The ballast is used to keep the roofing system cool and of out of the sun’s harmful rays, thus keeping energy costs down. The gravel top coat is also extremely resilient to heavy foot traffic and high-wind scenarios.
Why did they put rocks on roofs?
Pebbles or small rocks spread several inches thick over the outer roof membrane will protect the roof membrane from cracking and peeling due to prolonged sun exposure, thereby extending the life of the roof by several years. A layer of pebbles can substantially extend the life of a flat roof.
Why do they put gravel on top of roofs?
Gravel is added on top of tar (and sometimes Single-Ply EPDM) roof systems as protection from UV rays, foot traffic, and wear from weather. If the gravel stones break down, they become less effective and leave your important roof layers prone to wear and damage.
Why do some flat roofs have rocks on them?
Contractors and builders use gravel on flat roofing for two primary reasons; the first is to protect the underlying layer of roofing materials on built-up roofs (BURs), and the second is to secure or weigh down the roofing material, as is the case with single-ply flat roofs.
Why do flat roofs have gravel?
Gravel flat roofs and pea shingle flat roofs
Gravel and pea shingle have two primary purposes on a flat roof; they provide a ‘loading coat’ and they afford UV protection. As ballast, the gravel will help anchor the material underneath and lower the risk of it being blown off in high winds.
Are rock roofs good?
Of all the flat roofing options, a tar and gravel roof is the most budget-friendly and can have a lifespan of up to 30 years with regular maintenance and repair. It provides excellent protection against UV rays, it is energy efficient and is a great option for windows and decks that overlook the roof.
How long do gravel roofs last?
On average, tar and gravel roofs last for 25 years; with exceptional maintenance, they can last as long as 40 years.
Are tar and gravel roofs expensive?
The average roofing installation price for a tar and gravel (built up) roof costs anywhere between $3,750 to $6,750 depending on the slope, pitch, and size of your roof. You can expect to pay $2.50 to $4.00 per sq. foot or $250 to $400 per square installed on a standard sized single story home.
What is the best type of flat roof?
Quite possibly the best flat roofing membrane, EPDM is a relatively low-cost flat roof material that offers a number of significant advantages. Clean, straightforward installation, incredible strength, a long lifespan, and a smart finish combine to make EPDM membranes a difficult one to beat.
Do you put shingles on a flat roof?
Unfortunately, shingles for a flat roof are not advised. … If you have a low pitched or flat roof, tar, bitumen, rolled, or rubber roofing material is recommended. If shingles are your hearts desire and no other method will do, put down a rolled or rubber roofing material first for protection.
How long does a flat roof last?
How many years does a flat roof last? Most traditional flat roofs are made from either mineral felt or asphalt and will have a maximum life span of between ten and 15 years. Unfortunately though they have a bad reputation due to their propensity to leak or become damaged through pooling water.
Can you put gravel on a roof?
If you have a built-up roof, adding a layer of gravel is a very good idea. … Adding gravel over the final layer of roofing mix will protect it against ultraviolet rays, hail and other weather elements. Do not worry; the gravel will not be washed away by rain because it is embedded in the top coat of asphalt.
Is Moss on a flat roof bad?
Why is Moss Bad for Roofing? Moss and algae tend to grow in damp, shaded areas and can cause damage to your roof both directly and indirectly. If you allow large patches of moss to grow on your roof, these patches hold water against the surface of the roof, which can cause the roofing materials to rot.