Possible cause of degraded Western Red Cedar

**Russhort** · 2nd July 2013, 12:15 PM

Hi All, new to this forum, so sorry if I have posted in the wrong place.

I built my home about 25 years ago and used western red cedar for the windows and doors, and ended up painting it. I am now having an issue with some of the sills developing a fluffy type of degradation. It is obviously (I assume) where water has got into the timber, but it swells and rots, goes black and fluffy is the best way to describe it. You can rub it away with your fingers and just keeps rubbing away. Sanding just cloggs the paper.

There are other parts of the wrc cladding where the paint has given away, but it doesn't degrade like the inner parts of the sills.

Any ideas?

I am cutting the pieces out, but don't know what has caused it really, so I can avoid it in the future.

Thanks

Russell

**timboz** · 3rd July 2013, 06:34 PM

G'day Russhort,

Unfortunately WRC has good durability as heartwood but not as sapwood. This may be your problem. Do some research on the net and see if what you find matches your observations.

Best of luck, Timboz

**John.G** · 3rd July 2013, 08:13 PM

Sounds like dry rot.
Soooooo... you can't fix timber damaged by dry rot, or any other rot. The only thing to do is remove it and replace.
However if it's not gone that far to warrant removal here's what you do to stop the damage getting worse.

Remove paint/ varnish/ whatever protective system you have in place.
Then make a mix of 25% sodium borate (available from most hardware stores) and 75% propylene glycol (antifreeze concentrate) and paint it on. You may need to heat it to get the borax to dissolve fully. Give it a couple good coats. The glycol will penetrate the timber and carry the borax in with it. Glycol by itself is a timber preservative... glycol and borax is more of a good thing.
Repaint.

This is the same as one of the commercial treatments at about 10% of the price. You can use ethylene glycol antifreeze rather then propylene glycol however be aware that you will then need to wear gloves etc. Propylene glycol is generally sold as the environmently friendly antifreeze... ethylene glycol does a better job of penetrating timber however repeated exposure can damage heart, kidneys etc.

**nifty** · 8th July 2013, 02:41 PM

Dry rot for sure! If its not too bad you can treat it with a sikkens product. I think from memory it's call Cetol HLS, it has an anti fungicide in it. The black you mention will be a fungal attack. We used to coat all of our weather boards with it when I was a chippy.

**cadas** · 8th July 2013, 08:21 PM

Dry rot is identifiable by the spores, do you have a white spiderweb type mold anywhere (usually in cavities).

If you've got timber cladding and framing you need to check inside as dry rot has a 1-2m spread from anything visible. So even if you fix the window, it will still be there and it can live in concrete.

If its surface degradation only may not be dry rot, but poor timber. If you can't sand back to a sound surface then it's going to get fairly drastic.

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