Concrete to timber connections

[Thehardway]

I am getting ready to pour ICF walls and place timber framed trusses on top of them.  Also I will be framing out the windows with wood and would like to use KD lumber rather than treated to avoid warping and shrinkage as well as health issues.  There seems to be a lot of confusion as to whether I can place untreated wood in direct contact with concrete surfaces or not.  I have read that roofing felt should be used as a barrier and have also read against it.  Are there any foolproof methods of placing the trusses on top of the concrete and insuring that it will not absorb moisture form the concrete? Steel, rubber, plastic, silicone, sealers etc.?

[Jim_Rogers]

As far as placing not treated wood against concrete, that is a big no-no that's why there are code rules that say you can't. You should check with your local code enforcer to see what solutions you can do and still comply with code.

I have seen things like ice and water shield placed between wood and concrete, but again you should discuss this with your building inspector or whoever will be reviewing your structure for code compliance...

Jim Rogers

[Left Coast Chris]

You should also think about top support of the wall for horrizontal loading (wind or seismic).   The typical detail would have embeded bolts into the concrete with a pressure treated or redwood sill on top.  Then place a nailed metal L clip to connect the truss to the plate.     The redwood is generally not strong enough to take the horrizontal loading for a concrete wall depending on what seismic zone you are in.  You could use Simpson connectors such as the META with TSS shown in their catalog.  The horrizontal loading and connection to the roof diaphram is important.   If you are in a hurricane area uplift may control also.   So the proper attachment is important.  See www.strongtie.com for the connectors.  You will need to check with your building department or find an engineer to make sure you meet code requirements for your specific location.

[Raider Bill]

What was the downside of using roofing felt?
I know treated lumber got a bad rap a few years ago but I am under the impression that they have changed the chemicals used to treat it. Anyone know.
IMHO if you are just using treated for the sill plate and to buck/frame window and door openings how can that hurt you?

What ICF system did you use? Any comments. suggestions on ICF's? I've been considering reddiforms.

[TexasTimbers]

My buddy who is the PolySteel rep here used to use treated 2x10s or 2x12s ripped to the ICF thickness plus the finished thickness of the interior and exterior clads, secured with imbedded anchors.

I don't know if he uses the new carp they call treated or if he uses something else. I'll try and remember to ask when he comes over to supervise me while I stack our pantry/saferoom. He just retired and turned it all over to his son him this week.

My devious plan is to snag him, put a lawn chair under thge shade with a 12 pack (Diet Vanilla pEpsi for me;) ) of that watered down 3:2 Oklahoma junk beer he likes. That way I know I don't make any "oversights". Something inadvisable when building a room to keep tornadoes out. 

Hardway, are you putting a saferoom in your home? I know it is a source of debate to have one in an ICF home since some say an ICF home is a tornado shelter itself, but if you are going to build for tornadoes, build for an F5. Even an F2  can rip a truss roof off of ICF walls and suck the occupants out or fill them with projectiles.

[sawmilllawyer]

Hey, Hey so now we's putting down the ole watered down Oklahoma 3.2 non liquor store beer, eh?  Actually, it has its benefits, he has to drink more and possibly stay sober longer, maybe.

[TexasTimbers]

He does not get out of control but since he is retired I better watch him closer. ;D

THW, theoretically if you flash and seal your window bucks properly you could use whitewood. But code, and an imperfect world will not allow that of course and I would not do it code or no code. Speaking of code, are you building in a code-enforced area? I don't ignore codes carte blanc when I build in a non code-enforced area but it can be handy. There are some times where ignoring the book is not just expedient but better.

[Thehardway]

Horizontal loading should not be an issue here even at the top of the wall as there will be adequate steel and concrete lintels over all openings.  The walls are 6" monolithic concrete with 4- #4 horizontal rebars and vertical #4 rebar every 48" OC and tied 6" deep into a 20"W X 24"D perimeter footer with 2-#4 bars in the bottom 2" up.  Walls would easily withstand horizontal loading of backfill to 12' and are 150MPH rated.  They also have a 3hr.+ fire rating and STC rating of about 48-50.  I am using the i-Form by Reward Walls.  I chose them because 1) I have a local dealer for support, 2) it is one of the strongest forms in the ICF business, 3) has received all code approvals and 4) the 2.5" of EPS they use gives enough space to run 1.5" PVC with fittings for drain pipes without having to box out in the wall.   I did not use Polysteel because of thermal bridging issues although they are perhaps the most popular in this area.

My main reason for wanting to avoid commercially pressure treated wood is warp and shrink.  Nothing more anoying than broken seals in your thermal pane windows or sticking sashes caused by warping.  Code is loosely enforced in my area and so far building inspector seems to be a common sense type guy more than a letter of the law type guy. I like the ice/water shield idea or maybe I could use some galv. metal flashing between wood sill and concrete wall with it also serving as a termite shield. Has anyone ever tried this approach? I will bounce it off the inspector tommorrow and see what he thinks. ICF guy wants me to use V-Buck but I'm not sold on the vinyl approach.  I wonder what most vinyl siding will look like in 50yrs. let alone 300yrs.  I know what wood with a good coat of paint will do. 

I have seen the Simpson Strongtie tiedowns/straps but it appears they are engineered primarily for lightwieght truss application.  I am planning to run a 4"X6" sill along the top  of the wall held down with anchor bolts embedded in concrete at 4' intervals.  a galv. strap embedded in the concrete will go over the top of each sill and rafter foot hidden from view to secure the assembly and prevent uplift.  Heavy timberframed Kingpost trusses will span the ICF walls.

  I will be building in a saferoom and a vault in a future phase.  I actually have sheet lead taken from a X-ray room demolition that I plan to line the saferoom/vault with.  Not sure what section of the code deals with sheet lead for radiation proof rooms.

[Don P]

A few more thoughts to bounce around. Sill seal or something at wood to concrete joints to gap seal. Naturally decay resistant species, locust, white oak or like Farmer77 said, foundation grade redwood. KDAT treated (kiln dried after treatment) I can't find it here. Superior walls uses borate treated for bucks and it is code approved for sills.

[TexasTimbers]

You have done your homework. The thermal bridging of Polysteel is so negligible so as not to be noticed on your electric bill according to my buddy and I believe him I personally know at least half a dozen of his customers who vouch for the R performance, but by coincendence Reward is who I would actually go with also if he had not been a Polysteel dealer. I did lots of ICF research a few years ago even though I figured I would not build a ICF house because this may not be the house we die in. We are thinking to build one in east Texas after we get all the kids out of the nest.
My wife's cousin in Austin went with Reward and he raves about it too. I like the thick EPS as you mentioned for running plumbing on exterior walls and other things I can't remember now. I just remember that I could have bought them at $15 each from the oklahoma dealer right across the river. I bet i could not get them that cheap now.
I ended up making my own SIPs and knew going in I would have to build out for exterior plumbing. Like I said, I will probaly be building another house within 5 years or less, and it will be ICF, and it will probably be Reward.

[Thehardway]

A few more thoughts to bounce around. Sill seal or something at wood to concrete joints to gap seal. Naturally decay resistant species, locust, white oak or like Farmer77 said, foundation grade redwood. KDAT treated (kiln dried after treatment) I can't find it here. Superior walls uses borate treated for bucks and it is code approved for sills.

Don,  Do you know where in the code that spec is?  Would not be a problem to borate treat some KD with Boracare or Timbor etc. 
I mentioned it to the inspector yesterday when he inspected my footer forms and he said he thought the Galvanized metal flashing might be OK and he would discuss it with the Chief of inspections and they might grant an exemption. He said he has seen a lot of poured basement walls where they used Treated to frame out the windows and the morning after the pour they came back and it was all bowed out or twisted so the window would not fit.



Kevjay,

I heard a report on the PolySteel that some homeowners were having problems years after install with rust stains through the sheetrock where condensate has gathered on the steel and sheetrock screws or has wicked through the walls internal brace.  I cannot verify this and have never seen it but if true it would be a mess to fix.

[Thomas-in-Kentucky]

Hardway, here's the "overbuilt sandwich" I built to rest my house upon the basement.  Mind you these are timbers that are within 18" of outside grade:

white oak 8x8 sills
pressure treated 2x10's
stainless termite flashing
foam sill-seal
concrete

Where my fireplace foundation comes up through the basement, I skipped most of those steps and poured concrete right up to oak floor joists.  There I supported the timbers on 2x pressure treated material (mainly to get the height the same as the perimeter of the house), and just painted the ends of the timbers before pouring the concrete up to them.  For moisture to come up from the ground, through the concrete, it would have to wick up 9 feet.  I just do not see that happening, but I could be wrong.

At the extreme of what one might get by with, I have 50+ year old barns here on the farm that have oak posts resting on dry-laid sandstone piers.  No signs of rot.  I think the dry laid sandstone layers provide a "bond break" that prevents capillary action of water wicking up from the ground into the timbers.

My sister's old farm house in OH is built of brick (3 bricks thick) and simply has walnut window and door jambs up against the bricks.  She recently had some replaced (I cut them for her on my saw mill), but these were over 100 years old and probably failed due to leaky windows and water infiltration from a retro-fitted porch, not from ground wicking or anything like that (I doubt pressure treated pine would have lasted as long under the same abuse).  There are several examples interior to her house (which used to be on the perimeter of the house before it was added on to) where walnut and white oak is laid into the brickwork and shows no sign of degradation.   Her house was built in the 1800's.

I favor historical precedence, common sense, and personal comfort level, over "code books."

-Thomas

ooops - forgot to mention... for basement windows, we formed those with plywood and rough lumber.  Wrecked that stuff out when the concrete cured.  (typical poured walls, not ICFs) Then used tap-cons to attach pressure treated lumber inside the perimeter of the concrete opening.  Attached wooden windows directly to the pressure treated.  Filled gaps with "great stuff."

[Don P]

I don't disagree about the code books, but some of us have to obey them to the letter. All of us will someday but that's another rant  ;).
You cannot home treat and satisfy code in a treat required location, it has to be treated in a third party monitored plant, so stamped store bought treated. What I'm saying is that for non exposed, non ground contact foundation wood, borate treated is approved. This is a link to the approval report for Osmose's approved borate treated lumber.
http://www.icc-es.org/reports/pdf_files/NES/Ner648.pdf

Your inspector may allow home treated, I can say the stuff in the Superior Walls (Amelia, VA plant) had more borate than I've ever gotten in.

[Thehardway]

Thanks Don.  That info is very useful.  You will be happy to know my goal is not to cut corners or build sub-code. It is to avoid some of the pitfalls of building that the code does not take into account.  I am a firm beleiver in evaluating each case on its own merits rather than a "onesize fits all" approach. I want to work with the inspectors and have them work with me.   I want my window framing to not only last but to work well.  There are also a lot of things that are required to meet code but later get outlawed and cost the home owner big money to remove.  Asbestos, lead pipe, lead solder, Arsenic treated wood etc. 

Sounds kind of Utopian but if you don't try you never succeed.

IMHO we have to many builders that are just trying to meet minimum code requirements and are never asking how they can exceed the code and still stay on budget. Timberframing tends to be the exception to the rule but stick building is full of it.

[beenthere]

Thehardway
Just drop off "arsenic treated wood" from your list. Nothing wrong with it, just that the producers have shyed away from making it, as the word "arsenic" sounded bad, got bad media hype, and they decided not to put up with the hassle. So we, the user, lost.
But I think you are on the right track to protect your wood from the moisture in the concrete.

[Jordan]

Go find a source for SBX treated lumber. It meets the code requirements, is half as corrosive as the _old_ CCA treated lumbers (similar to untreated), and is entirely non-toxic.  The SBX stands for borax treatment, and is acceptable for use wherever "normal" preservative treatement is required as long as there is no surface water around - i.e. anywhere within the building envelope.  It should not be used in exterior locations where it will be exposed to water, as the borax will eventually leach away.  It is exceptionally useful for termites, as borax is one of the lower toxicity products used to discourage them - apparently it tends to grind up their little insides as they try to digest it.