Exterior walls when building from scratch.

After spending hours searching this site and reading/re-reading Rod's book, I've still got a few questions about exterior/load-bearing wall construction. I originally posted a thread in the studio design, but it seems like it's more fitting over here and would help when people search this forum for the same question. And hey, my appologies if this has been covered before. It seems like it must have been, but I honestly can't find the issue addressed in much detail. Ok, so out of my babbling, into the issue. I'm planning to build a studio from scratch. I've got a wooded lot. Plans at the moment are to tear out the necessary trees, grade the land, and lay a slab. Stick building will commence on top of the concrete. I've got a good amount of land (2 acres) out in the country with no neighbors in veiwing distance, however, sound travels like crazy when you've only got insects around. So, on account of this, I'd like to build it to be as quiet as possible to the outside world. Or at least reasonably so. The main thing causing me grief at the moment is that I can't figure out the best way to construct the exterior walls. My reasearch from this site and Rod's book offers loads of advice in respect to beefing up existing walls and MAM structures. However, this is a bit different because I don't have any restrictions in terms of pre-existing structures to work with. SOOOOOOO, from what I've read, it seems like my general plan should be this (from the outside world to inside the studio): Cedar siding Tyvek OSB Studs 16" strips of drywall cut to run vertically between studs Insulation ----5" air gap---- Insulation Studs Drywall layer 1 Drywall layer 2 I've uploaded a sketch of this structure as well as a rough studio floorplan (I'm sure it will end up changing and changing)... In his book, Rod says that these exterior walls will be one of the biggest challenges to deal with, largely because, by design, they are not airtight and will allow for sound leaks. In effort to counter this, acoustical caulk will be used on all baseplates, corners, and joints. My plan at the moment is to get a crew to outsource the clearing, grading, slab, and initial framing, which would be only the perimeter wall. So I'd start working on it myself when it was dried in with Tyvek and a tar papered roof. I would have the contractor put up the exterior walls to this point: Tyvek OSB Studs 16" strips of drywall cut to run vertically between studs Insulation ----5" air gap--- From that air gap, I would go in and construct the remaining parameter wall and all of the inside walls (and put up the exterior siding). The house is cedar siding, thus the studio to match... Some details on the studio: There will be no HVAC. It will be heated/cooled through 2 hotel style wall units. There will also be no plumbing. It will run me in the ballpark of $6000 to get the land cut, graded, and a slab poured. From there, I'm waiting on a few bids for the construction. My budget seems unreasonably low, I know, at $25,000 or so. But I'm looking into other ways to help finance, and I'm sure this will take quite a long time to complete, so I'd rather not focus on my low-ball budget :>. Where there is a will, there are many ways. And there are many wills here, so even more ways. But for the moment, my question lies with this exterior wall. Am I overlooking something? There seems like there should be a better way to do it if it's going up from scratch then cut 16" strips of drywall to fit between the studs. Or maybe I would achieve better isolation with a completely different technique? In any case, I'm baffled at the moment. Any help you guys could lend would be greatly appreciated. It seems like this must have come up in the past, but I couldn't find any posts directly dealing with this scenario. Many thanks in advance! tasker

A bit more cost but much easier to obtain similar mass for your outer leaf - instead of inserting drywall strips between studs, put at least one more layer of 3/4" OSB on the outside of your outer frame; this will get you more mass in that leaf WITHOUT having to have the PITA of cutting individual inserts for between your studs - it will also leave you a slightly wider effective air gap between inner and outer leaves, so better LF TL by a couple dB. Other than that, just remember you want two independent leaves of mass separated by an insulated air space; this applies to the roof/ceiling as well... Steve

Tasker, Personally - if it was me with new construction - I would construct a masonry exterior wall - then sand fill the cores that aren't structurally grouted. If you want to stick build - then just add the multiple layers on the exterior of the framing (adjusting the frame (of course) so that everything flushes out with the foudation accordingly. I would approach it by installing my structural sheathing directly to the framing - and then would add aditional layers of 5/8" densglas outsaide of that - total of all layers equaling what you are doing inside. Densglas is an excellent exterior gypsum board that is fiberglass impregnated and had a yellow fiberglass mat surface that resists water. Good luck........... Rod

Thanks guys. That's exactly the info I was after! The thought of cutting all of those drywall strips seemed like a serious endeaver. Or... more like a giant PITA! I'll look into the densglass. Seems like that could be the way to go. And Rod, one more question for ya. If I'm doing 2 sheets of 5/8" on the inside, you're saying that I should have equal amounts on the outside, correct? Of course I'd have studs/OSB/densglass/densglass/siding, so I'd have a bit more mass on the outside wall when you add it up, but the goal here is to be even within the 2 mass sections, correct? Thanks for all your help!!! It's incredibly helpful and valuable. Cheers, Dave

I agree with Rod on the block exterior 110% - in fact that's been my plan for the outer leaf of my next studio ( surface-bonded block, sand in all cavities that aren't already grouted for tie-downs, etc) - Rod, good to hear that the Densglas stuff has your approval; I'd seen it but had no "tire kicking" to go by. How is it for attaching outer siding - do you need longer fasteners to reach the wood, or does the fiberglass solve pull-out problems too?? Steve

I agree with Rod on the block exterior 110% - in fact that's been my plan for the outer leaf of my next studio ( surface-bonded block, sand in all cavities that aren't already grouted for tie-downs, etc)

Hmmm. This is interesting and not something I was originally considering. If I went this route, would I still need to construct the inside wall. Following this approach, the block exterior would become mass, then I have the 5" air gap, then I have the stick framed interior wall? Also, this may sound silly, but how do you fill the blocks? I imagine you would need to do it as each one is laid in, as they'll probably be set in a brick-layers pattern. It looks like the cost of this could actually be lower than stick building. Am I wrong? Any resources you could point me to would be fantastic. Thanks again and again, Dave

http://www.quikrete.com/diy/QUIKWALLSur ... ement.html http://www.masoncontractors.org/newsand ... 002801.php http://www.taylorconcrete.com/azar.asp Yes, you would still want your inner studwall and its second leaf of mass; together with your sand or grout-filled block wall, this makes a VERY effective mass-air-mass isolation system. The blocks typically have two cavities per block, and they are offset by ONE cavity so the entire wall can be erected and you'll still have a continuous "tunnel" from top to bottom. However, if you're using sand fill (except where grout/steel/allthread is required around doors, corners, and windows) it would be easier to add sand every 2-3 courses of block, especially if you're working alone. You'd want to make sure there's no sand left on the top edge of the last course of block before adding the next one though - The beauty of this method is its DIY friendliness - and even if you're hiring it done, dry stack is quicker (therefore cheaper), not to mention MUCH stronger... Steve (one downside, if you use "normal" concrete blocks instead of blocks that are specifically designed for this method - standard blocks aren't 16", they are 15-5/8" long to allow for a 3/8" mortar joint. This means that if you dry stack these blocks, you'll end up with odd-sized wall lengths for nearly every quantity of blocks you can name. 16 blocks comes out to 250 inches, or 20'10" - 24 blocks = 375", or 31'3" - 32 blocks = 500", or 41'8" - so it is much better to buy block intended for the purpose...

Steve, do you know if dry stack is allowed in earthquake prone areas? --Keith :mrgreen:

This is getting interesting. I've been doing lots of research on drystack in the last few day. From what I've found, you can only drystack block that is made for that purpose (please correct me if I'm wrong), which all have some sort of interlocking mechanism on them. Unfortunately, every system that I've found is almost boutique in its production, which is to say they only come out of a single factory in the US and none of them have good distribution. There is virtually no distribution for them down here in the south east US. I'm still looking getting a few quotes on them. The good news for people interested in something like this is that the blocks don't cost much more (if any more) then normal concrete block. Locally, I can get traditional block for $1.39/stretcher (free delivery), which is the same cost as the VOBB block. On a more realistic note, it seems that block construction is the only thing that makes sense in my situation. It will take less than 2,000 blocks to make the perimeter wall on a 1200 square foot building, which is about $2800. If I get the excavation and foundation done for roughly $6000, it seems like I should be able to get the walls (provided the walls go up completely DIY with no labor cost) and foundation for under $10,000 (include mortar/rebar/grout). Then a simple roof and I'm pretty much dried in for under $14,000. From that point I need electrical work and the interior walls that will be stick built, but I can take my time there. So what I'm figuring is I should be able to work this thing out (figuring in doing everything except the foudation/slab and excavation with no labor cost - including electrical), for somewhere well under $30,000. No thrills but not skimping on it's functionality. If you can see where I may be missing something big, please let me know. Something worth noting is that you said you would infill with sand. Is there and advantage to using sand vs conctete grout other than it's probably much easier to work with? And finally, is it possible/safe to drystack traditional concrete block like the quikcrete link above implies? I could deal with the awkward measurements if it was safe to do this on loadbearing walls. A guy at a supply shop told me it wasn't, but I don't think he was aware of what I was talking about... Also, I'd like to share these links to the sites of people making mortarless drystack concrete block. I don't think it's going to work for me, but if I was in a location that it was produced in, I'd jump on it in an instant: VOBB Azar Block Haener Block Sparlcok Durisol Omni Block Also, this is an informative article about it: From Masonry Magazine And I'm uploading a PDF that's good to. Seems like a good idea to have all this stuff in one place! Dave

sharward wrote:

Steve, do you know if dry stack is allowed in earthquake prone areas?

I just found this from a publication of the Mason Contractors Association of Northeast Ohio...

Does any one unit fit all situations? Not likely. Since tthe units are highly variable, why couldn't the mortar be too? Matching unit and mortar is the answer and that's "prescription mortar." It's a sticky topic, we know, but mortar is one of the most basic elements of masonry construction. Yes, you can build without it these days as dry-stack blocks are becoming more popular but when nature becomes pushy, you want that tall wall to withstand gale force winds and even earthquakes. That usually means mortar joints. . . (Source)

I've found other vague references to dry stacking possibly not being appropriate or allowed in earthquake prone areas, but nothing concrete (no pun intended). I did find some references to post-tensioning, both dry stacked and mortar jointed blocks. However, that gets more complicated and less DIY-friendly... :roll: --Keith :mrgreen:

Post tensioning isn't so bad from what little I've found; sounds like you just replace rebar with all-thread, buy some coupler nuts (really THICK nuts) and screw allthread together til you reach the needed height, then put washers on top of top plates and tighten. (this would be done around any header application, doors and windows and corners) - Just found this http://www.quakewrap.com/urm_walls.php Which sorta sounds like a VERY similar thing to doing dry-stack with fiber-reinforced surface bonding mortar. Hope to find time to look into this more, but not sure how soon - maybe Rod's already done this in one of his past lives; Rod, whatcha got on the subject of quakes vs. dry-stack block? :wink: