Why is my Mash and Sparge volume larger than my boil volume in BeerSmith?

[lmorse]

I am just about to brew my first all-grain (was hoping to do it today, but unless I find an answer to this question I may have to postpone).

My brew sheet tells me...
* Mash in: Add 12.75L of water at 74.4c
* Hold mash at 67.8 C for 60 Min
* Sparge with 18.47 of 75.6 C water
* Add water to acheive boil volume of 26.33 L

My equipment profile is:
25L mash tun
0.25L Lauter Tun deadspace
0 L Top Up water for kettle
Material Plastic (0.300)

Looking at this, I would assume that my wort volume (out) would be somewhere in the region of 31 L (12.75l + 18.47 L), and NOT 26.33 as calculated by BeerSmith.

What am I missing here? Does the grain soak up 4.67 L worth of water? Is something else going on that I am missing? Have I set up Beersmith incorrectly?

Any help would be greatly appreciated.

Lee

 

[MaltLicker]

Post the recipe so people can see the equipment profile; that is usually the source for any issue. 

The numbers don't look too off, though.  Grains can hold up to 10% of the water fairly easily.