Isolating rake wall cavity from ceiling cavity
Houghton123
| Posted in Construction Techniques on
Homeowner/weekend worrier converting a shed I built some years back into a workshop with finished walls. Simple gable roof. Cathedral ceiling (my sweetie finally gets a space with a cathedral ceiling), with 3″ of sheet foam insulation in a 2×6 rafter bay and 2-1/2″ of ventilation space above the foam; each rafter bay will be ventilated at the soffit, with a ridge vent on top.
The rake walls are built on top of standard double-top-plate walls. At the moment, there’s no barrier between the rake wall cavities and the adjacent ceiling cavity. Is it necessary/desirable/code to install 2x stock in a manner that isolates the rake wall cavities from the ceiling cavity?
Replies
In residential construction...
A wall must be seperated from the ceiling with a min 3/4" of wood, or sheetrock. Likewise a floor system must be seperated from walls. If holes for wires, etc are pored in the wall's top plates or bottom plate these must be caulked with fire-stop caulk or other approved material. So, in your case you should probably add some 2x? blocking at the top of the rake wall. The idea is to prevent a fire from "racing" through the structure by easily traveling from floor system to walls, and then from the walls to the ceiling/attic. It's kinda building 101.
Of course, what you are doing isn't really residential construction, although it would probably be required if you have it inspected. Some of it may depend on where you live, what the local code requirements, or more specifically if the inspector is "on the ball.
I'd do it regardless just as a good general practice..
A little off your subject, but does your foam ceiling insulation fit tightly between the ceiling joists/rafters?
The plan is to cut the foam to fit pretty tightly, and then foam it in place with expanding spray foam before sheetrocking.
your welcome.
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