Insulation

I have dismantled an old house and plan to use some of that wood in a new one.
In the old house, the siding was nailed directly to the wall studs and the inside was bare. I intend to put insulation between the studs and cover it with sheetrock (gypsam boards) on the inside.
Where do I look for fibre glass and foam board insulation?
Also, considering to add plywood between the studs and the siding as is normal in the States. Besides adding structural strength, that would also contain the leak through the nail-holes in the old siding. Could I get by using 1/4" ply instead of using 3/4' exterior type as per code in the U.S.?

RC,

The best source of insulation is HomePro. Global and HomeMart carry it as well, but I found that HomeMart is slightly more expensive for the same brand and Global is not well stocked.

The fibreglass insulation here is wrapped or covered in alum foil and easy to worked with (unlike the stuff I typically saw in the US). I'm not familiar with foam board insulation, but I've seen thin sheets of a type of insulation covered with alum foil. Actually it comes in sheets and rolls and is commonly fitted on the underside of the roof tiles.

If you're not in too big a hurry HomePro periodically has some really good promotions on their house brand insulation. Their prices are frequently a bit higher than Global but with the promotions they're substantially lower. And they have it in stock or can get it quickly.

I've looked for foam board in Udon and never found it.

I bought 10 bags this month I paid 119 baht at global per bag I will need 50 more bags so I will check out H/M