Moisture Control | Roof Decks | Rigid Insulation | Roof Membranes

 

ROOF MEMBRANES

Preinstallation Conference & Project Walk Through
The owner, designer, general contractor, roofing contractor, inspector, deck contractor, mechanical contractor, and any other interfacing parties involved with the roofing project shall be requested to attend a preinstallation conference. The conference shall be scheduled well in advance of delivering the roof system components and the start of the roofing project. If a guarantee is requested, a representative from Fields is required to be present. A written record shall be made of the preinstallation conference by the designer, and shall become a part of the job record. The deck shall be inspected, and if any deficiencies with the deck are observed, a second deck inspection shall be done to verify that corrective action has been completed, and that written approval to proceed has been obtained from the designer and from Fields for guaranteed system.

The roofing assembly plans, specifications, building codes, and contract documents shall be reviewed during the preinstallation conference. Any discrepancies between the foregoing and Fields’ requirements shall be resolved for guaranteed systems.

The Following are Required during the Preinstallation Conference:
1. Coordination of interfacing trade schedules, with project sequencing, including timely installation of any required equipment on the roof so as to avoid or limit traffic over the roof system membrane.
2. Establishment of construction trade schedules and practices including installation of a temporary roof and walkways so as to prevent damage to the roof system membrane.
3. Construction of walls, curbs, drains, and other deck penetrations prior to start of installation of the roof system.
4. Designation of access, staging, and storage areas on the project site.
5. The definition of acceptable weather conditions and working temperatures. For guaranteed systems, Fields must agree in writing to less stringent weather conditions than those stipulated in the Waterproof Membrane Construction section at the bottom of page 62.
6. Provision for on-site monitoring after the roof system has been installed so as to ensure that other trades do not damage the roof system.
7. Clarification of related EPA and OSHA regulations, including the safety of all personnel on the project site.

If any changes in the project specifications or conditions are desired, the party requesting the change shall:
1. Send written notice requesting the desired changes to all interfacing parties.
2. Obtain written agreement of the desired changes from the designer, and for guaranteed systems from Fields.

Wood Nailer & Back-Nailing Requirements
Each layer of reinforcing sheet shall be back-nailed on roofs with slopes of 2” or more per horizontal foot. Reinforcing sheets fastened to concrete decks, shall be fastened to preservative treated wood nailers embedded into the concrete. The wood nailer dimensions shall be a minimum of 1” x 4”. Nailers shall be installed perpendicular to the roof slope, and on 16’ centers or less for slopes greater than 2” per horizontal foot, and on 4’ centers or less for slopes greater than 3” per horizontal foot.

General Waterproof Membrane Construction Criteria
1. Roofing components shall only be installed during dry, frost-free conditions with precipitation forecast at less than a 10% chance for rain, and with temperatures above 50æF.

2. Slope shall be provided for positive drainage of the roof assembly. The criteria for determining positive drainage is that there shall be no standing water on the roof assembly 48 hours after a rain following dry weather conditions. A positive drainage design also includes the correct number, size, and placement of roof drains, scuppers, and gutters as well as crickets and saddles with sufficiently sloped valleys.

3. Entrapment of moisture shall be prevented during installation of the roof system components. Moisture in or on components can cause the roof system membrane to blister. If precipitation occurs prior to the completion of the roof system membrane, the installation area shall be dried or allowed to dry before continuing the project.

4. On roofs where the slope is greater than 2” per horizontal foot, the roof system reinforcing sheets shall be installed parallel to the slope. This method of installation is termed as “strapping” the sheets and may be employed on lower slopes as well.

5. Roof system reinforcing sheets shall be installed continuously. Irregularities, such as ridges, blisters, or raised seams shall be cut and repaired prior to installation of additional reinforcing sheets, surface coatings, or the application of reflective surfacings.

6. If conditions do not permit installation of the complete roof system membrane, and the area must be exposed overnight, it is required that the ply sheet laps be sealed either with the specified Fields Asphalt coating or M300 RubrMastic prior to departing the project site for the day. All installed reinforcing sheets shall at a minimum be glaze coated with asphalt to temporarily seal the surface at the end of each day’s installation. A wide blade squeegee shall be used to uniformly apply the glaze coating so as to help achieve a thin film of 2 gallons of ambient applied asphalt or 15 pounds of hot applied asphalt per 100 square feet.

7. Roof traffic shall be prohibited over recently installed reinforcing sheets so as to prevent the displacement of soft asphalt which is termed a void, until the asphalt has set-up firm enough for light traffic.

8. The substrate shall be dry, frost free, clean, smooth, and firm. Only the products specified are permitted on the project site. All products, including coatings and mastics, are required to be asbestos free. Each layer of reinforcing sheets, or pre-manufactured membranes shall be started at the same location and installed parallel to all other layers. The flow of water shall be over or parallel to seams, but never against seams. All reinforcing sheets shall be adhered into the specified Fields Asphalt. Each base and ply sheet shall be broomed into the asphalt to ensure a fully adhered, smooth installation. Base sheet side laps shall be a minimum of 2”. The quantity of shingled ply sheet layers is the basis for calculating the ply sheet side laps. In no place shall any sheet touch sheet. Reinforcing sheets and pre-manufactured membranes shall extend a minimum of 2” above the top of cants. End laps shall be a minimum of 6” and offset at least 36”. The specified Fields Asphalt adhesive, shall be uniformly applied at the following rates per 100 square feet: Ambient applied asphalts 4 gallons, and hot applied asphalts 30 pounds.

9. The 4 types of membrane reinforcing sheets are: base sheets, ply sheets, BasePly™ sheets, and cap sheets.