FINISHED IN 2020! Sharward's Partial Garage Conversion

sharward wrote:

I guess I hadn't really seriously considered just leaving the gap empty. That may not pass code, though (think: termites)

You have cement eating termites in California!!!!???? Boy, things have changed a LOT since I lived there! :-) I'm not sure what the Roxul product would do except give them indigestion. Besides, from a few pictures back, it looks like you have a pretty effect moat system. If it worked for the Saxons, I don't see why it wouldn't stop termites. :-) len

No, no, no... :lol: My understanding is that if there's a hole in the slab (and a gap between slabs would qualify), termites can enter from the ground.

How about if I stuff a small amount of rockwool into the crevice, then use expandable spray foam sealer (closed cell) over the top? The rockwool would act as a backer rod of sorts, and since it wouldn't go down very deep, it probably wouldn't soak up much moisture. Quick, easy, fairly cheap... :roll:

sharward wrote:

How about if I stuff a small amount of rockwool into the crevice, then use expandable spray foam sealer (closed cell) over the top? The rockwool would act as a backer rod of sorts, and since it wouldn't go down very deep, it probably wouldn't soak up much moisture. Quick, easy, fairly cheap... :roll:

Keith, I have only been on this forum for a couple of months now and have probably read 90% of what's been written since August or so including all of your thread. I don't see how you find time to work on your project with all the posting you do! I have a building that I plan on building a studio in in about 6 - 9 months. This stuff has been great for me as I get ready to enter the planning stage early next year. In your drawing above, you might wan to look into something like this to fill the gap between the two pieces of concrete: http://www.apscork.com/apscork/fiberboard.shtml This stuff is designed to fill the joint between two slabs and allow for the concrete expansion. Perhaps you could cut the expansion joint board to fit the depth of your hole, line the perimeter with it, then back fill about three or four inches of the hole with sand. Forget the rebar holding stakes, I believe you will have problems keeping the plastic seal around them. The flatter the surface you are covering is, the easier it will be to place the plastic. The sand will support the barrier until the concrete is poured and will provide an isolation under the barrier to ensure that there will be complete separation between your floor slab and the perimeter slab. I don't see why you would need two layers of the insulation. You may have to use wooden stakes in the corners to support them. I have poured concrete slabs before, and believe me, the weight of the liquid cement will ensure the form is pressed against the perimeter. I think the air gap in the photo under the short piece of insulation will cause you problems. I don't believe you need wooden forms where the existing concrete wall is the sole purpose of the form is to support the concrete and define it's edge, the fiber board can do that with the concrete perimeter behind it just fine. ...db

I just noticed, there is a resiliant rubber version as well: http://www.apscork.com/apscork/rubberjointfiller.shtml ....db

db, you rule -- thanks so much for your product recommendation, your ideas, your drawing, and of course your interest in my project! 8) You (and Len too) have given me lots to think about, and I want to fully absorb these ideas! :D Thanks again... :mrgreen:

One more thing to think about... If your foundation doesn't need a vapor barrier, why would your new slab? Is it because it's laying horizontally over a larger surface than the concrete footings of your current foundation? Inquiring minds want to know!!! len

len-morgan wrote:

One more thing to think about... If your foundation doesn't need a vapor barrier, why would your new slab? Is it because it's laying horizontally over a larger surface than the concrete footings of your current foundation? Inquiring minds want to know!!! len

It's a good questions with some merit.... my thought would be that plastic is cheap and I can't see how it hurts anything, and you already know there's water......db

But if that's the case, wouldn't the current foundation be sitting in the same water? len

It's just an opportunity to do something right on the new slab that should have been done on the main slab but apparently wasn't. :x It hardly costs anything... You know, the more I think about it, the more I'm leaning towards just stuffing the uppermost portion of the gap with some rockwool, pushing it down enough to leave an inch or so deep of a gap, then filling that inch with the foam-in-a-can stuff... It really does seem to simplify things. Can anyone think of a reason not to do that? :roll: :) --Keith :mrgreen:

this thread is amazing!

Can anyone think of a reason not to do that? http://www.johnlsayers.com/phpBB2/viewtopic.php?t=4847 Bert's not inexperienced in these matters... and spray foam is CLOSED cell, so would act as a (light, but) SOLID. Not sure what I'd use, considering the lake an' all... Steve

Thanks Steve (and all). In reviewing Bert's thread, and something specifically that Sir Woodlock wrote in it -- since I will be using a 6 mil plastic sheet under the new slab, and since that plastic will extend into the gap, I really don't need to seal the top of the gap, as long as I have a seal between the plastic and the existing foundation. I'm posting another illustration that demonstrates this. So, I think that problem is solved! At least I think it is... Hopefully termites won't get through the plastic! :roll: I received my "How to build a monolithic slab" DVD this week and I started watching it last night. It's very cool. 8) However, I did discover one mistake in it -- they recommend putting sand above the moisture barrier, which I have read in various places is a very bad idea. So I'm kind of wondering now whether there are other bad things in this video that I don't know about! :? Anyway, I had planned to do forms this weekend, but I've been bothered by a few things. I have three different footing depths right now. That might be an issue with my city building department. If it is, then I see two ways to fix that -- do more excavation so that they all match -- which would mean more water seepage... :evil: ...or backfill the deeper ones... :roll: ...but I'm almost certain that is a no-no code-wise. :evil: I have also done some more reading about expansive clay soils, and what I have read give me reason to be more than a little concerned about rushing this important part of my project. So, before I do anything I might regret or that might cause me to fail my first inspection, I'm going to pay a visit to my building department early next week. I will ask them:

• Whether or not it is a problem that my footings are varying in depth, and if so, how they would like to see me resolve/address that
• Whether or not it is a problem that I have water seeping up into my deepest footing, and if so, how they would like to see me resolve/address that
• Whether or not it is OK to attach my plastic sheet to the existing foundation, specifically as it relates to termites;
  Edit: I learned that termites can easily chew through the plastic sheet... :roll: ...so I clearly need to do something much more brute. The posts that immediately follow describe a new pesticide-impregnated membrane that is used in lieu of the conventional vapor barrier.
• If I may substitute 2x4 framing on my walls instead of 2x6 without resubmitting my plans;
• If I may change my stud spacing from 16" o.c. to 24" o.c. without resubmitting my plans; and
• If I may add one layer of 5/8" drywall to my existing ceiling, resulting in about 5 total psf on the bottom chord of my trusses, instead of removing the one layer of drywall that is there currently and mounting new 2x6 joists across the east and west top plates for multiple layers of drywall attached to those, with (or without) submitting my plans.

Hopefully these worries are overblown. If they are, then I'll have the confidence I need to move forward. If they are not, then I'll get educated in what I need to do to pass my first inspection! By the way... In looking at this illustration, I wondered about the position of the plastic during the pour and then during removal of the forms. Well, I think the plastic would have to be on the inside of the forms for the pour... Otherwise, the stakes would go right through them... :roll: ...and the forms might stick to it with dried concrete and rip the plastic upon removal. That means there will need to be extra care taken not to scuff or rip the plastic during the screeding process -- and, if any damage occurs to the plastic along the tops of the forms, those holes or rips would have to be fixed with moisture resistent tape, with or without pieces of plastic sheet patches. This stuff may not keep me up at night, but it sure is the first thing I think about when I wake up every morning! :lol: --Keith :mrgreen:

Maybe you could check out a similar product to this. It comes as termite barrier only or barrier and dpm combo. I'll probably use a combination of standard plastic dpm and the termite barrier for the edges. I'm watching your thread with great interest. Are you fixing the bottom plates of your walls directly to your new slab, or are you trying to decouple in some way? eg sylomer striphttp://www.kordontmb.com.au/

Thanks huddo! I'll definitely give that product (or anything similar) a good look! It looks quite promising! 8) I plan to hard-fasten my new inner leaf walls to my new slab. I don't really have a choice here in California -- the seismic requirements are strict. But, since in theory the inner slab won't have any firm connection to the rest of the house, with the exception of the ground they both sit on, then I should be OK! I'm delighted that you're getting a benefit from my thread. :) I know I sure am! :D --Keith :mrgreen:

According to termite.com:

Western subterranean termites regularly infest homes in British Columbia, Washington State, Oregon, Idaho, California, western Nevada and western Mexico. They cause severe economic loss to homeowners in northern California, particularly in and around the San Francisco Bay Area, Santa Rosa, :shock: Sacramento :shock:, Fresno and Monterey regions. The Western subterranean termite is a serious economic timber pest causing millions of dollars of damage throughout northern California. It is estimated that more than 1 in 5 homes in the urban areas of most northern California cities have been or will be attacked at sometime by these voracious little insects. (source)

I am really impressed with the product that huddo recommended. After lots of Googling, I've discovered that a similar product is indeed available here in the US under the brand name IMPASSE™ Termite Blocker. At first I assumed that product was only for pipe and conduit penetrations (the "Impasse™ Boot"), as that is the most common image in the manufacturer's marketing materials -- even the ads I have seen in publications here over the last couple of years. However, much to my surprise and (I think) delight, they also make the "Impasse™ Barrier," which is "a uniform multi-layer polymer sheet consisting of an interior layer of . . . insecticide, surrounded on either side by layers of polymers that are impervious to the active ingredient . . . The 16-mil thick polymer sheet provides a pliable yet highly durable construction-grade product. The Impasse Termite System is an effective pre-construction treatment for subterranean termite prevention. . . [It] is impervious to water and vapors [and] may be used in place of the traditional polyethylene sheeting commonly used under concrete foundations as a vapor barrier . . ." (source) I'm sure this product is quite expensive, especially considering the fact that it must be installed by an authorized installer. One termite and pest control professional was quoted as saying the cost is ten times that of soil treatment (source). I'll be contacting some authorized installers over the next few days. For those interested in learning more about termites, I found this publication to be very informative:

ANR-1022: IPM Tactics for Subterranean Termite Control Published by Alabama A&M & Auburn Universities

Edit: Here's another very helpful resource on the subject. It's much shorter, summarized in bullet form, with a map that shows termite concentration levels across the US:

Termite Facts & Figures Part of the IMPASSE™ Termite Blocker Web site

OK, you guys are going to think I'm crazy. Correction: you guys are going to think I've really gone off the deep end. Tonight after the wife and I returned from dinner at one of our favorite restaurants, I pulled into the garage and was amazed by the amount of water in the "moat." Previously it was only in the deepest trench along the southwest wall. Now it's in that as well as those along the south and east walls. (It's been raining a lot over the last 24 hours.) So before heading into the house, with the headlights on the car still lighting up the area, a stepped onto the "island" to take a closer look at the foundations. I was intrigued by how moisture appeared to be wicking upward from the water level, but not evenly -- like some spots sucked water up more than others. I noticed that the rougher the concrete was, the wetter it was. So, I concluded that rougher = more air pockets, which translates to the path of least resistance for the water to travel. :roll: What a fine job those concrete folks did on this house, eh? :evil: I got close to one of the wet spots and I touched it with my finger. And just then, I saw an insect crawl out of the crevice -- about the size and shape of an ant, but lighter. Holy crap -- I think I might have come face to face with a subterranean termite worker! Either that, or I saw an ordinary ant whose body looked lighter because of the reflection of my headlights. I got up to turn the "real" lights on and to quicky find a container to capture it. Unfortunately, by the time I returned, it was nowhere to be found. One thing's for sure -- I did see an insect and it did come from the footing adjacent to my laundry room. We do have ants in this part of town, and we sometimes spot a few in the house. The two houses across the street from us have a huge ant problem. And with the rains we've had, it's not surprising that I would find an ant in the house. Anyway, this just proves beyond a doubt that I'm right to be concerned about protecting the area from termites. Even if it wasn't a termite that I spotted, if an ant could get there, then a termite colony surely can too.

sharward wrote:

# If I may substitute 2x4 framing on my walls instead of 2x6 without resubmitting my plans;

As I have learned building my studio (soon to be a "Do/Don't" elsewhere on this forum), if you change your framing from 2 x 6 to 2 x 4, look VERY closely at your design. I forgot to take into account that every layer of drywall I put up takes away 5/8" from my top plate nailers and corners. We hare having to put the corner screws in at an angle to make sure we hit enough wood. If I could tear it all down and start again, as an absolute minimum, I'd use 2 x 6s in the corners and 2 x 8s for the top nailers just to make sure I had wood under the edges when it comes time for the second layer. You also have to remember that on the 2nd layer of ceiling drywall, you are starting over 5/8" (at least) from where the first layer started. If you have ceiling joists made from 2x? on edge, you'll be able to get the first piece up but it will completely cover the joist so you won't have any thing for the sheet that butts up to it to nail to it. There are two solutions to this: 1) Shave the 5/8" off of each 2nd layer sheet so that the edges will line up with the joists. 2) (What I did), use doubled 2x6 or 2x8 nailed together for ceiling joists. It's more wood but for two layers (and probably 3) it makes it so you can use whole sheets and still hit the wood (boy than sounds nasty! :-8 ) Sorry to take so much space in your thread but your statement just sent up a red flag because that's what I'm going through right now. len

Thanks for the tips, Len -- I'll definitely take that into account! 8)

Hey Keith old buddy, long time no post. wanted to give some thoughts on the water problem. ideally a house should be built on a little hill, so the ground slopes away from the house in all directions. this is seldom done. more than likely you have ground around your house that slopes toward the house, and the water is going downhill and ending up in the soil under you house. so when you dig a hole (and the ground is wet) you hit water. i had this problem in my old sacramento house, i had a crawlspace that was full of water and it caused the people buying my house to pull out. they did the inspection right after a big storm. i paid some guys 500 bucks to run a drainage pipe around the house where the water was coming from and that seemed to fix the problem. at least i guess it did. i sold the house and never looked back. well so what. actually it may be a problem down the road if you do not fix the drainage problem. because when clay soil gets wet it heaves up, expands, etc. and then you could/would get cracks in your walls. so that would damage your soundproofing. i believe this type of thing is the common cause of cracks in wallboard in homes. not so much "settling" as periodic heaving. what you would need to do is dig a trench around your slab under the edge of your eaves or therabouts, fill it with rock and perforated pipe which has a special tube sock around it that will keep out sediment. yeah a big pain in the rear ... oh well sorry to bring up yet another PITA. Dan

I already have said drainage pipes around my house... :roll: ...Apparently they're not working very well. Perhaps I should get the builder to look at this. They've been pretty responsive about things in the past -- like the $75,000 plumbing fiasco I have mentioned in the past.

This is irritating... :evil: There are five pest control companies that appear in the Authorized Installers database on the Impasse Web site. I called one of them on Monday morning. I spoke to a live human and was promised a callback, which I assumed would be the same day. Two and a half days later, I called them back, and then learned the "one person" there who knows anything about it won't be back until after the first of the year. :roll: I left my contact info and asked to be called upon his return. I called the other four companies, none of whom have anyone available right now who can answer my questions. :? I left my name and number with each one. (One of them actually asked me to call back later -- and that was the one with a long distance number! :shock: ) Hopefully I'll get a callback from at least one of them today. cyeazel: I feel your pain, brother! :lol: I also called my homebuilder's water intrusion manager today. (He's the guy who managed my $75K water intrusion case last year. The guy's really cool -- he was literally on top of a customer's roof chatting with me on his Nextel!) He said that the water seepage in my footings is totally normal in my area of town -- in fact, he said he'd be shocked if that wasn't happening. So I'm less concerned now about the trenches filling up with water... Although I will be taking some steps to hopefully improve drainage around in the back and side yards and finally get those extra rain gutters along the roof line.

Good news! 8) One of the pest control guys called me back. He took a sincere interest in my project we talked about it with some depth for over 30 minutes. He thinks the product will work well for my situation -- he just needs to contact the manufacturer to verify that the kind of 50-year adhesive he's thinking of using along the existing concrete edges are appropriate/compatible with the product. He'll probably be visiting my house next Friday (December 30).

I just finished pumping out my trenches again! :lol: More good news! 8) While I was talking with my builder's water intrusion manager today, I got a lead on a good licensed concrete guy. I called him today and we spoke for quite a while about my project. Bottom line, he's not too turned off of doing a small job (he said it's kind of a slow period for him) and he's so far willing to take a shot at it! He also specializes in decorative coatings/stains/textures and he has a shed on a slab in his back yard that has a number of these decorative finishes on it -- kind of a showroom of sorts -- that I'm welcome to take a look at. I'll probably be seeing it in the next week or two. He guesstimated about $600-700 for the pour and plain finishing. I'm pretty excited about the prospect of working with this guy. It's too soon to tell whether or not it's going to work out, but I have some reasons to be optimistic! :D

Sounds like good news Keith. Can't wait to see what happens.