SaintCyr Posted October 28, 2009 Share Posted October 28, 2009 Whats the best isulation to use here in the attic? 1920s bungalow, with A/C unit and water heater in attic. I'm looking to put the insulation on the attic floor and cover it with 3/4 plywood. Whats the best type for this application? Link to comment Share on other sites More sharing options...
BryanS Posted October 28, 2009 Share Posted October 28, 2009 Whats the best insulation to use here in the attic? 1920s bungalow, with A/C unit and water heater in attic. I'm looking to put the insulation on the attic floor and cover it with 3/4 plywood. Whats the best type for this application?You need R-30+ in the attic. That means about 16 to 18 inches of insulation. Either blow-in (fiberglass, cellulose), batts, whatever. It's the depth that matters.You should not insulate and then pack all that insulation down with 3/4" plywood between 2x6 or 2x8 construction. If you want attic storage, pick a 5x5 or 10x10 area and deck just that part in the attic, with insulation underneath. Link to comment Share on other sites More sharing options...
travelguy_73 Posted October 28, 2009 Share Posted October 28, 2009 Also, since you have an old house, if you have knob and tube wiring, you shouldn't insulate around it. Air flow is needed! Link to comment Share on other sites More sharing options...
RedScare Posted October 28, 2009 Share Posted October 28, 2009 You should not insulate and then pack all that insulation down with 3/4" plywood between 2x6 or 2x8 construction. HAHAHAHA!!!! 2x6 or 2x8 construction in a 1920s bungalow. Oh, man!!! You're too funny!!! Link to comment Share on other sites More sharing options...
BryanS Posted October 28, 2009 Share Posted October 28, 2009 HAHAHAHA!!!! 2x6 or 2x8 construction in a 1920s bungalow. Oh, man!!! You're too funny!!! It's either that or rough cut 2x4? ... ceilings... Did they use 2x4 up there? That would be crappy, if they did... Link to comment Share on other sites More sharing options...
BryanS Posted October 28, 2009 Share Posted October 28, 2009 Also, since you have an old house, if you have knob and tube wiring, you shouldn't insulate around it. Air flow is needed!...if you have knob and tube wiring... still in use......you should not even venture into your attic... Link to comment Share on other sites More sharing options...
SaintCyr Posted October 28, 2009 Author Share Posted October 28, 2009 ...if you have knob and tube wiring... still in use......you should not even venture into your attic...Yeah I dont have knob and tube.... So, I know not to mash down insulation with decking, I was looking more in the direction of blow in foam or the rigid foam board. Any luck with either of these? I have roof vents and use the "hole" in my porch to help ventilate so don't want to add to the ceiling in the attic... Plus I've heard too many horror stories of roof leaks under the foam. Link to comment Share on other sites More sharing options...
musicman Posted October 28, 2009 Share Posted October 28, 2009 i'd put a small deck as well. but if you really want insulation that thick, in a small area you can put joints at 90 deg to those already there so that you can put another layer of insulation and decking on top of that.ensuring good attic ventilation is just as important. Link to comment Share on other sites More sharing options...
TJones Posted October 30, 2009 Share Posted October 30, 2009 Put the R-30 in.....then go find someone that sells THIS product and have it installed, it will save you a bundle. http://www.eshield.net/index.htmlhttp://www.eshield.net/index.html Link to comment Share on other sites More sharing options...
bluedobie Posted February 15, 2010 Share Posted February 15, 2010 What type of insulation did you end up going with? I'll be facing the same decision with a 1920 bungalow, in which I've removed the old attic insulation and connectors for the old wiring. Insulation will go in after new wiring is installed and it sounds like the best bet is blown-in and not flooring the entire attic. Should roll insulation go under the flooring and the flooring be put down before the remainder is insulated? The new roof is vented and I had new soffits w/vents added. What about radiant barrier? The attic insulation was the only insulation in the entire house, the walls are ship-lap, and the a/c is window units. I plan to add insulation to the exterior walls and had read the blown-in type can settle at the bottom. Is it a better long-term solution to use the roll type? I also saw a suggestion in here that crawl space insulation not be added, becaues it encourages rodents to nest. My house was placed on new blocks 3 high, so it sits "28 high at the beams and the select fill pad was sloped when I had it put in so water wouldn't sit. The neighbors do not keep their dogs contained and their Great Pyr decided he liked spending last summer under the house and did quite a bit of digging. That will be tended to, so I don't think there will be a drainage/moisture problem under the house. Suggestions welcome! I appreciate this forum, since there are so many who live in (and love) the old houses and have a lot of experience to share! Link to comment Share on other sites More sharing options...
RedScare Posted February 16, 2010 Share Posted February 16, 2010 ...if you have knob and tube wiring... still in use......you should not even venture into your attic...Not true. Knob and tube in good repair is not a hazard. However, inspectors will freak out about it (and apparently some HAIF posters), so the sooner it is replaced, the sooner your home value increases. Link to comment Share on other sites More sharing options...
texas911 Posted February 16, 2010 Share Posted February 16, 2010 Is it too hard to "condition" the attic? Meaning sealing it up from the outside? I head this is better for the attic than venting it. Link to comment Share on other sites More sharing options...
travelguy_73 Posted February 16, 2010 Share Posted February 16, 2010 Is it too hard to "condition" the attic? Meaning sealing it up from the outside? I head this is better for the attic than venting it.We did this to ours a couple of years ago. It's a large old attic, tall, but not quite tall enough to make it a usable third floor (and there isn't a dedicated set of stairs, but a pull down ladder). We were spending a small fortune on climate controlled storage, and so got rid of the unit and put the money into sealing up the attic, adding two a/c vents and an air return (from the second floor zoned a/c unit, which was oversized for that floor anyway). We added cel-bar from Payless Insulation into the walls/ceiling, and cellular shades to cover the three windows (east, north, and west exposure). My partner is happier with the end result than I am. As a climate-controlled storage space, it is really nice, easily the nicest attic I have ever seen, LOL. And you can be up there any day of the year. All the matching bins, holiday stuff, and our off-season clothes go up there. So that part is great. However, I'm not sure about the effect on our utility bills. I mean, in theory making the entire house climate controlled should be fine, but the hot air rises and needs to go somewhere, right? In the heat of the summer when the attic door is closed, all seems fine, and the first and second floor stay cool, because I guess the hottest air is going into the attic, and then gets recycled through the air return and cooled and returned to the attic (or not!). However, when the attic door is open, the second floor definitely gets warmer. So we keep it closed all the time. Having an air return on each floor helps keep the circulation/pressure proper, at least I'm pretty sure! OK I am just guessing.We probably spent $2.5k to have it all done (vents, insulation, shades), and it does the job, and who knows, it might actually be good for resale (in a house with two closets, it definitely is appealing). But I think we are paying more for our a/c than before, though our house is inefficient enough that it is frankly hard to tell one way or another. We were spending about $120 a month on climate-controlled storage ($1440/yr), so even if we are paying more for utilities, it is at least cost-neutral and probably saves us money after two-or-so years. Link to comment Share on other sites More sharing options...
RedScare Posted February 16, 2010 Share Posted February 16, 2010 I am going to insulate the roof rafters in my new garage so as to be able to use the attic floor for storage. However, the main house has so many gaps and is so large that I wouldn't attempt it there. The garage will get batt insulation between the rafters. The house, once I am finished with renovations and sealing gaps and holes, will get a huge bed of blown in insulation. There will be a floor in the garage attic, not in the house. Link to comment Share on other sites More sharing options...
SaintCyr Posted February 16, 2010 Author Share Posted February 16, 2010 Actually we just did it this weekend... So I'll give a quick run down of what I did for prep and all the other details... Started by going around and sealing all the holes in the attic that ran down into the walls... I used the "Great Stuff" from Dow to get in all the nooks and crannys... After that I went and created a bit of storage space by creating a wall with some old 1x6 lumber along the existing "walkway" in the attic and then put wooden boxes around the drain pans for my hot water heater and AC condenser and access panel. I also walled off around where my porch ceiling is... I went with the GreenFiber from Home Depot with the free rental... It was REALLY easy to get everything set up and blown in. Under the walkways I dense packed the cellulose with the hose. I had old pink and yellow batts up there so decided rather than pulling it all out to just blow on top of it. I put in about 15ins on top of the fiberglass... I figure it should give me an R-value around 50 or so. We ended up using around 74 bags. It prolly was a bit overkill but it can't do any harm. Took us about 6-7 hours working and went rather smoothly... My wife got a bit ahead of herself a couple of times and the machine plugged but other than that I wouldn't mind doing it again. We already notice the difference in uniformity of temperature and how often our heater kicks on (much much less) in the house... It also seems to have quieted things down a bit. We are planning to do the walls next during the fall or next winter. I would just stress how important the preparation is. Let me know if you have any questions. D P.S. It ran us about $700 with the insulation being on sale right now... Link to comment Share on other sites More sharing options...
texas911 Posted February 16, 2010 Share Posted February 16, 2010 I was thinking more like this kind of closed attic.... Link to comment Share on other sites More sharing options...
travelguy_73 Posted February 17, 2010 Share Posted February 17, 2010 I guess we have about half of that. We have the insulated attic walls, but the floor isn't sealed (because I guess why would you when it is just another floor). No ridge vents or soffit vents. By having the air return in the attic and on each floor, I guess it acts the same as if we had an opening between the attic and second floor. Because we have an old house, we have shiplap and sheetrock walls, so no insulation there.I do agree that any ducts leaks are irrelevant because it is all conditioned space, though we have our first floor vents in the crawlspace under the house, so those we have to keep an eye on. Link to comment Share on other sites More sharing options...
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