I am repairing a porch, and need to know if it was poorly conceived or just poorly executed.
the deck is osb (first bad idea), covered with an orange waffle mat glued down, to which the half inch brick pavers were mortared. it failed miserably, leading to rotten osb and framing (not treated). some of the flashing details were obviously blown, but what I want to know is – what is this orange mat, and could this system work if properly flashed and sealed?
thanks, I hope….
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Replies
The orange mat is an "isolation membrane". It is designed to reduce cracking from lateral movement. I don't like the idea of OSB as a substate, but I think your failure is more from the flashing details. If its a do-over, I would seal the wood and then use drypack or cement board, and re-install the mat.
1. 1/2 inch pavers are not water proof
2. Mortar is not waterproof
3. The waffle stuff is not waterproof
4. So the OSB got wet.
Got wet once, will get wet again if you do it the same way.
Support our Troops. Bring them home. Now. And pray that at least some of the buildings in the green zone have flat roofs, with a stairway.
"3. The waffle stuff is not waterproof"How can you say that without know what it is.If it is Ditra then it is;"Schluter¯-DITRA
Schluter-DITRA is a polyethylene mat with square, dovetailed recesses and an anchoring fleece laminated to the underside. In conjunction with tiled coverings, Schluter-DITRA forms an uncoupling, waterproofing, and vapor pressure equalization layer."Now I have no idea if Ditra is approved for this kind of appliation or if it was installed correctly (or if it is even Ditra).I see that they also have drainage plane systems that might be usefull. Again I have not researched it to see if they are appropriate for this application.
Schluter¯-TROBA
Schluter-TROBA is a cleavage and drainage layer for use above a horizontal waterproofing layer and below a screed or gravel layer. It consists of a pressure-stable polyethylene sheet with perforated studs for reliable drainage. Tile applications above screeds require the installation of Schluter-DITRA as an uncoupling and waterproofing membrane.Read moreRead more
Schluter¯-TROBA-PLUS
Schluter-TROBA-PLUS is a durable and reliable sub-surface drainage system that prevents the possibility of capillary action. The closely positioned, cone-shaped studs can withstand heavy loads and are covered by a water permeable, fleece webbing. The studded mat raises the entire surface assembly, creating a continuous drainage area.http://www.schluter.com/2080.aspx
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
what is this orange mat, and could this system work if properly flashed and sealed?
Probably a product called Ditra, which you can google to see if that's the case.
need to know if it was poorly conceived or just poorly executed
Short answer: Yes, to both.
Probably should have had a membrane roof installed (like epdm), to create a water-proof "plane" first. But, then, I'm getting hung up in whether I can recall a 1/2" masonry product that is a paver before deciding if it ought to be mortared/thinset down to it's substrate.
So, I'm winding up with more questions than answers, and that's frustrating. Things like, what is the porch "over"? Does it have any drainage? Is it roofed? Railings or some form of "solid" wall surface? Each of which leads off to another question.
Which makes me feel slightly the idiot, as all I can tell you was that the old install, by your description, was "bad," and not offer much to help right now at all.
Follow Bill's advice and look into the Schluter products. They have systems for dealing with the waterproofing, drainage, and freeze/thaw that you (usually) need to consider outdoors.
Also ask at http://www.johnbridge.com
Billy
thanks for your replies -
further excavation revealed that it is in fact Ditra (heard of it, never seen it). unless someone chimes in, I guess I will research wether it can be used in this application....but....
when I informed the client that this should be a total redo, which would be a major pain in the wallet as it would involve jacking the roof which they just added, etc. etc., they told me to just repair and replace, like for like, my initial demo area - an 8x8 patch where a foot could actually go through- avert my eyes, and walk away....
I've been working for them on another house for almost a year now, so naturally I've run them out of money - they need to sell this monstrosity to keep working on the other place, so I'm doing as they ask, trying to fix what I can, but knowing the rest of the porch is doomed....I should get a written waiver I guess....
anyway, trying to do my part right, I need to know what adhesive to use, and what to do at the Ditra joints to seal it...
...and where a pagan goes for confession....
Ditra can be used for exterior waterproofing, if used correctly. There is an article in JLC about 4 issues back that covers the application.
What the last poster said was on the money. Ditra CAN be used as a waterproof (and exterior) membrane, but it must be installed properly..Namely, the seems must be taped w/ the proper Schluter product. Surf their website and find out how.And Ditra is fine over OSB--but OSB for an exterior deck?? Bad idea.
OSB under tile is generally a bad idea, and especially outdoors.
Yea, that's pretty much what I said..But a lot of homes have OSB subfloors..Ditra is spec'd for these as well--I've used it plenty on OSB and there's no reason why anyone couldn't (See the TCA handbook for verification).