Talk:Flat roof

Orphaned Comment
Flat Roof's, more commonly refered to as low-slope roofs, come in a variety of system types. Low-slope roofs are available in 1) Metal, 2) Built-Up (BUR), 3) Modified Bitumen (MB),      4) Single Ply (PVC or Rubber) and 5) Sprayed Polyeurothane Foam.  Each system type has it's place.  The decision on which system to use should be based more on the use of the building, and not primarily on initial cost.

In "monumental" construction...buildings designed for long-term use of 1 owner (typically hospitals, schools, colleges), more consideration is given to the life cycle of a roof system than to the initial cost of the system. A 25 year system installed today with a $10.00/sq. ft. installation price has a lower life cycle cost than a 10 year system installed today with an $8.00/sq. ft. installation price. The 25 year system also has a lower succeptability to leaking, which often can not be tolerated in world of the "monumental" building owner.

On the other hand, a strip mall developer has no problem installing a 10 year roof with the lower additional cost. This is primarily due to the fact that this property will likely be sold before the roof reaches the end of it's life cycle.

When a building such as a large manufacturing facility has a roofing need, consideration should be given to the operation under each roof at the plant. It doesn't always make sense use one system type on all the roof sections at a given facilty. For example, let's take a tire manufacturer. A long-life system should be considered over sensitive areas such as administrative areas (where there is often expensive computers) and over production (where there is expensive equipment). However, why install a "bullet-proof" system over a warehouse full of tires....they're designed for bad weather aren't they?

If you are the person responsible for procuring roofing services at your facilty, engage the services of a roofing professional. This does not include the roofing contractor. Remember that the contractor generates revenue based on labor, and they would love nothing more than to replace your roof every few years. Talk with a Low-Slope manufacturer or Registed Roof Consultant (RRC)

Talk with a company that manufacturers each of the systems mentioned above, as they have no preference to they type. It is in their best interest to offer the best system today, in order to maintain a relatinship later.

Another point of reference would a Registered Roof Consultant (RRC). These individuals typically have extensive training specifically on roofing systems. I would caution you to ask for references. Often is the case that an RRC has established relationships with only 1 or 2 manufacturers. Ask the RRC to look at his/her last 3 local projects. If all the projects are the same type system by the same manufacturer, consider talking to another RRC. — Preceding unsigned comment added by 71.12.223.14 (talk) 03:52, 15 December 2005 (UTC)

What is their function?
I just read the article and still have absolutely no clue why flat roofs exist. What is the point? Why do people build flat roofs? Peoplesunionpro (talk) 00:38, 19 November 2007 (UTC)


 * That is a good question. Intuitively, I would think that a flat roof, being a construction with only flat surfaces and right angles, is the most simple, and therefore often the cheapest construction. Warehouses and simple office buildings, where esthetical (architectural) aspects are relatively less important often have flat roofs, so these are probably the cheapest to make. From a structural point of view, however, if you look at the required strength to keep the roof from breaking down, flat roofs are at a disadvantage compared to slanted or dome-like structures. Johan Lont (talk) 09:16, 19 June 2009 (UTC)


 * Off hand, I would say that the flat roof more easily spans distance at a more affordable price while maintaining a horizontal aesthetic. Image a peaked roof on your local mall, for example - what a huge piece of construction that would be, with the ridge looming high up into the air and dwarfing all beneath it. Another point is that the amount of square footage of the roof, along with it's bearing load, would increase dramatically if a roof were peaked instead of flat. Yet another point is that flat roofs are where much of the utility equipment is located - heating, cooling, elevator mechanisms, electrical cabinets, blowers, and duct work. It's quieter inside with the equipment up there; not generally seen from the ground; and it really doesn't require taking up interior space, contributing to interior heat loads. I'm sure there are more points that I'm thinking about right now.


 * By the way, I would love to see citations inserted into the article. Thank you, Wordreader (talk) 19:51, 19 December 2014 (UTC)

Rigid insulation under membrane.
I recently had two large flat roofs re-done. The material used is a two layer heavy membrane. The base material is black with a thin top layer that is white. The installers used a motorized rolling machine to heat the seams by blowing hot air between the lapped sheets then immediately pressing the layers together. Underneath the membrane is a rigid plastic foam insulation, made from some type of expanded beads, with metal foil on both faces. The original roof on one building had been re done many times using various tars, papers and a top layer of tarred fiberglass mat with several coats of other asphalt and tar based coatings in attempts to stop leaks. Total thickness in places was over 2 inches and the total weight of the old material removed was around 6,000 pounds. The other roof is larger and it had up to three layers of asphalt roll roofing. Total weight of all that removed was also around 6,000 pounds. The new membrane and insulation roofs are much much lighter and they keep heat out and in. It's been much cooler in the buildings since having the roofs done and I expect heating costs this winter to be reduced a lot. The only downside I foresee is that escaping heat will be much reduced and won't be able to melt the snow, however this membrane gets next thing to frictionless when wet so snow should be able to slide off under its own weight, hopefully not wrecking the new gutters I had installed. Bizzybody (talk) 08:58, 7 October 2010 (UTC)

Solar Panels?
In the Benefits section it is mentioned that it is a good structure for solar panels. In fact a pitch of around 35 degrees is preferable and flat roofs are generally not very suitable for solar panels as the potential yield decreases dramatically past 25-35 degrees —Preceding unsigned comment added by 93.97.181.51 (talk) 13:12, 18 March 2011 (UTC)

Roof coating vs. Liquid roofing and Flat roof
The articles on roof coating, liquid roofing and flat roof seem to be related. I will label each with "see also" the others. Perhaps someone more knowledgeable than I will make better references. DavidMCEddy (talk) 00:36, 12 September 2013 (UTC)

Foam (polyurethane)
Spray on foam had been mentioned to me by several sources (roofers, green industry people, and friends) as another option for covering a flat roof. It is said to need an acrylic coating. Besides waterproofing, its insulation properties are touted as a secondary benefit of this material. It clearly is currently being installed/applied (at least in the San Francisco Bay Area), yet foam has not been included in this list of types of flat roofs.

I hope someone with more specific knowledge about foam as a roofing material would add it to this page.

Erysimum (talk) 01:36, 14 November 2013 (UTC)

non-encyclopedic tone
Much of this article reads like an industry promotional brochure.

--23.119.204.117 (talk) 06:37, 14 December 2016 (UTC)

History?
Currently, the article just says:
 * Flat roofs are characteristic of the Egyptian, Persian, and Arabian styles of architecture.

Presumably, the same can be said of American pueblo architecture in regions with equally arid climate.

But when did the concept enter the European architectural tradition? The German Wikipedia (Flachdach) has a few lines on roof gardens in the (Italian) renaissance era, on architectural theory in the 19th century and on controversies among architects in the early 20th century. However, again, no more specifical information.

Which buildings can claim to have been the first examples of flat roofs in a given country (in modern times)? Flat roofs are so characteristic for the modernist style that (in my opinion) this would be noteworthy information. -- Martinus KE (talk) 02:47, 10 November 2019 (UTC)

Improvement
I have started work on this article. It will take some time to clean up GRALISTAIR (talk) 13:13, 25 June 2021 (UTC)

More sources for water ponding
I added a couple sentences commenting on drawbacks. One issue that I am aware of is the potential for water ponding. Most sources I can find, though, are commercial sites for roofing or related services, which I'm not sure would be appropriate. I added a source from FEMA, but that only addresses ponding in the context of snowmelt. TornadoLGS (talk)

Snow
I don't have a reference, but as someone from a snowy climate I would add to the list of disadvantages the fact that flat roofs do not shed snow, which can be a serious problem. The weight of the accumulated snow often causes leaks and may even cause the roof to collapse. People with flat roofs often have to climb up and shovel the snow off. When I was a teenager we had a garage with a flat roof that we not only had to shovel but in which we had to install a jack in the middle to help hold it up. I imagine that this must be discussed somewhere in the architecture literature.Bill (talk) 16:20, 1 May 2024 (UTC)