WATERPROOFING DOUBLE TEE PARKING DECKS

[Spencer10]

I am currently in charge of restoration work to bring up to code a parking deck constructed of precast double tee sections, bearing on precast inverted T beams, supported by cast in place columns. The waterproofing membrane is very piece-meal on top of the deck, and ideally, I'd like to replace if all with one system. The only thing that I can think of though is 2 ply hot rubberized asphalt below a wear course of asphalt concrete.

Regardless, every 8 feet, there's a gap between double tee sections. Therefore there is a lot of movement in this deck, miniscule or not, it happens, and so a waterproofing membrane would have to bridge gaps and be able to stretch cyclically for a long period of time. I can't see any product being 100% effective for a long period of time in this application.

Any ideas out there???

 

[JAE]

May not be what you are looking for but try this:

http://www.neogard.com/AutoGard.htm

 

[Spencer10]

Thanks for the link. Unfortunately I'm dealing with a site in Toronto, where snow plows are a BIG problem and their blades would tear this apart in no time!

There is currently a similar system in place, which they have considered putting back. I'd like to avoid this though because they'll just have to replace it again in 3 years. I'd like a system to last 15 years if it's at all possible...maybe I'm dreaming though!

Thanks again! Good reference for sure.

 

[JAE]

Perhaps with the surface waterproofing, you don't use plows - I've seen brush type systems used. Takes more management and application sooner (don't wait until the snow is 2 feet deep), but might be workable with this system - you might call neogard and ask. There are also competing firms to neogard that can bid it as well.

 

[dik]

Can you set up joints every 3 DT's and provide a movable joint at those locations? You can use a stainless steel gutter beneath as req'd and drain. Good expansion joints are expensive. Do you have topping that you can use to construct the joint within? You can then use a proprietary membrane over the 3 DT's. Toronto doesn't have the same cold issues that other places have, but because of the high frequency of freeze-thaw, deterioration can be excessive. There is not likely an inexpensive fix.

 

[msquared48]

Why can't you remove the old roofing/sealant, caulk between the double tees with a flexible mastic sealant, and then put your membrane assembly over it all?

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[Prepakt1]

You could try HLM 5000 as a membrane it will accommodate some movement. Asphalt drys out and cracks with movement.
We recently did a large parking deck renovation in Vancouver using HlM 5000 and squeegeed it on reasonably thickly. It was then covered with concrete.

Intrusion Prepakt /marineconcrete.com

 

[concretemasonry]

It sounds like a "galloping gertie" that is subject to radical temperature extremes because of the different exposures on a daily basis. On a cold clear winter day the top deck can expand, while the lower levels are still cold. The reverse can can occur on a cold, clear winter evening where the top contractor more that the lower levels.

It is not just a just a freeze/thaw problem but a structural movement due to temperature swings and exposures on a daily basis that cause movement, compounded by the salt that attacks the concrete and sealants that is tracked in by cars. - They will always move move and are subjected to some severe conditions.

Engineer and international traveler interested in construction techniques, problems and proper design.