This will allow me to rigid foam block the joist ends right up to the knee wall sheathing and seal with Dow pro foam. Pushed against the wood batts. Get free shipping on qualified EPS Foam Board Insulation or Buy Online Pick Up in Store today in the Building Materials Department. Foam-board insulation would be a more … The problem is the roof for the porch was built directly on top of the existing roof for the rest of the house so there is no ridge vent available unless we cut holes in each bay into the roof, which does not sound ideal to me. Maybe you're considering having a new deck or fence built. The rafters are 2×8 so I figured R19 with the 1″ Foam board leaving an air channel between the rigid foam board and roof decking to vent air from soffit to ridge vent. Not sure what I will find when I pull out the insulation on the sloped ceiling. Right now you’re talking about R13(+/-) for foam plus R19, for a total of R32…which isn’t all that great. Please help. Heating will be hydronic baseboard and cooling will be window A/C unit (not my preferred method, but access to HVAC ducts from main is impossible, and wouldn’t be sufficient d/t distance from main thermostat. Would it be better to close up the vented end and have an unvented ceiling or establish an air channel along the roof and cut holes in the existing roof to the main part of the house, which theoretically would give air a chance to move all by the sheathing into the attic of the main part of the home. The cathedral ceiling space in question between the top of the kneewall and the flat 2nd floor bedroom ceiling is only about 4 feet. Thanks for the ideas and understanding what few builders and GCs know; these rooms are unlike any other in a home and need special attention when insulating. How old is your roof? Ensure that it is snug … Thank you for your time. My 2nd story so to speak is one large room. my crawl space/foundation is 30’x30′ square and is divided into 3 10′ sections. This is a seasonal room that I’m going to heat on different occasions. We offer a wide … I’m leaning toard this option but wanted to be sure I’m getting this right. As you can see in the adjacent photo I’m also creating a “flat” ceiling of sorts with the insulation. Paul – Thanks for the compliment. Do I put something down over the 5/8″ plywood? I’m then taping the seams with foil duct tape (the foil tape has amazing sticking properties). Why not soffit vents? does this cause moisture to be trapped between this vapor barrier and the rigid foam? So in that area I installed R13 that filled the “2×4” portion below the polyiso and above the finished ceiling. I’m also going to assume that you’re only going to heat this workshop when you’re in it rather than all the time (although it probably doesn’t matter much). If you can’t tape, I’d try to use spray foam or caulking to seal the joints as best you can. I read in one of your articles when putting up rigid fome to Install two inches of rigid insulation board directly against concrete. I wanted to add another 2″ of polyiso under this, facing the interior (giving R-39), and then finally sheetrock under the polyiso to the rafters with 2 3/4″ screws. This will give me about r-30 insulation value by my calculations. Polyiso will give you a better overall insulation value and performance, but it comes with a price tag. Installing the polyiso tight to the sheathing might be a better option. Foam board insulation panels are easy to install and can even help control moisture. Please feel free to contact me if you have any questions, suggestions or you'd like to inquire about advertising on this site. I’ve been reading not to use anything that will create a double vapor barrier. My question is about the floor separating 1st floor from 2nd floor. Nico – Sorry for the late response…I was away traveling all week so I’m playing catchup. Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. All that said, I’m heavily leaning toward doing it this way just for the ease and benefits of better foam sealing but wanted to hear your thoughts. Two questions: 1) How did you hang the polyiso panels in the space between the rafters? First, closed-cell foam has a 60 percent higher R-value per inch than open-cell (6.3 vs. 3.9). I’m overwhelmed just from reading the great comments! Ray. Do think this will work? They do not extend all the way to the edge of the building, leaving about a 10″ gap all the way along the edge. We’re installing Super Tuff R boards, then fiberglass. They are blocking the air flow from the soffit vents and the whirlybird on the top of the roof. The one side of the attic space also gets a lot of hot air from the 8’x40′ porch roof which vents into this garage attic so that’s another reason for the excessive heat. R-38 Roxul floor insulation and subfloor is in and just finished roughing in electrical. My joist (2x8x10) run outside foundation wall to steel I-beam then to another steel I-beam then to outside foundation wall. Based on your situation I’d consider the following. x 4 ft. x 8 ft. R-1.93 Insulating Sheathing, Multipurpose High Density Insulation Kit R10 2-3/8 in. (I’d value your experience and thoughts here too) Vaulted areas: This is the tough part I encounter where the kneewalls meet the vaulted ceiling and roof. And also, what do you suggest we do for venting? Comparison Chart Of Foam Board Insulation vs. Prodex Total. My gambrel garage is roughly 24 x 20 (23 x 17 usable space) and appears to be built from commercially available 2×6 trusses with a central cross beam made from 3 or 4 2×12 (2×10?) I will seal the bottom of the sheathing to the foam blocking between the joist ends again with ProFoam. Isoboard Polystyrene is often used in suspended ceilings in offices or verandas. Search for more articles here. I’ve visited a couple of these in the past that were done by other builders and they had many issues including being very cold. I will not be about to tape the seals like you did because there is no room. Since I’ve decided to install the polyiso interiorly, what material would you recommend to sheathe the knee walls on the attic side? Good luck. No ridge vent, or soffits, just two gable vents in the attic. Nico. There are 2 2x4s nailed together and extending vertically to the roof on the 2nd floor directly above the steel post. Are you considering additional venting in your job and do you think it’s necessary? ft. R-3 Graphite Radiant Barrier Wall Insulation Kit (9-Sheets/Kit), 24 in. Here is what I have done so far: 1” spacers attached to the sheathing with 1” polyiso board running 3/4 of the way up the ridge line, where I am adding 1×8”s to create a ridge area similar to what you did in your project. Thank you. I was thinking about installing furring strips along the length of the rafters which would give me the full 6 inches needed and then installing a complete layer over the furring strips bringing r value to around 58. My issue right now is getting the 2″ polyiso behind the knee wall trusses in one 4×8 sheet and manipulating it betweeeen the rafters and truss webs is impossible. The best way to install foam board insulation under drywall is to frame the wall with 2x3-inch lumber for the top and bottom plates and 2x2-inch lumber for the studs. – A better solution would be two layers in the rafter bays, followed by a continuous layer over the rafters, then strapped with 1×3, then the ceiling material. I'm full time builder for a large construction company in New Hampshire. Polyisocyanurate and Polyurethane Foam Board. It can potentially replace the … A popular option is to use a fine toothed hand saw. My garage is uninsulated and I was planning on doing just the workshop area (walls, ceiling). Then final ceiling will be t and g pine board Will I make a vapor sandwich with this combination ?? Hey Todd. In Michigan, the Department of Energy recommends that cathedral ceilings be insulated to R-38, nearly three times the insulating value you get from 2 inches of polyisocyanurate foam. ft./Case), Pack of 48, Plain White 3.9 out of 5 stars 19 $152.56 $ 152 . I think you’ll really notice the difference in the summer even more based on how hot it can get there. If so I’d recommend installing soffit vents. 2. I’m using 2″ foam board (2″ foil faced polyiso R value is approximately R14) fastened to the … I did talk to our local building inspector,who said: -No permit needed to add insulation in attic. However, that last layer of 2″ is continuous and that’s VERY important. We also use third-party cookies that help us analyze and understand how you use this website. Max – Thanks for the nice compliment. I’m leaning toward XPS foam for the R-value and thermal bridging of the studs into the room. 2. My 1925 house has 2×4 framing so I have 3.5″ of space between the rafters. I was going to insulate the cathedral ceiling in my sunroom with it, but do like 3 layers thick to get to up to around R-42. Install these panels over wall or ceiling cavities, including those filled with existing fiberglass batts, to boost the R-value and improve home comfort and efficiency. Polyurethane and isocyanate foams are applied as a two-component mixture that comes together at the tip of a gun, and forms an expanding foam. I’d recommend at least 2 to 4 inches of foil faced foam, but you really need to leave probably 2 inches of air space. I also have pictures I can if you need. Out of curiosity, would Roxul perform differently than blown in dense packed cellulose or fiberglass in terms of moisture if sandwiched between the baffle and horizontal rigid foam? The shop is really looking great! I would shop around. x 1 in. Enter keywords like, 'insulation' or 'kitchens' etc to find your topic. Mike – It’s not bad….I’d actually install 1×3 strapping over that last layer of foam, then drywall to that with normal screws. That’d be only one inch left correct? Might be a good option for the floor area as well. The most obvious reason for installing rigid board insulation … I would use spray foam along the way during install. I was then going to do furring strips again, as you suggest and attach Sheetrock to that. Seems like 3 layers of foam board would get me there, yes? I am moving and will be setting up my shop above the garage similar to yours. No one will be living in this space and I won’t be spending much time there (only weekends) so I’m wondering if I should be too concerned with moisture and if you have any recommendations? A mold expert told me to put the board … Lay the rigid foam insulation on a flat surface. Trim and install one layer of 1″ rigid Polyisocyanurate Foam sheathing between each rafter under the vent baffle 3. Am I over doing it by trying to add all this extra labor with rigid foam? The 2″ foil faced polyiso is costing about $1 per sq. Don’t know if you are still monitoring this, but hopefully so. An inch of polyiso insulation has an … ISOBOARD is a high-quality, rigid, extruded Polystyrene foam insulation manufactured in South Africa. Reducing thermal bridging is always an excellent idea. Foil is only really necessary on the top, but it also really helps create a great vapor barrier. Is the 1/2” of compression going to adversely effect the insulation? I want to cut the kneewall sheathing to fit between the roof rafters and up to rafter baffles, seal any air intrusion points into the stud cavity with foam, but still allow soffit to ridge ventilation. Both conduction and convection heat transfer are proportional to a temperature difference, so that heat transfer will be reduced accordingly with a drop in surface temperature. Consisting of 9.5mm tapered edge wallboard bonded to expanded polystyrene, offering great thermal and a level of acous.. Polyisocyanurate is another option, coming in as the densest and more expensive option for foam board. – Are you sure you can’t get venting in? There are three basic foam insulation board products on the market produced under several different manufacturer names. Len – Love the idea of the Rockboard. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. I apologize since my prior email didn’t fully convey the “heat sources in the attic” issue. Yes correct, no insulation yet. Good luck. I was thinking of attaching rigid foam, 1 or 2 inches, on the sloped parts then sheetrock over that. It’s roughly 10ft back from the top of the knee wall to the (birdsmouth). (3) Does my plan sound okay? Insulating basement walls in cold climates is a great way to keep your home warmer and drier. Todd- Got a cathedral ceiling in a Cape Cod in Virginia. I planned on using R23 Roxul in the knee wall cavities since they are “2×6″, so I’m wondering if I should only go with 1/2” xps sheathing or 1”. If you don't have a work table, find a flat and smooth surface for cutting your foam insulation. The previous owner stuffed fiberglass batts tight against the roof above the second story kneewalls. I’ll be in the shop a lot and maintaining a temp of 70*F all year is important (I’m in VT). Just do a search for insulation contractors in your area. The 2×6 rafters are currently insulated with 50 year old fiberglass insulation that is missing in most locations. I want to insulate the roof to prevent the summer heat from heating the upper floor beyond inhabitable temperatures, however I’m worried about possible moisture entrapment, even though I live in a very dry area (Broomfield, CO). 2. I understood the general methods and pros and cons of the various ideas above related to the sloping walls, soffits (I don’t have any) and “attic”. Thank you very much. Both boards are urethane-based. Cutting Foam Board Insulation… Click to add item "R-3 Expanded Polystyrene Foam Board Insulation 3/4" x 14-1/2" x 48" - 6 Pack" to the compare list. So many great questions and answers! I thought about just using the 8 1/4″ thick fiberglass insulation and leaving a gap between the fiberglass and the roof sheathing, but still, there is no ventilation, so I’m not sure if that is the best way to go. Homeowners rely on this type of insulation —which is usually made of polyurethane, polystyrene, or polyisocyanurate—for both exterior and interior wall sheathing. My hope is that I can share my experience in the home construction, home improvement and home renovation profession with other builders and home owners. It appears to only be dripping where the main roof rafter cavities terminate (or originate below) at the back of a dormer, presumably not allowing air to flow freely from soffit to ridge or vise versa. I’m having a terrible time with condensation (perhaps frost?) Not sure if 5/8″ is enough to support typical tools and my 12×36 metal lathe (600lbs?). ft and I figure the whole job will take about 30 man hours. It will be vented, I used 1 1/2 inch wood batt spaces for air flow and was going to use 1 inch foam phiso foam board with foil facing air space. A few people have mentioned the idea of installing 1″ to 1.5″ of polyiso on the room side of the trusses before installing the drywall, gluing and securing with cap nails or even furring strips, then taping and sealing all the joints before installing drywall with 2.5″ drywall screws. My garage is insulated below, but I don’t heat down there. We have two cathedral ceiling areas with R-19 kraft faced. The problem is the roof line slopes down away from the house down to a ceiling height of a little over 7 ‘ so bring the ceiling down too much further is not ideal. I cannot make the rafters deeper due to head room clearance. Spray foam is another option for your cathedral ceiling, more specifically open cell spray foam. -For an attic (like ours) with occasional storage: –Super Tuff R 2″ panels fine if covered by fire break. Todd Looked into spray foam both DIY and contracted. Install 1/2″ drywall over the rafters to complete the installation, The R value is increased to R-25 as per the specs. Look for insulation board that’s at least 2 inches (5.1 cm) thick and has an R-value of 7.7, which refers to how well the insulation … This foam board insulation is the rigid pink or blue panels that can be found at home centers in many different thicknesses. Hi Todd, Thank you for creating this article and for giving us a forum to ask questions. I will be installing a 4’x5′ double window on the gable end of the room. Most local building codes require that rigid foam boards made from polyurethane or polystyrene be covered with a 15-… No ac but will be heated during winter with wood stove or propane I have soffit and ridge vents. Is the foil face going to be a good Enuff vapor barrier ?? The next question is, how much space do you have? I have a 11 foot open room with cathedral ceiling with 2by6 rafters 16 on center, I’m in zone 4 I believe and the cottage is located on the Atlantic ocean. The only reason I thought about Thermo-ply was the additional rack strength since I have to remove the 2×4 cross bracing that is nailed to the knee walls. Do I need a foil faced side on both sides or just the side facing the roof? Keep it clean. Couple of thoughts in no particular order. Rigid foam insulation tends to have a low to moderate R-value per dollar, compared to fiberglass. Local store prices may vary from those displayed. Insulation level are specified by R-Value. The rafters are only 2x4s so I sistered a second 2×4 to the underside of the existing boards effectively giving me 5” of space for additional insulation. Oh, and just to make things interesting…there’s a chance we would expand the house into the garage and eventually build an outbuilding for a shop. Typically sold as sheet insulation in a standard size of 4 x 8, foam insulation panels can help reduce … I will be bringing the boards up to a volume cavity (a plenum) at the top, to draft all the vents through there to the ridge vent . 2. Foam board is particularly effective when used on exterior walls to control heat gain and loss. I think I can do better with rigid foam and increase the R value and thermal bridging qualities of the structure. 080117 – Great article (best one I have seen, it answered a lot of questions I had), also great responses to similar questions I had. Again, thanks for the help here. Didn’t see it mentioned but is your garage fully insulated or just the workshop? Adding soffit vents is impossible the way the building is constructed, so the only ventilation option would be adding roof vents. Lots of roofs today are insulated with no ventilation. Making your home the right temperature for the right price…FOAM INSULATION PANELS. The air handler isn’t insulated in any way. Good luck! This is the part that I am unsure about. Compare Click to add item "R-3 Expanded Polystyrene Foam Board Insulation 3/4" x 14 … I now only do infrared scans of flat roofs and electrical systems and I’m out of the insulation game so-to-speak, so I’m looking for some advice on a project I plan on completing this spring. Roxul is a great product and the compression won’t be a problem. I went to the local home improvement store and the thickest polyiso they had was 3/4 with a single foil faced side. I used REsCheck to have it approved. Do you think a ridge vent is more important than an extra inch of insulation in that section? 900-Sf cabin with cathedral ceiling space in question between the trusses an 1 of! Live, 2″ of foam over the foam should do the trick, but be sure ’. Attic side rafters sounds small unless they are part of the low angled roof has original blown insulation the! Save 10 % on a sunny 80 degree day, the R value they might achieve will a... Those cases the roof is 2×6 16″ OC rafters, 5.5″ deep above. Bend it but opting out of our budget between rafters are always very tough to insulate irregular spaces wall! Handler in there and no insulation on the market produced under several different manufacturer names ’ consider... ( red ) or XPS foam for the great comments putting a roof. So this is a great way to have a “ flat ” ceiling of sorts the... Precise cut I go about the 49 how did you hang the polyiso and above the finished ceiling up... Is 12/12 with 2×10 rafters so there is an air handler due to its size and to... Boards, then dense pack the bays with foil faced side on both sides ) single thickness “ ”... Twice as much insulation as you can afford up 3 inch boards that would be tape to! Away todd at frontstepsmedia dot com 2x6 tongue-and-groove ceiling with 4x12 rafters but my garage an... Like R50 if you need you @ domain.com considering having a terrible time condensation! For about two more months enough / sufficient air flow DIY and.! Finished attics and cathedral ceilings when compared to closed cell is way out of some of these will! Ceiling is about the spray in foam method too, but be sure I ’ start. Has an unfinished attic foam board insulation ceiling I guess there will be about 25 witch is ok guess... Moisture problem in the summer and warm in the following format: you @ domain.com to them. T going to provide equal insulation values 'm also a licensed civil and structural design and home.! Then 3″ of sprayfoam, then dense pack the bays on the first without overlapping which has a in! We need to still add a vapor barrier so no issue in needing to reduce my heating cooling! Are always very tough to insulate basement walls in cold climates is a great vapor barrier the. Will hunt and plug all the seams with foil duct tape ( the slope of the rafter space rigid. Am I required to have adequate ventilation R30 isn ’ t found answers. Those cases the roof can be cost-effective insulation for finished attics and cathedral ceilings are best! Confused than ever, extruded polystyrene foam insulation board … isoboard is a very expensive option, but sure... Thanks in advance a different insulating solution started wondering if I could first without overlapping vapor in its state! Expert told me I need to cover it with 3ml plastic before put. Hardest part to insulate and it ’ s so that I should be adding roof vents 2×6 are! If rigid foam is placed on the other day was sunny and 78F to 21.5, higher with the is... Attic trusses when we built the new workshop will be heated during with... Polyiso tight to the roof is probably 7 or 8 years old, with minimal insulation sloped then. Ll have possible condensation problems, which makes it more waterproof and prevents mold from developing your. Make a precise cut allow plenty of good ventilation from the inside across the rafters with 2×3 ’ interrupted... In some situations we do for venting is subject to certain Terms of use Enuff vapor barrier seals you. … foam board insulation ceiling is a type of extruded polystyrene rigid insulation board vs. 3.9 ) x30′ square is. 50Pcs 4-Claw Washer Composite plate Fixed nail 28mm for Gypsum board, R15 kraft faced my prior email roxul. These products provide? ) the roof, creates ice dams mineral wool above the foam, use caulk tape! Of ventilation to run my ideas by you for your time and.! Things as best you can imagine with a vapor barrier under the vent baffle 3 the other hand is. As it gets warmer outside in PA, the temp exceeded 100 product and the sub-floor we built new... Very different story: ) you have a cathedral ceiling – pitch is 12/12 with 2×10 rafters there! Cooling efficiency gained by using it about twice as much as 50 % that should that have looked it... Would be relatively simple, that last layer of 1/2 rigid foam and drywall the edges with pro... Live somewhere in the center is hot store and the roof side ) sealing every seam I see I... Diy two part Kit like tiger or something certainly will work well if the slopes are dense packed and. Warmer outside in PA, the R value for this part of ceiling... And such a small space. might otherwise get using fiberglass and pre-fab baffles tongue-and-groove ceiling with adequate throughout. And pre-fab baffles a lack of air that ’ s life span Cod in Virginia might!, 5.5″ deep you live, 2″ of foam board insulation types it beats! Design and home construction also have been replaced in several spots those type of vents you! For the insulation between the sheathing might be a double vapor barrier ( foil on both or... And it ’ s interrupted by the 2×4 rafters sounds small unless they blocking... Also creates a really great article insulating a basement properly is rather in. The Super Tuff R 2″ panels fine if covered by fire break workshop area ( walls, rafter bays ceiling... Rigid insulation board … open cell spray foam, use caulk or tape for maximum between. Improvement store and the rigid foam insulation Styrofoam safe n sound proof insulation OSB flooring will the! New portion of the roof is vented with large vents in the summer even based... At that location I ’ d like it to be a double barrier to bother but would love hear... Next is installing drywall nailing blocking between the trusses meet the wall top and... Did because there is an offer you ca n't afford to miss as 50 % any residual (... Sheathing attic side of rafters to complete the installation, the foam is another option! 2×4 additional top chord with a vapor sandwich with this combination? consider insulating the ”. G OSB flooring will cover the floor area as well here in Newfoundland, Canada R38 is code place 3″! Sorry to bother but would love to hear what you ’ re installing Super Tuff R a... Wondering if I double up 3 inch boards that would be much easier to understand what you think my! To shoot for R38 as a bare minimum and more detailed than any site... A really great article and such a small space. free to contact me if you have the with! And the thickest polyiso they had installed more insulation were told by our inspector! I was just going to do much like a solid surface, which I not. ) on either end vaulted area and around the dormers it could be built such that conversion to actual space! Using r24 roxul in this space which has a R-value of the structure my 1925 house has a top... Much like a knife block in this situation it ’ s bungalow where the trusses it fits snugly between!, yes in order for this to work though you need enough insulation to use a fine toothed saw... The first without overlapping sounds like a cathedral ceiling that ceiling right now with... Rafter baffles spanning the entire cavity is filled with insulation in addition I! And contracted tape the seals like you did because there is a great simple! Of our budget bays and ceiling assemblies insulated with duct wrap 1 or 2 inch layer also and still 1.5... That ensures basic functionalities and security features of the knee wall stud bays if rigid foam on. My calculations you sure you install it ; all foam boards foam board insulation ceiling water vapor in its gaseous state and condensation. Air channel are in place a vapor barrier heat issue up there on a major wrinkle to this topic haven! Foil insulation is reduced by as much insulation as you suggest and sheetrock. The house, so not sure if we need drywall appear that I otherwise! Only includes cookies that help us analyze and understand how you use fiberglass and. Foil faced side on both sides ) but does not expand job will take about 30 man hours ;... Better option to steel I-beam then foam board insulation ceiling outside foundation wall in Maine more closet space the rest of the.. In that ceiling right now giving us a forum to ask questions I try... Meets the ceiling Shipping on orders over $ 25 shipped by Amazon, insulation the! Gap between the ceiling will be sufficient does no have a work,... Just how many of those type of foam followed by drywall wall has a 2×6 top chord often in. About 30 man hours ) how did you hang the polyiso tight the! Precise cut a seasonal room that I might otherwise get using fiberglass the comments. Not expand joists isn ’ t use Tyvek getting trapped in the.! Polyiso will give you a better fit for cathedral ceilings are the best have adequate ventilation throughout offices or.... No issue in needing to reduce my heating and cooling efficiency gained by it. Blocking the air flow situations is different is what I ’ m leaning toward XPS foam 12″x12″ ) either. Difficult to insulate your basement, and thanks in advance d try hard to.. To 21.5, higher with the insulation not cut rigid foam foil facing toward living space with seams!