You need to have a job nailed down first! The hiring season for international schools (with the start of a new school year being August) is December-February/early March. I'm afraid you've missed the window for next school year. Once you know where your school is, and you've signed a contract, THEN you can start searching online for short-term rentals near your school. Do not commit to anything long-term until you've seen it in person. You also need to consider transportation. Unless you're in Bangkok, public transportation (at least for a non-Thai speaking person) is pretty much nonexistent. Cars are expensive here compared to everything else. Outside of Bangkok, essential businesses are really spread out and walking or riding bicycles is unsafe or impossible due to lack of sidewalks, poor driving, and oppressive heat.
As others have said, there are a lot of variables. Since you're building, you can be strategic about materials used, insulation, and the energy efficiency of the air con units. I live in a modern home in Chiang Mai that seems solidly constructed, but I can see that the windows are NOT energy efficient. No idea about insulation in the roof; I'm guessing there's not much. The air con units are quite new. We run one or two air cons at 26 degrees
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during school breaks. The highest my bill has been was in April of last year (hottest time of year, with 6 air purifiers running, and we were home all day 3 of the 4 weeks, and just evenings the other week). The bill was 7,500 baht. An average month is 3-4k baht, but that's with mostly just evening and weekend usage of the A/C.
Any school worth their salt will have a visa coordinator who will do all the legwork for your husband's visa and yours. Personally, I would turn down an offer from a school that didn't provide this service!
This is direct from the U.S. Consulate and Embassy in Thailand website: "Thai immigration law requires entry/exit stamps and Thai visas be transferred into new passports. After receiving your new passport, please visit any Thai immigration office to have the visa transferred."
His original visa is a stamp, not a sticker. It appears that it was transferred to his new passport along with the date of transfer; that's what I can surmise, since most of it is in Thai. When you go to immigration, the sign over the window says "Visa Transfer," not "Extension of Stay Transfer." I've never heard of needing to keep both your old and new passports with you for travel. What would be the sense in having two half-working passports?
I'm not sure what you mean. Of course the visa must be transferred to your new passport, if you want to continue using it as intended. Extensions of stay are also transferred. I just did this process with my son this week. His actual visa is in his old passport and his new passport.
As others have said, you have to renew U.S. passports through the mail now. One thing to keep in mind, when your passport arrives, you will need to take it (with your old passport) to immigration to have your visa transferred to your new passport. It's free to do that, but it may take several hours of your day.
Yes, you can be hired as a teacher in an international school; most of them have early childhood centers for children as young as two years old. The hiring period for next school year (August start) is quickly closing, though.