particular gate that we're looking at here, does it have to be set back, is that right? the department of public works and the building code both address issues that say doors cannot swing more than 12 inches over public property. there are certain exceptions to that. you can get minor variances and get sidewalk encroachment or get a minor variance. it is not an easy process. many (speaker not understood). >> the other thing about these gates is why they want to limit it to swinging 12 inches over the sidewalk. it's because people are walking down the sidewalk. and on this particular sidewalk you've got two squares. that sidewalk is six feet wide and that gate swings out 3 feet. you have to avoid the pool and so one of the concerns why they

limited it to 12 feet, the pedestrians and the disabled community, you're not swinging the gate into someone walking down the street. >> okay. we're going to ping the case so we can get through our 40 slides. we see that gate. here is something we see on the street. we see this accordion gate. the building code says you're allowed to use other than swinging doors where the occupants are less than ten. no special knowledge or effort required. can we use one of these things in egress travel, like on the right-hand side where you had -- it may be special knowledge required to operate this. theoretically, you're allowed to have alternative way to open the doors. then we have, right along here, we have a construction fence in the same block, eight foot height. that's been there 30 years. which i think is under

construction. usually it is a wellness part of the construction permit under the building permit. once that permit expires, because all building permits eventually expires. there's one common feature of all constructions, the retaining wall. graffiti. absolute common feature. so here is just a little (speaker not understood) of this fence. you know, we get the idea. here is only other side. this north beach graffiti. [laughter] >> continuing through graffiti. and the owner of the property is required to maintain graffiti in here. >> let me talk about graffiti for a second. i wanted to pass on a few

numbers. the mayor sends out department of public works on an aggressive campaign against graffiti along with the public department. if you see (speaker not understood), dpw-28-clean. what is that number? it turns out to be after some searching, 2 82-53 26. also san francisco police department has a very aggressive action team going after people doing graffiti. and if you see graffiti and you can relate it to the people doing it, you should call the san francisco police department graffiti number. and that is 558-54 45. i've seen some definite improvement in the city over the last couple years. certainly in the last six months.

but graffiti is an unfortunate fact of life now. on the other side is our dog, sunning himself, whatever he's doing, relaxing. at the back end of the slide here, right above the dog is a rolling grill that provides privacy for the private entry area to a building back there. that is in fact a new building back there. they would have to show that fence probably as part of their new building permit application. >> and they may not be able to get it that big. moving along, backyard fences. this is a view out of my upstairs room into our common open space. one of the characteristics of san francisco is that we share a common open space in the

center of our block. that's a really important feature of the layout of the pattern of development of san francisco. and the code design is to try and preserve the common open space. there is a tremendous pension for persons who wish to develop their buildings to build out into the common open space. or to provide census to provide their own individual privacy. the concept here, they want the buildings built around the perimeter of the block and in the center like a donut, they want open space. so your open space blends with everybody else's. everyone wants to build on their property and share everybody's open space. and planning is saying, no, we want to keep it as somewhat common open space. that's why they restrict huge fences back there to kind of carve off your property. >> right.

so, we have -- i want to point out a few things about the slides and jim can chime in as well. you see the ubiquitous six foot high ridge fence around people's back yards. -- red wouldth fence. -- redwood fence. you see the wire fence. you see the shed. the building code says sheds that are less than 100 square feet and projected roof area, that is looking straight down on them, 100 square feet, are exempt from building code requirements. in fact, they are exempt from pretty much any requirements -- >> it matches the planning code. we have the foot height limit on it. it's 8 feet. >> right. you can build a shed in your backyard, doesn't have to be fire rated. [multiple voices] >> get in there and heat it.

>> a lot of development that happens in san francisco is very incremental, as we can see. so first it's for tools, then a place to wash your hands. the next thing you know, it's got a microwave, then pretty soon it's got a fireplace. yes, sir. (inaudible). (speaker not understood). >> okay, let me repeat the question. the first question was where is grade and sloping lot with respect to the fence and the rear yard. the second one is how do you measure the height of the fence if it is on a retaining wall, and how high from the retaining wall, jim. >> if it is the required rear yard, the wall is maintained three feet above existing grade. it is measured from grade at that point. there is a difference if you're

building structure. the height limit has different rules whether you're down sloping or up sloping, that are permitted (speaker not understood). >> (speaker not understood). >> well, it would be a seven foot fence. the fence would still be measured to the top relative to the grade, so yes. there are circumstances, there is a zoning administrator's interpretation if you have a case where you're retaining a grade and you have a neighbor whose grade is much higher than yours, there are case by case circumstances where they would allow you to maintain a fence on top of the retaining wall. you wouldn't want it falling into your backyard. one questionv question then we'll be moving on. (speaker not understood). >> it can be up to 10 feet high. you need a permit, anything 6

feet to 10 feet needs a building permit. once you get a building permit, -- >> you have to get calculations. >> through appeal building permit. your neighbor might say i don't want a fence 16 high. since there is a permit issue involved, they can take issue with it and go to the board of appeals. (speaker not understood). >> the question was do we then regulate for views to be preserved? no, we do not. there is no right it a view in san francisco. if you wish to have a view or you wish to preserve your answer, the best way to do that is to cooperate with your neighbors and buy the rates to maintain your view. you cannot expect them to preserve your view over their property, or light and ventilation from their property. you are not entitled to take your required light and ventilation from your neighbor's property. you have to be entirely on your own property. you don't have the right to

expect anything from your neighbor's property. yes, ma'am. (inaudible). >> so how small can a fence be? a fence can be any height. there is no required fence. so these fences in our backyard are not required by the city so there is no minimum requirement. let's move on. we have retaining walls and that is a big interesting topic. here is another, once again, gates or doors. gates have to meet the door requirements. it's interesting because the building code chapter 10 says even if the door is not a required door, if you're putting it in for your own convenience, nonrequired doors shall meet the door requirements. but you don't have to have a fence between your property. you don't. >> there are a few blocks in the city i where there is no open park. people like to preserve their property and their asset and

they don't like other people's dogs on their property for many reasons. the people who do it, there are few that are very nice and workout fine. let's go along to retaining balls. -- walls. this is down here where the thick bakery is that's going to be closing. what is it, wonder, hostess? potrero hill. the city has soil which holds itself up pretty well. [laughter] >> and in many cases (speaker not understood). here is a case where this rock is not going to move most likely. it may spill a little bit over the years. as you can see at the top of the slide, people have prevented from blocking off the edge, it's a large fence properly embedded and it has a van here and it says happy 2000 anniversary year, 7bc to 1994.

here is another building built up on top. no retaining rail necessary. as i walked along the wall. i kicked it away, nothing is forever. it's gradually degrading, everything is gradually settingdown and flattening out. how quickly does that happen. as we look at retaining walls you see things a short term solution, how long are you trying to preserve this? how long would it last? >> probably 30, 40 years. one thing to be careful about, wood retaining walls after being made out of pressure treated wood or dry rot resistant wood which is generally clear hard and redwood. all pressure treated wood were copper arsenic suetion solution. when it got wept it would leak

out the larsening and kids would put the hand on the wood and put their hand in the mouth, and they were getting lars anything. >> they changed the formulation of the pressure treated formula to prevent the hazard of children to arsenic. now it's a copper based formula. >> and the problem with the new pressure treatment is not that it's toxic to children, but it increases the corrosion to fasteners, nails and staples and bolts so that if you take the new pressure treated lumber and you nail into it, the nails will deteriorate quickly. quickly. in a matter of maybe a year. if you're going to use the (speaker not understood), nothing is simple any more. when you build these fences, you have to be careful. the other thing, the killer of any retaining wall is

groundwater. you always want to be careful what you're doing with the groundwater. if you trap the water on the wall, the mold on the wall goes higher. if you let the water weep out, sometimes letting the water come out causes issues, too. so there's no simple answer. >> we're going to get to the water stuff in a second. no permanence is required for a retaining wall up four feet high from the bottom of the footing to the top of the wall. from the bottom of the footing to the top of the wall. that is not a very big wall. >> particularly since those footings are wood posts that go down probably four feet. it's kind of hard not to need a permit for a post. foul build a conventional l shaped wall you should make a -- i don't know how you can get around that. >> okay. here is a big wall. you can see one of the issues in the slide, that pat was just addressing.

how did you get rid of the water behind the wall. a lot of water fib increases pressure. here we have -- we have pested sips we are actually working. water stain market street on them. building code doesn't allow you to drain water property onto the sit is regardth away. there's another way to do that and we'll see it in a second. the a lot of fences, the retaining wall is built into the building itself. and here over somewhere, top of market is a billion that's been demolished. we can see it's been used as a retaining wall and look up close and we can see the -- so in many cases it's in use. i have a question right here. (inaudible).

>> the question was is there a limitation of what kind of material you can use for a property line retaining wall? >> under the building code, i don't think there is a limitation that you would have to use something permanent al volume 2 says it has to be designed in such a way that it has to meet the demand for requirements. there is nothing about durability. so basically any settlement material here's another case where there is an old foundation or an old wall that is being used as a retaining wall. in the san francisco building code it says when you're demolishing buildings, you have to remove everything on the site except those portions of the building which are used to retain other property. that may be the case. (speaker not understood) are

often held in place because they're holding up the next property. on the bottom we see some new contracts. i often say if it isn't cracks, it's concrete. what someone tried to do was hatch over the foundation. the lower portion let, what they've done is done a parch coat. the old deteriorated concrete on the right-hand side cracks right through. >> there's no structural engineering. >> cosmetic. >> cosmetic. especially the thin little coating. (inaudible). >> okay, okay. here is the big question. who is responsible for failed retaining walls. we're going to look in a couple of second. i was able to consult with a

couple of well known locals. the issue of who is responsible for fences and retaining walls is the same issue, really. the advice i did not get back -- the advice i got is this. first of all, this is not a matter that is resolved in the building code nor is it addressed in the planning code, nor does the city have any authority whatsoever to get involved in negotiating who is responsible nor may we report any agreement that has been responsible. we have no other way to get involved. however, the twov neighbors -- here is how the courts -- we have a couple attorneys in the room. mr. rums field, please feel free to speak up and anybody else. the courts will say, if the wall or defense is hep tirely

on one person's problem and it was built on that property, the property line hasn't been changed, then frequently, but not always. it's not the law, but sort of the way the courts often decide. frequently it is the responsibility of that person to maintain. if it is entirely on somebody's property. if it's on the property, the property line, if it straddled the property line and it appears to have been built in such a way that it straddled the property line, the court decides there is a share of responsibility. and -- unless the bern proved i built it, but it was someone else's property. it is between the property owners and not part of the city requirement in any way.

easements, by the way, where there are big retaining walls, often you will find recordation between the property owners at the city assessor-recorder's office. it should go to the assessor-recorder's office and look at your -- anything recorded against your property, and also look at what is recorded against your neighbor's property to make sure that you understand the whole picture of this thing. so both of the attorneys i talked to said the same thing. and they both said -- they said the same thing here, but tell the neighbors 0 to work it out. it costs so much money to litigate these things. so here's a large wall, we have the fence on top, the wall cracking. we said everything is settling, everything is in permanent. this is in permanent, a strong wall. i'm sure it will be there for a while. okay. so here is somebody building a

new retaining wall. and i have another slide in a second. what we can see is that behind you will the steele sticking up is a black mesh fabric type material. and that is an interceptor if water comes and hits this open black mesh stuff, it will drain down between the concrete and go to something that collects usually a pipe at the bottom, and that pipe will be connected to the sober. you don't have to connect it directly to the source. you can connect it to an north bayv near (speaker not understood). some other way. >> or you can collect the water and use it to irrigate the backyard. >> maybe. [laughter] >> okay. but that is really a good way to solve this problem, how to get rid of the water behind the wall. give it a place to go, and then get rid of it, pipe it out.

water is the enemy of every retaining wall. here is a more close up of this stuff. look at the size of this retaining wall. where this is the bottom of potrero hill, and here at the top of the slide, drilled tie backs holding this wall up, there is construction going on there. it needed interim measures to stabilize it. and once again graffiti is the big player in it. a place we often see retaining walls on hills is the faces of buildings and that provides opportunity for people to dig in there and build their garages and san francisco, we see people excavating in front of houses, making curb cuts, relocating trees, digging in there, putting in walls and it's built. >> the issue is when somebody

next door wants to build a garage, you need to go to them about when they're digging out under their house. how are they going to dig close to their house? most likely they'll dig close to your foundation. most would be considered substandard under today's code. orange building, you probably need a footing 18 to 24 inches into the ground. you'd be lucky -- >> your advice, maybe pat, get your own engineer to look at their drawing to make sure they're adequately considering -- >> first there is an issue. when someone is digging next to you, you need to pay attention. >> here is a large brick wall. you know where that is? russian hills druming to the public rate of way.

>> they probably were therein stalled historically. you can drive upper market and you can see all that city retaining wall and every one of those city retaining walls have four inch (speaker not understood). legally probably this was 20 years ago. denying 20 years ago. >> this is interesting because it has so many different kinds of retaining walls all together. a rumble wall, roth wall little concrete turf no older concrete retaining walls. there was a transition where they went from cobble retaining walls to brick retaining walls to common reinforcing. there was a transition where they said we built them out of

cobble stones for thousands of years. why do we need to build this new fangled stuff. >> they can settle, which doesn't happen very often. they can slide the whole thing sliding, that doesn't happen very often. they can rotate. that happens all the time. it's happening -- or they can just kind of fall or come apart and break and fracture apart. here we see, we can see a detail of it. next slide is rotating and you can see that is happening in the slide. it is not tide together. >> there is no rebar in it. >> no reinforcement bar at all. >> cobble stone. >> this is not brick which you'll see in a second. >> for and against brick.

>> fail and rotate it. the other thing that happened a lot in san francisco, they built a five foot wall examine it would work. and the next door neighbor goes, i want an extra two feet. so they built something on top of a five foot wall to make it sec hep foot to make it level out the yard. there are a lot of retaining walls so you can see how they've been added to over time. >> retaining wall like this, you don't need to put anything extra. if it's minor, often people will put these tiny gauges. and you epoxy it onto the wall. it will show -- it just stays there and it will show whether or not this crack is opening up or moving one way or another. and you'll see these around town occasionally. this is a sign of a potential (speaker not understood). [laughter]

>> okay. so along the sidewalk here is a failing retaining wall. give it a couple years and it will be replaced. >> it's interesting, when these walls rotate over, as the wall rotates over, it unloads the is soil behind the wall because it creates a gap. that's why (speaker not understood) failed dramatically. (speaker not understood). push on the wall again and leans over. this is the technical issue of strained versus unrestrained walls. the fact the wall is leaning over it's trying to move away from the soil to unload itself. >> this is a buttress wall and the buttresses come down in the spaces between each of the garages. an interesting, unusual design, but we see it around the city. here's another one, gigantic

buttress retaining wall. here is a good wall. >> cobble stone against a rock face in russian hill. >> right, what is that, about 40 feet? >> i think that one has cyclone fencing. (speaker not understood). that's 40 feet if it's 40 feet. cyclone fencing, hold the fencing pinned to this wall so it doesn't fall off to create sort of the beginning of a failure. last line, sort of, kind of. right, sort of kind of. here is an enormous wall, russian hill, i believe. this thing is probably 50 feet. it's used as an exit. and i love this fire scape. comes down from the top, vertical ladder to a landing, down another vertical ladder to another landing and then has a ladder at the bottom. counter balance, flip down about 15 feet down to the ground below as their exit.

fascinating. the city is filled with huge walls. >> because we're on a very steep hill and everyone wants their lot flat and the one down below wants their lot flat. >> this is part of the edge of the mid-block open spaces, by the way. it's within the mid-block open space. here we have a wall, broadway is (speaker not understood). no dog, but we have a guy on a bicycle. >> and graffiti. >> and graffiti. okay. here's one edge of that wall, okay. and with these gentlemen climbing these stairs, i think our slides are over. that's all for today. thank you all very much and we'll see you next week. [applause]