maybe one per continent, maybe two or three in this country, then once they are all networked, they begin to communicate with one another and share information. in 2010 the website will launch, but it will be what you would call an informational website and then we are going to try to, by 2011, invite people to add a memory. so in a funny way the member rely grows and there is something organic about how this memorial begins to have legs so to speak. so we don't know quite where it will go but i promise to keep on it 10 years. my goal is to raise awareness and then either protect forests from being cut down or reforest in ways that promote biodiversity. >> biodiverse city often argued to be important for the world's human populations because all of the medicinal plants and uses that we can put to it and fiber

that it gives us and food that it gives us. while these are vital and important and worth literally hundreds of billions of dollars, the part that we also have to be able to communicate is the more spiritual sense of how important it is that we get to live side by side with all of these forms that have three billion years of history behind them and how tragic it would be not commercially and not in a utilitarian way but an emotio l emotional, psychological, spiritual way if we watch them one by one disappear. >> this is sort of a merger between art and science and advocacy in a funny way getting people to wake unand realize what is going on -- wake up and realize what is going on. so it is a memborial trying to get us to interpret history and look to the past. they have always been about lacking at the past so we proceed forward and maybe don't

commit the same mistakes.

>> thank you for coming and welcome to the department of building inspections brown bag lunch. i'm lawrence cornfield chief building inspector. today we will talk about being dry. i hope. we will talk to 2 exerts on roofing. e lan hansen from align roofing he does roofing and residential work and involved in boma the buildings of manager's association. we in the building department have to work with various industry groups. and henry navarro who is the roofing supervisor for the port of san francisco. for 20 years? >> 23 years. >> you have seen roofs come and roofs go. >> 38 years worth. >> how long does a roof usually last? >> dependos the climate and the

pitch of the roof. >> uh-huh. from? >> a couple of years. >> from 15. i asbestos roofs go for 15 years. you said you put a roof on your house you expect to last? >> 75 year. i wish you luck. >> only going to do it once. >> people know what they are doing with their roofs that will last for a long time and not have to redo it. is this the same concept as painting where it takes a lot of effort to get ready and the prep work and the materials are such a large part of the expense or the materials are a big piece of the expense. i tell people in painting, buy the best material you can because you don't want to keep redog it. is this the same concept. >> it is the prep work is important if you go over a bad

part tell effect the roof. >> going over a bad surface. the implication is most buildings in san francisco are existing buildings. we don't have that many new buildings that you can put a brand-new work o. most of the work we see and you guys do are reroofs. which is trying to going out what the problem is and how to fix it? is that what you do? >> yes. i was thinking the subsurface. when we see oftentimes someone put a beautiful tile roof on that can last 50 or 70 years the waterproofing under is not up to snuff it the last 15 years you have a 75 year old roof that will last for 15 because the underlayment is not up to the quality of roof itself. that's an example we are seeing

here. >> what is the primary cause of failure? failure means that the roof leaks? we can agree the roof doesn't work it leaks. >> it's supposed to rain tomorrow. >> the most important thing is application. >> the failures do to misapplication. joot poor work manship. >> what are the -- there are a couple of different applications. we have application of the edges and the flashings and application of the actual surface covering. is it reasonable to divide roofing into the 2 big pieces? like flashings which are how you deal with all the edges where a vertical surface meets a horizontal surface or where you have a nosing there are all the edges. there is the field. >> right. >> there are 2 different concepts; right ? >> one can have the best roof in the world if the flashes are

not acceptable they will leak. >> the majority of leaks of the roof is due to flashings and the penetration of the roof. typically the field is not the issue. >> we have 2 basic pieces of roofing. the flashing and the field. let's talk more about what these mean and what a flashing is. this is such an important concept when we talk about roofing. here, henry brought samples of flashing. >> a raised edge. >> this would go on the edge. let's put it on the edge pretend our table's a roof. >> around the perimeter of the roof. the reason we call it a gravel stof the lip holds the asphalt in place. >> gravel roofs were a traditional san francisco roofing style until recently

since it lost fashions? >> it lost fashion due to the fact when one deals with a gravel roof, such as this one here, the weight of the gravel alone. if it's properly applied there is 400 pounds of rock per square foot extra weight you are holding up for no reason. >> is that would fit against the gravel stock. like that on the gravel stop sdpt gravel stop keeps the stones from rolling off. >> what's the best materials to use for flashing. >> i'm sure all of you have seen the plastic gutters and things like that which i don't recommend. plastic gutters dry out of uv race. the best flashing is metal and

top of the line is copper. >> what is this material? >> this is the basic metal. >> this is what we see around the city. galvanized sheet metal how long will this last? >> close on the ocean? 10-15 years. >> is that how long you expect the roof to last? >> if it's a shingle roof it's like this without the raised edge. the steeper the pitch on a shingle roof the longer it lasts. >> using flashings and one of the things we find when we find leaks when you put a piece of metal down it needs to be primed correctly before you attached roofing to it. if it's not primed, which we find often it will separate over time. >> how would you prime it? >> you take this metal and prime it with a brush or spray.

that gives the metal, the roofing something to bite on the metal. >> it's an asphalt primer. the reason it needs to be primed. there's a fill of oil on it. with the oil it keeps the asphalt from sticking and it's a smooth surface. >> you have to clean the oil off. >> the primer takes care of that. we find that's an area that people, cut the corners or don't pay attention to the detailed. when you deal with the metal you have to be careful how you attaching roof to it. >> this is one type of edge. this is for a built up roof with gravel. or this for the [inaudible]. >> okay. this other one you have was -- >> that's a shinnel node. >> show us how this one.

>> this goes up the bottom of our roof up the side of the house. and the reason there's no lip is to keep the water to get off and the shingles to lay flat. >> this you don't have to prime. >> the shingle is on top of this? >> right, right over top of it. >> at an angle? >> most likely. >> follows the pitch of the roof. >> the difference between the shingles and the built up roof and the reason you prime it because this has to adhere to it it has to stick to the metal. in shingles we are not looking for an attachment. we would like at a flat roof and a steep roof is that a low slopped roof has to have a complete water tight membrane on

it. where as the shingle, the shingles are there to shed the water under the shingles is the felt or whatever you put that is the waterproofing. because you have a steep roof. we don't worry about water going up under it and rolling up to where the flaps are. this is a complete sealed system this one is not. >> when i came to san francisco 30 years ago and saw the flat roofs i was surprised. i came from new england and you don't see flat roofs in new england you see pitched roofs. why do we have so many flat roofs. >> the style of design. >> labor material. >> uh-huh. >> you don't have to frame up the attic space. >> the other thing is we don't have snow. >> we don't have the issue with weight and the issue with you know loads on the roof.

that's why you see more flat roofs in california. >> another reason for that on roof is they are improperly nailed. these sheets come in 10 foot links and should be nailed every 4 inches. some people go and put a nail 12 inches, 18 inches. and whenever the 2 come together there's an area of failure. what should happen when these 2 over lap. prior to over lapping, there should be a lar of roof between the joints if it doesn't it tends to sweat in there and rust and tell move. when it moves it breaks the seal. >> we look at roofs and say, water will hurt my receive. it's not the water that hurts your roof the biggest enemy is

the sun. the uv rays that come from the sun. they dry out the roofing membranes and materials. once they dry them they get brittle. that's where your issues are. we talk about the gravel roof. gravel is probably still the best uv protective balist there is. >> gravel serves a number of valuable purposes. protects the roof from uv. reducing the speed of the run off of water. increasing the surface area of the roof for greater evaporation. it has a variety of benefits, which when you don't use gravel we have to make up for. >> with gravel after a job is don and the roof is rocked it's very easy to hide bad workmanship. >> i live in pacific where it's

windy. i was wondering if there was preventive maintenance to go on my roof if i feel lose shingles can i glue them down. i don't think my roof is very good. >> one of the things you can chose, depending on the wind uplift in your area. if it has a higher nailing pattern the more wind in our area the higher level of nails are installed with the shingles. that's something you have to be careful with you want to make sure, i'm in a high wind area what does that require for shingles. >> if it's not properly nailed how do you hold this down. >> you can't. with the shingle try to get a nail. >> the shingles will break. >> you can actually get a little calking gun and tab the

shingles. the shingle pulls up like that you can actually put a little bit there and tab it down. >> does that help? >> it does when she's in a situation where wind has torn that that's the only other thing -- if you nailed it you will put more holes. >> it's not going to do this. you don't want to -- you shouldn't be able to walk on your roof and see the nails if you can see the nails there's a problem. those nails should be under the laps so they are not exposed. if you get a calking gun and lift and tab and lift and tab. the ones that are lose you take the calking gun and squeeze little and push it down. >> could be the fact you were

shingles are old. before organic shingles. and a lot of the old organic shingles didn't have a tab. >> i have an aluminum roof i don't know what's under it. i want to replace it and i don't know how many lay ares are under. do i pull everything up and go aluminum or? >> good question. >> about how does one figure out what to do when they want to reroof their building? >> you have to figure out how many roofs are on it. >> i have a core. it's just a cylinder with a handle and makes a little hole this big and i can pick it up and count the roofs and i know what's underneath it. usually when i see a roof as you

are talking about, it probably chances are it's a 28 pound with 2 flights of just ply sheets. number 4. sometimes they give it an asphalt glaze and let it sit for 30 days and paint it aluminum or they will put a coating on it prior to the aluminum. >> you could have 2 or 3 roofs already. when you ask code questions. we don't let you put more and more roofs. when you do the core they can look at that and see -- we have henry if you were to look at that. i can count, 1, 2, 3, 4. this roof has 4 sheets. that's a standard roof. if you see sometimes they may have put another roof on top of

the rock roof. >> yeah. you can -- when they look they will see how many layers of roofing on there. there are options of over laying if you only have one and it meets the requirements of the city. joot city building code says you can have 2 builted up roofs or 3 shingle roofs. this is one layer of a built you have roof here, you could have 2 of these roofs you would have to remove one or both before you put the next flat roof on. if you had a shingle roof you could have 2 and put a third one on. i don't know if it would be a good idea. >> it's legal under the building code. >> if you notice on the bottom of that sample that was installed over a gravel roof. see, how the gravel from the roof under is wearing into that

roof. that's why i never recommend going another roof over gravel. i recommend being torn off. fine over smooth but not gravel. what should this lady do about her roof. >> find somebody that knows what they are doing and have them core the roof. find out what is this there. how many roofs are on there. they can repair it on site. it shouldn't leak. once they have done that you can ask them, give me some specifications. tell me what kind of roof you recommend to put on this roof. they should be able to tell you a couple. they may talk to you about the new rubber roofs that are going on. the tpo roofs. they may talk to you about a cap sheet roof. may talk to you about another

gravel roof or a coating. the aluminum coating. one of the ways people put on another roof they have a roof wearing down and they put the coat on and it gives it a uv protection and you might get a few more years out of it. >> i have a tar and gravel roof put in several years ago. they tried to pitch it to drain the water toward the drain. by putting boards under. it still collects water. i was wondering after a few days it does dry up but it pools water. does that do harm to the roof? >> the building code requires that roofs drain. you are not spoed r supposed to have ponding on a roof surface. you see it alo lot the roofs ar

heavy and they settle. what's your take. >> if you have more than one roof if the previous contractor didn't take out the old drain ask and put in a new drain and ran over the top of that that would cause the water to pond. the drain is higher. >> than it used to be. yeah. >> okay. >> if you have, i've been on roofs in the city where i have seen 4 or fives on houses in the avenue. you get all that weight and it starts giving your roof deck a deflection. that might be the cause of that. the only way to do that is take everything off and raise it back up. >> it sounds like a tried to put in a cricket. when we do reroofs we see a lot of this as the building settles and gets older the pliwood deflects you see ponding that will happen.

unless you spend a lot of money and put a full paper system to push the water where you want it to be. one of the main manufactures jm, gives you between 48 and 72 hours. if the water evaporates in 48-72 hour in the ponding areas it will not effect the manufactures warranty. what i find is that, again, i don't think the water itself hurts the roof. in the areas it ponds that's where the dirt ends up. it tends to wear the cap sheet down faster. what we recommend is every 4 years you may need to go on the areas where it a wearing the cap sheet and put emulsion and reimbed the granules.

>> it's really difficult get a pond off an existing roof. when you raise an area you push it to the next. when you raise another area it pushes to another area. it's difficult to do on some of the roofs. if they tried to do this and took the roof off and tried to do it you might want to ask, why is the taper not working the way it was supposed to work? >> it's not reasonable to say, let's take it off and rebuild the roof do routine maintenance. >> i roofer would know how to do it? is >> yes. >> let's finish talking about flashings. how many roofs there are one of the ways you can sometimes tell is by counting how many of the metal stops you have on the edge of the roof like that? the simplest of all ways if you see 2 or 3 you know they are

there because there was a roof put on. >> sometimes that works other times it doesn't. when they put on the first one the gravel stop might be an inch. the next will be an inch and a half and the next will be 2 inches and 3 inches. you might be covered but if you see a few -- >> there's another type of flashings we should talk about. one is where there's a wall that come down. here's a wall coming down to a roof surface. and you have to figure out how to keep the water from going to the joint the wall and the vertical surface much the other we will talk about is penetration and pipes. and ducts and equipment. how do you flash the vertical wall to the roof surface? >> basically the first thing we do is when you come to the roof deck is depending on the type of wall it is.

there is a cap to soften the 90 degree break. the base strip is brought up and the fall in plaza brought in 2 inches over that and 2 inches over that. that's a triangle piece. it's not a sharp edge. the roofing can roll up. >> that's right. >> there you go. okay and then we -- the base sheet come to the top and the other dmries go higher and higher. the wall would be counter flash. >> what is counter flashing. we have flashing. which is from horizontal surface up to the wall. the next part, it's the critical element is the counter flashing up the wall and over the edge so

the water doesn't get in the edge. >> one of the things we see that causes probleming when they don't put cant strips in. somebody will cut a corner 1 thing they leave out the cant strips and try to do this. bend it and make it go straight up. what tends to happen is it will start to split in here. the other thing is it doesn't get tight and there is a void if somebody goes up there they put their foot straight through it. >> so, we have the roof coming up like this. and we are attached to the wall. the next thing is -- this is our exposed edge the edge we want to cover so water doesn't get behind that gap. we take -- we do often is use

metal. if your wall that's coming down has stucco you want to put the metal in before the stucco and neither of these work. i can't -- but. you will be flashed over the top of the piece and a second piece that come from behind your stucco. now -- >> the stucco a bit. put the metal on and restucco on top. when you are able to put 2 pieces in when you replace your roof you pop the bottom piece off, put the roof in and pop the piece back in it's nice in not having to tear out the whole wall out when you want to replace it. sometimes you can't do that. so, the other thing we see is what we call [inaudible] one where you don't have anything on top of it. it's exposed. it's nailed off and --

>> this would be across there like that. >> it typically has a kick at the top. we will nail that in place and put calking along the top of that. that sheds the wars coming down the wall. the calking and the maintenance item. you need to look at the calking joint every few years because the sun dries out the calking. it sheds the water and doesn't allow the water to get under our system. that's the counter flashing we call surface mounting counter flashing. >> don't recommend using silicone. what holds up is [inaudible] calking. >> buy the good stuff. >> one of the important lessons i'm learning listening to this is you don't just do a roof away and expect it