[MassHistPres] Seeking insulation recommendations

[Anne Lusk]

For the roof in my 1820 cottage, the rafters were 4 by 4 and much farther
apart than 16 inches apart.. There also was no insulation.  The roof also
had the original old roof boards which were in questionable condition.
This design for the insulation had been recommended by an architect
friend.  My carpenter took off the old roof sheathing boards and installed
2 by 8's 16 inches apart.  Then, he installed foam sheets 1 inch thick.
These foam boards were placed close to the plaster and cut to fit between
the old and new rafters. From the outside, he installed batts of fiberglass
insulation and the thin pink channels that allow air to flow.  This left an
air space between the roof ridge and the soffit so he was able to install a
ridge vent and soffit vents. The soffit vents really don't show because
they are above the wide gutter.  On both gable ends, I had him install
appropriate simple moulding because the ceiling rafters were wider, which
raised the roof.  I think the ceiling now has an R value of close to 40. It
also has the air space from the ridge to the soffit. On the new plywood
roof sheathing, he put the rubber membrane so I don't get ice dams.

Finally, for a story, I was clueless about ice dams when I bought the
house. When I took down the plaster ceiling in the living room and kitchen
and saw all the water stains on the ceiling beams, I thought the prior
owners, for all those years, must have just spilled lots of water
upstairs.
Anne

On Sun, Dec 5, 2021 at 9:30 AM Garrett Laws <copperandslate at gmail.com>
wrote:

> Recomendation
> 1) Read, read, read and then read some more at
> https://www.buildingscience.com/document-search There are some documents
> with case studies regarding old houses and how they perform and what
> effects insulation have in old houses.
>
> 2) Why do you think you need to reach the minimum R-49? It’s my
> understanding that does not need to meet all of the building code
> parameters.
>
> 3) As “there is no insulation in the entire house” I’d recommend verifying
> that knob and tube isn’t in the house and then check Mass Save to see about
> having wall insulation blown in, there may be a longer discussion about
> this one...
>
> 4) To the attic question I’d go with the following. I would use rigid foam
> sheets cut to fit the bays and install against the roof deck. The whole
> house will have some level of air circulation so I wouldn’t wrap the beams.
> I’d install either pink insulation or rock wool and then I would install
> more rigid sheets on the face of the rafters. I didn’t do the math on the
> different materials but it likely wont get you to R-49 but stopping /
> massively reducing the air exchange will allow the insulation to do the job
> properly.
>
> 5) If you install ridged and then spray foam and eventually want to
> reverse the process OR add living space or a dormer, any area with spray
> will need to be ripped out and then thrown into a dumpster / landfill.
> Installing rigid / pink / rock wool insulation is a process / installation
> that can be disassembled and the materials can all be reused in the future
> build.
>
> 6) See 1) and read, read, read some more.
>
> Garrett Laws
> Copper & Slate
> 781-893-1916
>
> On Saturday, December 4, 2021, Marcia M Wengen <
> mmwe at mmwe.digitalspacemail8.net> wrote:
>
>> New owner of historic property has contacted Stoneham Historical
>> Commission for advice. Any help would be greatly appreciated.
>>
>>
>> Greetings,
>>
>> I’m looking for suggestions to insulate an attic as part of the living
>> space of the building for a 130 year house.  The property is historically
>> designated and as such I would like to avoid using any methods that are
>> non-reversible (i.e., spray foam).  The house is located in Stoneham, MA
>> (climate zone 5) and will require a minimum attic insulation of R-49.
>> There is currently no insulation at all in the entire house and my
>> immediate attention is on the attic space and will subsequently be the
>> basement (walls of floors 1 and 2 will remain uninsulated).  The house is 3
>> stories above grade with an unfinished basement and floors one and two
>> currently livable space.  The attic is unfinished with the roof being
>> constructed as a main gable and two smaller perpendicular gables, main roof
>> pitch is 10/12 with 2x6 rafters spaced 24 inches all throughout.  There is
>> 2.5 foot knee wall around the entire perimeter of the attic with no
>> existing ventilation.  As indicated prior I would like to avoid using spray
>> foam insulation directly on the rafters/roof deck and I’m looking for
>> suggestions on how to insulate the space as I would eventually like to
>> include a portion of it as part of the living area.  A couple of ideas I
>> have though over include purchasing  polyiso sheets of insulation and
>> wrapping each individual rafter and then attaching to the roof deck space
>> in between and subsequently using closed cell spray foam on this assembly
>> to reach the minimum insulation requirement.  I am also open to the idea of
>> building out the rafter and wall space to insert mineral wool insulation
>> and then finishing with a few inches of polyiso sheet insulation/plastic
>> sheet as a vapor barrier but I will admit that this is not my field of
>> trade so I may be wrong in my thoughts.  Any help will be greatly
>> appreciated and if necessary I can make myself available for discussion.
>>
>>
>> Marcia M Wengen Co-chair
>> Stoneham Historical Commission
>>
>>
>
>
> --
>
> Many Thanks,
> Garrett Laws
>
> www.copperandslate.net
> The Copper & Slate Company, Inc.
> Fine Roofing and Historic Carpentry
> 238 Calvary Street,
> Waltham, MA 02453
> (781) 893-1916
>
> *LEAD FREE SINCE 2008*
>
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