Brewing a big Holiday Ale - Questions

I'm brewing this recipe tomorrow for Christmas gifts this year (Jamil's Holiday Ale from Brewing Classic Styles)

19.5 lbs britsh pale ale malt
.75 lbs Crystal 80
.25 lbs Black patent

1 oz Horizon (60 min)

last minute
1/2 tsp cinnamin
1/4 tsp ginger
1/8 tsp nut meg
1/8 tsp all spice


I have never brewed a beer this big (1.090). It calls for a 90 minute boil, so I'm trying to figure out how to adjust my mash/sparge volumes accordingly. In other words, how do I know how much volume I need to add to compensate for 90 minutes of evaporation? I have only done 60 minutes boils before. do I even need a 90 minute boil?

Also, does 1 oz of hops seem a little low for a beer this big?

That does seem a little light on the hops, but I like hoppy beer. A 90 minute boil is not hard to adjust for. If you know how much you lose in an hour, do the math and plan to collect that much more wort. Beersmith, or any one of the online software can help if you don't want to do the math manually (although there is generally a learning curve to those softwares).

A beer that big, and by all appearances it's a type of barleywine, is normally pretty sweet and malty, relatively speaking. I'd let some others chime in before committing to a recipe. Just to get a consensus.