Insulation Surprise on the Davenport Restoration

[pharding]

We encountered an insulation surprise on Davenport last December that I am going to share with the group. We had a plaster wall that had issues and had to be redone. In the course of redoing there no choice but to take the plaster down to the wood lathe. This was a wall where we left the original plaster, re-anchored it, applied plaster on top of it. A subcontractor blew in insulation into the cavity.

When we opened up the wall I was amazed that the blown insulation had filled only about 75% of the cavity space. The blown insulation would get hung up in some locations and a bottle neck created stopping insulation from filling the entire cavity. Sometimes there was an obvious obstruction. Sometimes there was no apparent reason other the insulation just clumped together.

In the future we are going to have thermal imaging done after blown insulation is installed as a quality control check. If there are issues, then the subcontractor will need to be fix them before he/she is paid in full.

[JSL]

Common problem with blown-in insulation. Happens more fequently than people know.

[RA]

Probably a huge opportunity for another product to be developed especially with government funding for efficiency and the current push to go green. Balls or pellets would be less likely to get hung up...

[Laurie Virr]

I have has some experience during the past few years, when working on alts. and adds., of using polystyrene balls of the size used in bean bags to fill the cavities between the two wythes of external brick masonry walls.

This followed meeting a man who wrote his doctoral thesis on the flow characteristics of polystyrene balls. His experiments demonstrated that the bean bag balls behaved in a similar manner to water, and having had the masonry walls I was involved with subjected to infra-red photography, I was able to confirm his claims. The cavities were completely filled.

With the top plate bridging the cavity, it was necessary to penetrate it, after which the beads were poured into a large funnel, the spout of which was placed in the drilled hole. Periodically the funnel was removed, and an air line attached to a compressor inserted, just as a precaution. Care was taken with the flow of the balls into the funnel, so there was minimum wastage as a consequence of the material being blown by the wind.

[Oak Park Jogger]

How about the sprayed foam insulation that has been used on This Old House projects several times in the last few years? It has generally been used when walls are opened up, I recall, and I've wondered if it would work when the wall isn't open.

[pharding]

My concern about foam insulation is the possibility of creating exterior walls that can't breathe. I didn't even use a vapor barrier in the exterior walls of Davenport because of concerns about trapping moisture within the walls.

[DavidC]

On the most recent episode of 'Ask This Old House' (i.e. - yesterday) I believe they said you can use a more liquid, slower setting form of the open-cell version of spray foam insulation in existing wall cavities.


David

[DavidC]

My concern about foam insulation is the possibility of creating exterior walls that can't breathe. I didn't even use a vapor barrier in the exterior walls of Davenport because of concerns about trapping moisture within the walls.

"Open cell foam is more permeable to moisture vapor, with perm ratings of approximately 16 per 3 inches thickness (up to 30-35 perms at one inch). However, the foam allows for a very controlled diffusion of moisture vapor whose consistency can be managed by the builder / architect."

Open-cell vs. closed-cell


David

[pharding]

Without tell anyone my age, I have seen numerous great new construction products fail with time. I like products and strategies that are conservative in their impact on other original historic building materials and are reversible. We did try foaming insulation as a test around an original 1901 window. When it set up it bowed the window frame in the middle. We cut out it all of the foaming insulation around that window. These Frank Lloyd Wright Houses are incredibly unique and special. IMO caution and reversibility are key to preserving them for future generations, future maintenace, and even anticipating future restorations.

[Paul Ringstrom]

There are also two types of expanding foam. High expansion for open walls in a new construction application and a low expansion foam for closed walls in a renovation application.

The problem with foam or any type of blown-in product is the presence of horizontal 2x material in the 16-inch bay cavities. Their locations would have to be identified and marked with an infrared scanner so access holes could be drilled above and below each of these members.

[pharding]

Some of the blown insulation on Davenport hung up without an obstruction.

[TaliesinRed]

Uhhhh.... I LOVE spray in foam insulation BUT IT MUST NOT BE USED AS A WALL RETROFIT in any Historic home as the wall must be built with and for ventilation. If not built correctly the wood framing members will ROT and any masonry will degrade with trapped water. NO NO NO NO!!! Right impulse, wrong material!

[pharding]

I agree completely.