re-caulking joints between precast concrete wall panels

[ajk1]

How frequently should the joints between precast concrete spandrel wall panels be routed out and resealed?
See the building at 131 Torresdale Avenue, Toronto, ON. (use google earth).

 

[cooperDBM]

CPCI has some good publications at

http://www.cpci.ca/en/resources/technical_publications/

including a maintenance and inspection manual.

 

[ajk1]

To cooperDBM - Thanks very much. That is just what I am looking for.

 

[ajk1]

Unfortunately, to-date I have not been able to download the free copy.

 

[ajk1]

I have now succeeded in downloading it. Thanks.

 

[OldBldgGuy]

To answer the OP, "as often as needed". To qualify that, it depends on the materials you use and how they were installed. I know of no reason to remove properly performing sealant just because someone says this should last 10 or 15 or 20 years and that time is up. On the other hand, why would you leave obviously failing sealant that is 5 years old when someone says it should have lasted 10?

 

[dik]

yup OBG... and I've done projects where the caulk is intact for 40 years... Tremco Dymeric or Dymonic depending if you want a one part or two part mix...

Dik

 

[Canuck65]

You may be interested in CSA-S478 - "Guideline on Durability in Buildings", although you may already be familiar with this standard. A bit dated, but somewhat useful information. Generally it benchmarks 'sealant' with a 5 to 20 year life, however, in their tabulated summaries they always record the design service life of sealants as 5 years. In my experience I generally adopt a 5 to 10 year life span. As OBG says, I agree 100% that there are some sealant install jobs where good materials were used and installed by good crews and they can perform well for 20 years. Unfortunately the contrary is often the case as well. However, without the benefit of hindsight, an average of 5 to 10 years is a normal, expected design life. Annual maintenance is a good thing.

 

[ajk1]

Thank you all. Special thanks to Canuck65 for providing information on his actual experience, and reminding me about CSA S478. All much appreciated.

 

[OldBldgGuy]

I'm with dik on Dymonic. It's the best there is for many, many applications, in my opinion.

 

[dik]

OBG: have used it with success for decades... even used Dymonic for our windows in our home in Oshawa... I asked the sales guy where I could pick up a couple of tubes... and had a case delivered to the office... It will likely outlast the windows... my first use of vinyl triple glazed low E... about 20 years back...

I was going to note that contrary to many engineers in the firm I'm with, I often spec 'actual products or an approved equal', not a generic item. If it's a product I've used successfully, then I like to stipulate that product.

Dik

 

[Archie264]

The old paint tiles blimps potions caulk had lead asbestos hydrogen gas gremlins PCB’s in them it and worked well and lasted a long time. ‘Shame about the lead poisoning mesothelioma explosions Black Plague whatever it is that PCB’s cause. The new stuff doesn’t and doesn’t last as long.

So your old stuff may contain it and if it does it may have many more years of viability. However, with each passing year comes the risk of greater regulation for its abatement so that’s a risk / benefit tradeoff that only you can determine.

Look into to PCB's to determine if it's something you need to be concerned with or, alternatively, dletee this psot and pernetd yvu’oe neevr hread of it.

 

[dik]

Archie:
Dymonic tasted OK to me...

Dik

 

[Archie264]

Then it should be good to go!

Unless you grind it up, put it in a pipe and smoke it.

Just when you think you've got all these things taken care of they add a new one...

 

[ajk1]

On a bit of a different subject - they want to put Dow Allguard Elastomeric Coating on the exterior face of the above-grade exterior precast panels of the 20 storey condo. Has anyone experience with that? Is it sufficiently breathable that is will not trap moisture behind the coating? What is the purpose of the coating? The wall is continuous glazing with precast panels below the glazing, on each floor.

 

[dik]

Not me... but, with masonry restoration, you have to be very careful in choosing a coating that doesn't discolour, or attract surfacial 'dirt'. Is the coating really required?

If the coating 'sheds water' then you may be introducing 'drip lines' that add different 'streaks' to the outside surface.

I remember talking to an Architect when the Roy Thompson hall was being constructed in Toronto about the crossing intersection of the aluminum glazing mullions that there could be streaks on the glazing from water dripping from the intersection. My concern was the long time 'etching' of the glazing... sure enough, there are drip lines, but, I don't know what the long term effect is.

Dik

 

[ajk1]

To dik - an interesting thought. Silicones have changed since Roy Thompson Hall - then they were acidic and corrosive ...I know because I encountered a project where post-tensioned tendons were end encapsulated with tubes filled with silicone to protect them, but when these encapsulations were removed after about 3 years we found the tendons were heavily corroded under the silicone! However today silicones are neutral and not acidic. Nevertheless I will check your point with what Dow says, as it is a very good thought. Thanks.

I don't see any "engineering" reason why 35 year old precast wall panels need to be coated with this silicone (Dow Allguard Elastomer). Can anyone on this forum think of any good reason? The cost is $260,000. Perhaps in cleaning and coating the panels will look better, but just cleaning them would perhaps make them look better.

I am also interested if anyone is involved with precast wall panels who is aware of them being coated with silicone. Is that a common thing to do?

The condo President who is a builder, says that it "protects the condo owners investment". I don't see how.

 

[dik]

ajk1:

The example for the Thompson Hall was not related to silicones... but, unanticipated drip patterns which you can have using old silicones or new silicones... sorry for any confusion. There are issues in applying waterproof coatings, as I noted, and very little improvement unless they the precast panels are continually saturated. I would suggest that coating precast panels is not common. Maybe best to spend your money elsewhere... new caulking if needed?

Dik

 

[ajk1]

The latest info I have now is that they want to coat with silicone to improve the appearance. They made patches to the concrete about 10 years ago. I can only surmise that the patches were made due to corroding rebar. Why the rebar would be corroding in precast wall panels is a mystery to me, but if it was, then the silicone might protect against further corosion (as well as covering prior patches and improving appearance). Anyway, my question now is: is there any significant downside for the precast panels due to coating with silicone? I know there is downside to coating masonry, but maybe that does not apply to precast concrete.

 

[dik]

Patching is often a problem. Different materials will absorb sealant differently (that's why they are called different <G>). Once the sealant is applied... it is forever, earthling...

You may get different light 'reflection' from different areas in both wet and dry conditions... the appearance may not improve. Does anyone have examples where a similar treatment was applied?

It might be a good idea to do a couple of test panels.

Dik