As far as I know, credit for housing is something that works quite good in microfinance. I remember reading about a peruvian program in Mi Banco that worked well, it´s name was Mi casa ("My house" in spanish). See Acción Insight nr. 4, January 2003, that has interesting information about it,
I have been in the microfinance scetor as academia and a practitioner. In my country Ghana, we do not have MFIs that go into housing. I believe some attempts made some MFIs did not yield any results. The usual practice has been the traditional banks and housing companies that are seriously into housing. Maybe, microfinance for housing projects require somehow huge capital which I think most MFIs in Ghana may not be able to raise. It is important to note that in Ghana MFIs loans do not usually go beyond 1 year. Housing loans or mortgages are long term financing which most MFIs are not interested. We need to think through to design workable microfinance housing programmes in Ghana because there is huge demand-supply gap in housing both at rural and urban levels. Any one who might be interested could come on board for partnership. First, I thinks an empirical research will do! A baseline study could be the starting point.
I´ve just read this article in the FAI (Financial Access Iniative) newsletter: "Saving for a Home: When Commitment is Too Much and Too Little" (Part 1)
December 9, 2015 Daniel Rozas. Perhaps it may help
There are a number of sucesfull architecture designs whinch have been rooted on affordability for quite low incoming families. Some of these designs are much more than justa a design but a broaden startegy involving microfinance and the spatial solution. Mr. Barlkrishn Doshi, the Indian architect has designed a masterpiece on this: the "Aranya housing estate" in India. I recommend you to have a view on it. There are diverse websites (the official one is at Vastu Shilpa Doshi`s Foundation: www.vastushilpa.org ). This other link is interesting: http://urbz.net/aranya/
There are also non formal ways of fitting incoming and house bulding. For example incrmental startegies. In Mozambique people designed a tipolgy, known as "Ventoinha", (little mill), that grows ass the incoming are coming. My research group have already written a book about Ventoinha House in Mozambique. Please find it at Researchgate in the link:
Book Inhabited processes Architectures where the other 90% lives....