Exterior Rigid Roof Insulation

In its guide to insulating sheathing bsc describes the use of exterior rigid insulation board in the enclosure assembly to act not only as insulation but also as the primary sheathing and in certain areas as the drainage plane and vapor control layer for the wall assembly.

Exterior rigid roof insulation.

At r 4 it also has the lowest r value per inch. Rockwool insulating roof boards offer warranties long term thermal performance. Rigid insulation layers exterior to existing roof sheathing must provide sufficient thermal insulation r value to control condensation risk see climate specific guidance. Install nailbase for cladding.

There are at least two good reasons why this approach makes more sense than installing the insulation under the roof sheathing. Nailbase must be vented in high snow load areas. The glass fiber reinforcement contributes to improved fire performance and dimensional stability. Falls in the middle of the three types of rigid foam insulation in both cost and r value used most in walls or below grade applications recyclable and at about r 5 per inch costs around 42 per sq.

The ideal roof there s a reason polyiso rigid foam insulation is used in more than 70 of commercial roof construction as well as in many residential builds. 1 inch and 2 inch thicknesses are common. The boards are available in several thicknesses and r values. Continuous rigid insulation is a construction solution that provides a thermally efficient building enclosure.

No matter the climate zone rockwool stone wool does not shrink and does not lose its r value from install to reroof. All three types of rigid foam insulation expanded polystyrene eps extruded polystyrene xps and polyisocyanurate are suitable for use on the exterior of walls and roofs though they do not perform equally. Eps is the most vapor permeable of the three types. The easiest way to increase the value of your roof assembly is to insulate the insulation with a hybrid roof system.

Thermax sheathing is a non structural rigid board insulation consisting of a glass fiber infused polyisocyanurate foam core laminated between 1 0 mil smooth reflective aluminum facers on both sides. Install roofing underlayment flashing and cladding as per best practices. Rigid foam must be thick enough to prevent condensation on the roof sheathing. For a 1 in thick 4 8 panel.

Rigid insulation sheathing is made of a rigid plastic foam that is typically sold in 4 8 or 4 10 foot boards. Polyiso is an easy cost effective sustainable and energy efficient construction material. There are lots of different ways to insulate this type of roof but one of the best methods calls for the installation of rigid foam insulation above the roof sheathing.