Agreed with /, especially if there’s a porch on back or a dormer or something we can’t see (backed up gutters, etc).
Also, we’d need to know if there is a kickout on the vertical to fascia termination @ the garage.
To the customer: What I just said is where the R box (‘main house’) meets the less deep garage roofline, water will run down the wall to roof joint. Where the roof ends & the wall gets water washing across it, there is often a problem with rotting (no matter what kind of siding product you have, it needs proper flashing).
As for the measurements asked about a few posts prior, we don’t expect YOU to know how to measure it (although on a house like this, it’s the easiest type: up one side of the “A”, then down the other… that’s your 1st measurement. For the 2nd number, measure from L to R. Multiply the up & over x the L to R & that’s the basic start).
If the house is 23 years old, chances are you are past the expected life of your shingles & a total re-roof is in order. You’ve mentioned 2 or 3x about shingles not being properly secured or installed back when the roof was originally done, however if those are 3 Tab shingles (the smooth, flat variety, some know them as 20 year shingles) then it’s NOT the method of attachment you’re having issues with, it’s the age of the shingles.
You might also get suggestions to do a ‘roof over’ or ‘lay over’ where the old shingles don’t get taken off… BAD IDEA. The savings are marginal & the added damage is in the long run not worth it. Think of it like this: Would YOU want to buy a house that had a roofover?
Back to the ‘improper method of attachment’. If your inspector said the house needed shingle repairs on a 23 year old roof job (especially, again… with 3T’s) then he did a bad job. The only thing I’d expect out of a 23 year old shingle is to need a full replacement.
& That’s MY opinion.