Starting with this
I have an existing railing but it looks like it is installed wrongly. The bottom rail is clearly a sill to allow water to drain outwards. But how are you supposed to attach the vertical strips of wood. It must be obvious or there’d be instructions somewhere but it’s not obvious to me. My installation has a horizontal bit of wood on the outside effectively blocking the water escaping. That has to be wrong. It’s also falling to bits.
Welcome to the Bunnings Workshop community @Rods. It's great to have you join us, and many thanks for your question about constructing balustrading.
It sounds like the bottom rail has had the additional strip of timber added to neaten the appearance. Unfortunately, that has retained water in the cavity it created and accelerated decay. You could re-install a strip of timber like this, but you should elevate it slightly off the bottom rail so water can escape underneath.
The balusters are screwed or nailed into the bottom rail. The best approach is to construct the balustrading panel entirely before installing it between your posts. That way, you can screw through the bottom rail's underside and into the balusters' ends. You might be interested in reading through this datasheet for handrail construction.
Also, remember your PPE when working with timber and power tools, including safety glasses, gloves, a dust mask and enclosed footwear. If you are working at heights, please have a read through this helpful article: How to use ladders safely.
Please let me know if you have further questions.
Thanks Mitchell. The data sheet was very helpful. On further inspection I noticed that there have been multiple repairs already. Makes another repair more difficult. It’s good to know the cover strip was cosmetic and optional. It should not be necessary if the installation was done better in the first place. After a lot of bog filler and painting I’ll use one big screw as shown in the data sheet.
Keep us updated on your project @Rods, and please reach out if you need further assistance.