Roof Vs Ceiling Insulation

See the department of energy s doe ranges for recommended levels of insulation below.

Roof vs ceiling insulation.

Unless in air conditioned attics insulation is typically installed on the ceiling plane not on the sloped roof assembly. For example cathedral ceilings built with 2x12 rafters have space for standard 10 inch batts r 30 and ventilation. Looking upward through the open ceiling if the exterior wall and roof deck assemblies both contain spray foam then a continuous insulation and airtight layer is established from the base of the walls to the peak of the roof. It s more effective and easier to install insulation on the attic floor than in the roof assembly.

A very energy efficient enclosure results. Typical recommendations for exterior walls are r 13 to r 23 while r 30 r 38 and r 49 are common for ceilings and attic spaces. Wall insulation is not suited for use in a ceiling cavity space and wall insulation r values would not be adequate for your ceiling area. If you do need to install insulation in the roof assembly take into account some rules.

Ceiling insulation sits on top of your ceiling plasterboard whereas roof insulation also known as roofing blanket sits directly against the underside of your metal roof. Insulating in and around your roof attic space also prevents long term damage from moisture build up or ice damming which results from the warm air trying to escape through the apex of the roof but instead heating up the snow. Water is insulation s enemy. Unvented hot roof design cathedral ceilings are also an option.

Check behind knee walls which are walls between living spaces and the garage or attic. Image courtesy of d7 spray foam insulation houston tx. Check garage walls and ceilings that are adjacent to conditioned spaces. The highest r value that wall insulation reaches is an r2 7hd however we recommend a minimum of r4 0 for ceiling insulation.

Box out light fixtures. The hot roof design allows more insulation to be installed in the roof cavity as the need for a vent space is eliminated. Additionally insulation serves as a way to enhance sound proofing on the uppermost envelop of your house. While ceiling insulation is a simple job for a diy er s new or existing build roof insulation can only be installed during the construction of a new roof.

Exterior walls and floors. Look for water stains on the roof sheathing or damp or moldy spots on attic joists and existing insulation as a clue to where leaks might be.