How to Install MBI
Recommended Installation Methods
Roof insulation rolls are cut to lengths that will cover the distance from eave to eave, leaving a one foot overhang on each side of the building. Occasionally more than one roll may be needed to cover the entire roof, at which point it is common practice to make a splice at a point nearest the ridge.
- Start at the end of the building and temporarily secure one end of the roll by attaching the insulation to the eave strut with double-faced tape.
- Pull the insulation across the purlins with the vapor barrier toward the building interior. Double-faced tape attached to the opposite end of the insulation will keep tension on the roof roll while the metal panels are being attached over the insulation.
- Install the next roll in the same manner, making sure the rolls are stretched tight, aligned properly and closely butted.
- Fasten tabs using one of the methods described on the following page. Any rips or tears must be covered with matching facing tape to ensure a tight vapor seal.
- Trim excess insulation flush to prevent it from acting as a wick and moving water into the building.
R-30 Banded System Installation Diagrams
CMI will usually pre-cut wall pieces to length, rolling multiple cut pieces together into one roll. The label will indicate the length and number of pieces. If the pieces are not pre-cut, we recommend that all rolls be cut at a clean location to avoid staining the insulation facing.
- Cut the dimensions of the insulation from the base angle to eave strut or rake, plus 6″-12″ extra.
- Attach one end of the insulation to the base angle using double-faced tape.
- Pull from the other end to stretch the insulation tightly outside the girts to the eave or rake, and attach with double-faced tape.
- Make sure the facing is toward the interior of the building and attach the panel to the structure.
- Install the next roll in the same manner, with edges butted snugly. Then fasten the tabs using one of the methods described.
Most facings are 6″ wider than the laminated fiberglass. This extra facing usually consists of two 3″ tabs or one 6″ tab, each of which requires a different method of fastening. It is advisable to use a starter roll for any method so that the insulation is 12″ wider than the metal panels. This prevents you from having to work directly at the panel edge when folding and stapling the tabs.
Two Tab Method
- At the seam where two rolls of insulation are joined, pull the tabs upward (toward the outside of the building) and staple approximately every 8″, ½” from the bottom of the faced side of the insulation.
- Next, fold the tab over and staple between each original staple. CAUTION: Do not staple too close to the base of the tabs or the staples may pull out, resulting in a poor vapor seal. The tabs will now be stapled approximately every 4″ assuring a tight vapor seal.
- Tuck the completed sealed tab back into the joint.
- Be sure to use matching facing tape to repair any rips or tears in the insulation to guarantee a tight vapor seal.
One Tab Method
This method is used when one 6″ tab is supplied. The advantage of using the one tab method is that it can be done from inside the building after the panels have been placed. A high quality moisture-proof adhesive, or double-faced tape, is applied to the back of the tab. The tab is then extended over the facing of the next roll of insulation and fastened.
The extent of their usefulness is mainly cosmetic. Made from either aluminum or plastic, trim strips are used to give insulation joints a more finished look. They provide very little support and do not act as vapor barriers.
Installing Trim Strips on Walls
- Pre-cut trim strips to the height of the wall rather than working with a full roll.
- Locate the center line of the trim strips at the joint of the insulation.
- With the finished side facing the interior of the building, attach one end of the strip to the eave strut. Pull down over the flange of the girts to a taut condition and fasten at the base angle. Be careful not to put too much pressure on the strips as to pull the girts or eave struts out of alignment. Only a few runs should be placed prior to installation in order to minimize the possibility of misalignment.
Installing Trim Strips on Roofs
Trim strips are installed on the roof in the same manner as on the walls. However, we do suggest that longer rolls be used, and that each strip be cut as needed.
- Position the first run to cover the joint of the insulation.
- Attach the trim strip to the top of the eave strut.
- Stretch the trim strips over the flanges of purlins to the opposite eave.
- Fasten the trim strips to the eaves and to the ridge purlins once correctly aligned.
On extremely wide buildings, it is advisable to install additional fasteners at intermediate purlins to ensure proper alignment. Special consideration should also be given to making sure that trim strip fasteners are located under the panel corrugation so that they don’t interfere with panels.