Insulating from the outside

Hi everybody, I am wondering what,how I should go about this. I will be tearing off the old siding,and the boards under it and replacing it, I want to insulate the walls while I have everything off. What type of insulation should I use? What about vapor barrier?

 

WElcome the site. Depending on where you live, some zones want the vapour barrier on the inside some on the outside and some don't use any. I hope you planning on doing this a piece at a time the sheeting is structual.

 

We live in minnesota,i am planning on doing a section at a time.As for insulation should i use faced or unfaced?If it is supposed to be on the inside shouldn't it be between the sheetrock and the studs?

 

In theory, your vapor retarder levels should be to the warm side.

In your application, you would want it to be unfaced in a perfect application but if you get enough R-Value to the exterior, it is less imperative.

What is the wall construction?

Plan on spending some money on spray foam and getting it done right. If you take your time, you can detail and build a really fantastic wall system.

Vapor Retarder Levels

http://www.buildingscience.com/documents/reports/rr-1012-residential-exterior-wall-superinsulation-retrofit/view?searchterm=exterior%20foam

 

There are a few ways to go, doing it wrong is as bad as not doing it. The idea is to stop air flow from inside from getting into the wall. Paper faced would go against the interior but there is no way to seal all the gaps. So if that's what you use you would have to seal all swtch and outlet boxes to stop airflow and then paint inside with a retarder paint. I would use poly 6 mill and wrap the stud and tuck it into the gavities. tape the joints and seal it to top and bottom plate with acoustic sealer and use batts. In a wet zone some gaps want to be left in the sheeting so moisture can escape to the outside, every bay.

 

As far as I can tell the walls a regular 2x4 framed walls,I was told it could be balloon construction, don't know if that would make a difference. Unfortunately I have to do this myself to keep costs down,but it still needs to be right so I don't have any issues later. What I need is the best way to do it this way,as the siding and the boards under need replacing. This is why I am doing it this way.

 

Balloon framing does make for some more leakage but if you are stripping the walls on the exterior, you can cut and install blockers between the floors. This should be done from a fire standpoint anyway.

Get some putty pads to go around all the outlets and penetrations in the walls.

Check with code or engineer as to what the requirement is for either let in bracing or plywood sheathing.

 

Thanks for the info, I will check what code is,and figure out if it is balloon framed.

 

Being able to get to the backside of the interior wall (plaster and lath or drywall) is a great benefit but will require the additional expense of pulling the sheathing.

If you are going for high performance envelope, that is what you are going to have to do.

Dense packing the walls, while not requiring the tear down of the sheathing, is going to be near impossible if you don't know what is in the walls or if it is balloon framed.

 

+1

If they are old skip sheathing, you will see everything you need to see.

Do not use that drip foam for closed cavities in my opinion. I have used it on a couple of jobs and the results were disastrous in a couple of cases. Much better suited for hollow blocks.

I have yet to use AirKrete but I would love to try it.

 

The foam they use for closed cavities is deffernt and chemicals can get into house that does not have vabour barrier.

 

The house was built in the 20's or 30's, i do know it has boards running at an angle behind the siding,don't remember if it was rough sawn or not. There is no vegetation over grown, it was neglected for a lot of years, some since I have lived there. The siding is rotting,not on all places, and the boards behind are also in places, I also have to replace some windows as the wood around them is rotting too. There is nothing between the siding and sheathing, what insulation is there is compacted at the bottom. So let's figure it is a balloon framed house, if I were to do small sections at a time, that should not affect the rest of the house right?

 

The braces on an angle let into the studs were put there to keep the house square, because the board would not keep there. Plywood or osb on newer house do that job. So you could likey work on half of a side at a time. If the studs are rough cut, any blocking you have to put in if it is balloon will have to be ripped to fit. Hang a tarp first and roll it up above the work area because you know as soon as you open the wall the wind will blow and the rain will come. The area around the windows will likely be the worst and I would start right at one of the worst windows. Depending on what you find in some cases it is easier to change whole sections of wall.

 

Someone help me understand why this is more difficult than just removing the old and putting new on.

 

It's not but what ever you expect to find when you get there will change, sometimes better and sometimes worse. No one that has done this before wants you to be really surprised when you get there. You will run into problems that are unexpected and there are people here that will offer suggestions on how to solve them. You have suggested some rot, we think "more rot" insects, mold and knob and tube wiring, all things that will have to be addressed when you get there. It may be easy and we hope it is.

 

I thank all you guys for your help and I was not trying to be a dink,I was getting more confused than before I asked.i will be starting maybe this wknd or next and I will let you guys know how things go. Thank you again.

 

I also learned of quite a few things I have never heard of before,or would have thought to look up,thanks to you guy's. I appreciate it.