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Question DetailsAsked on 8/31/2014

Name of a contractor that builds above ground cement deck patios over living areas. Decks are exposed to weather.

We have a new waterfront home in Gig Harbor and need a builder who has experience building above ground cement decks that are exposed to the weather, are water tight, and drain correctly.

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I presume you have an architect or engineer designing this and detailing the water barrier elements of it - they should be able to help you find a concrete building contractor who can do this. You will almost certainly be looking for a commercial building concrete contractor, not a residential one, if you want this done right.


And remember - concrete is NOT waterproof - so on a deck over a living area that is not really going to be a deck - that is a concrete roof - has to be built to carry roof loads (as does the supporting structure below it), serve as a waterproof barrier, etc. Usually, in that environment, the concrete is covered with a membrane liner for true waterproofing, then a walk-on surface like pavers or rubber matting, so the underlying concrete is strictly a structural member, not the water-retaining element any more than plywood or steel would be.


You REALLY need to talk to an architect about this, because a basically flat roof like this can be a major leakage risk, and to minimize that requires special design of the slopes, edges and flashing, shrinkage crack control (commonly done with post-tensioning), special water-resistant concrete mix design, and a waterproof covering membrane or coating.

Answered 5 years ago by LCD

0
Votes

Here is more specific information about our cement decks:


Our contractor convinced us that he could build cement decks that would be less expensive and would work just as well as pavers. The architect's plans show only that the designed decks were to be built with pavers over a 60 ml membrane attached to exterior plywood slope at a 1/4" per foot.


We had an engineer provide the structual calculations for the two cement decks, but he did not address the waterproofing of the decks. We assumed that the builder knew how to correctly build the cement decks or that he would consult with or hire a certified waterproofing company.


The master bedroom cement deck (173 sf) is under a roof but exposed to the weather on the southeast side and built over our garage and laundry room; the living room cement deck (396 sf) is uncovered and exposed to the weather. It leaks between the cement slab and the house with water dripping down the shingled siding onto the patio area below.


Two waterproofing companies have stated that the decks were built incorrectly using the wrong membrane; wrong application of the membrane; wrong type of flashing between the house and slab; wrong type of drip cap; wrong preparation of the plywood underlayment, and stated that there was no permanent remedy other than replacing the waterproofing material and slab.


Even with this information, my builder says he will only replace the living room cement deck and I must pay for the new waterproofing materials. We have not placed water on the master bedroom deck, because it is likely to damage the garage and laundry room ceilings, etc. It is built the same wrong way as the living room cement deck and is likely to also be defective.


We need to get quotes from a reputable contractor who has experience building above ground cement decks like ours. Due to the small size (569 sf total) of our decks, I have been unable to find anyone who will replace our decks or provide a quote that I can use in my legal claim against my builder.


I am disperate! Can you provide me with names of contractors or engineers who have experience with the construction of above ground cement decks and will work on this small of job in our area?


Thank you,

Doug


Answered 5 years ago by Guest_9937634

0
Votes

Here is more specific information about our cement decks:


Our contractor convinced us that he could build cement decks that would be less expensive and would work just as well as pavers. The architect's plans show only that the designed decks were to be built with pavers over a 60 ml membrane attached to exterior plywood slope at a 1/4" per foot.


We had an engineer provide the structual calculations for the two cement decks, but he did not address the waterproofing of the decks. We assumed that the builder knew how to correctly build the cement decks or that he would consult with or hire a certified waterproofing company.


The master bedroom cement deck (173 sf) is under a roof but exposed to the weather on the southeast side and built over our garage and laundry room; the living room cement deck (396 sf) is uncovered and exposed to the weather. It leaks between the cement slab and the house with water dripping down the shingled siding onto the patio area below.


Two waterproofing companies have stated that the decks were built incorrectly using the wrong membrane; wrong application of the membrane; wrong type of flashing between the house and slab; wrong type of drip cap; wrong preparation of the plywood underlayment, and stated that there was no permanent remedy other than replacing the waterproofing material and slab.


Even with this information, my builder says he will only replace the living room cement deck and I must pay for the new waterproofing materials. We have not placed water on the master bedroom deck, because it is likely to damage the garage and laundry room ceilings, etc. It is built the same wrong way as the living room cement deck and is likely to also be defective.


We need to get quotes from a reputable contractor who has experience building above ground cement decks like ours. Due to the small size (569 sf total) of our decks, I have been unable to find anyone who will replace our decks or provide a quote that I can use in my legal claim against my builder.


I am disperate! Can you provide me with names of contractors or engineers who have experience with the construction of above ground cement decks and will work on this small of job in our area?


Thank you,

Doug


Answered 5 years ago by Guest_9937634

1
Vote

Ahhh - caught by the old "I thought the builder knew how to do it" syndrome. Hate to break the news to you, especially after you have learned the hard way, but probably about 80% of builders and contractors have no formal education or training in the right way to design or build things, at least a majority of builders did not go through an apprenticeship where they hopefully could have learned their trade, and a great many just do what "feels right" rather than find out the right way to do things.


In your case, you learned there is a reason cast concrete slabs are not used as lay-over decking like you did - if done that way, it is over full-seam waterproofed steel ribbed decking, the same as a normal composite steel-concrete floor.


I would guess there was no deliberate waterstop embedded in the concrete and fastened to the house, between the house and the concrete, and it should also have had a definitive flashing at the house edge and overlapping the top of the concrete and flexible caulk sealed to it.


Also, with cast concrete on membrane roofing, which is a bad idea anyway, there should be a drainage path between the concrete and the membrane - commonly soft vinyl troughs which are put down before the pour, or sometimes a filter fabric covered plastic filter mesh or a coarse clean sand layer, to drain out water that makes it through the concrete - otherwise it gets trapped at the interface between the concrete and membrane and can't drain. There should also be a slip-sheet (usually heavy polyethylene above the membrane to protect it against being gouged and torn when thermal moements occur in the surface materials, though this is commonly omitted IF board insulation is placed under the surfacing material.


I would say you need to talk to your structural engineer, and find out if anyone in his company has serious expertise in IRMA (Inverted Roof Membrane Assembly) roofing - and if not, if he can recommend an architecture firm that is to help you with this. This is almsot certain to be a larger commercial-building architecture firm, not a residential one, as IRMA roofs are really rare in residential jobs, particularly in wet areas like yours, with good reason.


If you google the following phrase and then click on the images link that comes up at the top, you can see the type of details an IRMA roof typically needs (several different variations) - and that there is a number of reasons they have pretty much gone out of favor where avoidable after a 70's-90's craze about them. Google - images for IRMA roofing


I am guessing that an architect is going to recommend either a total tearoff and going back with the pavers over membrane (which are simply a walking surface and hold down the membrane, and can drain through the gaps between them), tearoff and go with a wood deck supported on gapping supports (pillars), or doing after-the-fact flexible joint sealer like fibrous bitumastic bulb strip overlain by flashing on the concrete, and a walkable membrane overlay on top as the primary water shield. Or they may recommend a high-end epoxy or urea finish on the concrete, though that does NOT stop leaks from subsequent cracking of the concrete, which WILL happen, especially when you get your infrequent heavy wet snowfalls. When your next rare heavy snow melts is when I would expect to see the new in-room waterfall features showing up.


As for what you can do about it financially - assuming this was built for you and not a prior owner, you need to talk to an attorney, because it involves issues of how much input you had into the design (since your engineer did the structural calcs), who chose the roof type, whether the contractor who (as I read it) convinced you to go with cast rather than paver concrete was even licensed to design concrete structures, whether he is bonded, what warranty was providede and how long it has been in place, etc.

Answered 5 years ago by LCD

1
Vote

On the cost for claim issue - while it is not a secure as an actual replacement bid, you could find an architectural/engineering firm that works on residential projects (a full-blown company, not an individual) that routinely does construction/rehab cost estimates and who also provide expert witness services - they can do an evaluation of the issue and prepare an "engineer's cost estimate" of the removal/replacement or repair cost that would hold up in court.


It has been too long since I worked in your area for me to be able to give a specific recommendation - plus most of the companies I know in that area do only very high-end houses (thinkk Bill Gates) or commercial projects.


Now the bad news - probably talking $600-1500 range for their services above - plus hourly rate of about $100-200/hr for any depositions or court appearances, including travel and sitting around waiting time, so can get pricey.


Your attorney, if you are going the bond claim or lawsuit route, can help you find one - they are listed in expert witness directories all claims attorneys have.


Not to throw a kink in the works, but one other thing to check on - make sure the concrete the contractor used matched the engineer's design assumptions - concrete on roofs is usually latex-modified waer-resistant lightweight or even foamed concrete, not normal concrete - so be sure if that was the assumption that the concrete placed was not normal weight or thicker than designed, as you can very rapidly overload the structural system. For instance, normal flat roof in your area is designed for 25 psf snow load - an extra 1-3/4" of regular concrete, or alternatively - using normal weight concrete rather than lightweight on a 2 inch clab (and you are probably thicker) takes away half that snow load capacity, so it can be critical. If a 4 inch slab (more likely), then normal weight concrete rather than lightweight foamed concrete, if that was specified, would take up almost all the load capacity intended to carry snow load.

Answered 5 years ago by LCD




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