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Simple insulation, attic roof structure
A single Isoflect reflective membrane, installed beneath the rafters, in strips perpendicular to the rafters, with the joints sealed with adhesive tape.
Technical content: Bogdan Ivănescu, graduate engineer, PhD candidate at the Technical University of Cluj-Napoca · updated on 17.10.2026
One membrane, staples and adhesive tape
This is the simplest insulation for the attic roof structure: a single Isoflect membrane, unrolled beneath the rafters, from one rafter to the next. The strips are fixed with staples to the rafters and butt-jointed, and each joint is sealed with Power Tape.
Perpendicular to the rafters
The membrane is unrolled from the eaves towards the ridge, across the rafters, from one rafter to the next.
Staples on each rafter
Each strip is fixed with staples to all the rafters it crosses.
Joints with Power Tape
The strips are butt-jointed, and the joint is covered with Power Tape, pressed down completely, with no air beneath the tape.
Installation steps
Click on the central image to enlarge it.
Products for this application
Frequently asked questions
Is anything installed between the rafters?
No. In this application a single membrane is used, installed beneath the rafters.
How are the strips joined?
Butt-jointed, without overlap. Each joint is sealed with Power Tape, pressed down completely along its entire length.
What is the membrane fixed to?
With staples, to each rafter, along each strip.