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turin39789 01-04-2010 12:18 PM

Adding insulation and storage to Cape Cod Side Attic
I'm planning on plywood to our side attics so we have some storage space in our new to us home, and need to add insulation while I am at it. We have 2x6 joists on IIRC ~18 inch centers. I'm pasting below a writeup I did from a non DIY site before I was pointed to this forum. I think we are going to pick up loose cellulose and a sprayer from lowes or HD. There is no current vapor barrier, but I have read that when there isn't one vapor barrier paint can be put on the ceilings on the first floor, and other people who say a few layers of regular paint will form an effective barrier. There appears to be 1-3 inches of original mineral wool in most of the attic, and some spotches of R-19 have been installed here and there, with the kraft paper facing the wrong way.

Rolled around in the insulation today. There are no soffit vents on the house, actually no soffit. So two large triangle gable vents at the ends of the main ridgeline and a round one halfway up the attic space on a front facing extension.

It appears that there are fiberglass batts on the sides of knee walls and pushed up into the area above part of the top of the finished area upstairs. There were a few spaces where the insulation was not stuffed into the upper cavity, and I started to add some here but I'm thinking they need to stay open to allow air to get up into the peak area between the two gable end vents.

I'm going to try to use 2x4s as furring to place on top of the 2x6 joists leaving me with 9 inches of space to blow in cellulose insulation below the plywood I will be adding to the attic. I'll probably just be adding 4-5 sheets of plywood leaving most of the space empty but giving us enough room to stash the christmas crap and old boxes of junk. I'm thinking I need to add some sections of 2x4 to most of the joists or it will be impossible to walk the attic in the future as the joists will be covered in 3-4 inches of cellulose.

I noticed that on the half of our front wall where our roofed porch is, there appears to be no top plate to that wall. I can see the wall cavity, and through it to the area inside the porch roof. I'm tempted to check out the electrical in that area and make sure there are good boxes behind the outlets and then spraying some cellulose down into that area and then adding a top plate. Right now that front wall, and probably many more don't have insulation at all. Right now where the wall meets the joists, there were paper bags to keep the original mineral wool insulation from falling into the walls. Just not sure if I should let the insulation down into this wall or if I should keep it simple, block them off again and just add the attic insulation.

The attic doesn't appear to have ideal ventilation, but the roof has been on for a good long time and it doesn't appear to be suffering. My concern right now is to try to improve or at least not screw up the ventilation anymore than it currently is. Also to get the electric cleaned up and checked out(thats what my electrician brother is for after all) as right now the outlets upstairs in the kneewalls are exposed without boxes, and I need to get that cleaned up before the insulation goes in.

Going to try to snag some pictures tonight so everyone can see what I'm talking about. This is our first project we are tackling, so help if you can.

ccarlisle 01-05-2010 08:49 AM

Want help? well, let me say that many of us here IMO have ADHD and reading pages upon pages of information about: "The type of wallpaper you saw in Home&Gardens magazine last July I believe it was and wonder if the shade of green on page 68 will match your mother-in-laws greenish with beige stripes loveseat and chair combo in the den...what do you think?" or: "I have 3/4" plywood, maybe OSB sheets that seem to cover an insulation material that looks like dirty wool but there's no vapour barrier neither here nor on two of the other walls of our attic that is supposed to be R16 but I'm not sure of that and don't even know what the building codes we ought to have, either on the walls or on the ceiling..." - as you see - doesn't get you many replies.

OK I'm being probably unjustifyably cruel and facetious here and I know you're just trying "to connect". But you'll notice that many members here are professionals in their own domain to whom time-is-money and vacation time precious...not that yours isn't - but don't think we're not sympathetic to your plight.

We just perceive things as more task-oriented, I guess.

Scuba_Dave 01-05-2010 09:32 AM

I think what ccarlisle is trying to say is...What are you asking ?

Lots of people here to help but need to know specific question(s)

Also if you fill out your location in your profile that will help too

ccarlisle 01-05-2010 09:55 AM


"Location" should be mandatory.

Feelin' punchy this mornin'...:laughing:

user1007 01-05-2010 10:04 AM


Originally Posted by ccarlisle (Post 377107)

"Location" should be mandatory.

Feelin' punchy this mornin'...:laughing:

Some mornings can be that way. I do agree that at least general location for people on this site should be mandatory and would save those of us who try not to be harsh some aggravation. I think Dave and crowd are working on this issue.

As for the insulation issue in the post, you are certainly not going to hurt anything blowing cellulose into any cavitities you can cram it into and the equipment and material Lowe's rents and sells is not bad I guess. I would use a pro myself and be thinking of the highest R value I could get. I would use a spray foam guy if I could get one out for a small project. Usually they are available if you give them some time and allow them to piggyback on top of other projects.

People have a tendancy to overseal their houses these days so I am pleased you have ventilation in mind. Houses need to breath or they can become really sick. Before you wrap yours up too tight and stuff it with insulation I would think about a vent or two in the soffets. Attic fans with automatic shutoffs are not bad investments either and will save you a fortune off your summer AC bill if that is an issue where you are. You will suffer some energy loss with any sort of vent of course but the gases coming out of paint, furniture, draperies, carpeting, kids, pets, us adults, etc. have to have a path out. A little well thought airflow even in a modern energy efficient home is a great thing in my opinion.

And of course, as you are planning, all the electrical and plumbing issues you may have should be addressed before you insulate and especially if you use foam. And by the way, my California house was insulated through the exterior. It had no wiring issues and blowing the insulation from the outside was the best approach and did the least damage. Just offering food for thought. I had cellulose blown into all the external walls and it made a tremendous difference in the power bill. The stucco experts patched all the holes nicely so you would never know they were there.

Why do you have a wall missing a top plate of some kind though and especially if it is along the exterior and one guesses trying to bear weight of some kind? What is holding the top of it in place? Maybe I misread your post but that sort of framing sounds scary to me. I don't think I would pack too much material and extra weight behind a wall not secured at the top. You might want to look at that issue along with wiring needs before going to far forward packing insulation behind the wall?

WillK 11-08-2010 10:50 AM

This may be an older thread by someone who made their one and only post and may not read this, but in case anyone such as myself is coming across this I wanted to note some things.

The situation described sounds similar to my own. The poster sounds like they are describing a balloon framed house. Balloon framing suggests this is an older house, and as an older house it is also possible it was built with knob and tube wiring. Generally speaking it is probably fine to blow insulation into the wall cavities, but if you have knob and tube wiring do not allow any insulation to contact any wires that are live.

Also, I think that addressing the ventilation should come first. Inadequate insulation may mean higher heating bills. Inadequate ventilation may mean major repair bills. In fact, when your house is inadequately insulated, the leakyness can make up for inadequate insulation and make it seem like no consequences are resulting from the ventilation problems. Insulating without ventilation can increase temperature differences, cause condensation and moisture and trap it resulting in wood rotting and premature roofing deterioration.

My house was built in 1917 and was later insulated in the attic with fiberglass batts and blown in cellulose. Vents were inadequate and what there was became obstructed with bird nests. The roof had been sheathed with 3/4" OSB over the original plank sheathing, huge areas of plan sheathing were rotted and rafters over both dormers had rotted and sagged (2x4 rafter boards could be broken in 2 by hand). Much of the cellulose insulation was blackenned, probably from mold. Lath and plaster interior walls had been covered with some sort of ceiling tile like material, when this material was removed the paint and plaster was chipping and the lath was weak.

My project has been much more extensive, I replaced roofing, added ridge and soffit vents, rebuilt dormer roofs, resided dormers, gutted second floor interior walls and ceilings, rewired and reinsulated with baffles and 2x4 furring to add cavity depth for R19 on the sloped portion of the ceiling.

Which it's also worth going into a little more - the house is a 1-1/2 floor house with 2 bedrooms on the second floor, side attics from the soffit to the knee wall, then a 9/12 sloped ceiling then a flat ceiling... The flat ceiling was below an attic to which there was no access but it was filled with cellulouse to the top of the 2x4 joists. Batt insulation was put in the side attics on the exterior. The sloped ceilings were uninsulated but had fiberglass stuffed into the ends (and 1 dead bird that fell in from one of the birds nests above). Except for the blown in cellulose, whose only sin would be that it was inadequate, pretty much all of this is an example of things done wrong.

In this case I don't have a question, but I want to emphasize the importance of a whole system approach to a project such as the original poster described.

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