Ask the BuilderAsk the Builder
Ask the Builder's on:

Subscribe to askthebuilder's videos

Air Conditioning
Asphalt - Blacktop
Brick
Building Tips
Cabinets
Caulk
Ceilings
Ceramic Tile
Checklists
Chimneys
Concrete
Concrete Defects
Concrete Installation
Condensation
Countertops
Deck Construction
Deck Maintenance
Design
DIY
Doors
Drainage
Drywall - Plaster
DVDs
EBooks - EDocs
Electrical
Energy Savings
Engineered Wood
Fences
Fireplaces
Flooring
Foundation
Garage Doors
Glossary
Glue
Hardware
Heating Design
Home Builders
Home Depot Stories
House Plans
Hurricanes
Insects
Inspections
Insulation
Interior Walls
Kitchen
Lighting
Lots
Miscellaneous
Mold
New Construction
Newsletters
Online Courses
Outdoor Projects
Painting - Staining
Patio
Payments
Plumbing Design
Plumbing Supplies
Projects
Radiant Barrier
Remodeling
Retaining Walls
Roofing
Rough Lumber
Screened Porches
Sheds
Siding
Specialty Accessories
Stone
Storage
Structural
Stucco - EIFS
Tools
Trim Lumber
Vapor Barrier
Ventilation
Videos
Walk Throughs
Wallpaper
Windows






Membrane Roofing for Flat Roofs

By Tim Carter
©1993-2008 Tim Carter
Summary: Roofing membranes and synthetic rubber roofing compounds for flat roofs outperform gravel roofing materials and make roof leak detection far easier. These roofing materials are basically seamless and fight UV damage. Used mostly commercially, flat roof membranes have many residential uses.

Do you have an old fashioned ballasted flat roof? This is a roof covered with gravel. The gravel is used to hold down the roofing materials in high winds and it also protects the old asphalt from ultraviolet (UV) light from the sun. UV rays really hurt asphalt. If you have one of these roof systems and a leak(s), forget about locating them. It will be virtually impossible! The gravel does a fantastic job of hiding leak locations.

Synthetic Membranes

The use of synthetic membranes has just about eliminated the need for gravel on roofs. Why? Because many of these new roof membranes are glued down to the roof sheathing. Not only that, the new membranes contain materials that resist UV degradation. If you can install a new flat roof without gravel, DO IT! It will make future leak finding much easier.

The synthetic membranes have many other benefits. Imagine being able to cover your house with just one giant piece of roofing material? No seams to worry about! It is possible if you find the right roofer and get the right membrane. Some of the membranes come in widths up to 50 feet!

The Actual Material

Have you ever seen how a flat tire is fixed on a tubeless tire? The rubber patch is actually vulcanized to the tire's inner surface or wall with special solvents. The patch and the tire basically become one in the same. This is how some of the new membranes work. As a roofer seams pieces together or makes cuts for flashings, they can actually weld pieces of material together.

Some of the top performing materials, in my opinion, are the synthetic rubber roofing compounds. These are commonly referred to as EPDM and CSPE materials. I have installed these materials on many of my jobs where low slope roofs have caused leak problems using conventional materials. These membranes work very well where old rolled asphalt materials, hot mopped asphalt, or even shingles were used before. The only disadvantage, I can see with them is that they are not DIY friendly. In other words, you will probably need to locate a professional to install them. You must remember that this technology is not really used much in residential work. Commercial roofers use these materials most frequently. There are many residential roofers in Cincinnati that have experience with these materials. I am confident that you will find residential roofers in your town as well who can successfully install the membranes.

Where Can You Use Them?

The membranes have many uses in residential work. You can use them on shed roofs that commonly have low slopes or on a Cape Cod style house with a dormer. There are many older houses that have low sloped worn out tin roofs. The membranes are far cheaper to install than replacing with tin or copper!

How about chimney crickets? These are little hip roofs that are found behind chimneys. Membranes work well here. Does your house have the old fashioned tin box gutters? If so, you can reline the gutters with these membranes instead of expensive tin. An additional benefit is that you don't have to maintain the membrane like tin. Tin requires periodic cleaning and repainting.

Periodic Inspections

If you have a flat roof on your house and do install a new membrane roof, I suggest that you perform an annual inspection. Since the roof is flat or nearly so, it will be easy to walk around. I urge you to inspect the roof for the first time immediately after it is installed. Take photos of the roof and close up photos of all flashing locations and seams. Keep these photos in a safe place and make sure they are clear. As you perform your annual inspection, you can refer to the photos to see if an area, seam, or flashing has begun to change. Photos are wonderful tools. As they say, "The lens doesn't lie."

Don't Do Old Asphalt Again

Don't be tempted by the lower price (possibly!) to do a quick mop over of your existing asphalt roof. Asphalt is simply old technology and is prone to failure. The system is dependent upon expert workmanship for long term high performance. Excellent workmanship is harder and harder to find these days.......

Also, you will be surprised at the warranties you can get with the membrane materials. When you sit down and analyze the cost versus the benefits, you will do well by upgrading to the membranes. So far, every membrane roof I have installed has been leak free. Some have been on for more than 12 years. If I had a low slope on my own house I can tell you that I would put an EPDM or CSPE membrane on it so fast your head would spin. Leaks cause anxiety. Don't get cheap when it comes to your roof. Buy the best and relax......

 






Comments

John Badenhope
25 Nov 2007, 10:15
I need to help a friend install a roof THEN a tile surface on a entry for a house . The area is approx. 14'wide x 10' deep.They want a traditional style white handrail around the porch area. It is accessed @ 2nd story level.How or can I install a membrane style roof THEN a mounting medium for a tile porch floor? OR.. is there a whole 'nother' way to do this thing? Keeping in mind I need to mount newel posts. Another project is 8" Walnut floors,new construction over Advantech. sub floor or no, floating or not. should I peg it? 8" prone to crowning/cupping? (unfinished and back is grooved)With a tile perimeter. Looking for resources/ advice. Thank You! John Badenhope
ATB
25 Nov 2007, 11:18
John,
Sounds to me like you need a seasoned architect on this job who can produce the much-needed detail drawings that illustrate all of the critical steps.
Mike
28 Nov 2007, 17:51
Is it okay to install the EPDM roof in the winter when temperatures are below 40 and sometimes as low as the teens?
ATB
28 Nov 2007, 17:56
The answer is *maybe*. You must follow the instructions on the adhesive container. Also follow the written instructions of the rubber roofing as you could have expansion/contraction issues when it is 95F next summer!
Mike
28 Nov 2007, 19:35
I am having a contractor do the job and I have two bids. One bid is for the EPDM and one is for hot tar with an aluminum coating. The roof slopes to the middle and the rear of the building with a mostly Northern exposure. The current temperature in Salt Lake is predicted to range between 25 and 41 degrees Farenheit. I am debating which material to go with. Both jobs come with warranties, but it would be nice not to have to exercise that warranty if possible. Your feedback is helpful and much appreciated.
ATB
28 Nov 2007, 19:38
EPDM is my choice. But *get* the written installation instructions from the mfr. to ensure the material is being put down correctly! They are often a .pdf file at their website.
Rhod
13 Dec 2007, 13:45
I have a flat roof/ balcony on my house which retains water to 0.5 - 1.0" over the entire surface. The surface is a waterproof membrane with in-built drainage channel about 2" deep, which is also full of water.

The builder of my house assures me this is part of the design that this water lies there. However I believe the water should drain away through the drainage channel fitted. I think the drainage channel has been fitted below the level of the external drain fitted in the wall surrounding the flat roof/balcony and I believe this is a construction fault.

The flat roof/balcony is normally covered by a decking which is above the level of this standing water, and the water is normally concealed by the decking.

What do you think?
Rhod
Susan
14 Dec 2007, 07:32
Hope someone can help me here ,I have a flat asphalt roof over my bedroom,my neighbour above me insists on putting her potted plants on it,she previously had a table chairs etc on there and I asked her to take them off and she did ,now I have noticed the big pots are slowly being put back on ,she is going to think I am just being a miserable git by asking her to remove them once again, the only thing I know about these roofs is that they are not as strong as a "normal" roof what should I say to her ? Help please
Sue x
AsktheBuilder
15 Dec 2007, 10:44
Rhod,
I think you are right.
AsktheBuilder
15 Dec 2007, 11:26
Sue,
I think you should send her some flowers and say you were misinformed. The pots will not cause a problem if any and all water is allowed to drain away from the underside of the pots.

     View all comments
*Name:
Email:
Notify me about new comments on this page
Hide my email
*Text:
Security Image:

Visual CAPTCHA


 







Ask the Builder Comment Help

Helpful Comment Tips: If you need help with a problem, please try these things now before you type in a comment. You could discover your answer in just minutes.
  • Read ALL Comments Before Submitting One: If there are lots of comments that are already part of this column, there is a very good chance your question has already been answered by me or someone else.
  • Read Similar-Titled Columns First: The column above is almost always part of a two-or-three-part series. The answer to a question you may have is probably in a related column or in comments that are part of that column.
  • Read Columns in a Category: Take the time to read many columns in a category. The amount of information you will discover will amaze you.
  • SHARE a Story: Please share any tips or amusing tales of glory! Tell others what has worked for you. Maybe you have a disaster you want to discuss. Let's collaborate so we all learn together.
Don't show this alert again.