how to build a martin box for trapping

I thought wind-washing would degrade the performance of the batts. Vent sideways out the blocking between outlookers? You have to follow the usual rules for continuity: You need air barrier continuity and thermal barrier continuity. My home built in 63 here in Ohio has a cathedral ceiling with no ventilation. Thank you guys for your input / answers. With that, and my ship-lapped ceiling, I’m thinking the Tyvek might be a good idea, in case any house moisture does get into the rafter bays. As I mentioned earlier, I also have two skylights taking two 16" o. c. rafter bays each on my cathedral ceiling. - install horizontal strapping (2x3's) on 24" centers Other pictures show the roof deck or spray foam layer as the exterior side air barrier: http://www.greenbuildingadvisor.com/sites/default/files/Insulated%20cathedral%20ceiling.jpg, http://www.greenbuildingadvisor.com/sites/default/files/Cathedral%20ceiling%20with%20all%20insulation%20on%20the%20exterior%20side%20of%20the%20roof%20sheathing.jpg, http://www.greenbuildingadvisor.com/sites/default/files/images/Flash-and-batt%20method%20of%20insulating%20a%20cathedral%20ceiling.jpg. And we are now at a place of deciding how to finish off the inside of the ceiling in a way that 1. is air-tight 2. allows inward drying (if outward it seems like is not a possibility) and 3. achieves our desired thickness.". A. In the scenario with the conventional ventilation channels under the lowest level of roof sheathing, the rafters have some contact with the ventilation air space. Had I read this article first, probably would have skipped the cathedral ceilings--I have two of them. Would you guys recommend this solution, or would you go a different route? - Synthetic underlayment stretched over roof framing An alternative would be to remove the 2” EPS over the cathedral ceiling and put down 4” total of polyiso or XPS (and and additional 2” EPS elsewhere), but it sounds from your posts like polyiso and XPS are not the best choices in cold climates (and for long-term performance). When the roofing has been removed, you can install rigid foam insulation above the existing roof sheathing -- as thick as you can manage. ), (Side Question - couldn't you just compress two layers of the R-11 together when filling a 3-1/2" deep space and achieve R-15 that way? Mansard I was thinking that I would spray in cellulose from above, then put on 3/4 sheeting, then rigid foam, then the 1/2 OSB required for membrane roofing, then the membrane. The code formula is explained in this article: "All About Attic Venting. If the underside of your roof sheathing gets wet, and the wool insulation gets wet, that's a problem. Cheers , You could then cover the rafters with rigid foam to bring your insulation up to required R level and reduce the risk to the rafters and sheathing, and then install your airtight drywall underneath this. 4-1/2" polyiso I haven’t been able to find any information on insulated floors. 1x3 furring cross top of 4 inch boards I'm guessing over rafters. You need an air barrier to keep your sheathing from rotting. This room is a bathroom, so moisture is even more of a risk I imagine. Yes, duct condensation can be a problem. Once your ventilation baffles are installed, you can insulate the rafter bays with fiberglass batts, mineral wool batts, cellulose, or even the flash-and-batt approach. Cathedral Ceiling repair work 1. We're going to give it a try. I have built log homes in the Yukon Territory in northern Canada for 30 years. Thank you in advance, looking forward to your thoughts on this! Given my amature status I feel an intentionally "breathable" wall will help with some inevitable errors/misses on my part. EPS is somewhat squishy, and I can imagine problems from your plan. So you need to seal the vent openings near the soffits and at the ridge. An open pier foundation? No matter what insulation method you choose, you can't expect your insulation to prevent roof leaks. Another issue that comes up in that scenario is whether that could promote condensation on the underside of the 1" XPS when it is cold enough outside because the underside of the XPS could be below the dew point? you close with the following If you have a leak, you have to fix the leak promptly. The polyiso will not create a mold problem. Rather than extend the rafters, if I execute the unvented roof as designed and put 4" of polysio on the roof deck, can I then use open cell foam between the rafters? "Even in this location (which has about 2000 annual heating degree days & 2000 cooling) you do see the closed-cell foam as a prudent investment?". These circled soffits were added when we dormered this section of roof shortly after we bought the house in 1990. 1/2" ply First, we are planning on our primary light source throughout the house being can lighting. The right way to proceed is to install rigid foam above the roof sheathing. "Does that cavity need to be filled all the way? (If your rafters are 2x6s that measure 5.5 inches deep, and you have fiberglass batts that are 6 inches deep, you must have compressed the fiberglass -- and I'm not sure if you even have any ventilation channels. 6. Of course, I'm speculating. At one point we had a relatively small tank raised on a stand (but below the roof line) alongside our bathroom that caught rainwater, with any excess running off into a bigger tank. The ventilation here seems adequate although the baffles would not be the ones of choice used today; they are better than nothing! A. We use a water transfer pump, fitted with strong, larger hoses, to move water from our biggest storage tank to the smaller ones during long periods of no rain. This tank holds 1,000 litres of water. Right now rafter bays are insulated with kraft faced r-11 fiberglass batts. Response to Joell Solan After that I want to find a way to get some insulation into the void around the beam for the whole length of the beam. With the thermal bridging of the rafters it's going to underperform R49 of blown fluff on an attic floor by quite a bit, and even HFO blown closed cell foam has a substantial carbon footprint: https://materialspalette.org/wp-content/uploads/2018/08/CSMP-Insulation_090919-01.png. "Would it be OK to use another layer of foil faced polyiso (vapor-impermeable)? I plan to fill the rafters with rigid polyiso to yield r-30, but might opt to fur out the rafters and use fiberglass or cellulose instead. If you need long screws look to Tru-fast screws from Cor-ten.com When it comes to the screws, make sure to use a slight upwards slope of about 5 degrees to create a truss out of the screw. Most of the information I run across seems to be from the cellulose industry that claims wind-wash is a big problem with fiberglass; and from the fiberglass industry which asserts that the cellulose group overstates the issue and that to the extent wind-wash occurs it is really inconsequential. The roofer advised me against installing a hip ridge vent due to water penetration concerns. I would really appreciate a prompt reply, as it is winter and I need to wrap up my project ASAP. Vented Over-Roof Hybrid Do we have to put a pump in the water tank to get pressure inside the camper? There is some possible benefit to using 1x4 purlins -- especially if you specify vapor-permeable roofing underlayment (in which case you would be providing a possible mechanism to allow your roof sheathing to dry to the exterior). Appreciate everyone's input - this site has been an excellent resource. Debra, You need a good air barrier on both sides of your fiberglass batts. It's possible it varies based on the type used. Another concern is heat gain as the current design calls for a dark grey metal roof. Thanks! Still, I wonder if it would help to add vent channels to the bay sections above and below. ", Q. Having a knowledgeable answer from someone who knows what they are doing would mean a lot. 1. You can feel on your face, the heat radiating from the underside of the roof. If you add fall protection equipment, it becomes even trickier. Re: Replies 196,197,198 Stephen,Brad,Martin So my questions are: Hot humid climate-all metal cathedral roof-must use R-11 batts Luke, Jen, A: I actually laughed out loud at the elves on mushrooms idea. There are no caps where it meets at the hips of each the panels of the octagon. Ah ha. Appreciate your help immensely. Once ANY moisture gets down to lower sheathing, it is game over...imho. Roof is plain gable with 12/12 pitch. However each of those sections is adjacent to a fully ventable section. No. We chose standing seam to minimize the risk of any leaks, and we plan to focus intently on getting all of the flashing details right. ", https://www.jm.com/content/dam/jm/global/en/building-insulation/Files/BI%20Toolbox/BID_285_CA_Title24_Flyer.pdf, https://www.homedepot.com/p/Commercial-Electric-4-in-Selectable-New-Construction-and-Remodel-Canless-Recessed-Integrated-LED-Kit-for-Shallow-Ceiling-4-Pack-91364/306079859, https://www.greenbuildingadvisor.com/article/how-to-install-rigid-foam-on-top-of-roof-sheathing, https://www.greenbuildingadvisor.com/article/insulating-low-slope-residential-roofs, https://www.greenbuildingadvisor.com/article/how-to-build-an-insulated-cathedral-ceiling, http://apps.gaf.com/content/documents/23303.pdf, https://inspectapedia.com/insulation/Insulate_Cathedral_Ceilings.php, https://inspectapedia.com/interiors/1382s.jpg, "Sandwiching Roof Sheathing Between Two Impermeable Layers.". My question is, based on this assembly, do I need a vapor barrier at the ceiling or does this roof assembly need to breath to the inside? Indeed, it has disadvantages from an environmental standpoint. Where your sloped ceiling meets your horizontal ceiling, make sure that your air barrier is continuous -- with no unsealed seams -- and make sure that your insulation is continuous (with no uninsulated voids, and no areas where the insulation isn't in contact with the air barrier). Right now, I'm leaning toward using closed cell where it is required (no open air flow) for the dormers and baffles and blown cellulose everywhere else. This assembly seems like it would have poor drying potential and as such taping the seams of the polyiso seems like a bad idea. Is your contractor doing it for free? My feeling is that putting this backing against the rafters in contact with that vented air might be inviting a mold problem, and if i face it towards the room i lose the radiant barrier.". At 3" or more closed cell foam becomes structural, and at R30 (4.5" of HFO blown 2lb foam, or 5" of the more environmentally damaging HFC blown goods) would be enough that even if the sheathing rotted away completely the roof still wouldn't collapse. Then perhaps I can do that and kill 2 birds with 1 stone and create cross-bracing plus more space for insulation? How you finish your ceiling is the least of your problems. Response to Jim Boyd If it only leaches out when wet, how much is going to leach out of damp sheathing? Snow load here is 30 lbs., and rarely lasts more than a few days, so I don't think condensation will be a problem (Joseph Lstiburek points out that > 50 LB snow loads must be ventilated due to the R value of the snow!). Regarding dense pack cellulose: not sure why dense pack would be negated - I think it perfectly suited. If you use plywood, you have the advantage of strength (and a grade stamp) -- but you lose vapor-permeance. Unless you’re catching water from the roof of a nearby building and can locate your water tank high enough to make use of gravity feed. Home Depot and Lowes have 1" thk or 2" 2x8. The second option lacks an air barrier, although you could install the OSB in an airtight manner if you wanted, by including a high-quality tape like Zip System tape at the OSB seams. The second problem is that not all building inspectors will accept the "above-the-roof-sheathing vent channel" approach, and may deem that your proposed roof assembly is non-compliant. is that airflow always plays a role in problematic roofs. *Should I not vault the areas I planned to vault because there is no good way to ventilate the backside of those areas in between the rafters? The owner of a dog is expected to control it. For the life of me I can't confirm my climate zone. For example, you wrote, "it's not vented at all." Light on regarding vapor & air barriers It sounds like the insulation consists of "tight-fitting wood fibre board" between your rafters -- thickness and R-value aren't specified. The newly installed rafters in the vaulted areas are milled 2x10 rafters on the 20' spans spaced 16" on center, and on the shorter span they are milled 2x8 spaced 16" on center. "The air barrier is to be placed above the pine T&G ceiling and below the foam. but it appears that the areas that were packed with cellulose(lower left) show less damage. Therefore, I’ve been considering all options for achieving adequate insulation and venting under the roof deck. But even if one is hesitant to use commercial or homebrew formulas, simply making a borax solution in water and painting or spraying it on the sheathing surface and letting it dry should be way better than nothing for preventing any accidental rot. During the winter, the moving cold air pulls heat out of the fiberglass batts as it moves by. 3.5” BATT The detail provided doesn't seem to match the text for this roof type: It's missing at least one air barrier. Yes. Alternatively, we could forego a self-adhering layer and go with a synthetic underlayment attached directly to the old built-up roof underneath all layers of foam. All the other tanks catch water from our various sheds etc and are used for our gardens. My fiancé spent 6 hours the other day digging the car out of the mud, the water went down so he got home, but it was way to much for the car to handle. Most homeowners are happy with their spray foam jobs. -Roel, Roel, I am changing my ceiling to a cathedral ceiling. New 1x T&G. If it seems like I'm out of my depth here... yeah, you bet, I am. Thank you for this article. It just seems it would be easier to work out all of the details with 2 fewer inches of wood up there. One room with a cathedral ceiling is maybe 55% within the attic and about 45% is no attic. Eric, Using the minimum necessary for dew point control would be kinder to the planet, and kinder to your wallet. I'd be using the type of lights youre talking about Malcolm. This type of roof differs from an uninsulated roof over an unconditioned vented attic. If you have an existing house with air leaks at the perimeter of the ceiling, you may, indeed, need to "just leave it alone and live with the uncomfortable temperature." But say i'ts $3 per square foot, added to the $2-2.50 for 2" of foam it's still quite a bit cheaper than an all-foam solution. In other words, these synthetic roofing underlayments are vapor barriers. So if we permit non-simple geometry, then we need solutions that do not rely on venting. Looking for any suggestions or opinions on what my best option or two looks like? Q-3: What to do when we re-roof. I’ve read your article on site-built baffles, but as I’m new to all this, I still keep going back and forth. For more information, see "How to Install Rigid Foam On Top of Roof Sheathing.". I am envisioning some combination of XPS board, Roxul Comfortbatt, and/or Roxul Comfortboard IS underneath and directly adjoining the pine T&G. The roof deck or insulation chute.baffle would be an air barrier Could you please provide a detail of above sheathing ventilation using a continuous Ice&Water membrane, and metal roofing for a mixed climate? I like the detail provided but I wouldn't call that a cathedral ceiling condition as it includes ceiling joists spanning at the bottom of the roof rafters. I can do 5.25 inches closed cell (R-37) on the non-attic and still do the 13.5 inch batts (R-49), sticking out 8.25 inches above the rafters into the attic. This job is in Coastal Carolina, which is quite humid. Client wants exposed cathedral ceiling (cool moist climate - Zone 5-6). I figure the gap between the beam and drywall needs to be sealed and I also want to clean up the look of the beam by sanding off the water stains. The EPS will work. If you are using a fluffy insulation like fiberglass batts to insulate a vented cathedral ceiling, the lower air barrier would be (as you correctly noted) the drywall, while the upper air barrier would be ventilation baffles installed in an airtight manner. Here in Chewelah WA, about an hour north of Spokane, no insulation company I've talked with will blow cellulose in a 6/12 pitch. Perhaps the way to go is to settle for 4" of foam over the cathedral ceiling, rather than 8" of foam, and NOT continue the foam over the vented attic. It was clear that success on the farm would be influenced by our ability to collect and store rainwater, so our first major expense was the construction of a dam. Thank you very much for your quick reply! Debra, But ideally you'd have the air barrier on the underside of trusses, then strapping, then your drywall to allow for elec and non-puncturing LED puck lights. • Any moisture that does make its way there seems to be incorporated into the rafters via sorption. Rake venting via screens behind the rake boards. It was one of those light bulb moments. There really isn't any reason, however, to install an air barrier between your vented section and your unvented section. Katy, We plan to convert to an improperly vented cathedral ceiling to an unvented one. So, whatever baffle material you choose, make your installation airtight.

Dan Flynn Net Worth, Mountain Lion Growl, Bruno Mars - Count On Me, Cucumber Planting Guide, Michelina's Fettuccine Alfredo With Chicken & Broccoli, Push Press Muscles Worked, æthelred I, King Of Wessex,