Should I insulate the interior or exterior?

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  #1  
Old 07-04-15, 08:21 PM
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Question Should I insulate the interior or exterior?

I'm closing on a house and plan on doing some renovating. Very excited about finally being a homeowner! The house was built in 1940 and most likely has mud and lathe behind the horrid wood paneling.
My plan is to hang drywall and I'm presented with two options: 1) make a mess, rip out the mud/lathe, and throw in some insulation OR 2) insulate from the exterior when I side over that aged asphalt siding. I don't feel like having an empty wallet when my heating bill comes around this winter.

Any other things I should do while I have the walls open?

Any advice is welcome!
 
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  #2  
Old 07-05-15, 03:06 AM
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Welcome to the best DIY forum on the Internet.

Now as to an answer to your question...I would plan on leaving the interior walls intact unless they are in poor condition and insulating from the outside. How to go about it depends upon the construction of the wall, the prevailing climate and how much money do you have to spend. If you are going to tear out the plaster walls anyway then it makes little difference.

IF, you have the asphalt "siding" that looks more like roofing then it should be removed before adding any other siding. This will also give you a chance to inspect the sheathing and add a "house wrap" such as Tyvek to help air seal the house. While the wall cavities are open you should do all the electrical upgrades, plumbing upgrades, and any other services that will be hidden inside the walls.

ALL galvanized steel piping, supply or drainage, needs to be replaced, usually with plastic and ALL knob and tube electrical needs to be replaced. Any ductwork for ventilation, heating or air conditioning needs to be thoroughly inspected for leaks and sealed with foil tape or mastic and then insulated. If the heating system does not have the supply ducts to the outside walls, generally under windows, it should be re-configured in that manner or you will experience temperature gradations across the rooms.

Lots, lots more.
 

Last edited by Shadeladie; 07-05-15 at 08:13 AM. Reason: Removed some wordage. Be nice. Not that big a deal.
  #3  
Old 07-05-15, 04:54 AM
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A house that old may also be balloon wall constrution, if it is you also need to add fire blocking at the top and bottom of every stud bay in the wall.
Is there at least R-40 insulation as a minimum in the attic with baffles to allow air flow, soffit vents, ridge vent?
 
  #4  
Old 07-05-15, 06:42 AM
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Hi DiyGirl and welcome to the forum, Some questions have been asked by Furd and Joe which will help us guide you, but the important one IMO is what is your objective? Is this a long term house for you to live in or just a flip?

If you plan on living there for many years, then you should be sure each step is optimized for the long term.

I'll list some questions, some may repeat what the above has asked.
1. Balloon construction?
2. Modern wiring or knob and tube?
3. Does that plaster and lath contain any asbestos?
4. Any other asbestos concerns in the house?
5. High probability of lead paint, on the surface or buried under many layers??
6. Do you have a basement or crawlspace, dirt floor or concrete?
7. What is your current heating system?

Bud
 
  #5  
Old 07-05-15, 10:14 AM
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Use blown cellulose for insulation. You won't have to remove the interior walls or exterior sheathing to do it. If you need to rewire, do that before hand. You can blow the insulation in from the inside or out. The outside is preferential because that stuff can make quite a mess.
 
  #6  
Old 07-05-15, 10:18 AM
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One drawback to overlaying your existing walls with sheetrock without removing the lath and plaster would be the relief. Your door and window jambs would need extending, all your base molding removed and replaced with new, since the measurements would be no good, and you would overall lose one full inch of wall space in a room from side to side.

I agree with droo, that blown in insulation from the outside would be best, AFTER the electrical is retrofitted. Less messy. That way you can leave your plaster walls alone and just paint them.
 
  #7  
Old 07-05-15, 10:21 PM
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Thanks for all of the responses!
@furd: Great info. Now I have a better understanding of what I need to replace behind the walls. As for the house wrap, I'll definitely do that.. but someone had mentioned that I should just side over the shingle-like siding with vinyl. Still weighing out my options. I definitely want to update as much as I can while I have the walls open.

@joecaption: There is insulation in the attic. I noticed some coming out of the attic floor while I was up there checking it out. Not sure what R value though. I'm glad that I at least have insulation up there since heat rises.

@bud9051: My objective is to update the place and make it more energy efficient. I'm not just flipping. I plan on living here for years, but not forever. I'm not familiar with balloon construction, but I'll check it out. All of the wiring is updated, unless the previous owner didn't update behind the walls for some reason. Dirt floor basement. No asbestos concerns. And as for heat, it's gas steam radiators.

@drooplug: I'm also considering blown cellulose.. although I don't know how expensive that would be. It sure would be a lot easier compared to tearing everything out from the inside.

@chandler: You're right. That's gonna be a pain in the *** to adjust all the trim pieces and lose about an inch on each wall.


I don't mind doing most of the labor. I'd like to learn everything I can about this stuff, so thanks for giving me a lot to think about!
 

Last edited by Shadeladie; 07-06-15 at 08:26 AM. Reason: Language
  #8  
Old 07-06-15, 03:24 AM
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...someone had mentioned that I should just side over the shingle-like siding with vinyl.
I strongly disagree with that person. The asphalt shingle siding is quite flammable and would put out dense clouds of choking black smoke were it to ever catch fire. It will do nothing to enhance any insulative properties of the wall and it will not be a good backer for the vinyl siding.

There is insulation in the attic. I noticed some coming out of the attic floor while I was up there checking it out. Not sure what R value though. I'm glad that I at least have insulation up there since heat rises.
Sometimes the only thing that old "insulation" does is take up space that could have been used for proper insulation. Some of the "insulation" used decades ago was of minimal insulative quality. If you have one of these types of insulation it would be better to have it removed rather than add additional insulation over it. One thing that is almost certain, if you can see the tops of the ceiling joists then you do not have sufficient insulation, regardless of the type.

Also, heat does NOT rise, it moves equally well in all directions. Hot AIR however DOES rise and therefore all ceiling penetrations need to be sealed against air movement. This includes all penetrations within the stud (wall) cavities.

I'm not familiar with balloon construction, but I'll check it out.
Balloon framing was a technique used that required very long studs. The studs would go from the sole plate (on the foundation) to the top plate of the highest room, often the attic space. This essentially left each stud space a chimney from the basement to the attic. While it made the installation of wiring and plumbing in the walls easier it required long, straight studs that are simply not economically available these days. In addition the "chimney effect" made these houses susceptible to a total loss if a fire ever reached the stud space. Proper construction required a "fire block" of a horizontal member closing the stud space vertically every eight feet or less of vertical measurement.

All of the wiring is updated, unless the previous owner didn't update behind the walls for some reason.
Much of the wiring in a house is behind the walls and ceilings and cannot be easily replaced. Unless the person doing the rewiring was very conscientious it is quite likely that some parts of the wiring is still original to the house. This is especially true of ceiling fixtures in houses of two or more floor levels. In my opinion this is not necessarily an item of huge concern as you can use new technology lamps to reduce the power requirements on these old circuits to a minimum and that will go a long way to reducing the hazard of older wiring.

Dirt floor basement. No asbestos concerns. And as for heat, it's gas steam radiators.
Are you SURE there is no asbestos anywhere in the house? Just having the asbestos removed from the piping immediately adjacent to where the boiler was replaced is no guarantee that the rest of the house is clear. And I hope that the boiler is not the original one because it would have had asbestos insulation as well as probably having been converted to gas fuel from oil or coal with a resulting lessening of overall efficiency. As for the steam heating distribution and the dirt floor, you have my condolences as I would have neither in any house I owned.

I'm also considering blown cellulose.. although I don't know how expensive that would be.
Blown cellulose would be the most cost-effective insulation. Foamed in place closed cell polyisocyanurate would be perfect but it is way more expensive than any other insulation. Properly installed mineral wool batts (Roxul) would be an excellent choice if you open all the stud spaces. I do not recommend fiberglass as it does nothing to inhibit air movement and it is much less forgiving regarding being overly compressed.
 
  #9  
Old 07-06-15, 06:54 PM
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Ok, I'm going to remove all of the siding before I go with vinyl. I'm leaning towards ripping all of the plaster walls out. I know it'll be a mess, but I think it'll be best in the long run. I was looking at the Roxul insulation the other day that you mentioned and it looks like a great product! Mike Holmes recommends it, which basically means it's the way to go lol. I'll check out that insulation in the attic and see how old it is. And about the electrical.. the house was updated to 200 amps, which is great for an old house. I heard that the house was condemned, so they had to update everything to code. I'm not sure if updating to code includes behind the walls too, but I assume so. I'd be pretty disappointed to see knob and tube when I get down to the studs. Also, the inspector told me that there weren't any asbestos concerns. I read that that there isn't asbestos behind plaster walls, that it's mostly just horse hair or something like it? Asbestos is NOT something I want to mess with.
 
  #10  
Old 07-06-15, 08:18 PM
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If & when you rip out the plaster, you will likely want to just pad the studs out so that the final thickness remains the same... once you remove the lathe and plaster, measure the distance from the studs to the face of your window and door jambs... often you just add some strips of 1/2" plywood onto the stud faces before adding 1/2" drywall and that equals your roughly 1" of lathe and plaster. (or 3/8" ply + 1/2" drywall if it's 7/8", etc.)

Removing the lathe and plaster will be a great time to upgrade all the outlets on those exterior walls... they rarely have enough. If you have grounded outlets, make sure they were wired properly. Most houses of that age won't have grounded outlets.
 
  #11  
Old 07-06-15, 09:27 PM
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I can definitely pick up some plywood so everything ends up flush at the end. On every single stud though? I didn't think about the outlets on the exterior. You're right, I should get to those too. I better make sure I've got the dough for all these extras! Thanks
 
  #12  
Old 07-07-15, 05:20 AM
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Yes, on every stud, on any wall that has a window or a door. One sheet of plywood will go a long ways. (will make about 30 strips, 8 ft long)
 
  #13  
Old 07-07-15, 05:51 AM
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Just a review of resources, available work hours, help available, and where this project will be comes cold weather. You have stated money concerns which is common with beginners once they uncover all of the problems they face. Not criticizing, just stating a common reality.

Start gathering the information you are getting and see how much of that you can realistically get done by end of October. By that time you will want to transition most of your efforts inside. But, you will also want the inside to be sealed and insulated well enough to be heated. I have a mental picture of you getting all of the siding and plaster removed and watching the snow coming down. I know you are thinking ahead, but as more and more issues turn up, the timeline is sliding and there are always more issues yet to be discovered.

Question, how much help do you have and how experienced are they and what do you have for tools? When X suggests adding a strip of plywood to each stud, those of us in the trades see that as a simple project because we all have a table saw and could rip out those strips in 30 minutes.

Do you have an account with a lumber company who delivers? Organizing your material needs and being able to call or email in your orders for next day delivery in a real time saver. Chasing your material needs one item at a time will seriously delay your work.

Just trying to help on the organization side.

Bud
 
  #14  
Old 07-16-15, 11:45 PM
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Well I work at Lowe's so I've got some connections there and a pretty good understanding of most projects that need to be done. Sometimes I don't know exactly what to do until I see it in front of me though, so that's why I was questioning where exactly to put the plywood strips.

I have most tools. The only one I don't have is a table saw, which I can go out and buy if need be. I'm about the most motivated person for the job, working tooth and nail to get this house and renovate it. I don't think I've met anyone as passionate about this as I am. I'm not letting the snow come while I have all the siding and plaster off lol. There's no way I'd be that unprepared, but I understand your concern, seeing as I'm a beginner. I might not be as fast and experienced, but I'm as meticulous and organized as it gets. I appreciate the advice though. Don't worry, I can take criticism.
 
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