How to Install an EPDM Rubber Roof
EPDM roofing provides the best protection against leaks on low-pitched roofs. It’s an easy-to-install, DIY project. Most home centers now carry rubber roofing in standard 10 x 20 ft. sheets for less than $100. Some also will sell 10-ft. wide roofing by the linear foot from a longer roll. When possible, buy a large enough sheet to cover the entire roof. This greatly decreases the likelihood of leaks forming because it eliminates the need to seam the roof covering.
For roof decks with minimal pitch, even rolled asphalt roofing may not offer enough protection against leaks. In these situations, ethylene propylene diene monomer (EPDM) rubber membrane roofing may be your best—or only—bet. EPDM roofing is easy to install with minimal tools by a do-it-yourselfer. Unlike other membrane systems that must be applied with a torch, EPDM adheres with liquid adhesive. It comes in 10 x 20- or 20 x 100-feet rolls so you can plan your installation to minimize seams.
Installing the membrane involves removing the previous roofing material down to bare roof decking and any flashings around vent pipes or other protrusions. Make sure your roof deck material is clean, dry, and in good repair. You may be able to overlay the deck with a layer of high-density fiberboard or 1-inch isocyanurate insulation board to create a fresh, flat deck surface if the previous surface isn’t sufficiently flat or shows signs of minor deterioration. Avoid using insulation products with a waterproofing layer or film. Glue will not penetrate properly into the insulation.
Once the deck is prepared, lay out the membrane sheets so they overlap the edges of the roof and one another by 3 inches. Make any necessary cutouts to allow for roof protrusions and to allow the membrane sheets to lay flat and relax. If your roof abuts a vertical wall, the membrane should extend up the wall 12 inches so it can be adhered to the wall and sealed with a metal termination bar.
Adhering the membrane to the roof deck involves applying liquid bonding adhesive onto the roof deck with the membrane rolled back, allowing it to partially cure, then pressing the membrane into place over the adhesive, and brushing it thoroughly to remove any air pockets. Once the membrane is fixed in place, you seal the overlapping seams with strips of soft seaming tape and liquid primer, rolling the seams flat. Finish up the roof by trimming the membrane at the roof edges, installing the appropriate boot flashings, and adding any termination bars that may be required.
Follow the EPDM manufacturer’s instructions carefully, particularly if they differ from the step-by-step process you see here.
Rubber roof coverings require special adhesives and primers, as well as flashing and accessories such as rubber pipe boots. Shown here, from left to right, are pipe boots (A), EPDM adhesive and primer (B, C), hose clamp (D), insulation plates (E), termination bars (F), exterior screws (G), caulk (H), seaming tape (I), EPDM membrane (J), and J-roller (K).
Most rubber roofs are fully bonded to a substrate of insulation board, but they can also be bonded directly to a plywood roof deck or even installed with a perimeter bond only. In some commercial applications they are installed with a layer of river rock on top for ballast.
How to Install an EPDM Rubber Roof - Step 1
Prepare the roof deck for membrane roofing by removing the old roofing material down to bare decking. Look closely for signs of deterioration. Replace deteriorated decking. For a smooth surface, cover the roof with a new layer of high-density fiberboard (sold at roofing materials suppliers). Secure with fasteners recommended by the manufacturer for this purpose—usually long screws with large insulation plates.
How to Install an EPDM Rubber Roof - Step 2
Sweep the roof deck thoroughly, and spread out the membrane so it has a chance to relax. Make any cutouts in the membrane that may be necessary to allow for vent pipes or other protrusions. Overlap the sheets by 3" and wipe them down with the recommended cleaner to prepare the surfaces for adhesive.
How to Install an EPDM Rubber Roof - Step 3
Apply the latex adhesive. Fold half of the first membrane sheet over on itself to expose the roof deck, and roll a heavy coat of adhesive onto both the deck and membrane surfaces with a medium-nap paint roller. However, do not apply adhesive to the overlapped section of membrane. Once the adhesive begins to set (about 20 minutes in normal conditions), carefully roll the folded rubber down into place. Avoid wrinkling the membrane.
How to Install an EPDM Rubber Roof - Step 4
Use a stiff-bristle push broom to brush out any air pockets that may be evident under the bonded half of the membrane. Brush from the middle of the roof outward to the edges. Then fold the other unbonded half over, apply adhesive to the rubber and roof deck again, and adhere this half of the membrane to the roof. Apply all sections of membrane to the roof deck in this fashion, but do not apply adhesive within 3" of the edges of any overlapping sections of rubber; these must be accessible for applying seaming tape along the seams.
How to Install an EPDM Rubber Roof - Step 5
Roll the top section of overlapping membrane back along the seam area, and chalk a reference line 3" from the edge of the bottom membrane. This marks the area for applying seaming tape.
How to Install an EPDM Rubber Roof - Step 6
Tape the seams. Use the recommended cleaning solvent to clean both halves of the overlapping membrane in the tape areas, then apply seaming tape sticky side down to the bottom membrane within the marked area. Press the tape down firmly to ensure good adhesion to the membrane.
How to Install an EPDM Rubber Roof - Step 7
Fold the top membrane overlap back in place on the tape. Slowly pull off the tape’s paper backing with the membrane edges now overlapping. Press the overlapping edges down to create a tighter, smooth seam. Roll the seamed areas with a J-roller or seam rolling tool to bond the seam.
How to Install an EPDM Rubber Roof - Step 8
If the roof meets a vertical wall, you may need to remove siding so you can bond the membrane to wall sheathing. Use contact adhesive to apply the membrane 12" up the wall. Seal the edge with a metal termination bar fastened to the wall with exterior screws. Trim off overhanging membrane around the roof edges, and flash it according to the manufacturer’s recommendations using rubber adhesive flashing and rubber boots.