[MassHistPres] Seeking insulation recommendations

[rcsmitharch at verizon.net]

What is driving this?  Is it simply the home owner’s desire to add insulation?  The Massachusetts amendments to the 2018 International Energy Conservation Code, which Massachusetts uses as its base energy code, does not require full compliance with new building requirements.  They allow alterations to include simply filling wall and floor cavities with insulation (N1109.1), as long as the work doesn’t increase energy consumption.  IF the homeowner is trying to get closer to meeting new building requirements, note that the energy code has a proviso that if R-38 insulation can be carried across the top of the wall plate below, R-38 is acceptable for the entire attic.  See Paragraph N1102.2.1.  Batt fiberglas or blown in cellulose is the most reversible approach; cellulose seems better at stopping air leaks.  If the insulation line is at the attic floor, getting the required depths could mean filling above the existing floor, with added raised walkways to accommodate access to mechanical equipment.  If the attic is to be finished, it probably means framing under the roof rafters to create adequate depth for insulation.  Old attic floors often do not provide for modern floor loading requirements, and joist depths are shallower than they would be today.

 

In existing buildings, the code requires that the available wall and ceiling cavities be filled with insulation with a minimum R value of 3.5/inch, which cellulose can satisfy.  Before adding any insulation, make certain that there is no active knob and tube wiring in the wall and ceiling cavities, as this can present a fire hazard when surrounded by insulation.

 

Richard Smith

Swampscott Historical Commission

 

From: MassHistPres <masshistpres-bounces at cs.umb.edu> On Behalf Of Marcia M Wengen
Sent: Saturday, December 4, 2021 3:05 AM
To: masshistpres at cs.umb.edu
Subject: [MassHistPres] Seeking insulation recommendations

 

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 
 

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