• Flat roofs are common in warm climate areas.Home image by Andrew Breeden from Fotolia.com
  
  Flat roofs are susceptible to many different kinds of damage that can be caused by anything from intense weather to people walking on them. Whatever kind of flat roof you have installed on your house, there are several options available when it comes time to replace the old roof with something new. Depending on your budget and location, each type of flat roof has its advantages and disadvantages.
  
  

Single-ply

• Single-ply roofing comes from a single layer of a plastic or rubber material such as thermoplastic poly-olefin (TMO) or polyvinyl chloride (PVC). These two types of single-ply roofing are known to reflect heat well, which can help lower air conditioning costs. Ethylene propylene diene monomer (EPDM) is another common single-ply roofing material.
  
  

Multiple-ply

• Multiple-ply roofs are made from felt rolls or mats that are separated between asphalt layers. A covering layer of gravel or small pebbles is then placed on top of these multiple-ply layers to protect against damage and exposure.
  
  

Modified Bitumen

• Modified bitumen roofing is made of modified bituminous material, which is a mix of asphalt and a polymer, as opposed to straight asphalt. By combining asphalt with a polymer the asphalt then acquires certain polymer characteristics, which leads it to resemble singly-ply roofing in substance. Modified bitumen roofing is installed in a similar manner to multiple-ply roofing and is then also covered in a layer of gravel or other protective coating, such as certain liquid coatings that reflect light well.
  
  

Flat-seamed Metal

• Flat-seamed metal roofing is made out of sheets that resemble tiles or shingles. The sheets, which are generally composed of copper or steel, are then soldered together to create a cohesive roof. Flat-seamed roofing materials are more expensive than other flat roof replacement options, making them cost prohibitive to some people. However the lightweight and light- and heat-reflective nature of the materials make them long lasting, effective and aesthetically appealing.
  
  

Roll Asphalt

• Roll asphalt roofing entails rolling asphalt-saturated felt onto a roof over a base felt layer. After the asphalt is rolled onto the roof it is then either nailed down or covered in cold asphalt cement and then finally covered in gravel or some other protective layer. Roll asphalt roofing is the least expensive flat roof replacement option, but has a shorter lifespan than the other costlier options.