[Minotaar]

Hi,

First post - a question. Apologies for being clueless; I was not able to find an answer via searching the forum.

I'm house shopping in an area with lots of old stone and brick houses (100-150 yrs old) that are drafty and energy inefficient. Can these homes be made airtight without using spray foam and without removing the wooden framing?

Is it possible install foam panels between and inside the framing, creating thicker walls but achieving airtightness and greater R-value? Wouldn't that trap the wooden framing in a cold and moist space between the (Taped) foam panels and the stone wall, creating a mold risk?

Can rigid foam panels be installed between joists using spray foam at the edges, to minimize the use of spray foam and still achieve some airtightness?

 

[SeniorSitizen]

Wouldn't that trap the wooden framing in a cold and moist space between the (Taped) foam panels and the stone wall, creating a mold risk?

In my opinion, yes it would, but let's wait for the experts to tell us how they will keep the wood or any organic material in that area less than 12 percent MC ( moisture content by weight ) or less to prevent mold and possibly Lichen.

 

[Windows on Wash]

The short answer is yes. Where is the home though (in terms of climate).

The potential problem with your interior foam option is that the outer edge of the stud of sheathing because much colder and can be location of the condensation which creates the exact opposite effect you are going for.

You have also changed the way the wall can dry out with interior foam. If the bulk of the moisture in the air was from the home, that isn't as problematic.

 

[Minotaar]

Thank you both.

The house will be outside of Philadelphia; It gets cold and it gets hot. We're in Climate zone 4.

 

[Windows on Wash]

What is the wall construction in terms of layers?

 

[Minotaar]

What is the wall construction in terms of layers?

Well, I am looking at a number of houses, and I have not opened them up. Most are constructed around 1900, some before some after. I guess if I knew the exact layers of construction, my question would be easy to answer.

The typical house is stone or stone/brick and has reasonably thick walls. They appear to leak air. Energy costs are generally high - 400-600 dollars/month.

My question is just that if you have a stone wall house, you obviously cannot go through the stone to put in rigid foam insulation. So unless you want to take the frame out also, you have to go between joists and on the inside of the frame - but can that even airseal a house?

 

[Windows on Wash]

The first thing to do would be to air seal and insulate the ceiling plane as well as any gaps/cracks and a crawlspace retrofit if you have one.

Beyond that, when you get into wall modifications (again...still need to know the specific construction in terms of layers and how it currently directionally dries), you can create some issues if you aren't careful.

Air seal and insulate is first and even doing that will make the walls work much better from the outset.

 

[Minotaar]

How do you air seal an existing stone house? If it dries outwards, I suppose you can seal from the inside; if it dries inwards do you have to seal against the stone, using something like spray foam?

 

[Windows on Wash]

Still need to know what the Wall layers are in order to be safe. It's very possible that dense packing cellulose is an option, but we really need to know what and how the wall is constructed.