Dry rot - is it bad?

[gruffalololo]

We've just been told that the box around one of our windows (Edwardian original sash) has dry rot. Is this bad? We bought this house last summer, and had a level 3 survey done, and this was not highlighted. Not sure if it would've developed over the course of a year? Do we need to replace or repair the window? The quote we've had for that is eye watering, so I wanted to check if the situation is as bad as feared before I proceed. Hopeful tag @pigletjohn (thank you!)

Bump!

Yes, dry rot can be a nightmare. Your expensive quote is probably accurate - but please get at least 3

But why wasn't it picked up in the level 3 survey? Survey mentioned 'minor rot' which doesn't sound like the same thing.

Minor rot wouldn't be the same thing.
It's certainly possible that over the course of a year it could go from not noticeable to noticeable, especially if the seller painted over it just before, but it wouldn't have gone from fresh dry wood to rotten through in a year.

a long time ago, we knowingly bought a doer upper with dry rot in the upper bay window, caused by leaking gutters. We had to have the sash casement windows removed and new ones made. The surrounding bricks had to be chemically treated to make sure the spores of the fungus were dead.
I can’t remember the cost and it wouldn’t be relevant, but it was a major piece of work.
Dry rot was something that seemed common back then.

@Beebumble2 do you think we need our gutters treated to avoid further issues down the line then? It's a first floor bay.

The company who was supposed to make new windows for us has quoted to repair the frame. But do they need to chemically treat the surrounding walls too to ensure it doesn't return?

I would definitely get the gutters checked, as a matter of course. Do some research on dry rot treatment, as modern methods might be different. Dry rot is a fungus that destroys the wood, it grows on the wet rot that damages the wood first. You will need a rot specialist to treat it.
With ours, it had had many years to develop and the fungus, that looks like spiders webs, was travelling along the picture rail.
We knew the house was a wreck before we bought it, so no real surprise.

Thanks for this. We've had some quotes this evening for cleaning front and back gutters for £150. That seems reasonable (London)? I don't know. Maybe they'll comment on the dry rot situation too.

Make sure you get a wood preservation specialist to do the work - you need to make sure the dry rot is treated properly. Don't just get a new set of windows from a normal company.

It's a sash window specialist. They create double glazed sash windows that look like the originals. Is that professional/specialist enough do you think?

Dry rot can become an ongoing problem, have had it twice over twenty years. Treat to the highest standard remove wood at least a metre beyond what you can see.

No. You need someone who specialises in dry rot removal, treatment and prevention. It's likely the masonry etc around the frames will need to be treated.