Hi all, Im making another thread as this might be a totally different topic. Maybe you guys can help me analyze the situation.
1. The house have a 5" concrete roof deck and built 6 years ago (1 floor only). Thankfully, no leaks in the other parts of the house.
2. April 2013 - I saw some major staining in the masters bathroom ceiling, and occasionally saw water droplets forming at the ceiling. The stain and water droplets seem to form in a hairline crack about 30cm long. Btw, bathroom is around 250cm x 200cm. The ceiling is already the roofdeck, painted with boysen latex. Ceiling height is 240cm. As we are working during the day, it stays closed.
3. Rest of 2013 - I did not mind the area but when I look up, I seldom see those water droplets.
4. March 2014 - Decided to waterproof for peace of mind. Cleaned the roofdeck, applied primer/sealer, then painted 3 coats of rubbercoat. Topped with concrete for foot traffic. Some rain experience after and I looked up and no water droplets seem to form
5. April-May -- unprecedented heat here in Cebu. Temperature is at 32C with 65-70% humidity. Bathroom stays closed the whole day. Its very hot inside the house when we return in the evening and my 4 exhaust fans can barely remove the humidity/heat inside. Most of the time I go straight to the bedroom and just turn on the aircon.
6. Three days ago, after a big big rain and a good night's sleep, I decided to look up and saw the water droplets again (just 2-3 pcs). This is after a very hot day and a very cold aircon at the adjoining masters bedroom. Worse, the 30cm crack seems to elongate to about 200cm and saw two black stains. Those small stains last year seem to scatter to the length of the crack.
7. Two days ago, while I traveled, my wife decided to open the windows and no aircon. It rained at night and no water droplets.
8. Yesterday, it was a hot day also but since it rained the other night, there are still water pooling at the roofdeck (usually all water evaporate after two days). In the evening (6pm), I looked at the bathroom ceiling - no water vapor. At 11pm, the water droplets begin to form again. This happened even though there was no rain.
9. Which led me to believe that maybe, its not a leak anymore (or never was a leak in the first place). The rubber waterproofing just sealed everything and thus, humid air gets trapped during the day vs. some who would have escaped from the small pores of the cement upwards towards the atmosphere. The presence of black stains is also consistent with other posts about condensation moulds. (There were no black stains prior to waterproofing).
10. If its not condensation, then it is a leak. Unfortunately, its impossible to check the leak unless I will destroy the concrete topping and look very very closely everything at the roofdeck.
What do you think, guys? Your theories are well appreciated. If its indeed condensation, what might be a good long term solution and/or how to repair those stains? Today, I am opening the window during the day when we were out. Temperature here in Cebu is almost always 31-33C during the day with 65-70% humidity for the last two months.
Attached are the photos of the area :
(a) Original leak/stain is only the small portion on the right side with the dark stain.
(b) This is the stain that occured after waterproofing and this is directly on top of the shower. We do not use hot water in the house but water gets hot when summer.
Re: Roof Leak (Concrete Roof Deck) or Condensation
I wanted to respond to this earlier, but didn't have time for what needs be a long post.
If there is a leak, it's not where you see the actual paint discoloration, otherwise you'd likely
see telltale peeling, ballooning and/or fading of the ceiling paint. All this tells us is that the
discolorations indicate the lowest points in the ceiling, where water collected after flowing
from either a crack elsewhere, or interior condensate, before dripping and leaving whatever
dissolved/suspended minerals it had been bearing --the discoloration.
If the staining had been lighter, I might dismiss it as interior moisture: your ceiling has no
wood to provide tannins that can stain. Water leaking from the deck above is far likelier to
stain... but then again, it's only happening in a wetroom, so that points to condensation.
Tough to tell, really.
Better to address both possibilities simultaneously.
Thermocyclic movement of a structure is a fact of life. That's why you have evidence of it
at the joint between your wall and ceiling after severe temp change. Joints in motion can
create gaps, which can allow leakage. Even if the joint luckily recloses when the structure
reflexes, any stiff plaster at the corner joint can be shed, and you will observe permanent
evidence of the movement. Leakage due to joint movement is the reason why when you
waterproof a deck or even a bathroom floor, a waterproofing strip or tape is applied along
such said joints, and then a healthy fillet/bead of waterproofing is laid atop the strip/tape,
which can flex, uncompromised, as the joint moves. Some even top all that treatment
with GI-sheet cap just to keep moisture away.
Even then, the floor finish has to be graded to lead rainwater away from the joint, ideally
towards ample drainage. Not having good drainage is asking for trouble. The pros and cons
of area floor-drains vs. gargoyles should be obvious. The former leads water away from the
vulnerable joints, but then every floordrain requires a breach through the slab: a point of
potential leakage by itself (and each joint along the drain line is also opportunity for a leak).
The latter involves leading water right to the vulnerable joint(!), so that the water can be
spouted out, but does not require breaching the slab.
If your deck has no floordrains (doesn't seem like it from your description), it may be too
much work/risk installing them now. A simple gargoyle, set at slab-finish-level, is no worse
than having standing water, and is easier and less risky to do: you're only messing with the
parapet (or wall) around the deck. Bottom line, your deck will shed water faster, before it
can seep into, and find, a weak spot.
Condesnation? Get better air-extraction for your bathroom, and take cold showers, lol.
The colder the water, the less vapor it tends to generate.
When a structure's frame is robust, movement is minimized, and explains why some older
deck installations remain sound even without modern waterproofing solutions. In many
ways, the older waterproofing solutions (thoroseal, bituminous overlay, ample drainage)
work as good as, if not better than, 'modern' products --especially for the local vernacular
in construction.
Re: Roof Leak (Concrete Roof Deck) or Condensation
Horge ... thanks for sharing the ideas.
My top roof decks at times get overflowed during hard rainfalls. Age has taken it's toll on the downspouts and these are not as efficient as they use to be. Probably the Gargoyle approach can help even up the situation.
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Re: Roof Leak (Concrete Roof Deck) or Condensation
🙂
Good luck!
Re: Roof Leak (Concrete Roof Deck) or Condensation
Thank you horge for the post. Just to update, it was raining hard last night. The bathroom window stayed open during the day (very hot 33C weather) and I suppose not much moisture was trapped. No water drops this morning so I guess thats good news. Hoping its just condensation, really.
Again, thanks for the insights. Will see if a gargoyle can be made.
