Old house walls
LeoPaul
| Posted in General Questions on
So I have a 120 house with plastered walls. The balloon framed walls have no insulation, no tyvek, just won boards cover with stucco. Eventually we want to replace the stucco with hardy board. But with an estimated cost of $40k, it’s not at the top end of the wish list.
There are some rooms that are pretty uncomfortable. Insulating a ballon framed house without air barriers etc, may not be the way to go. So I was thinking of framing over the existing walls, spray foaming and then drywalling. Is this a viable option?
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L. Philip,
Q. "I was thinking of framing over the existing walls, spray foaming and then drywalling. Is this a viable option?"
A. What does "framing over" mean? You're probably thinking of adding 2x4 framing on the interior side of the existing walls -- not on the exterior side. Am I right?
The basic issue here concerns how far you are willing to go with this retrofit approach. If you really want to improve the situation, you need an air barrier in addition to insulation (R-value). The spray foam provides both, but the air barrier needs to be continuous -- which means that you need a plan for partition intersections, as well as a plan to continue the wall air barrier up to the ceiling or roof (with no discontinuities in the air barrier ) and a plan to continue the wall air barrier across the floor -- which raises questions about your foundation type.
Martin: Yes this is for the inside. However since I’m not gutting the interior. Each room has plaster walls and a ceiling. I know the walls are plaster but the ceilings are drywall.
The plaster walls are pretty good in that it doesn’t allow any air in. However, the walls are about 10 degrees hotter in the summer and 10-15 deg cooler in the winter at night. Unfortunately I have to heat/cool two floors to make the two rooms in question, manageable.
L. Philip,
To create a continuous air barrier, you can't depend on the fact that "each room has plaster walls and a ceiling" and that "the plaster walls are pretty good... [and don't] allow any air in."
At each partition intersection, air can leak into or out of your house. Air can also leak through electrical boxes in your partition walls, and escape through cracks between the partition top plates and the plaster.
Creating a continuous air barrier is tricky, and would require some plaster demolition if you want to perform the work from the interior.
So in short, it might be best to wait until take down the stucco, air barrier and insulate from the outside? I want to minimize inside demolition since I have young kids and older parents in the house.
There is no need to take down the exterior stucco if you are re-siding. You can cut holes in the outside, dense pack cellulose or fiberglass install a WRB and re-side.
If you don't mind "fake" stucco, going with EIFS is a pretty good deal in energy efficiency as it is installed over rigid insulation.
With a real 2x4 ballon framed house with dense pack wall, with EIFS on 1.5" of rigid insulation you would end up with an R20 overall wall. With the air sealing form the dense pack+rigid insulation, that is a way better wall than what you have right now.
We don’t have a stucco issues like so many of the horror stories. No moisture issues etc. But my contractor said it best for us to take off the stucco before we go Hardy. Which happens to be a major pain and is expensive.
We have old school wood planks under the stucco. But if I can wrap over the stucco, rigid insulate and hardy plank it. I think I could save some money and have great insulation.
FYI...I’m in the south Jersey region, will I have any long term moisture issues if I do this? Assuming it down right.
L. Philip,
It's also possible to drill holes in the interior plaster, and to install dense-packed cellulose through the holes. The plaster can be patched after the insulation job is done. That would probably be less disruptive than framing new 2x4 walls on the interior and installing spray foam, as you first suggested.
I did think about that. But I read one of the articles on this site that suggested not doing that since these balloon framed old houses with no house wrap needed to breathe.
L. Philip,
You can't have everything. You seem to want a solution that is inexpensive, not disruptive, and ideal from a moisture management perspective. That's impossible.
If you want housewrap, you have to install it.
The world is filled with cake wanters and cake eaters. If Akos’s Solution works it should cut down the cost of the siding bid which included a steep up-charge for taking out the old stucco.
I’m paying up for it either way. I might as well pay the premium to prevent further issues down the road.
Thank guys, you gave me material to challenge my contractor to think about his bid.
You can install the lap siding over the the stucco, I don't see how it would be any different than going over cinder block. The only downside is that if your stucco is too uneven, you will have to do a bit of shimming on the strapping to have the siding not be wavy.
You will might have to do a bit of demo work around your windows to flash them out. Properly flashing your windows/doors is a step CAN NOT skip.
In your area to should aim for at least 1.5" of rigid insulation on the wall for condensation control since there is no interior vapour barrier. If you can get a permeable insulation such as EPS or non foil faced polyiso, it will help with drying to the outside, makes a more robust wall.
Thank you! I’ll keep you posted.