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Semi finished attic with ridge vent, but no soffits and very old/missing batt insulation.

user-6344597's picture


I moved into a 1955 split level home on the north shore of Long Island this summer and my next project is to tackle the attic.  The house gets very humid in the summer from surrounding trees and the area in general, surprisingly there is no mold anywhere in the house, including the attic.  I am very actively clearing scrub trees and vines to allow in more light and air though.  I also encapsulated and insulated the crawlspace this summer, which was cement and had little evidence of water besides some effervescents from poor landscaping. 

Back to the attic.  It is a walk up attic with a bedroom style door leading to the stairway. To the left is a finished room that has a mechanical vent in the roof, an a/c duct, and an Andersen window.  To the right at the top of the stairs is a semi rough storage area touted as a 'cedar closet' because there is a large amount of cedar particle board in a portion of it, as well as a separate space for the airhandler for the a/c.  The house is heated through radiators and an oil burner, as well as a large high efficiency wood stove insert at the lowest level of the house.  

The right side of the attic, which is all open, has a ridge vent running the length, but there are no other areas of ventilation in the attic, besides another Andersen window that is always closed on the far side.  The floor is loosely insulated with old fiberglass, but it is not air tight by any stretch, plus again, there is a flimsy door leading straight up to the attic.  The rafters are 16" OC 2x6's, 'insulated' with +40 year old batt insulation that is thin, falling apart and is missing in entire sections. The hot air flows from the house directly out of the ridge vent unobstructed essentially.  Additionally, there are 3 layers of shingles on the roof, that I would like to have replaced very soon.  The roof is tongue and grove boards that appear to be in very good shape and should not have to be replaced from what I can see when the shingles are replaced.  

My worry is that I am going to fix the heating problem and create a mold problem.  One problem is simply money, or chopping more wood, and the other is health of my family and my baby...and LOTS of more money to fix.  

What I was planning on doing is this.  First leave the semi finished room to the left alone for now.  On the right side, I want to use spray foam cans to seal whatever openings I can find.  Then add a thick layer of unfaced Roxul sheets and take out all of the old fiberglass. In the rafters I want to add baffles the full length of the roof, from the bottom edge up to the ridge vent.  Next, I want to add R23 Roxul unfaced below the baffle.  In the area that is near the air handler and not used for storage, I would like to increase the 2x6 depth by 2 inches so the Roxul can expand a bit more and then apply rigid foam faced on both sides with radiant foil and seal that all with foam and Tyvek tape.  In this case, should the baffles be sealed completely? or is stapling them and making sure they are flush adequate?  In the storage semi finished area I was going to staple a vapor barrier sheeting (I need suggestions on type) and apply some kind of this lapstrake pine or cedar boards on top of that.  

I would like to have my roof replaced soon, but I wouldn't be for at least another several months.  When it is replaced, I was thinking of putting in DCI Smart Vents under the incoming shingles.  If the above plan is correct, a big IF, since I am a new home owner, can I do the insulation work this winter before the Smart Vents are put in place? Could that set up last a summer without the SmartVents and only the ridge vent?  Right now my roof looks like a zebra from entire rafter bays missing insulation and I want to get as much of the work done soon as possible.  I wanted to be as thorough as possible, sorry for the long explanation. HELP! 

Thiss is what needs to be (post #215716, reply #1 of 1)

Thiss is what needs to be done.

Draw a scaled picture listing all the upgrades.  Run a HVAC load calculation for heating and cooling.  This will tell you the actual heating requirement and cooling requirements in sensible and latent loads for humidity control.  I will also give you required duct sizing.

Check your system and see if I will handle the HVAC load and look at her possibility of zoning the current system.

I have designed systems for over 35 years for heating contractors and home owners building homes.   This is the correct way ttackle you poject.

Size the system for after the improvements.