On Top Of Roof Insulation

Insulated roof assemblies can be vented or unvented.

On top of roof insulation.

The later is used in new construction as the interior board serves as an inner wall. Most home and business owners opt for rigid foam on top of roof sheathing because it makes the most sense and it s an eco friendly solution. Rigid foam board is just above the roof deck or an exterior insulation option. Hack n stack sealed foam board between the rafters would be better since it s at least an air impermeable insulation but even that would require a vent gap below the roof deck to meet code and you d still be under r38 on that 2x6 rafters unless you fattened it out per holladay s recommendation.

By including a layer of stone wool insulation within your roof system your building will benefit in more ways than one. However most cathedral ceilings and low slope flat roofs are insulated roof assemblies. One of the most efficient and popular methods though is to install rigid foam insulation on top of roof sheathing. Bare foam board one sided sheathing board or double sided which is also reference as structural insulated panels.

The 6 inches of rigid insulation added to the top of the existing roof deck needed to be done in a manner that was invisible. Calculate the total square footage of the roof to determine the number of insulation boards you need to complete the installation. The ratio of insulation above the roof deck or air permeable insulation below the roof deck is a matter of climate and interior conditions. Measure the roof with a tape measure.

Insulation above the roof deck or air vapor impermeable insulation below the roof deck is needed for condensation control in an unvented roof. This will be a lot more expensive but will give you insulation value of about 18r and white pvc will reflect upto 95 of solar heat. The trim the frieze boards the fascia and the overhangs all had to look like they belonged. Another option is to install polyiso insulation about 3 thick on top of metal and do a pvc roof on top.

They had to look original. The easiest way to increase the value of your roof assembly is to insulate the insulation with a hybrid roof system. Introducing a stone wool roofing insulation and coverboard in one. It makes the most sense and preforms the best under most conditions.

A roof over a vented unconditioned attic does not need to include any insulation.