Hi buttercarp, I am very interested in your question as I am caught in same situation as you. In your mortage document, you can be listed as mortagor or borrower. I believe in your case, mortgage document states that you are borrower and both you and wife are mortagors. Have you tried to get 80% loan for your wife through any letter of offer from bank?
From what I found, the case for private is different for HDB. As in the case of HDB - all mortagors must be borrowers. So if you own HDB and you are the only borrower though both are mortgagors, don't need to think about 80% for wife.
However for private property, some banks define mortagor as owner only while the borrower is the person in charge of paying loan. So technically your wife who is the mortagor but not borrower, does not have any outstanding loan.
The LTV rule stated by MAS is
[1] Financial institutions are required to conduct checks with HDB and with one or more credit bureaus on whether
the buyer has an outstanding housing loan at the time of applying for a housing loan for the new property purchase. For joint buyers, if either buyer has an outstanding housing loan, the joint buyers will be considered as having an outstanding housing loan.
....so what I am trying to say is..as long as you are not buying new property with your wife, your wife may still be able to get 80% from certain banks that do not define mortagor as borrower.
I am in the midst of talking to lawyer and banker on this. Wish me luck. Keeping my fingers crossed on this one.
