Are the plans posted previously the ones presented to Lothar?
Yes, the plans posted previously are the ones I was assuming Tristan presented to Lothar. I was looking at them and the notes around them for the discussion.
It's just that I notice a few things that are missing from those plans. So I'm giving you all a chance to correct them before construction starts.
As I mentioned before, there is the matter of the hearths. With 4 hearths left to assign to those two houses, it won't be enough to have an hearth in each lab, unless there isn't any in the other rooms (like the kitchen). So I think it's Worth deciding how the magi want that handled. Of course, if the magi aren't too involved in the construction, the end result might be that there is no hearth in the labs... :mrgreen:
There's at least one other feature of the houses that have been left out from those plans, but I will leave it up to you (for a little while at least) to find out what it is before giving you a hint. 
I had explicitly included a question for Lothar as to how to handle the heating. We do not have the vis to create magical solutions for this, and possibly not even the skills. I don't know how larger houses were kept warm in this ear unless they had hearths, but I bet there was a partial solution somewhere.
the only answer on that I had come up with so far was to figure that for now, the magi use their labs as their living space, and we build three labs with hearths and one kitchen. That does seem to mean that the meeting spaces will get COLD in the winter.
I presume Lothar will eventually ask for confirmation that we plan to use outhouses for "waste" disposal.
Lothar might have a few ideas indeed. I'll list a few that he might suggest.
Shared hearth is one possibility. Have adjoining rooms with a single hearth between the them. Basically the hearth has no back wall, so that when there's no fire you can look into the other room. This reduces privacy, but there's nothing preventing you from closing off the hearth when there's no fire burning in it. Or installing a privacy screen in front of it.
Using an hypocaust for heating would make for a more comfortable building. But that is a much larger job, particularly for a single stonemason and his apprentice. Would make building each of the large house much more expensive and long, more than doubling both time and cost. Lothar's never done a job like that. He'd be eager to undertake it, but isn't sure how much time and efforts it would take, nor how well the system would work.
Use braziers in rooms that ddon't have a hearth. Ventilation might be a problem however. The cost of heating the houses would be a bit higher, but it has little in the way of initial costs or delays. It is also a bit of a safety hazard.
Arrange for the right to additional hearths. This may mean an additional bribe and contact with the officials handling that.
It gets quite cold in the winter indeed. But the villagers don't have houses that big, and they're mostly single-room houses in any case, with a central hearth. It's drafty and not very private, but such is the life of peasants.
They also keep some of their animals inside their house. That adds to the heat of the fire.
The main problem I see is the library. If it were not for that, I would say put Hearths in three labs, put the chimney through next to the fourth lab, but don't put in the hearth there yet. Then use a brazier for our meeting room and when needed for the guest room.
But that leaves the library unheated, which seems a problem.
So what if, for now, we use Sanctum 4 as the library, since we won't be using lab 4. We put a double-hearth in there, with a metal safety screen to keep the embers out of the library?
When I drew them they were just intended for ooc use to help give us some mutual understanding of the distribution of rooms. I didn't include hearths and privys intentionally just because I didn't want to go into that detail.
So I think the magi may have done a little more detailed version to present to Lothar before he arrived. Japik is not the most responsible person so he may have left it for the other magi to decide after the general plans and ideas were discussed. If these plans are the actual plans Lothar gets then he will freebase a lot. 
He would probably see them as rough drafts of what his customers want. So he'd probably draw new ones, more complete with annotations about supports, arches, hearths, cellars, etc. These would be some of the details he'd ask questions about.
Privys we can handwave. At the time there was seldom anything like a special room for that. Most would simply use a covered bucket, which the servants would take out, empty and wash every day. On a place like the plateau, the buckets would be dumped down the cliff (probably over the sea).
Another thing he'd have questions about is roofing and flooring. He's no carptenter, so he'd expect there would be one to take care of that. It's doubtful that the simple roofes that the villagers use would suit the magi. That's what the small houses have, and it's drafty and doesn't retain heat very well in the winter. It also needs to be replaced every year or two, exposing the interior to the elements during that time (a few days). For the large houses, that would be the labs, so you can imagine how that might disturb any activity going on during that season.
(Answering here because this is a bit long and I don't want to clutter the in-character story too much.)
Low end wouldn't add anything to the costs already estimated for the large house. This is much like the small houses are built. It is drafty in the winter, with some leaks when it rains in the spring and until the roof can be retatched during the summer. There is some maintenance cost, in the order of half a pound of silver every year.
High end would be something like a slate tile roof, backed with planks (instead of just interwoven branches). That can almost double the cost of the house (adding at least 10 pounds of silver) but is much more wind- and water-proof. Maintenance is less frequent, as most years there is not much to be done. But occasionally some of the tiles may crack or fall off, which requires more costly maintenance (1-5 pounds of silver).
In the same way, one can invest more into the carpentry for the inside of the house for floors and stairs, over what the basic cost requires. This creates a more comfortable living space, with floor that don't creak as much, walls where one cannot peak through cracks, and other small things like that.
Depending on how much silver the covenant adds to the cost of construction, I will assess that the characteristics of the house will be (structural flaws and/or virtues). There is some chance involved there, with the additional cost acting as a modifier to the die rolls.
Clearly, we need something better than basic. Having it leak on our labs just won't work. And such things are usually worth the investment. But I don't know that we have the money.
The covenant had 53 pounds at the end of 1210. In the initial planning, each large house was supposed to cost 20 pounds, but that was revised up to about 25 pounds when Yulia hired Lothar in the fall.
But that could rise again, depending on the decisions taken in regards to the roof, flooring, etc.
One of the main theme in this saga is that of making hard choices and compromises. Long term vs short term. Spend money on what the magi want and are used to, or on what their mundanes need to be comfortable. Each choice will produce different results and consequences.
Japik leaves the house building mostly to the other magi but he will agree that they should build something that means less maintenance. So try to get the best carpenter there is on the island is my vote.
Since we are a bit informal, and small, what if we just go with finishing one of the houses. Specifically, the one with the kitchen and the guest facility.
It means that the three of us will have to share the two labs, but we could do a much better job on the building.
That is actually a very good idea. We don't really need three labs at the moment, four is even more overkill, for now at least.
We better stop Lothar before he starts digging the ground for both houses then. By the way, no one has told him that we would like cellars and there was nothing about that on the drawings... 
Do we have the right to build cellars? I thought there was some restriction about digging into the cliff?
We are not allowed to dig very deep but some shallow cellars I think we can do. Originally we had big plans to excavate the entire rock but it might be dangerous. Japik just saw some of the rock had detached from the cliff during winter.
Would L6 be enough to move the Stone to create the excavation? ReTe base 1, +1 Touch, +2 Stone, +1 Larger amount, +1 Part? I would have to take a stress roll, but could do that as long as I don't botch (Re 5, Te 5, Sta 2). Tristan could reasonably suggest this to Lothar and Herman if it is workable.
That would be level 10
l agree on building one house well at first.
There is the usual matter of how blatant you want your use of magic to be. Lothar is there to direct them and is the main craftsman, but the heavy lifting and carrying is done by villagers from Ober.
Also, level 10 is a bit too hard. How much can I move out of the way if I don't add "Larger"? I could cast at night after the villagers have left, and tell Tristan to claim that the island must like us if the villagers inquire.
Could I use the spell in a fashion that broke up the rock a bit, before the villagers start working, so as to make it easier to remove without it being obvious? (I am having trouble seeing this as plausible myself, but I thought I would ask.)