home insulation

My house is 1919 and I have the original wood clapboard and double hung windows.

I insulated my entire attic and really cut my heating bill. I put insulation between the rafters and then put boards over it. Now it's excellent storage and it saves on the heating bill. I also installed a programmable thermostat. And I have programmable fans for the summer time. I have ceiling fans in the living room and bedroom for circulation of heat in the winter and to cool in the summer.

I also do not want to do anything to the walls from the inside or the outside.

The next thing I'd like to do is insulate the under the floor from the crawlspace.

After that, I might put insulation on the underside of the roof, but not until after I install Photo Voltaic panels.

I've also weather stripped doors. Every little bit helps. But I won't bastardize the house by replacing the windows. There is a company that can retrofit my existing windows but they don't have any trained contractors in California. I have put film on the glass.

 

<div class='quotetop'>QUOTE(barbaram @ Feb 11 2007, 03:15 AM) [snapback]388367[/snapback]</div>

I think more information would be helpful. I'll tell you what I've found out from insulating my house.

You can lose heat in at least 2 ways. One is by conduction through the walls and ceilings. The other is by infiltration of cold air into the house through cracks and openings. For older houses in particular, air infiltration can be more important than conduction losses, ie, more of your heat bill is due to air infiltration than to conduction losses. So, the advice about weatherstripping is right on the mark. That's been said, I'm going to talk about stopping conduction losses and R-values.

I can't talk about this without R-values, so to be sure we're on the same page, let me briefly explain R-values. R-value is the resistance to heat flow. The higher the R the better. A wall that is R-2 loses half as much heat as a wall that is R-1. And an R-10 wall loses half as much heat as an R-5 wall. And an R-80 attic loses half as much as an R-40 attic. And so on. You take ratios of R-values to figure how how much better one surface is than another. So, an R80 attic lets through half the heat of an R-40 attic.

There's is some inaccuracy in exactly how R-values ought to be calculated when you layer materials on top of each other, but everybody just adds the Rs, so that's what you ought to do.

Now, those statements about R-values can be hugely misleading unless you get it firmly in your mind what "half as much" means. So, an R-40 attic loses 1/40th as much heat as an uninsulated attic. And an R-80 attic loses 1/80th as much. Half as much as the R-40. But you have to bear in mind that the actual net improvement in going from R-40 to R-80, compared to the uninsulated attic, is tiny. You've cut out half of 1/40th of the original heat loss.

The main takeaway you should get from doing an R-value calculation is that the first inch of insulation is the most important, and it's all downhill from there. This tends to mean that addressing your least insulated surfaces first is usually the right thing to do.

Let me illustrate this with an exact calculation for the R-40 versus R-80 attic.. For example, the first foot of fiberglass insulation in your attic gives you R-40 (or so), and cuts the heat flow down to 1/40th of what you'd get with an uninsulated attic. That eliminates 97.5% of conductive heat loss through the attic (1/40 = 0.025). But the next foot -- to bring the attic up to what most contractors would term an R-80 -- only gets to work on the 2.5% of heat that got through the first foot. The second foot of insulation saves 97.5% of the 2.5% that got through the first foot, or a net additional 2.4% of the heat loss from an uninsulated attic.)

The upshot is that the first foot saved 97.5% of heat loss, the second foot saved a further 2.4% of heat loss, compared to the uninsulated attic. The second foot costs as much as the first foot does. So, you have diminishing returns to adding more insulation. The first inch is the best bang for the buck, and every inch thereafter gives a lower rate of return.

To evaluate what to do next, you have to figure the R-values of the surfaces of your house exterior and from there figure out what you can or can't fix. And then judge what to do. So, you have to have a rough idea of how much square footage there is in terms of exterior wall, window area, and second floor ceiling. And you have to guess what the R-values are for those three surfaces now -- exterior wall, window, and second-floor ceiling.

There are a lot of internet sites that will help you guess the R-value of what you have.

So, a single pane of glass is an R-1. A traditional storm window makes that an R-2 or maybe a little higher. A typical uninsulated stud wall with siding and sheetrock is about an R-4. Probably, with just viny siding and real plaster, you have an R-5 or better wall. A traditional modern construction wall (sheetrock, fiberglass in 2x4 wall, siding) is R-11 or higher, depending on what the siding is.

First question: When was the vinyl siding put on? If you were re-sheating the exterior today you would go with foam insulating board with a tyvek wrap under vinyl siding. If that siding was done any time in the past decade or so, I bet that's what they did. Even before that, they might have. So, my question is, do you have foam board insulation under that siding?

If so, and they used the highest-R-valued foam, your walls might not be all that different from a modern 2x4 stud wall with fiberglas insulation. Call it R-11 or better. An inch-and-a-half of foam, with the empty wall cavity behind it, would give you as much as I get with a modern 2x4 wall with fiberglas in the wall cavity.

Second question: what are your windows like? The main thing I notice about your house is the wonderful amount of window area. Bet that's pleasant on a sunny day. I'd guess that 50% of the area of your front wall is window.

If those are the original single-pane windows than that's a lot of heat loss. You'd be losing more heat through the windows than the walls.

An R-value calculation can make this clear: if the windows are half the area, at R-1, and the walls are half the area, at R-5, then how much of your heat loss in that wall is through the windows? There are a lot of ways to do this, but here's how I'd do it. You lose one unit of heat through the R-1 window, for half of your area, and one-fifth of a unit of heat (1/5 = 0.2) through the R-5 wall, for half your area, then:
Total heat lost through windows = 1 * 0.5 = 0.5
Total heat lost through wall = 0.2 * 0.5 = 0.1
Total heat lost = 0.5+0.1 = 0.6
Fraction lost through windows = 0.5/0.6 = 83%
Fraction lost through wall = 0.1/0.6 = 17%

So, on that front wall, if those are the original windows, and there's no foam insulation under the vinyl siding, almost all the current conduction heat loss is through the windows. It would scarcely matter what you did with the walls, for that wall.

But the whole house calculation is not going to be this stark. I just want to make the point that you need to find and focus on the weak points first.

And, the results can surprise you. On my 1950s rancher, with little tiny windows, the windows, even with storm windows on them, the windows and doors account for about 40% of the conductive heat loss of the entire building. But I have piled insulation in the attic.

So, if those windows are the originals, you might do better in the short run to focus on the windows. I'm not a fan of tearing out old materials, even windows. There are insulated window treatments that will raise the R-value of the window to quite a respectable level. I see claims of R-7 and up for the most effective systems. My observation is that, as a rule, the better they work, the uglier they are. And when they are in place they are blocking out the light, obviously. And they tend to be expensive with long payback periods. On the other hand, drapes are one of the easiest things to make if you can sew at all. Big pieces of cloth, and a few straight seams. But mainly, you get to pick the cloth, which keeps down the ugly factor. Yet another unobtrusive option is an interior storm window - basically a piece of plexiglas cut to size and framed to fit inside the window casing. And there are single-season "shrink-to-fit" plastic film storm windows that are a little tacky but quite effective - I use one on the largest window in my house.

What I'm saying is that, depending on what you've got, your windows might be the weak point. And you can fix those, to a degree, without altering the structure of the house at all -- but that can be pretty expensive if you want it to look nice.

Your attic seems to constitute a small fraction of the total wall-and-ceiling area of your house. (As opposed to my ranch house, where the ceiling area is a large fraction of total ceiling+wall area. By all means, if you can get to it and it's unfloored, laying down fiberglas batts is simple and effective. But if so, I can't believe that hasn't already been done. If it is floored, I would talk to a pro. I'm not sure you have any easy and effective options, and you don't want to just lay batts over the floor without talking to somebody first, because might or might not get condensation in the enclosed air space under the floor and rot the surrounding wood.

With regard to cellulose, your house looks very much like my parent's house, which my father modernized. At that time (1980s), blown cellulose was about the only option for filling the wall cavities without tearing out the walls. I just looked it up, and these days you could blow cellulose, fiberglas, or rock wool, but it all amounts to just about the same R-value. Cellulose settles more than the others, that seems to be about the only significant difference. So unless you wanted to re-side it, I think that's about your only tested option for increasing the R-value of the walls.

http://www.energyguide.com/library/EnergyL...;SubjectID=8375

But cellulose eventually settles and leaves an empty space at the top of the wall. And it doesn't stop air infiltration. So, yeah, it's far from perfect.

Another option that people mention is insulating the inside of the wall and sheetrocking over it, but ... I just won't go there. You'd lose interior space, you'd lose the plaster wall surfaces, and every piece of trim, molding, switchplate, etc has to be custom-refit to the new wall surface. I considered and discarded that idea for my house.

Hope this was helpful.

 

<div class='quotetop'>QUOTE(barbaram @ Feb 11 2007, 01:15 AM) [snapback]388367[/snapback]</div>

The ideal approach is injected urethane foam. High R value, easy to inject through small holes, expands to fill voids that cellulose cannot, and will "seal" your house from air infiltration so well that you may need to supplement fresh air intake in your HVAC. It's somewhat more expensive than blown insulation, but if you're going to live there for more than 5-10 more years it can pay for itself. It's also a hot selling point if you don't plan to live there. "This Old House" has had several segments on this stuff, and you can probably find more information on their website.

 

Important - In order to make any insulation applied in an attic effective, make sure there is adequate air circulation. If you install insulation and proper circulation doesn't exist, moisture will probably accumulate. Besides rot problems, the insulation will get settled down due to the moisture and render it not as effective. This will hugely affect the efficacy of the insulation in a negative manner.

Also, if your attic doesn't have a lot of insulation to begin with, maybe you want to have a contractor come out to check on the condition of your attic before laying the insulation. In this way, your attic won't be buried beneath a bunch of insulation and then you find out you out you have a problem.

 

Be careful with that expandable foam. It...expands. If it's not done right you can explode your walls.

I know my windows are the main weak point now. What I wanted to do was keep the windows and replace the sash cords and weights with a sash kit. There is one manufacturer I've found that has them so you can retrofit your original windows. He doesn't have a trained contractor in California and you can't just buy it over the internet. I wanted to do the tilt sash kit route so I could then fill the sash pockets with insulation. That would help with some air infiltration. And the sash kits themselves would also help with air infiltration around the windows. I'm still playing the waiting game on this. I haven't had time to search around to see if anyone else makes a similar product that will sell it to me. I saw this demonstrated on a house on the east coast on one of the DIY shows at least ten years ago and I said "that's it!". I guess they don't figure there's enough of a market for it in California.

Available in 1994 but still not in California.

This is the guy. They're still NOT in California.

I really don't need the glass. It's the jambliners with the tilt sash I need. Then I can insulate the pockets. I can't believe I can't get this without buying a whole new window. Which I won't do.

BINGO!
I think this will do it for me. Looks like I'll need to learn how to use a router. About time I guess. If I can hang a slab door, I can retrofit my windows for tilt sash jambliners.

Here's another.

Okay. Now I'm not so sure. Maybe I should look into putting, maybe 1 inch foam core insulation into the pocket that will still allow the weights to move. Maybe it will be a mistake to cut the windows and put in vinyl liners. My windows aren't loose and don't rattle, so I'm not sure they are bad enough to warrant the expense (about $200 per) of redoing the jambliners for all. Sure it will make them easier to clean, but other than that it might be a mistake if I have to replace the liners every 10-15 years. And when I can't get replacements, I'd have to replace the entire window. Maybe I'd better leave well enough alone. Charts and stuff.

 

<div class='quotetop'>QUOTE(Godiva @ Feb 11 2007, 11:24 AM) [snapback]388524[/snapback]</div>

Do you actually use much energy to heat your home? I rarely have my heater on, and I'm up in Oxnard (near Ventura), which is usually quite a bit cooler than San Diego. I would think the payback for the home improvement would be expressed in decades rather than just years. I think our gas bill last month was $60.

If the environmental concern is your major concern, switch to auxiliary heating with electric heaters for those few days you need to do so. Electric heat is 100% efficient, without any local gas being produced (it is produced at the electric utility, of course). The extra cost of electric heat wouldn't start to approach the home improvement cost for many, many years.