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A homeowner renovating a mid-1980s addition in Rochester, New York, reported removing cellulose that had sagged the ceiling drywall and stretched the polyethylene layer. The account describes a vented roof, irregular truss cavities and limited space for insulation, but the source material does not include an expert answer or a confirmed repair plan.
A homeowner renovating a mid-1980s addition in Rochester, New York, has removed cellulose insulation after finding it had weighed down the ceiling assembly, and is seeking a way to reinsulate a vented cathedral ceiling with shallow, irregular truss cavities. The account describes a project-specific building problem, not a published repair decision: the supplied source contains the homeowner’s question but no expert response or confirmed insulation design.
The homeowner said the drywall ceiling had significant sags between the truss bays, including one particularly wide sag. After removing the drywall, they found the cavities packed tightly with cellulose, which had been pressing on stretched polyethylene sheeting. The cellulose has since been removed as the renovation moves toward a new insulation approach.
The roof is described as a vented assembly with a ridge vent and several soffit vents on each side. The homeowner reported finding no ventilation baffles and suspects the airflow may not have worked well, but the source does not document measurements or an inspection establishing how the roof performed. The sheathing is a mixture of old and new material with visible gaps from below; the homeowner reported no active leaks and expects to replace the sheathing during a future roof project.
Space and geometry complicate the options. The trusses have 2-by-4 bottom chords, and the framing depth at the exterior wall is about five inches, according to the account. The homeowner says most bays vary in width, only two are 24 inches on center, and a 42-inch area has no framing because of old skylights. They are reluctant to lower a ceiling that is already about seven feet high at its lowest point and do not consider spraying foam beneath the roof deck a suitable choice given the sheathing’s condition and anticipated replacement.
Shallow Trusses Limit Insulation Space
The reported conditions matter because insulation work in a cathedral ceiling has to fit the existing structure while accounting for the roof’s ventilation and moisture behavior. In this case, the homeowner’s stated constraints include limited framing depth, bays of varying widths, questionable ventilation history and a roof deck expected to be replaced later. Those details make it difficult to treat the job as a straightforward installation of insulation between identical framing members.
The account also illustrates why the earlier ceiling failure cannot be reduced to one confirmed cause. The homeowner found heavy cellulose and stretched polyethylene beneath sagging drywall, but the source does not establish whether insulation weight alone caused the sagging or whether framing, installation, moisture or other conditions contributed. A repair plan would need to address the observed damage and the roof assembly as a whole, rather than assume a single explanation.
For readers planning similar work, the report is a reminder that a proposed material or method cannot be evaluated without details about the roof layers, air movement, framing and local requirements. The source offers no final specification, cost estimate or evidence that any particular insulation strategy has been selected.
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What the Renovation Revealed
The homeowner described the roof as part of a house addition dating to the mid-1980s and identified Rochester’s climate zone as 5A. When the ceiling drywall was removed, the homeowner found tightly packed cellulose, sagging polyethylene and a mix of roof sheathing materials with gaps visible from below. The reported discovery prompted removal of the insulation and a fresh assessment before the ceiling is rebuilt.
The homeowner’s background is in painting and residential renovation, including previous work with rim-joist insulation and mineral wool in wall cavities. They described this ceiling as a more advanced problem, particularly because they want to retain a vented assembly and avoid spray foam. They raised cut-and-cobble insulation and mineral wool as possibilities, while acknowledging concerns about fitting materials around the irregular framing. These are options posed in the question, not recommendations confirmed by an expert.
The supplied GreenBuildingAdvisor material is a reader question with a link to project photos. It provides the homeowner’s observations and preferences, but no dated follow-up, professional inspection findings or construction outcome. That distinction limits what can be reported about the condition of the roof or the appropriate repair.
““The ceiling cavities [were] packed tightly with cellulose, which was weighing down very stretched-out poly.””
— The homeowner, in the GreenBuildingAdvisor question
No Repair Plan Is Confirmed
The source does not say how the ceiling will ultimately be insulated, whether an expert responded, or whether a contractor or building professional inspected the roof. It also does not confirm that the missing baffles caused poor ventilation, that there is no concealed moisture damage, or that the visible sheathing gaps indicate a particular performance problem. The homeowner reports no active leaks, but that observation is not a full assessment of the roof assembly.
Other key details remain unavailable, including the exact truss layout and cavity dimensions, the condition of the framing, the roof’s full layer sequence, and applicable code or permit requirements for the planned work. The linked photographs may show some conditions, but the supplied material does not describe their findings. No insulation product, target R-value, ventilation detail, or construction schedule is confirmed.
Assessment Before Ceiling Rebuild
The homeowner’s next stated step is to determine an insulation approach before closing the ceiling. Because the source gives no confirmed design, the next development would be a documented assessment of the framing, roof deck, ventilation paths and moisture conditions, followed by a plan suited to the actual bay dimensions and local requirements. If the roof is replaced later, the relationship between that work and the ceiling assembly will also need to be addressed.
Until such a plan or follow-up is published, readers should treat the proposed use of mineral wool or cut-and-cobble insulation as ideas raised by the homeowner, not as approved solutions. The source does not establish when the ceiling will be rebuilt or whether the future roof work will change the insulation decision.
Key Questions
What prompted the homeowner to remove the existing insulation?
The homeowner said the ceiling drywall had significant sags and that tightly packed cellulose was weighing on stretched polyethylene below the trusses. The account does not establish that insulation weight was the only cause of the sagging.
Is the roof confirmed to have a ventilation problem?
No. The homeowner reported a ridge vent and soffit vents but said there were no baffles and suspected ventilation had not worked well. The source contains no airflow measurements or professional findings confirming a ventilation failure.
Has an insulation method been selected?
No confirmed method is provided. The homeowner asked about options including cut-and-cobble insulation and mineral wool, while expressing a preference to avoid spray foam and limit any reduction in ceiling height.
What remains unknown about the roof?
The source does not provide a full roof inspection, moisture assessment, exact framing measurements, final insulation specification or schedule for rebuilding the ceiling. The homeowner reported no active leaks and expects to replace the sheathing in a future roof project.
Source: rss
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