How to Install Liberty Low-Slope Rolled Roofing System

Are you looking to install a new low slope roof or do a re-roof on your home? With all the roofing products out there, it is really important to find one that will be reliable, durable, long lasting and leak-free for many years.

In the low-slope roofing market (roof pitch between 1 and 3 in 12), one product you can install yourself, is a Liberty roofing systems – an SBS modified bitumen roof. These systems are manufactured by GAF and are specially designed for low slopes with a pitch of 1/2 to 6 inches per foot. This product line consists of 3 membranes: the cap sheet and two base sheets: mechanically attached and self-adhering. You can either install one of the base sheets with the cap sheet on top, or for extra protection you can install the Liberty Premium 3 ply system, which includes the mechanically attached base sheet first, the self-adhering base sheet next and the cap sheet on top.

You can also use the Liberty roofing system for flashings at parapets, perimeter terminations, and typical roof-top penetrations, skylights.



Liberty Low-Slope Roof System overview:

Note: Liberty self-adhered rolled roofing system is a good product for DIY homeowners who do not have access to EPDM Rubber Roofing, and it is also easier to install and provides better puncture resistance than rubber roof.

Products like liberty are perfect for roof application on sheds, porches and other structures with low slope roofs, and they last a lot longer than traditional rolled asphalt roofing. However, liberty should never be used on completely flat roofs, or roofs without positive drainage, as this will not only void your warranty, but will also cause multiple roof leaks. For completely flat roofs, we recommend using PVC single-ply flat roofing membrane.

Installation of Liberty Rolled Roofing System:

Any roofing products is only as good as its installation, and Liberty products are no exception. Consequently, if you are installing the roof yourself, it is imperative to follow the right installation procedure to make sure that your new roof will be watertight. Our installation overview provides critical information you need to know prior to beginning your Liberty system roof installation.

To ensure proper adhesion of any Liberty self-adhered system it must be installed when the weather is dry and 45 degrees F. or higher. Liberty 2 & 3 ply systems are accepted and covered by the Golden Pledge and Systems Plus Ltd. warranties on low slope areas of shingle projects.



Take care of the substrate prior to installation

To ensure that your installation goes smoothly and successfully, the substrate must be clean and dry.
The substrate for the Liberty system must be clean and dry. All penetration curbs, perimeters, “kents, nailers”, must be in place???

Installation of Liberty Mechanically Attached Base Sheet (Liberty MA Base)

Liberty Mechanically Attached Base Sheet is a one meter or 39 and 3/8 inch wide membrane with a plastic film on top, designed to maximize the attachment of other self-adhering Liberty Membranes. This sheet can be mechanically attached directly to the deck or installed over ISO insulation. Over nailable decks, the sheet can be nailed with a typical base sheet pattern, using 1 inch square or round cap metal nails.

Important installation tips:

-You should let the sheet relax and remove any wrinkles to provide the smoothest surface for other plies.

-All Liberty systems require installation of primed metal drip edges on eaves and rakes.

– Make sure you use the correct adhesives and cements with Liberty roofing systems. All of them require the the use of SBS Adhesives and cements, as other none-SBS cements may have an adverse reaction and damage the Liberty membranes.

– To create additional wind uplift resistance, apply a bead of caulk in the overlap between the base sheets, and then nail the the overlap area a minimum of 6 inches on center.

– To reduce the risk of leaks, you should off-set the end laps in the adjacent course a minimum of 36 inches.

Installation of the Liberty Self Adhering Base Sheet

The Liberty Self-Adhering Base sheet is also a 1 meter or 39.375 inch wide membrane that has a plastic film top surface designed to receive the liberty cap sheet. On the bottom, the surface is a split back release film, designed to to be removed to uncover a self-adhering surface. Often, the self-adhering base sheet is a more popular choice, due to easier and quicker installation as compared to the mechanically attached base sheet. One major advantage of the self-adhering membrane is that it has superior self – adhering properties.

How to achieve the strongest adhesion bond during installation

When installed, directly to wood, the membrane will adhere very strongly. While it is possible to achieve decent adhesion to wood, without primer, the best and most long lasting adhesion can be achieved, if you prime the wood with one coat of matrix 307 asphalt concrete primer or a comparable ASTM D-41 type primer. It is important to allow the primer to dry completely prior to the installation of the self-adhering base sheet. This gives the self-adhering membrane an asphalt surface to bond to, so when the deck moves, the self-adhered base sheet can move with it. Priming is option, if you are applying the self-adhering membrane to the mechanically attached base or a wood deck.

Important installation tips:

– During installation, firmly press the sheet to avoid wrinkles and trapped air, as the ply adheres to the deck or to the mechanically attached base sheet, and press down the faccia.

– When adding additional length of Liberty base ply to the same course, you need to overlap the end of the previous sheet a minimum of 6 inches, which will create the best protection against leaks.

– After you finish applying the Liberty self-adhesive base sheet, apply uniform pressure to the entire area by using a either a long-handed push broom or a weighted roller. Do not skip this step, as this will ensure a solid bond between plies. Brooming also provides a clean surface for adhesion of the liberty cap sheet.

Installation of the Liberty Cap Sheet

Important installation tips:

– Before installing the cap sheets, let them relax on the roof. By allowing the ends of the rolls to lay flat, you ensure a much better finished look.

– To seal one row with another and to minimize the possibility of “lack blisters” forming, apply a bead of Leak Buster Matrix 201 Premium SBS flashing cement adhesive along the top edge of each cap sheet and of any salvaged edge T joints in any self-adhered system.

– It is required to install a bead of Leak Buster Matrix 201 Premium SBS flashing cement at the top of each Liberty Cap Sheet course on all Golden Pledge Installations.

– To prevent membrane movement on roof slopes with a rise greater than 1 inch in 12, back nail in the salvage area at 18 inches on center with roofing nails or cap nails.

– It is highly recommended to leave a minimum of 8 inches of release film on the back of the overlapping cap sheet. This prevents unwanted bonding to the granular surface of the underlying sheet when installing the adjoining sheet.

– To ensure proper adhesion of the cap sheet, apply uniform pressure to it using a broom or a weighted roller.

-If you have any remaining adhesive bleed out, you can cover it with loose granules, to achieve a more professional and nice-looking appearance.

14 thoughts on “How to Install Liberty Low-Slope Rolled Roofing System

  1. Do not wait whenever you need to have shingles replaced. Whilst you could possibly choose to put the operate off, this will most likely lead to higher damages. Replacing or repairing your roof as troubles arise can save you a ton of funds and heartache. Should you sustain your roof, it’ll final you a lengthy time.

  2. I have a 25×25 garage. I am going to rip the hip roof off, make it a semi flat roof, and I want to put a deck on top of my DETACHED garage. Can I do this with the Liberty system and if so could I get a quote on the Liberty material I need.

    • Hi Elaine,

      Making the roof “semi-flat” is easily done with Tapered ISO insulation. I imagine you wanted to rebuild framing to add slope? Tapered is a much simpler and cheaper solution.

      Liberty IS NOT a system you want to use for deck. Even with slope, the seams will pop open some years down the road and you will have to take deck off to fix it. I recommend a PVC membrane with Floating deck on top, or a IB DeckShield material (made of PVC) which does not require building a deck. PVC and deckshield both have heat welded seams, which are permanent, unlike those on Liberty and similar systems. Also you will have really hard time flashing around posts with Liberty, while PVC roof has prefabricated flashings that slide over the post and are welded to the roof.

      Also since garage is detached, I assume you will build a staircase on the outside – correct?

      As far as estimate, you can can get it from Networx

  3. In 2000 alone, sales have amounted to 870 metric tons since its introduction in the early 1960s.
    You may even come across numerous synthetic and artificial slates loaded
    up with rubber composites that will approve to shield from the damage of
    too much organic conditions like fire or harmful Ultra Violet rays.
    Help prevent it by having a qualified local roofing contractor to inspect your roof for
    damage or loose and leaky gutters.

  4. I’ve got a 3/12 pitch roof with EPDM. My problem is that snow slides off and lands in the driveway and walkway. I saw this material and it looks like the texture could provide enough friction to keep that from happening.

    Will the Liberty SBS Cap adhere to EPDM? I don’t need it to provide water-tightness. It just needs to stay in place and not damage the EPDM membrane.

    • Marc,

      I don’t recommend applying Liberty over EPDM. The bitumen in Liberty will damage rubber (they are incompatible).

      What we do in these situations is a much cheaper and effective alternative! We install 2 rows of clear plastic snow guards from SnoBlox. These cost about $3 each and you need 1 per foot (staggered 2 feet apart in each row). See image below.

      Snow guards on IB Flat Roof

      We use heavy duty rubber washer screws from home depot to attach the snowguards and SolarSeal 900 roof caulking ($9 / tube) to make them watertight.

      One important thing we do before installing IB Roof – we know that we will be adding snow guards, so instead of soft insulation, we add a layer of same thickness Plywood, where the snow guards will be attached. This will prevent the compression of insulation and make the seal much better.

      I assume you have fiberboard insulation on your roof. What i would do if I were you – undo the rubber from the metal edge the length of the roof, and 2-3 feet up. Cut out fiber board and replace with 1/2″ pressure treated plywood. Glue the rubber back, to plywood and redo metal edge. This gives you solid base to screw in snowguards without potential leaks.

      Then install snow guards – 1st row 6-9″ from edge, and second row 18″ up from first row.

      This whole thing will cost you under $600-800 in materials and if you do it yourself – free in labor. Much cheaper and much better than gluing crappy liberty over rubber.

      Good luck. Email me pics if you do this.

      • Thanks for all that, Leo. I don’t know for sure what’s under the EPDM, but from the feel, it’s probably fiberboard. Unfortunately, I’m a bit of a chicken where heights are concerned, so my ripping up the roof edge is not going to happen :-). And I’ve got about 50 ft of edge I want to take care of. But at least I know not to waste my money on this Liberty stuff.

        Also, it’s not a real dangerous snow slide. The snow only starts sliding when it’s warm and/or sunny. It’s a real slow migration, maybe an inch or two an hour. The snow sticks to itself and will overhang the roof by about a foot before chunks of it fall. I’ve seen it happen and it’s mostly a pain to clean up later, as that snow is pretty compact from the fall.

  5. Can the Liberty cap roll sheet be applied directly on top of 15 lb felt?

    • John

      Answe is no, becuase cap sheet needs to be glued to properly installed base sheet, and 15# felt is not a proper base sheet.

      In any case, I actually recommend a PVC or TPO membrane instead of Lyberty

    • I would recommend using SMOOTH Sureface Ice and Water Barrier, such as Grace or High Temp – high temp works the same as Grace ice and water shield, but is cheaper!

      I do not recommend liberty in valleys.

  6. What do I do if it rains on my base sheet before I get the cap sheet down? Is there any degradation of the material?

    • Chelli, if roof does not leak – just let it dry for a day and put on you cap sheet.

      Water will NOT do any damage to base sheet – no degradation.

      Good luck

  7. Insurance work roofers installed GAF Liberty, but the cap sheet was patched with a tarred seam on one course. It looks like they ran into one short piece and patched in another scrap, but the installer is telling me this is how it is done and is correctly installed. It sure is ugly, and seems like it would not be as durable and will eventually leak. Can someone tell me if this is installation method is typical or if they are just being difficult to cover poor workmanship?

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