Residing and rigid insulation techniques
I’ve purchased a 2×4 stick built house built in the 70’s. The exterior siding is 5/8ths T-111 and has seen better days. Some of the damage is water induced and the drainage problems have been corrected. The other damage seems to be sunshine related, mostly on the south side of the house. Any way the house needs to be resided, my wife and I feel and this would give us an ideal opportunity to add to the r value of the house and add some air penetration protection. I’ve searched the great electrical encyclopedia for ideas/techniques and have come away with more questions than answers it feels like.
My thoughts are to:
1. Leave the old T-111 in place.
2 Install 1 1/2 inch of iso rigid foam on the wall. At first I thought of using 4×8 sheets and give a thermal break for the 25% of the wall that is solid wood. I was looking at nailing horizontal Hardiplank directly over the foam but then discovered from their web site that they only recommend going over 1 inch foam. I had liked the idea of 1 1/2 inch foam for the extra r value and the ease of using 2×4 material around the windows to fasten the window/door trim (not the correct term for this but my brain is getting old).
3. I then thought of screwing horizontal 2×4 on the wall on 24 inch centers and cutting the 4×8 sheets of iso to fit between the horizontal 2×4. Then screwing 1×4 furring strips vertically on 16 inch centers to horizontal 2x4s to give the Hardiplank something to attach to. My wife’s question is that the Hardiplank is heavy and only attached to the 1×4, is that too much weight/force on a little 1×4
4. My other thought was can one use vertical 2×4 on 16 inch centers on top of the horizontal 2×4’s on 16 inch centers to give the Hardiplank some more meat to attach to? Also give another opportunity
to add another 1 1/2 inch of foam between the vertical 2x4s. Cost effective? Would take an extra 40 4×8 sheets of iso which sell for $26 a sheet here and 2×4’s instead of 1×4’s. Also require further window/door extension thingy’s but shouldn’t be too hard if starting from scratch.
5. Thought of attaching the base iso between 2×4’s on 16 inch center vertically , lined up on the wall studs. In doing so, have I defeated the purpose of a thermal break? If it is not that big of deal, that would be the easiest way to go, attach the siding directly to the 2×4’s. (Have also thought of putting the log siding instead of the Hardiplank)
So, there is my dilemma. What have the experts found that has worked for them. As a construction wannabe veterinarian, I know the frustration of phone calls, picking my brain for a diagnosis, but heck, I give out free advice all the time, right? Anyway, thanks ahead of time or your time/expertise/experience/thoughts.
docbert
Replies
Hiya Doc,
The horizontal strapping of 2x4 sounds like a good way to start. It is sturdy and it eliminates most of the thermal bridging right away. Vertical 2x4's over that would be great, both for the increased R-value and for the solid nailbase you would then have.
The "little" 1x4's for hanging the Hardi will be plenty strong if you elect to go that way. Your wife can rest assured.
Whichever thickness of final strapping you use, it is important to include a moisture barrier such as tarpaper over the strapping and under the Hardi.
A partner and I did a solid brick home in 1991 with two layers of crosswise 2x4 strapping and sprayfoam insulation. It was a tremendous success, and still is to this day. Intelligent detailing at the doors, windows, and foundation is the only difficult aspect of this process. The key thing is to always direct water out and away, and to use durable, maintainable materials.
Good luck with this project, and tell us how it goes as you proceed.
Bill
Hi Bert, and welcome to BT forums! =)
Just curious about your existing windows and whether you plan on replacing them. If so, it would be best to use "new construction" windows (as opposed to those designed as replacements) and mount them toward the newly created exterior shell. That will eliminate any possible water infiltration that may become an issue when extending the exterior jambs, since you'll be extending the interior jambs instead. You'll also get the benefit of the window flashing against the house wrap.
As for the interior, you end up with deeper window sills on the interior, which is always a nice touch. Of course, the downside is that the construction (and all it's wonderful dust) is then extended to the interior, not to mention the added labor and expense. But if you plan on upgrading the windows at some future point in time, seems this would be the time to do it.
Just some thoughts.
~ Ted W ~
Cheap Tools! - MyToolbox.net
See my work - TedsCarpentry.com
Edited 4/8/2009 1:18 am by Ted W.
Edited 4/8/2009 1:20 am by Ted W.
doc
Welcome to BT.
As a construction wannabe veterinarian, I know the frustration of phone calls, picking my brain for a diagnosis, but heck, I give out free advice all the time, right?
Don't feel bad about asking a question. This is an internet forum, we can skip this thread a move on if we don't want to give an answer.
If you click on your name a dialog box will appear an you can fill out your profile.
Your location might make a difference on the advice you get.
Good luck.
Rich
doc
You might enjoy this link.
http://www.taunton.com/finehomebuilding/PDF/Protected/021194051.pdf
Rich