Replies

1. 
   Norman | May 08, 2009 05:30pm | #1

   Your going to hear from people who know a lot more than I do, but:

   sheath the wall and blow in celulose or rock wool, or

   buy sheets of foam insulation, cut to fit the void between the studs and seal with foam like Great Stuff.

   Either option is apparently superior to FG. The foam option will stop air infiltration.

   Good luck.

2. 
   rdesigns | May 08, 2009 05:34pm | #2

   From the inside, cover the exposed siding surface between studs with Tyvek or other air barrier (NOT polyethylene sheeting for fear of creating a condensing surface.) Caulk the perimeter of the Tyvek where it meets framing. Then insulate with craft paper-faced FG batts.

1. 
   peedee | May 08, 2009 10:04pm | #3

   This is what I was thinking; have you done this yourself before? And in which case how do you feel about the results?
   Thanks,
   David

1. 
   rdesigns | May 09, 2009 03:18am | #4

   You got me there.

   No, I've not actually done it. My comments were the result of arm-chair research. (Read: sitting on my butt, thinking about it.) But, I believe the suggestion is based on sound principles, such as those found in Building Science.

   You want the wall assembly to maintain its drying potential, both from outside moisture, and inside moisture. You also want to reduce/eliminate air movement in and out of the assembly. Thus, Tyvek on the outer side, and craft paper on the inside. Tar paper on the outside would do the same, but Tyvek is probably easier to work with. (I don't know if it's cheaper.)

1. 
   peedee | May 09, 2009 06:05am | #5

   Thanks, likewise I came to the same conclusion in the same manner,m sittin'n'thinking. Since we're not stripping the outside (and hence have the opportunity to sheath and wrap the house properly) this will likely need to suffice, unless someone suggests a better idea.
   David

2. 
   DanH | May 12, 2009 07:53pm | #10

   I've heard this proposed a lot, but I've got to question how practical it is. You've got wires in the bays, and sometimes pipes. If the house is sheathed in wood then often the siding is nailed on with nails in random places, penetrating the sheathing and creating a bed of nails for the Tyvek.I'm sure it can be done, with enough effort, but I'm skeptical of how easy it is to do an get a decent seal.
   The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith

3. 
   cargin | May 09, 2009 03:42pm | #6

   	peedee I would do one of the following #1.  Cover interior walls with 3/4" XPS (dowboard) seal edges with foam and seams with Tyvek tape. Then blow cellulose insulation. Cover with sheetrock and use 2" screws. substitute FG only if you have to. #2.  Fill cavities with 2 "and 1.5" XPS and foam the edges (leave a 3/8 gap on sides it will make it easier to foam) #3.  Do #1 with 2" XPS and add 1x3 furring strips for hanging drywall Picture is 2" XPS over old lath with cells in walls, I did ceiling and walls. Steel plates over wires. Rich View Image

4. 
   DickRussell | May 09, 2009 06:08pm | #7

   I'm concerned about the suggestion to apply pieces of housewrap against the exposed siding from inside. The intent is good, to keep rain leakage out of the cavity. If the wrap had been applied before the siding went on, it would be continuous. Doing it now, piece by piece, will result in a gap in the wrap at both sides of every stud, and that is where your leakage could occur.

   Then there is the almost certainty that the windows and doors were not flashed correctly on installation. How do you integrate flashing with a secondary drainage plane that isn't there?

   If your part of CA doesn't often see rain with wind, you may be OK with the proposed patching in of housewrap. Otherwise, for peace of mind, you should consider swallowing the cost of removal of the siding, proper application of wrap, flashing all the windows correctly, and reinstallation of siding.

1. 
   DanH | May 12, 2009 07:57pm | #11

   The purpose of the housewrap isn't to prevent rain leakage -- that's a secondary benefit at best. The idea is to prevent air infiltration.When properly installed housewrap can do an amazing job of preventing air infiltration in conventional construction -- reduce it probably 80% relative to the same construction without the housewrap. (Of course, there are unconventional ways to reduce infiltration, but we're stuck with conventional construction here.)
   The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith

1. 
   DickRussell | May 12, 2009 08:34pm | #12

   "The purpose of the housewrap isn't to prevent rain leakage -- that's a secondary benefit at best."Then we must differ on this. I think most will argue the reverse, that the wrap - or secondary drainage plane, aka WRB ("weather-resistive barrier") is essential from a building science point of view. It is understood that wind-driven rain can get behind almost any kind of siding under some circumstances. Not having the wrap, in the form of plastic wraps or simple asphalt felt, is inviting water into the wall.First priority is always keeping the water out of the wall. Reducing air infiltration is secondary. I agree that the wrap can be effective for that as well, if detailed properly. Most of the time the wrap installation misses some of the critical areas for air leakage, such as under the sill. Typically the wrap stops at the bottom edge of the sheathing, leaving air a free pass to sneak in at the sill, between sheathing and framing, and between sheathing and wrap. It's always the edges where the leakage is worst.There are other ways to create an air barrier, particularly at the inside of the cavity, using the airtight drywall approach (ADA). I wonder if getting the drywall installer to do that correctly is any worse than getting someone else to detail the housewrap correctly.Edit: I went back and read my post (#8). If what you mean by the use of wrap stopping rain leakage being secondary to air blocking is that in the OP's situation the pieces of wrap would be applied to the inside, between studs, then I wouldn't think wrap applied that way would be of much help at all against water leaks. But I don't see how application of pieces of wrap will help much against air leakage either.

   Edited 5/12/2009 1:43 pm ET by DickRussell

1. 
   DanH | May 12, 2009 09:16pm | #13

   I am quite confident when I say that housewrap was originally invented as an air barrier, back in the 70s. There is no obvious need for it as a secondary rain barrier in much of the US, including here.
   The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith

2. 
   DanH | May 12, 2009 09:18pm | #14

   Also, if fiberglass batts are used, air sealing on the inside surface does not effectively prevent the degradation of insulation efficiency that can occur due to infiltration.
   The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith

1. 
   DickRussell | May 12, 2009 09:37pm | #15

   I won't dispute the claim that the original intent of plastic wrap (Tyvek) was for air barrier. I think I read that somewhere as well. Before that, tar paper was regularly used, and some advocate its continued use. I refer to Paul Fissette's (sp?) papers out of U.Mass on the performance of various WRB materials. There is need for both WRB under the siding AND an air barrier in much of the US, particularly the heating-dominated areas. They can be the same material, if installed correctly, but they can be separate.Doesn't it rain in MN? Would you build a house without a WRB under the siding? Would your BI pass on a house without it?I agree on the effectiveness, or lack of it, when you have air movement through a FG batt. It is generally understood that optimum performance of FG as an insulation is attained only when contained all around. FG is generally a low-end insulation for much of the US.

2. 
   DanH | May 12, 2009 10:05pm | #16

   The code apparently requires housewrap (a la Tyvek) or equivalent. I don't know if they say why. I do know that when we resided our house (built before this requirement) there was no sign of rain penetration through the original siding. (Of course, "permanent" siding is a whole different ball of wax -- it likely needs the rain barrier.)Prior to the advent of Tyvek common practice here was to put nothing behind the siding (when using fiberboard sheathing). I think tar paper was often used behind the siding on wood sheathed homes, but the purpose would have been primarily to serve as a wind barrier.Remember, there's not much other than barbed wire fences to stop the wind between us and the North Pole.
   The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith

5. 
   MadisonRenovations | May 12, 2009 04:04pm | #8

   I don't know about cost, but check out:

   http://www.rhhfoamsystems.com

   It's a DIY foam system, and they have high density product they say is 98% closed cell. The canisters are disposable after you're done. I haven't used it, but it seems interesting. I think high density foam is the way to go, but I had mine professionally done. No worries about infiltration, moisture/mold, which side to let breath, etc. plus it's R-7 per inch.

   ---mike...
   Madison Renovations
   Cambridge, Mass.

6. 
   mmoogie | May 12, 2009 04:46pm | #9

   The foam guys in my area charge by the board-foot regardless of the total area sprayed, so I could have them out room-by-room and it would cost no more than doing the whole thing at once. You may want to check with your vendor to see if they operate the same way or if they add a per-trip setup fee, and if they do, how much it is. If you can afford the foam, it'll give you the best performance. And if you can afford the foam on a whole-house basis, then you can most likely afford an extra setup fee on a room-by-room basis, as it will probably be a drop in the bucket as compared to the coast of the foam itself.

   You don't say if you house has sheathing behind the claps or not. If there is sheathing, even just board sheathing, then don't worry about the house wrap or rigid foam. Just blow dense-packed cellulose and be done with it. Do a search on dense-pack cellulose here, and you will have more information than you need.

   Steve

1. 
   peedee | May 13, 2009 01:20am | #17

   Thanks for the thoughts. No, there is no sheathing, hence the big concern and experience with AirInfiltration. I considered dence-packed-cellulose, too, but again on a room by room it's a lot of overhead for setup. But I'll check into the previous poster's suggestion regarding cost-per-foot with no setup fee from an installer/ vendor(s) as well as the DYI kit mentioned.

   Regards,

   David

7. 
   jonblakemore | May 13, 2009 05:51am | #18

   I would look at a froth pack (DIY spray foam) first. I doubt that you will get any insulator with a spray rig to come out and set up for much less than $1k, but I've been wrong before.

   With whatever you do, your moisture control will be very important. Maybe I missed this, but does the house have sheathing, or is the lap siding directly applied to the studs?

   *edit- I now see that the house does not have any sheathing. I would search high and low for any evidence of moisture problems in the past. Even if you don't find any, this may just mean that the moisture dried out (no insulation, lots of air movement to promote drying) before it could accumulate. That's a tough situation to deal with. I'll have to think about it. Does BuildingScience.com have anything to say about insulating against the exterior cladding?

    

   Jon Blakemore

   RappahannockINC.com Fredericksburg, VA

   
   

   ---

   Edited 5/12/2009 10:54 pm ET by JonBlakemore

1. 
   peedee | May 13, 2009 06:07am | #19

   I'll be sure to check for signs of moisture, include historical, as well as the DYI kits. I didn't find anything on Building Science about retrofitting insulation and the pros and cons of each type (not that there isn't something there necessarily) though I'm pretty certain they are supporters of the foam solution also.
   David

2. 
   mmoogie | May 16, 2009 03:42pm | #20

   Jon,I've had my foam guys out at their standard bd/ft rate for a section that was only 300 dollars worth.Steve