Which is why i was suggesting base CrTe spells.
Even at Touch range it is possible to create very large volumes at relatively low magnitudes.
Simply place hand on window ledge or under a door ,
provided that it is inside the room.
Down a chimney works also , but perhaps not so much for the blind.
(without assistance anyway)
...And the definition of target room is a room no larger than 100 individuals, so unless you're targeting very small rooms...
Yes, but this was an attempt at explaining why you don't really need the target room in any event...
You can simply start the effect at your fingertips and extend it towards the room... Guess the question here becomes where you feel the room starts... If you mean to say that you are touching the room when you're touching the door to the room, then you're probably right... Personally, I kinda feel you need to touch the inside room itself...
RAW p. 111: "Thus, if the caster is touching the external wall of a room, he can cast a Target: Room Corpus spell on the people within at Touch Range, even though he is not touching any of those people, and indeed cannot see them."
Not much to argue about. But just to add that this has tremendous importance to a blind magus who might otherwise have trouble sensing his targets and thus use his magic on them.
Guess it's been a while since I dived in the great book now...
But, for the blind magus - he can allways target whatever is in front of him (starting at some point he is touching - like the air at his fingertips, and extending forward)... Shouldn't be too hard hitting unseen targets that way...
He sure could, but it would require an area of effect spell and AoE is such a crude tool. First of all the are a magnitude sink, secondly they will hit the caster and his allies aswell, or might destroy other things in the vicinity of value to them.
Target: Room is AoE, and would actually be harder to control for a blind caster - after all, he has no idea what the room actually looks like... And if said caster hits himself with a Target: ind spell, then he aimed for himself... And if you're afraid of harming whatever else is in there - use something other than fire?
Room is not AoE - it discriminates between forms, whereas AoE using Creo and boosting the size will hit anything in the vicinity, no matter whether it burns, buries, crush or crash it.
I was making a general comment on AoE spells - and not one in favour of Target Room spells. But if comparing these two, the Room would still have it perks to the blind caster as he could cast all sorts of spell without him or his allies being affected because they could simply stay out of the room - a luxury they will not have if the magus makes himself the center of an AoE Creo spell. With Target Room he could also choose to use any other from combo (except Creo) and thus pin point his opponents bodies or minds and leave all else safe.
A Blind Caster could learn a CrTe (Stone) spell for creating rooms outdoors.
(Flexible Formulaic Magic might be very useful to a Blind Magus)
The room you create is effectively a stone box.
Even 01 inch thick walls would be enough.
The best shape to use is a d04 pyramid (04 equilateral triangles).
You maximize the area covered.
Why should the caster be the CENTER of the spell? Why not the edge?
Besides, you could probably use such a form blend in any case - using a Re/In/Co* combo to ensure that the flames (or whatever) only causes damage when they encounter a human(oid) body.
*not certain all those would be required...
Especially since the rules support that very interpretation:
"RANGES
The range of a spell is the distance to the nearest part of the target of the spell..." (p 111)
So, if your mage can affect a castle, they don't have to be standing at the center of it, and so on.
(See Abe? You're not the only one confused.) 
It's a shame that the original authors chose the word "Target" for this spell parameter, and that no subsequent re-writes have had the nads to change it, since "target" is, clearly, an ambiguous choice at best, and badly confusing at worst. What's the target of a fireball? That ogre? That dry wood? Nope!... it's the fireball itself. Right...
Excellent! (Phew!) Yes, that is the proper interpretation - but hardly a "work around"- it's the RAW! Thanks, A.