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Answers (6)
- Pasadenan
- Contributions:21466
By the way, two layers of 15 pound felt are equivalent of one layer of 30 pound felt, so just because you may have more layers of felt does not mean that the roof is necessarily any better. But you definitely DON'T want additional layers of finished roofing materials, whether shingles or otherwise. They don't add to the life of the roof, nor the durability, nor the aesthetics, nor the weight loading. They only shorten the life of the roof and create problems.
Would you install new carpeting over your existing damaged worn carpeting? Of course not! You remove the carpet first! Would you install two layers of carpet to get a carpet that holds up better? Of course not! If you want more padding, you put in different padding or more padding. If you want more durability, you use a better quality carpet! The same holds true for roofing. You DON'T want multiple finished roofing material layers on top of each other! The code allows 2, and then you must strip down and start over.
And for thermoplastic membrane roof coverings, and thermoset membrane roof coverings, the roof height is typically built up with Styrofoam to get the proper slope and roof drainage, not felt.
Would you install new carpeting over your existing damaged worn carpeting? Of course not! You remove the carpet first! Would you install two layers of carpet to get a carpet that holds up better? Of course not! If you want more padding, you put in different padding or more padding. If you want more durability, you use a better quality carpet! The same holds true for roofing. You DON'T want multiple finished roofing material layers on top of each other! The code allows 2, and then you must strip down and start over.
And for thermoplastic membrane roof coverings, and thermoset membrane roof coverings, the roof height is typically built up with Styrofoam to get the proper slope and roof drainage, not felt.
- Pasadenan
- Contributions:21466
Extra layers of felt and asphalt shingles alternated does not add to aesthetics nor durability. Nor are asphalt shingles typically used for "built up" roofing. Look up Uniform Building Code section 1502.
"Built up Roofing is two or more layers of felt cemented together and surfaced with a cap sheet, mineral aggregate, smooth coating or similar material."
"CAP SHEET is roof covering made of organic or inorganic fibers, saturated and coated on both sides with a bituminous compound, surfaced with mineral granules, mica, talc, ilmenite, inorganic fibers or similar materials."
Do not rely on real estate agents for information on roofing! Make sure you hire a qualified home or building inspector, and make sure your building inspector gives you the specifics about the roof. Not a useless title that can mean 100's of different things and gives no clue as to age, number of roofs, wear condition, ponding, nor compliance with codes. Remember, if such a term is used in a real-estate advertisement, it has a high probability of being wrong. Roofing construction and maintenance is not their field. Most of them have never removed nor installed a roof. Some of them have never even walked on a roof.
(No, I'm not a roofing contractor nor a building inspector, but I have personally installed 15 roofs, and have been on at least 200 roofs, and I know several roofing contractors quite well).
"Built up Roofing is two or more layers of felt cemented together and surfaced with a cap sheet, mineral aggregate, smooth coating or similar material."
"CAP SHEET is roof covering made of organic or inorganic fibers, saturated and coated on both sides with a bituminous compound, surfaced with mineral granules, mica, talc, ilmenite, inorganic fibers or similar materials."
Do not rely on real estate agents for information on roofing! Make sure you hire a qualified home or building inspector, and make sure your building inspector gives you the specifics about the roof. Not a useless title that can mean 100's of different things and gives no clue as to age, number of roofs, wear condition, ponding, nor compliance with codes. Remember, if such a term is used in a real-estate advertisement, it has a high probability of being wrong. Roofing construction and maintenance is not their field. Most of them have never removed nor installed a roof. Some of them have never even walked on a roof.
(No, I'm not a roofing contractor nor a building inspector, but I have personally installed 15 roofs, and have been on at least 200 roofs, and I know several roofing contractors quite well).
- Bob Blevins, "Bob Blevins"
- Contributions:60
Built-up roofing is most popular on commercial buildings. This type of roofing uses alternating layers of asphalt shingles and felt covering to build up the roof appearance and to add durability.
- Pasadenan
- Contributions:21466
Normally "built up" is not a derogatory term when applied to roofing. But multiple roofs on top of each other is a definite negative. The term is usually not used that way, but an home inspector should always indicate how many roofs are on top of each other. It used to be you were allowed 3, then had to strip down to the plywood and start over. If you only had nailing strips, you stripped down to the nailing strips, applied plywood sheathing, and put your new roof on that.
I've seen many roofs that had 4 or 5 layers of "finished roofing" on top, completely in violation of all codes.
Codes have changed recently, and now you are only allowed a second roof, before having to strip down to the sheathing to start over.
As when there are many layers, it is not only a weight issue, but often you have no idea how bad the previous roofs were before adding the new roofing, and in many cases the sheathing or roofing joists have dry rot, or other damage. Only if you strip down will you see the extend of the damage and be able to properly address it.
Get your home inspector to give you all the detailed information about the roof, especially the age and life expectancy. Do not rely on the information provided in a listing by a real estate agent.
I've seen many roofs that had 4 or 5 layers of "finished roofing" on top, completely in violation of all codes.
Codes have changed recently, and now you are only allowed a second roof, before having to strip down to the sheathing to start over.
As when there are many layers, it is not only a weight issue, but often you have no idea how bad the previous roofs were before adding the new roofing, and in many cases the sheathing or roofing joists have dry rot, or other damage. Only if you strip down will you see the extend of the damage and be able to properly address it.
Get your home inspector to give you all the detailed information about the roof, especially the age and life expectancy. Do not rely on the information provided in a listing by a real estate agent.
- Ron Scott, GRI, "RonScottRealtor"
- Contributions:192
In addition to Pasadena's answer, I have heard the term used when there are several layers of shingles on the roof.
- Pasadenan
- Contributions:21466
"Built up" says very little about the actual roofing material used.
It usually applies to flat roofs, where the roof slope required for drainage is foam or other material to build up the height needed for the proper drainage.
Most "built up" roofs are asphalt roll roofing usually applied with a hot tar. But it could just be rolled roofing with lap cement and Henry's wet-patch.
Or you could have a rubberized plastic membrane roof that is "heat-welded" (melted together) at the seams.
Or it could mean that they installed the felt, then a hot tar over that, and then a gravel finish on top.
If all they tell you about the roof is that it is "built up", they are being lazy and providing you very little information.
Your home inspector should provide you more detailed accurate information.
It usually applies to flat roofs, where the roof slope required for drainage is foam or other material to build up the height needed for the proper drainage.
Most "built up" roofs are asphalt roll roofing usually applied with a hot tar. But it could just be rolled roofing with lap cement and Henry's wet-patch.
Or you could have a rubberized plastic membrane roof that is "heat-welded" (melted together) at the seams.
Or it could mean that they installed the felt, then a hot tar over that, and then a gravel finish on top.
If all they tell you about the roof is that it is "built up", they are being lazy and providing you very little information.
Your home inspector should provide you more detailed accurate information.
What does it mean when it says the roof is built-up?
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