need help...bad rainstorm...wet drywall/insulation new build
smitjere
14 years ago
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david_cary
14 years agoRelated Discussions
Need Advice on Build - Insulation
Comments (6)I am not sure I understand what they are proposing. If it is what I think it is, it is incorrect and does nothing for you. From what you put, they are wanting to blow cellulose and also use fiberglass batts? This makes 0 sense and not even sure how or why they would do that. Also r26 is a dream. The most you can possibly hit with that combination is an r20. I am assuming you mean they will blow closed cell foam first and then use r13 batts. That would be roughly 2.5" of closed cell foam and then 3.5" of batts, which gets you close to that r26, and also makes sense with the price you listed. However Do I think you should do this? No, I do not. You are FAR better to install rigid insulation on the exterior of your studs and use air tight sheathing instead of closed cell spray foams. Closed cell will seal up the stud bays and make them air tight, but it does nothing for thermal bridging and does not seal up places such as top and bottom plates. Also, the r26 they claim is only cavity space insulation values, and not clear wall value. Due to framing and thermal bridigng, you can expect to reduce that number by 15-20% for your clear wall value. Adding exterior insulation keeps your r value the same for the cavity, but increases the areas where you have an r1, whcih is at every single stud, header and framing member in your wall. For zone 5, here is what I find is the go too wall assembly that will perform extremely well, is cost effective, and does not rely on spray foams to seal things up. Assuming they have not framed the walls, then I would recommend as such: use Huber ZIP exterior sheathing with taped joints. This will give you an exterior air and water tight barrier everywhere on your wall, and not just in the stud bays. They omit Tyvek. Install 1-1.5" of XPS foam sheathing over the sheathing to give your shelf a thermal break and an r5 to r7.5 boost. Your r1 studs now change to r8.5 (if using 1.5" XPS) and your stud bays now change from r19/20 to about r27. Your whole wall average increases as you can see since you have higher r over your studs than before. This also continues to create an air tight shell. At this point, you can fill your stud bays with whatever you want and it will perform much better. I would still recommend a blown cellulose or fiberglass, however going with batts would also work, just not quite as effective. Air sealing if far more important than higher r value. Focus on this, and then put money into boosting the r value. Keep in mind, the more r value and air sealing you add, you can start to reduce other costs such as your mechanical system. You install a smaller mechanical system, which means lower upfront cost there (helps to offset added exterior sheathing) but more importantly lower heating/cooling costs for the life of the home. As for the ceiling, it is just as important as the walls. these need air sealed as well. I find one of the best and easiest ways is to have them do an "attic seal" with open cell spray foam. All they do is spray all penetrations where they come through the drywall in the attic. They only need a couple inches, and not over the entire ceiling, just at the penetrations. This includes electrical, plumbing, framing, etc. If you have can lighting, wrap them in some fiberglass batts and spray around them to form a cocoon. Cans are extremely leaky, even so called "air tight cans". After this, then BLOW insulation in, do not use batts. And r38 is very low. Blowing in thicker insulation is pennies per inch typcailly. Bump it up to atleast r50, better yet go r60. Invest in GOOD windows with good u values. Shoot for u values of .30 and lower. Consider windows with higher SHGC values (.45 and higher) on south windows if you have good overhangs. These sorts of tweaks typically do not cost anything. Bumping of values mentioned about can shift your "rule of thumb" HVAC sizing (I will say, rule of thumbs are completely inaccurate and you need to have a manual J preformed for your equipment, espeically if you increase r values) from 1 ton of heating /1000 sqft to about 1500 sqft. This means you can decrease your equipment by 1 to 2 tons easily. My home, which similar square footage in a higher heating zone 6 only needs 24k btu for heating, which means it costs about $45 in Jan to heat 3800 sqft. It cost me $16 to cool my home this last month with high 80s and low 90s daily with a set point at 72. It does not have much higher r values than I recommended above. infact its very similar given the different zones. But it has been meticulously air sealed and then r30 in the walls and r60 in the roof with triple pane glass. You are building a million dollar home. I assume your finishes, both exterior and interior are high end and quite nice. You would be doing yourself a serious diservice by not putting more money into the shell of your home since after all, that is what protects you and yours, and also is the ONLY place you can see financial payback. Its your money, but these are my proven recommendations to your questions. I am confident my recommendations will cost roughly the same as what they are giving you as an upgrade for your foam. Also eheck with local utilties, they may ahve rebates for higher performing homes. Around here, if you build to Energy Star 3.0 you can get up to around $6k back in rebates. Worth looking into....See Moreremoving lathe and plaster, insulating, drywalling
Comments (45)"My general contractor offered me to hang a drywall on top of plaster but I dont see a value of this." Oh for the love of God - I wish if people didn't know how to do something or it was outside their range of expertise they would just say so and not propose these ridiculous things that do more harm than good. So he adds more thickness with a layer of drywall - what does he do with the trim then? Rip it out and install skinny cheap modern trim from Home Depot (some do exactly that - ugghhhh) Sorry OP I just had to vent there!! Ive been looking at old houses to buy and theres no end of goofy, futzy things that people have done to them. Im glad you saw the folly of that esp in such an old house. Like fine antiques, as time goes on people more appreciate the old things - esp if well maintained in original condition. You may want to go over to thehistoricdistrict.org, which has many old house lovers on the forum including professionals who can advise in great detail about how to do plaster repair. Especially with your age of house - you might want to confirm what type of plaster you have . There was an earlier type of lime plaster with different composition with materials you might have to hunt for (but certainly are obtainable at reasonable cost) The later type of gypsum based plaster used in early-mid 1900s - materials not available at big box - I think Ace had a type of patching plaster that can work but the plaster of paris that they (and home depot) sells is not good - sets up way too fast and hard. Otherwise any small-mid size city should have a building supply store where they carry the more specialized types of materials - while traditionally plater walls had a three coat system, for repairing cracks Ive just used plain patching or veneer plaster - if a bigger hole you can get a rough coat plaster for first layer and veneer plaster for the top layer. Use a bonding agent on the edges of the old plaster and the lath to help the new plaster adhere well to the old. There's various other techniques for bigger areas and different types of situations - and other people will have their favorite methods and materials (some use drywall compound but IMHO if you have extensive repairs its best (and considerably cheaper) to get the real stuff. Re very fine surface hairline cracks - ignoring those works the best! In a nutshell - plaster repair is exactly the kind of labor intensive but very doable thing that a typical home owner can learn to do, and do well....See MorePlaster in finished attic replaced with insulation and drywall
Comments (5)I do think from your description that the failure of the drywall ceiling is a result of lack of venting between the top of the insulation material and the underside of the roof. For starters, I would poke around and see if you have pre-formed (often pink, but possibly blue) foam pieces with ridges tucked up under the roof. These are installed between the rafters in cathedral ceilings (which is technically what you have from an insulation point of view, no matter how garrett-y your rooms feel). If not, then that's your problem (or problems) in a nut shell. You can research this on the Owens-Corning website which has lots of instructions about venting cathedral-style roofs. And you can look over these pieces at any Home Depot/Lowes. It will make sense when you see them. You may need to remove, install roof venting and replace the wall/ceiling surfaces. The plaster may be damaged more from aggressive removal of adjacent surfaces than from roof deflection, but one can't tell without studying it. And you may also need additional venting on the kneewalls now that the attic has been converted into living space which generates a good deal of moisture. You can cut down on this by installing proper vent fans for the kitchenette and bathroom areas, but you will still need under-roof ventilation, if not soffit vents, as well. It sounds as though the attic work was done by DIY amateurs. And that brings me to the most serious point that occurred to me: is it possible your attic has been converted into living space on the QT, and without benefit of building inspections, permits, (and unfortunately, increased property taxes) etc.? It may seem like a persnickety issue, but the chief risk in my opinion is that your attic living space - if done sub-rosa -might not have sufficient, legal, means of egress in an emergency. If you never have an emergency, it might not matter, but in the case of fire, inadequate escape routes can lead to the death of occupants and firefighters attempting a rescue. This is a very serious risk, and not one I'd care to undertake; it has the potential for devastating financial, legal, and even criminal consequences. While you noodle on that risk, you can research the catherdral ceiling vent issues on line. If you think structural compromise might be the reason for the plaster cracking, then an old-house friendly structural engineer (and many are not) would be the one you need. Consultations with roofers, insulation contractors and plasterers will not resolve the central issues and may lead to unnecessary, off-point work at this stage. Aside from permitting issues, however it doesn't sound that dire, though ripping and venting and replacing the wall and ceiling surfaces won't be any fun in the heat of the summer. HTH, Molly~...See MoreQuestion about building envelope/insulation for garage area
Comments (4)No easy answers with attached garages and the dangers they introduce to otherwise healthy homes. At least you don't have the dreaded bonus room or living spaces above the garage to worry about. I would encourage further insulating the garage, especially since you are already using exterior foam. Great choice by the way! Fiberglass batts might be fine for the cavity insulation with good air-sealing in place. Assuming you are doing forced-air, I would try to expose the supply duct to the bathroom to put in an inline damper to better control that seldom used room. Might just be extreme cold weather, cracked open to keep the plumbing from freezing. You need to be very meticulous with an air barrier to separate the garage air from the house air and need to install a garage exhaust fan to try to overcome the physics of the garage air mixing with your indoor air. It depends on how complicated any existing framing is. If building a rigid air barrier up to the roofline is overly complicated or broken up, I think using spray foam at the garage flat ceiling and in the cavities of the shared house walls would be best. Ducts in the attic means keeping the thermal barrier at the roofline but if they come from below, I would be tempted to create redundant insulation at the flat ceiling level for those isolated areas. It again depends on what plane will be easier to airseal. The most overlooked area is the mudsill sealer at these shared walls. Also be sure to air seal the door jamb to the framing and maintain the weatherstripping. It's a great question and concern that I wish more people building new were paying attention to....See Moremacv
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smitjereOriginal Author