Rocon

Nope it is national... CBC refers to ASCE/SEI 7-05 "Minimum design loads for buildings and other structures" 12.10 Diaphragms, Chords, and Collectors. 12.10.1 Diaphragm Design. Diaphragms shall be designed for both the shear and bending stresses resulting from design forces, at diaphragm discontinuities, such as openings and reentrant corners, the design shall ensure that the dissipation or transfer of edge (chord) forces combined with other forces in the diaphragm is within shear and tension capacity of the diaphragm.Thats fine but where in there does it say that a ridge vent can't be used and that a ridge vent weakens the diaphragm to the point where it can't do what it is supposed to do? Where is the residential code reference? ONE TEAM - ONE FIGHT!!! Mike The site in question is in California and falls under the CBC which refers to the ASCE document. The SE's that I have spoken with on this issue all say that "it is a basic tennant described by 12.10.1"

Hi, This is a new one on me. How do they effectively ventilate cathedral ceilings done with conventional rafters and not scissor trusses in California if they don't use a ridge vent and eave vents? Do they stick a pot vent on either side of the ridge in every single rafter bay? I've driven through California a few times and I've never noticed that having been done on any houses. We have rules for seismic bracing here too and I've never seen where the use of ridge vents is said to weaken the roof diaphram. Does it really weaken it enough to be a concern? References please. Is this some kind of La-La Land specific rule - like the one that says fiberglass insulation has been proven to cause Cancer in California but nowhere else? ONE TEAM - ONE FIGHT!!! Mike Nope it is national... CBC refers to ASCE/SEI 7-05 "Minimum design loads for buildings and other structures" 12.10 Diaphragms, Chords, and Collectors. 12.10.1 Diaphragm Design. Diaphragms shall be designed for both the shear and bending stresses resulting from design forces, at diaphragm discontinuities, such as openings and reentrant corners, the design shall ensure that the dissipation or transfer of edge (chord) forces combined with other forces in the diaphragm is within shear and tension capacity of the diaphragm.

Click to Enlarge 64.26 KB would something like this solve that problem? leaving plywood between the rafters say...4 inches on each side alternating on rafters... A structural engineer might accept htis after reviewing. It appears in my humble opinion to be an intereesting solution if it had additional blocking and nailing.

P.S. Do not use a ridge vent in California. You will loose diphragm continuity of your roof. What that means is the house will be less capable of resisting earthquakes.

Here is what it looks like in 5-6 years. Download Attachment: 2009 06 30 RRO 8610.JPG 1973.04 KB Ballasted it looks like this. Download Attachment: 2010 04 21 RRO 7595.JPG 1801.34 KB It is my understanding that the ballast adds 5 years to the systems warranty. Each of these projects have 1500-2000 squares of roofing. Each has a fair number of water leaks. The ballast makes it that much harder to locate the source. Due to the way the system is applied over the existing roof leak detection is allways very difficult.

I saw the ridge vents installed on 20 buildings recently, all of the attics were very cool to walk in. The downside was that there were active leaks at the vents (6 of 240 units). Download Attachment: 2010 03 30 RRO 5548.JPG 1674.09 KB One word of warning. They cannot be used in California due to the roof daiphragm continuity being lost.

What is causing the staining on the shingles above the flashing?

Yes it is a mini horn that is atached to the life safety system. The internal smoke alarms will sound when there is smoke in the particular unit. The mini horns will sound when there is water motion through the fire sprinkler lines or a fire alarm is pulled.

"The hardie panels in your case would be the first line of defense. A rain screen wall is not designed to allow water beyond the outer layer. It is designed to manage the water that enters the system. With the closure strips on thie proposed system very little water should ever get in, when we discussed bugs earlier. I believe in the system of foil faced foam as far as this. I do not have a track record of how well the tape at the seams will last. The tape by nature is a reverse lap at horizontal joints. If there is any failure of the tape either due to application or product failure you will have fish eyes at the edges. The fish eyes are conduits for water intrusion. I bet everyone here has seen what happens to peel and stick that has fish eyes. I to am a belt and suspenders guy, last week I sent out a design recomendation, and for no other reason than what if it is inadequate. I put in an additional point for water to get out of a system. So what I would do is over the foil faced foam and tape I would apply a waterproof barrier, probably spray applied with reinforcment over the joints and avoid the tape alltogether." I do not consider myself a building scientist either hence my recomendation for a WUFI by someone qualified to perform the analysis. It just seems close enough to the assembly that I thought I would mention it. The building I mentioned is a very high profile failure that required over 70M in repairs. The condensation was primarily caused by interior conditions, combined with the wall assembly.

The particular assembly that the proposed wall reminds me of had exactly that. The dew point occurred between layers of XPS foam, the WRB outboard of the foam did nothing to help drainage. The differences that are pertinent are that the wall in failure had a Titanium panelized Rain screen, and the location is colder than what I believe Oregon might see. That being said I am a firm believer that when you vary from the norm as much as the proposed assembly seems to be the more likely it is to have unexpected problems. Like someone once said to me “we never have time to do it right but we always seem to make time to do it again when it failsâ€

ECO RETRO, After reading your comments above I have new concerns. These concerns I do not believe can be answered on this forum. The assembly you mention, in my opinion has several possibilities for problems to develop. In my opinion you must perform a WUFI analysis on the wall assembly to see how the wall will perform in your climate. As you have described your modified assembly, I think you have potential for condensation in the wall. The wall system you have described is very similar to walls that I know to have condensation forming internally. The only way to determine if my suspicion is correct is to model the wall. I would be happy to give you some referrals for companies that can perform the modeling for you. I think it would be a cheap insurance policy for you.

Brandon, As with many rain screen systems there are some entry points. I believe the reason they say up to 3/8â€

That is to let the water out that is trapped by the confined rake flashing!

Here in California there is a "cool roof" statute in place. it is part of our title 24 requirements under the CBC (modified IBC). Performance of cool roofs is good and as you say the coating needs to be maintained due both to degradation and also dirt that accumulates through the life of the coating. It is very effective in southern California. Areas farther north, and in colder climates do not benefit as much, buildings in cold zones do not benefit from thawing of snow due to solar gain during the winter. There is some discourse as to how much money it would save. I think some of our fiends in Canada could probably shed some light on this for you. I have seen some documents from the Canadian government dealing with these issues.

I see similar paint failure/damage to painted three coat plaster on a fairly regular basis. The cause is usualy sprinkler heads spraying against the plaster.

NJ ain't sunny California. So the laws of chemistry and physics don't apply in New Jersey? Silly me, thinking that Industry standards applied to all 50 states. As long as the sun shines on New Jersey and mastics contain bitumen and solvents the reactions will be the same, the only variable is time. I have seen mastic applied to PVC vents at roof penetrations. The PVC has become gelatinous then two inches away where exposed to UV the PVC is brittle. If we do not learn from our mistakes we are doomed to repeat them.

And what prevents plasticizer migration? And not it is not accepted by the manufacturers.

Does the PVC pipe penetrate the roofline? If so is it UV protected, and does it have mastic on it?

Given these items and looking at the picture I do not think it is thermal expansion. At first glance it does look that it is. In the photo I noted that the cracks are somewhat wider at the top than the bottom which kind of tells me that it is structural. I would check to see if the collar ties are low enough at the attic. some pressure from splaying or sagging trusses could be asserting itself due to framing issues in the attic. You say that there are alot of foundation problems in the area, and that the corner occurs just out of photo shot. If there is no framing problems in the attic it is most likely something going on at the foundation at that corner.

Do you have a wider view for perspective?

Not to be obtuse, but what is Amanda's law about? I am not familiar with this one.

The information Mike gave you was absolutely correct. I have a building where everything is the same in two bathrooms located in different units, all of the systems are working and the only difference is how the owners use the spaces. One bathroom is pristine, and the other has Microbial Growth. The difference is that the unit with MG, the owner keeps the door to the bathroom closed and only runs the vent as long as they are in the bathroom. They have a humidifier in the bedroom and when I went to the unit (three hours after shower usage) there was standing water on the floor. Your same habits in different buildings/homes do have an effect. With an open mind ask yourself these questions that could have an effect. 1) do you keep the interior at the same heat that the previous owners kept the home at? 2) Do you cook any more or less than they did? 3) Do you shower any more or less than they did? 4) Do you have the same number of occupants that they did? 5) Has anything changed with the roof, walls, or windows? (It sometimes rains in Louisiana right?) 6) Do you ventilate the house as much as they did? 7) Did they have a de-humidifier? Any number of more questions. If you answered any one of these questions with I don’t know (not just I don’t think so) then you do not know and you will not be able to push a lawsuit. Because they will say the only thing that changed was you now live there. You need to find the cause, even if you have to take some responsibility.

FYI http://www.nbnnews.com/NBN/issues/2010- ... index.html

You too, I am also finding them more and more often.

I had a unit that was acting up similarly, and the problem was the thermostat. The thermostat had a run cycle setting that was causing the problem. Try disconnecting the thermostat and connecting the wires directly together.