Insulation in 100 year old house
I just opened up the kneewall that is over the second floor of my 95 year old tutor style house in the Philly area. I was able to access it by taking out the back of a third floor closet.
The rooms on the third floor are framed with 2x4s on the side, so there is only limited space to put insulation in. After much thought about how to do this I think the best appoach is to put in R-11 insulation (pushed in so that it can fit the 2in cavity), then put up a sheet of foam on the outside. The foam will give me another R-7, plus it will hold the fiberglass in place. It will also allow me to use the kneewall for storage since there won’t be stray fiberglass on the wall.
Will this method work, and does it make sense? Does foam insulation pose any problems if I later need to put an electrical box in any of the third floor bedrooms?
I am also in the process of insulating a bedroom on the second floor. I gutted it out and did the electrical rough in. The two outside walls were never insulated so I want to put some in. I was originally planning on using fiberglass batts, but was concerned that the old sheathing and tar paper may let too much moisture in. I don’t see any signs of leaking, but there are some water stains from long ago on some of the studs and joists.
Thanks for the advice.
Replies
blow the whole kneewall area full of cellulouse. That stuff will pack out the little nooks and crannies much more easily than trying to stuff batts in there (and less scratchy too, when you are all done).
for the bathroom, decide first if you really have any water issues to deal with (all insulation systems will be harmed if you let liquid water thru your walls - you have to fix that). Once you've confirmed that issue is history then choose between FG batts + vapor barrier, Cells blown in (wet blow into open bays or dry blow into drywalled bays (leave a space open at the top to blow in)) or have spray foam applied to the open bays. These options are listed in order of cost/performance.
Hope this helps,
Norm
oops, I just re-read your post, you want to use that space for storage.
Hmm, in that case, your foam sheet may be the best choice (max R, min thickness).
I wish Prospero would let us see the previous posts while we are typing our replies!
Norm
"I wish Prospero would let us see the previous posts while we are typing our replies! "
Actually, you can - Sort of.
Right-click on the "reply" button and select "open link in new window". (Or whatever your browser says) That allows you to flip back and forth between windows and see all the posts while you're composing a reply.Do you study the law, or do you study the loopholes?
"I wish Prospero would let us see the previous posts while we are typing our replies! "
"Actually, you can - Sort of."
Boss,
I know I can. Just scroll down in the same window and there is the post you are replying to.
Jon
"I wish Prospero would let us see the previous posts while we are typing our replies! "
He said postS.
You can do that if you think ahead. Right click on one of the message (or maybe even on the reply button) and open a 2nd window. Then you can go back an forth between the whole thread and what you are writing.
You're right - But you can only see the post you're replying to.
If you open the reply box in a new window, you can flip back to the other window and see the entire thread. his is the time of year when there are a lot of commencement speeches in the air. And there's a lot of air in the commencement speeches.
Thanks Norm,
So, should I use fiberglass first, then the foam, or cut the foam to fix between the studs, then add an outer layer of foam over that?
For the bedroom, if I am concerned with the draftiness of the walls (and possibility of getting moisture) - would it make sense to put in some tar paper (or tyvek), then the fiberglass with the vapor barrier toward the inside. This will add one more level of protection to the fiberglass (just in case), but it seems like a strange way to do it. Does that make any sense.
Is the roof already insulated? No point in insulating the kneewall if not.
Hiya Matt!
Am I correct in thinking that you want to only insulate the kneewall, not the roof? So your storage area will be uninsulated?
If so, then I would skip the fiberglass batt. If you try to put the fiberglass into the small 2x4 done sideways cavities, not to mention the plaster smashed in thru the lath, you won't be able to smush the fiberglass enough to get the foam down to the studs. Just put the foam in over the studs and call it a day. To be fancy, you could seal the top and bottom openings at each stud cavity with touch foam. Wiring later won't be a problem. Just get earmuffs for when you keyhole saw the squeaky foam.
Alec
Well, Yesterday I did the insulation. I sistered on some 2x4 to the existing 2x4 studs (to make 4x4). That gave me enough room to put the R-13 fiberglass. Unfortunately, each cavity was a different width, and none was 14.5, so there was a lot of cutting to do. While I had the wall open I put in two electrical boxes and fed them. Then I put in the 1/2in foam polyisocyanurate over the studs. The trouble came when I tried to secure it to the studs.
I tried to use a drywall screw to secure the foam, but that didn't hold. The foam has no strength. So I considered what to do and decided I should staple them, and use a luan strip to hold the staples from penetrating too deeply into the foam. Problem was I only had staples that were 7/8.
Went to Home Depot and picked up a box of 1 3/8 staples, got home (30mins each way), and realized they were 7/8! I hate when that happens. Ended up cutting 1in strips of 3/8 plywood scrap, and using my finish nailer to put in 2.5in nails. That now holds really well.
For the floor, I carried up a full sheet of 3/8in plywood to the 3rd floor by myself, and got it in position, then realized that the ductword was in the way. I had to trim 1ft off to make a 3x8 sheet. Of course it was easier to trim it off outside.
Half the kneewall is done (one bedroom). I will be able to do the second half much faster now. That project comes later. Next project is to put up some drywall in the closet that I knocked down to get access to the kneewall, and come up with a design for an insulated access door.