How much could 19% wood shrink inside

[ColeyS1]

Is there a way to calculate how much 19% moisture content 240mm wide oak might shrink when used inside? It's some really ropey character oak/firewood that someone wants to use for window cills. Inside content is recommended around 8-12% for furniture so I'm wondering if this will be asking for trouble.
The cills will be plastered in so even kiln dried oak will be exposed to some moisture while the plaster dries. A few coats of finish might stop it sucking up quite as much.

A few planks have got splits like this already. When it dries further I'm concerned it'll just fall to pieces.
Thanks
Coley

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[MusicMan]

Yes there is. The shrinkage is different along radial and tangential sections (usually negligible along the grain, unless it is reaction wood from near the surface of a branch, or tilted trunk). The factors are tabulated for a large number of woods in The Wood Database, http://www.wood-database.com, along with explanation of how to use them.

 

[ColeyS1]

Lesson learnt- assume nothing. "Out of curiosity what finish are you going to put on the cills?" PAINT !!!!! [SMILING FACE WITH OPEN MOUTH AND COLD SWEAT] roll on 5.30pm

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[ColeyS1]

Thanks Musicman. That looks like a very useful website ! I'll have a look later tonight and see if I could calculate the shrinkage.

Needless to say I've advised against using the oak on cills that are circa 500mm deep and painted.
Cheers
Coley

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[thetyreman]

I'd presume it would crack the plaster as it moves??