Old House, no insulation, interior plaster removed...what to do?
Old House, no insulation, interior plaster removed...what to do?
(OP)
I am working on an old house in Oakland, CA which was damaged by fire several months ago. I am designing a new roof and will be doing the interior as well. THe problem is, the client demo'ed the interior down to the studs and there is no building wrap between the studs and the siding as one would see in a newer house in CA. There was also no insulation in the walls. We will be completely re-drywalling the interior.
I am trying to figure out the best way to insulate the walls and need to know what to do in terms of vapor and moisture control. Options I am considering include...
1) leave the walls the way they are and use batt, foam or cellulose insulation.
2) paint the interior of the walls/studs with an elastomeric paint such as Henry-BES, then use insulation.
Any ideas?
Primary concerns are that the house breathes, does not pull moisture into the walls and does not cause any damage that can be traced to the remodel.
I am trying to figure out the best way to insulate the walls and need to know what to do in terms of vapor and moisture control. Options I am considering include...
1) leave the walls the way they are and use batt, foam or cellulose insulation.
2) paint the interior of the walls/studs with an elastomeric paint such as Henry-BES, then use insulation.
Any ideas?
Primary concerns are that the house breathes, does not pull moisture into the walls and does not cause any damage that can be traced to the remodel.





RE: Old House, no insulation, interior plaster removed...what to do?
The only place to apply a water vapor membrane is immediately behind the drywall. That's why fiberglass has the foil or kraft paper; those are vapor barriers.
Painting the interior stud cavities with elastomeric would not be a good idea since it would seal in the water vapor.
RE: Old House, no insulation, interior plaster removed...what to do?
So then, what is the best way to seal the house against air drafts without creating a larger problem with water vapor?
RE: Old House, no insulation, interior plaster removed...what to do?
Unless the exterior is to be removed/replaced. In that case you could apply building wrap before the siding.
Fiberglass batting is quite popular, and I use it, but I think it's weakness is effective draft control.
You mentioned foaming the stud cavities. I think it's a nifty idea, but it's not mainstream.
RE: Old House, no insulation, interior plaster removed...what to do?
If you want to stop drafts AND water vapor, that's what plastic sheet is good for, but you cannot have plastic sheet between the insulation and the outside conditions.
The junction of insulation and outside condition (winter) is colder than the junction of insulation and living space. So.....if the vapor barrier is at the insulation/outside junction, there is an excellent chance that the warm moist air of the living space will migrate through the insulation, be stopped by the vapor barrier, and accumulate as moisture.
The above behavior can be seen on the windows of your automobile. In winter, the fogging will be inside the auto, when only the heater is running (A/C usage would dehumidify, and screw up the effect) . You may also see fogging of your auto's 'vapor barrier' on a summer evening, if you have the air conditioner sending the chilled air directly onto the windshield. In the summer, the fogging won't be on the inside, it would be on the outside.
I had the experience of growing up in an old house without double-glazing. Nothing like watching ice build up on the inside of a window to understand that air contains moisture. You more 'fortunate' types may have difficulty comprehending the dynamics of vapor barriers.
Also, sleeping in a sleeping bag in winter is another excellent demonstration of water vapor. Inside the bag, everything is fine, the insulation (sleeping bag) is doing it's job. However, as the vapor migrates though the insulation, it passes through colder areas, and may eventually condense, and perhaps freeze. The outside of the sleeping bag may become rigid from the ice.
RE: Old House, no insulation, interior plaster removed...what to do?
Too bad they don't have anything that means something to anybody else!
RE: Old House, no insulation, interior plaster removed...what to do?
RE: Old House, no insulation, interior plaster removed...what to do?
RE: Old House, no insulation, interior plaster removed...what to do?
Just as in cold climates insulation keeps heat in, in warm climates it also keep heat out. The two most widely used types of insulation are rigid and fiberglass batt. Each has it's own positive attributes and applications. Don't go with blown-in insulation. In my opinion this stuff is simply one way for someone to get rid of their trash and place it in your walls.
If you use batt insulation use a vapor barrier. The trick is to not allow moisture to develop within it, otherwise it's useless. The location of the dewpoint must not be within the thickness of your insulation. The way to do this is simply by installing a vapor barrier with proper joint preparation, lap and tape, even eletrical boxes. This done the only way for moisture to escape is at the holes in your structure, i.e. windows and doors. Make sure these are good quality and have a thermal break.
You don't want to make a building that is too tight though. Because then too much moisture can remain and condensate on other interior surfaces. Air quality can then also become an issue (mold spores, mildew, etc.) when a regular exchange of air is not taking place.
I wouldn't advise anyone of putting leaves or any other combustible material within the interstitial space of a wall. Check your local or state building code to see what are acceptable materials for insulation.
RE: Old House, no insulation, interior plaster removed...what to do?
Forced air heating/AC will take care of excess moisture accumulation if properly designed. It is of paramount importance to properly design the heating/AC system to keep interior humidity to around 55%. If the dwelling does not have forced air heating/AC, I suggest spending the dollars to install a properly engineered system above all else. A properly designed system can handle excess infiltration, summer or winter. Oakland, CA has relatively mild weather year round, I do not think that it would be important to provide vapor barriers or limit infiltration. Dollars would be wasted that could be spent much more constructively. The key here is human comfort year round and as such make that the goal through research.
I routinely design these systems in existing and new construction, infiltration ranges from extremely tight to almost barn like. Proper design can accomodate ALL conditions.
If you would like more info let me know. I have a wealth of information and knowledge I will share.
RE: Old House, no insulation, interior plaster removed...what to do?
RE: Old House, no insulation, interior plaster removed...what to do?
http://www.wfionline.com/Icynene%20Insulation.htm