Finish my attic - planning

I’m starting planning for finishing my attic and would very much appreciate a little advice and guidance. I am in New Hampshire, the house is a new build colonial (3 years old). My attic has a walk up staircase, is what I believe referred to as part finished - the floor is boarded but the roof is not insulated.

I have a couple of immediate questions but would welcome any thoughts on what I’m not asking but maybe should be.

Insulation - I believe I need to run rafter vents from the soffit (where there are single pieces already) up to or above where the insulation will end. I have horizontal trusses at about 7’ which I think will determine where I have a flat ceiling. Are there pros and cons to insulating up to the ridge vs. up to and across the ceiling? I realize this would mean the small remaining attic space would or would not be insulated depending on the approach but do not intend to use it.

Soffit vents - I can see daylight around the soffit so feel sure it is vented as is the ridge. I believe I need to extend the vents up between the roof joists as mentioned earlier to ventilate the roof. What I’m not sure about is how to “seal” by the soffit so that the roof is ventilated but the living space is insulated. Do I just vent then stuff insulation in? Wouldn’t that in theory expose the insulation to the weather outside?

Knee wall - I have been told a 3’ knee wall is typical, is this usually a code requirement or am I free to do it as I prefer? I’m inclined to do a 18” or 24” knee wall, essentially just enough to slow for electrical outlets. I realize that space wouldn’t be particularly usable but I think it will make it look bigger.

If relevant the house is 28’ x 38’ and the staircase to the attic comes in around the middle (above the staircase to the basement and the one to the first floor).

Very much appreciate and advice!

Chris.

 

Here are some pictures of what I am starting with...

The vents do not seem to act as a blocker/baffle as such I think the insulation is directly exposed to airflow coming in from the soffit vents.

As for the ridge from inside at least I don’t see anything that looks like a vent, should I be able to see a ridge vent from the inside? I’ll also look from outside to see if it offers more clues.

 

Apologies that the attachments seemed to go awry, the one of the soffit area came in upside down and I managed to post the picture of the ridge twice!

 

The black strip along your ridge is probably the ridge ventilation. The baffles and thin fabric usually block the light.