Attic venting and insulation for an old 1 1/2 story Cape home
I’ve been reading this site for a while in hopes i’d find exactly the answers to my problems (I and/or my home have many)… But it was always bits and pieces and the specific advice didn’t always sync up and so I’m hoping that finally taking the time to outline my issues can find answers and peace of mind i’m looking for to ensure I take the correct steps with my home going forward.
Basically, I have “inherited” my in-laws 1 1/2 story cape cod home which was originally built in the 40s. it is our main residence and on the smaller side (Sq ft wise). we live in northeast NJ so climate zone 4 or 5 ish depending on where the towns curve.
The first issue i noticed was the humidity and basement which had quite a bit of mold which needed remediation. It has since been remediated (Fall 2018) but am still unsure the best DEHUMIDIFIER I should purchase as the RH levels in my home are high.
caveat, is that this MAY be due to all of the air leakage that i have throughout… per an energy audit i had done it is quite leaky, basement, 1st and 2nd floor all around.
It may also NOT be due to that, and it could be just that my cinder block or concrete floor are allowing moisture through. (there is no outer wall or sub slab water proofing). I don’t want to focus on if actual water infiltrated the basement cinder blocks or anything as i’m going to try to continue on assuming that was not the case (inklings maybe it did, but haven’t been able to confirm since remediation was done)
But digressing back on point… I am looking at hiring a home energy audit company to do work in the home to help seal/insulate my house, but also need my roof to be redone showing signs of issues that its about time (more on the roof later)
When my home was remediated the attic was also checked and it looked like on the attic side roof decking there may be or had been some mold up there… they fogged the attic instead of invasively gutting my whole house and after basement was done and home re-inspected, mold levels were gone.
Currently in my attic, I have a ridge vent, have powered fan which stopped working automatically when attic reached 90 degrees per thermostat and now only goes on manually as well as 2 gable vents (1 on each side) located in the middle top of each side.
As i mentioned it is a 1 and 1/2 story cape house with the 2nd floor converted to living space via knee walls. This leaves me with corner crawl spaces on each side as well as a tight hatch space in the ceiling.
I’ve attached 3 pictures, 1 is a general birds eye view of the home to give you an idea and then 1 picture is from the ceiling hatch shooting across the house to a gable vent, and the last is just a picture of a knee wall opening to a crawl space corner.
Right now the entire attic is stuffed with fiberglass insulation, some kraft faced, some foil faced, some in plastic bags… the slopes that parallel living space walls are stuff as well, the whole thing is not air flow efficient…
my first project is going to be removing allof the insulation in my attic to save money before the energy audit contractor work come to reinsulate “properly”. I use quotations because as i mentioned i also need my roof redone.
the order of operations is important to me so that 1 job doesn’t cause issues with the previously done job
1) seal/insulate first = what appens when roofers need to replace decking that is rotted/moldy or damaged that had been sprayed with closed cell spray foam?
2) roof job first = what happens when the seal/insulate job needs to vent the 2 bathroom fans out of the roof instead of where currently going, just being left to vent into attic.
those are my 2 biggest concerns on the order, and is leading me to believe i should have my roof redone first and make sure that any/all roof decking will be good for when the seal/insulate job is done.
next is the issue of all of the different types of ventilation i have.
from the proposals i read and way i understand is that the team would be insulating closed cell spray foam along the roof slope rafters top to bottom… in my understanding, creating a closed attic and now part of the conditions space.
if this is the case do i want to have a ridge vent, will they just spray foam and close it? what about the powered attic fan? the fan is technically scheduled to kick on at 90 degrees in the attic, but if conditioned would never get that hot any more correct? And the gable vents, should i have them board those up and spray foam over them?
i guess if the answers are that i am to now have a closed cell conditioned attic i don’t want all or even any of that ventilation correct? and if that is the case then i want to make sure i tell the roofers to change the job to just remove the ridge cap instead of putting a new on, or to just remove the powered fan instead of replacing/fixing…
The other small issue is from the birds eye view and the “porch” add on you can see in the back. this is the only part of the house that has soffit vents, now while those soffit’s then run through the ceiling of the porch, when in crawl space of the attic where it would be assumed the venting leads to, there is no air flow it seems…. should i have the roofers remove soffits in that case assuming that the seal/insulation team will be covering with closed cell spray foam?
Lastly, is it possible or doable, to switch from Closed Cell Spray Foam to Dense Packed Cellulose for the different parts of the sloping rafters?
crawl space corners exterior rafter side = closed cell spray foam
sloped rafter with sloped ceiling = dense packed cellulose
attic sloped roof to ridge = closed cell spray foam
is that a thing or should i be questioning anything that isn’t 1 or the other all the way through?
please ask for any additional details that may help in explaining my predicament as I just feel like my case is quite niche and am just trying to balance a whole load of things from an air flow, energy efficiency, insulation ratings and moisture issues that my head is spinning. (i don’t always trust “professionals” who are the ones selling me the way to do things either)
Thanks so much!
GBA Detail Library
A collection of one thousand construction details organized by climate and house part