Repacing beading on wooden Double Glazed windows

Hi Guys

I have some wooden framed double glazed windows (about 9 years old in a build of the same age).

The sealed units are held in place with the sticky foam backed tape both sides and then held in place with wooden beading.

Despite being regularly painted, there is some water ingress - I think from between the beading and the wooden window iteslf, rather than from between the beading and the glass unit.

Anyway, the beading is rotten in a couple of the windows at the bottom corners and I will have to replace rather than trying to persevere with stripping, sanding and trying to reseal them.

If I am making new strips of beading, what type of wood should I use? I have access to some Jelutong or Pine, but don't know if either is suitable. Maybe buying some treated wood from B&Q and then forming into the correct profile in lengths to be cut as required?

Any thoughts?

Also, in order to prevent future problems with both the new beading and the existing beading that is sound and not in need of repair, I was thinking of sealing between the glass and the beading with silicon - is this a good or bad idea?

Hi, no point in buying treated timber and then shaping as the treatment only goes a few mm into the timber.
If you can get hardwood in the correct profile that would be best.
If you use silicon make sure it is suitable for D/G as normal silicon can attack the seal.
Be aware that you can't paint over silicon

I think I'll have to buy square section timber, or use what I have in terms of the Jelutong and shape it to the correct profile. I have access to all the tooling/machinery required to profile whatever I wood I use.

Jelutong is a hardwood but I don't know much about it's durability as an external wood, even if coated with Ronseal or whatever.

I'm intending to make quite a few metres of the beading so that I can cut it to length as required both now and possibly in the future.