How far would you stress test your mortgage

Pythagorous

I'm currently decided whether to make an offer on a house based on what I can 'comfortably' afford. I'm taking out a 5 year fixed at 2.94% (85% LTV) which I feel comfortable with although there isn't a huge amount of margin and I'm therefore thinking about the risk of mortgage rates being much higher in 5 years time when it comes to renew. 
I'm therefore curious to know for those of you in similar situations, how far would you stress test interest rates in 5 years time when making a decision about buying?

MovingForwards

I doubled my APR and could still afford it on my then income. I'm with a sub-prime lender and make overpayments each month as I planned to clear it within 10 years of it starting, fixed my rate for 5 years.

getmore4less

The trick is to give more payment margin and overpay,

Take a longer term. 

for your 2.94% in 5 years depending on term you will be at a lower LTV(unless prices crash)
years - LTV 5y - payment as  % of 20y - % rate for same payment as 20y
20y 68.2% 100% 2.94%
25y 72.5% 85.4% 4.43%
30y 75.5% 75.9% 5.24%
35y 77.5% 69.2% 5.72%