Two-stage Joint Detail 1

Use a PVC waterstop; I prefer the ones that mount on the surface and not the ones in the 'middle' of the wall. Don't rely on backer rod and caulk if you have a serious water issue... I also prefer bentonite rod for waterstops.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

DIK,

I am sorry.
I forgot saying these are precast concrete walls.

JRW

I wouldn't use fig. 3 unless there is a cosmetic requirement or there's moisture (actual water, not just vapor...) on the inside of the wall.

Generally, Fig-1 does not sense because backer rod will be exposed to the interior space.
(Unless another interior wall is standing nearby, Fig-1 cannot be applicable.)
Fig-3 looks expensive to implement.
What about Fig-2? What is wrong with Fig-2?
I think Fig-2 detail is generally used. Wrong?

JRW.

Here is an article describing [link]https://www.buildingscience.com/documents/insights/bsi-004-drainage-holes-and-moderation[/url]. My understanding is you are creating a chamber for two purposes. 1) secondary seal 2) pressure chamber so air pressure has some where to lessen similar concept to a water hammer arrestor

Then a good caulking on the inner and outer edges... nothing in the middle. If you can place a foam insulation between with backer rod it would be good. Have to place your backer rod carefully to control the thickness of the caulked joint. Irregular thickness would likely cause a failure. You also need a 'super' caulk. Tremco Dymeric, a two part caulk, used to be my favourite. I used Dymonic (a single component) caulk for all the windows I installed in my house in Oshawa.

Maybe the insulation is a bad idea... you want drainage... properly done at the bottom.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

Where did these details come from? Fig 2 is the common detail. The problem with some of the details is the application. If you have a 1/2" - 3/4" gap between the two panels it is not easy to lay a bead without the foam backer. I suppose one could do #1 from the inside, but if your total panel thickness is say 14" that is not simple. I would stick to the PCI or CPCI details.

You have to use backer rod to control the thickness of the caulk. If the caulk is too thick it is really prone to 'tearing'. It's nice if your joints are wider than 1/2", hopefully 3/4" to 1". There are likely other caulks, but my experience with Dymeric is extremely good. I seem to recall a lawsuit about discolouration with the First Canadian Place in Toronto that used Dymeric (if I recall... been 50 years and a little fuzzy).

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

Here is a sketch showing which side is the exterior. Brad805: Here is the link to the details. Link

Maybe this snip is a little more clear

I believe John is working on a project with sandwich panels. It is not uncommon for the exterior skin = 3", insulation = 2" or more, structural wythe = 4 - 8" for typical one- two story buildings. Fig 1 or 3 are not incredibly practical and if I were to suggest that to my clients I would lose that argument. In my 20years working with precast I have dealt not dealt with many leaking caulk joints. We do a lot of two wythe panel designs and we have spray foamed the space between panels in the past to maintain our insulation line.

I do not think the precast example in the link is great. Without looking at the complete envelope I think it is missing some important aspects.

If a caulked joint is made properly, it should have longevity. What is your caulk of preference?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

I am adding another sketch(Fig A) saved from the internet.
I was involved with precast cladding wall projects long time ago;
I remember at that time this two-stage joint was called open concept...

I am sure two-stage joint concept should be applied to curtain walls and precast walls of high-rise buildings.
If Fig-2 is used for the precast walls in the high-rise office buildings, what will happen?
As inside backer rods are exposed to the outdoor moisture, will they lose functionality to some extent?

Can I apply two-stage joint WITH VENT HOLE (Fig A) to sandwich walls in the low-rise buildings?
Like food processing facilities or cold storages?
As drain space, wind chamber is open, doesn't it cause insulation problem?
Can I adopt this concept for 3 story tilt-up office building, for example? (Insulation is not critical.)

Thank you very much for your comments!

JRW.

I have done very detailed variations of these types of details frequently. This is specialist weathertightness design, if you are not assuring for weathertightness, you are best to let the architect/envelope consultant take the reigns.

Fig1, is impossible to achieve. even skilled caulking applicators would make a mess of this. its too far to reach your nozzle, tool, the backer rod can too easily be pushed out the far side.

Fig3 is someones "good idea", going overkill, which is actually a bad idea. how does moisture drain from between the two seals on either side of the single backer rod if it finds a way in? yes, moisture should be assumed to always find a way in. also, same issues of installation as Fig1

Fig 2 is totally appropriate. the only reason people deviate from Fig 2, is they wonder, how will the seals be applied on the interior side when they cannot be accessed at brackets, slabs, etc? the secret is to use a short run of expanding foam tape like Emseal or sika600 to form the barrier, slide it in by hand, and butt your caulking joint into that. its only acting as an air seal, and does not need to be perfectly weathertight, as the airspace between the two seals needs be formed as a drained and ventilated cavity.

similar to this last detail posted by JohnRwals. every cavity need drain, dry, and be broken up regularly. every level is best, so if there is a leak, it doesnt originate 8 floors up and manifest 30 metres to the west and leave some poor sod scratching his head about how its getting in

As I mentioned, I have used only Fig-2 detail.
So, I was surprised to see Fig-1 detail first time.

I am adding another detail from Canadian Precast Concrete (CPCA) precast joint detail brochure.
This description seems to be more reasonable..."accessiblity"
Is there really difference between Fig-1 and Fig-2 except visual effect or field application difficulty?

JWR

This problem could happen everywhere.
For instance, what can you do when you cannot access joint due to the adjacent column?
Can you skip this interior joint caulking?
Or, do you have to follow Fig-1 detail?
Though subcontractor omits this joint, you may not know that until serious leaking issue shows up.
This means both Fig-1 and Fig-2 details should be applied...

What do you think?



JRW.

at the joint you have circled, use a foam seal like sika600 or emseal.

this may need to be placed on the panel before it is lifted into place.

note, the important details are not these 2d details you are showing, but what happens at splices, joints and ends. thats where the leaks will happen