Laminate 1.5 x 2" (actual) to 2 x 4" (1.5 x 3.5 actual) to create 2 x 6 ext. wall
This may sound crazy, but I'm going to be removing the sheathing on my exterior, 2 x 4, walls. If I laminate 1.5 x 2" (actual) to the 2 x 4's, I could make the wall cavity equivalent to 2 x 6" walls--allowing extra insulation/R value. I can only do this on the long sides of my ranch home (East & West facing). The gable ends have no overhang. I know that foam board is often recommended to cover 2x4 walls, but I'm not a fan of the impermeable nature of the foam. This will be labor intensive. I realize that, but it is my home, so I'm willing to expend some energy to make it better. Question is, however, is it a really dumb thing to do? Are there structural problems when moving the weight of the sheathing and siding "proud" of the foundation?
Thanks in advance for any feedback.
Apr 16, 2013, 01:33 AM
Can it be done? Sure. There are no structural issues with adding on the extra 2" framing layer on the outside.
Should it be done? Maybe.
What will the exterior sheathing or siding material be? And what type of insulation is inside the 2x4 walls now? The answers can help determine if doing this makes sense.
Here's the deal: You currently have 3.5" framing and let's assume that you have fiberglass batt insulation. R-value = 13.
If you add on 2", you are not going to spend too much money on framing materials, just a fair amount of labor. At 5.5" thick, you can now go to R-19 for insulation. The thing is, how do you get to R-19? About the most efficient way will be to get more R-13 and peel the batts down by half. This is possible but somewhat labor intensive and inexact.
A second option would be to keep the 3.5" framing and add a layer of solid foam to the exterior, then your exterior sheathing. 1/2" foam carries an R-3 rating, 3/4" is R-5. that's for the closed cell type of foam. You may have to shop around a little to find the right thickness and the maximum R-rating. Even better if you can find a high R-value with a foil barrier - especially on that West facing wall. 1/2" will give you a total of R-16. A 4x8 1/2" sheet will run around $15 - more than the cost of extending the framing but the same or a little less than the combined cost of framing and extra fiberglass. Much easier to install.
Here's where the sheathing type comes in to play: If you are doing panels like T1-11, then it can cover the foam. Same for other types of large sheets for the final siding product. Most wood lap sidings can go over foam too. Hardi cannot - it's designed to go over a more solid subsurface like plywood or OSB.
Overall either option is worth doing IF YOU HAVE TO REMOVE THE EXISTING SIDING ANYWAY FOR SOME OTHER REASON. If you are just doing this to get a little more insulation value then it's not very cost/labor effective. This will especially be true if your existing siding material is destroyed and must be replaced with new.
Make a materials cost list for all the options. Factor in your time and see what makes the most sense.This message has been edited. Last edited by: Jaybee,
Apr 16, 2013, 06:42 AM
Thanks for your reply Jaybee. Ultimately (if I ever get this project off the ground), the sheathing will be 1/2" CDX Ply. Over that, house wrap, then the Hardi, shingle look, panels. It is fiberglass in the walls currently, but am thinking of replacing or augmenting with Roxul. Current sheathing is that black, Homosote, kind of stuff. Structurally, kind of wimpy.
Apr 16, 2013, 07:34 AM
Got a picture of the home? There's far more involved then you may know to add to the depth. Mainly all the windows and doors would need to be pulled out and reset or at least the trim will need to be added onto so it's proud of the siding. All outside and inside corners, soffits would have to be redone. And your right to be concerned with moisture being trapped inside the walls. No way will you live long enough to see a pay back on the expencice involved. Only time I'd suggest doing this is a really old house that had little or no insulation and also needed to be rewired. Air sealing the attic adding insulation in the attic, better windows, making sure all the windows and doors are air tight, insulation under the home, air sealing the rim joist, making sure the roof is properly vented. Will give you more bang for the buck.
I agree that sheathing you have was a bad joke pulled on home owners but unless your seeing something inside that makes you think the whole house is moving I'd not be concerned with it. The outside corners are most likly plywood to control any swaying.
Apr 16, 2013, 01:37 PM
Jaybee, You mentioned that foil faced foam would be good on the West side. That reminded me, half of the West side has foil faced fiberglass insulation (foil on the conditioned side of the wall cavity of course). Maybe that's the wrong side to have it on. I'm not sure. I'm considering skipping the vapor barrier altogether. I don't want moisture trapped between the barrier and the backside of the drywall.
Joe, Here's a picture of the Eastern side of the house, taken from the North. It shows some of the trickier areas (like the box window). As I said, I'm not going to build out the gable ends, since there is no overhang. The rear portion of what you see is the garage. I'm not going to build that out. East-side-of-house-taken-from-the-North This picture was taken not long after I painted, but I'm already getting lots of paint peeling. I can't seem to keep paint on those cedar shingles. Plus, the woodpeckers love to peck them (that's one of the reasons I want to use the Hardi siding).
Thanks again.This message has been edited. Last edited by: SturdyNail,
May 19, 2013, 06:34 PM
I realize I may be a little late with this post, but perhaps it might help someone else reading this thread.
While I understand your concern to use more insulation, there remains the fact that the vast majority of heat/cooling loss occurs thru the ceiling, more so than the walls.
It may be better to put your extra budget toward additional insulation in the attic.
You could also spray foam the walls, which you could do all 4 exterior walls then without framing issues, window issues, siding issues, etc.
Foam is quite expensive, but if you plan on staying there another 5-10 years, you should look into it. I've had foam in the last 2 houses, and I'll keep having it, until they come out with something better. My heating and cooling bill is 1/3 of what my neighbors bills are.
Hope that helps a little.
May 20, 2013, 10:27 PM
I appreciate your thoughts "briteboy". When I took a closer look at the work that would need to be done, I did kind of back away from the idea. There is a concrete "landing" at my doorway that goes right up against the house. I'd have to cut that back or something. There is also a gas vent that barely peeks out of the existing siding--I'd need to have the gas company extend that for me (who knows how much that would cost). Similarly, the faucets would need to be reworked. JoeCaption and Jaybee also warned that it may not be the best place to spend my limited dollars. Although, that West facing exterior takes a beating from the sun. We have to run the air conditioner in the afternoon even when the outside temp is barely 80 degrees F.
Not long ago, I was convinced that foam was the greatest thing since sliced bread, but then started hearing about off-gassing problems, trapped moisture, shrinkage, and, of course, expense. I'm glad it has worked out well for you though.
Something else that occurred to me. I wonder if the building code enforcers would even permit me to do it.