box square when it comes to putting it together.

I did choose to use my brad nailer to pin the rails onto the ends after a healthy application of PVA glue.

If you are fitting portals now is the time to drill the holes. Its easier to prevent tear out at this stage.

Add the Sides

Now you can add the sides and rails of your choosing. I find using two 600mm sash clamps helps to hold everything together. I dry fit the first side before wet fitting the second. I secure this with a nail top and bottom being sure to pilot dry the sides but not the ends. Then I wet fit the other side and repeat the securing. Once this is done and with the sash clamps refitted I square and add the remaining nails.

The image on the left shows the downside of using a brad nailer with long nails. Any change in the wood hardness can curve the nail out the side and they are pretty tough to remove so its often easier to pull them on through.

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