Siga Products
chrislene
| Posted in General Questions on
Hi,
An unexpected delay caused Siga Majvest to be exposed for maybe 4 weeks beyond warranty period. We are experiencing approx major water intrusion at window heads where it is wrapped around with 3/4” window buck (poor design) and at the base of the south facing walls. Anyone else have this problem?
Thanks
CL
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Sounds like something isn't flashed, lapped, or secured properly. Even if the WRB was failing (very unlikely given only 4 weeks beyond warranty), the windows shouldn't be leaking.
Is it still exposed and you therefore can try to diagnose how water is getting in?
After another rain that soaked the interior of 10 windows, I ripped apart one of the window flashings myself and found that the Majest wrapped over the buck and into the window. THe majvest was not adhered to the plywood. Water was either saturating the majvest and penetrating or getting behind it another way and traveling down wall and onto/into the buck and then into the house. I am horrified - this installation was done by a prominent GBA/fhb/jlc contributor/educator.
Do the windows have flanges? If so, was the Siga membrane lapped onto the flange before installing the Wigluv tape? Using exterior bucks like that is the typical approach and usually works fine.
In your second photo there appears to be discoloration above the folded membrane; is that a photographic illusion or is the membrane itself damp or holding water?
The windows do have flanges but they are not for nailing. The membrane is soaked as is the plywood behind it. The membrane was not lapped over the flange it was wrapped over the buck and into the RO. I cut it off to investigate (there is a piece still behind the flange and at the head or the RO) - which was easy since it was not adhered at all.
How do I fix?
Thanks
A clearer picture of how the RO was flashed. Majvest into the RO on all 4 sides.
Deleted
Chrislene,
When you have brought this up with your builder what is their response?
He is no longer on the job. This is the latest of multiple issues.
At this window, the issue is they did not run the Siga up behind the WRB. Those mini window bucks are now perfect water dams to channel any water coming down the side into your window frames.
Slit the WRB at the window corners and fold it up. Get a piece of wide flashing tape, and run it under the WRB up as far as the strapping allows. Lap the tape with the folded up WRB and tape the corner slits cut earlier.
Thing are now properly shingled and water will drain out past your window instead of behind it.
If you want better, include a metal flashing above the window trim, the layering would be:
-window flange
-tape to up to about 1" past the bottom of metal flashing.
-metal flashing bedded in caulk
-tape over the top of the metal flashing running up under the WRB
-WRB laps both tape and top of metal flashing
I believe I still have to remove the window(s) and reflash the RO since there is leftover majvest behind the flange. also need to peel layers of tape off the flanges. The rest of your suggestions are doable. The water is getting behind the majvest which is poorly adhered leaving pathways for travel down the wall. Thanks
CL,
The window heads should be protected by metal head-flashing with end dams, not rely on a WRB or membrane.
And those head-flashings need to be either VERY reliably taped to the WRB behind them, or the WRB needs to lap over the vertical part of the head-flashing, 'shingle style', my preferred approach.
If the head-flashing is applied over the WRB water coming down the surface of the wall can run behind it.
you should provide a detail or photo. as Malcolm said this area should be flashed with metal head flashing but it is hard to suggest a fix without more detail.
I've seen SIGA tape sit outside for 1+ year and still be intact so I don't believe the tape would fail in just 4 weeks past the exposure date. Plus, manufacturers are very conservative on the exposure dates. A lot of factors play into it like time of year (UV is more intense in summer vs winter), elevation, south or north facing, etc.
Like others have said. Need some pics/details before advice can be given.
The windows do have flanges but they are not for nailing. The membrane is soaked as is the plywood behind it. The membrane was not lapped over the flange it was wrapped over the buck and into the RO. I cut it off to investigate (there is a piece still behind the flange and at the head or the RO) - which was easy since it was not adhered at all.
How do I fix?
Thanks
While the people here are very good, you are unlikely to find a specific solution to a complex problem on the internet. You will most likely need a local buildings expert to investigate this and provide a correct diagnosis and recommendation for repair.
That said, we can learn some things from your photos and description. If the Majvest and sheathing above the windows are soaked, then the water is coming from higher on the wall. If there is another window above the ones that are leaking, it is possible that the water is getting behind the Majvest up there and travelling down behind the membrane to the lower window head. This is somewhat common and often not diagnosed properly.
Therre is also a possibility that this is condensation. What is your climate/weather and what is the condition of the interior right now? Are you running salamanders or other combustion heaters inside the house? Are the walls finished or not? Do you have other sources of moisture inside the house (houseplants, unvented cooking, humidifiers, etc.)? Water vapor that gets to the sheathing and/or Majvest layer can condense there, soaking the wall.
One way to tell whether it it condensation or not is the weather when the leakage occurs. If it happens in cold, clear conditions, condensation is most likely. If it happens in warm rainy conditions, leakage is more likely.
The good news is that your siding is not on yet. If this is actually an exterior leakage issue, it should be relatively straightforward and inexpensive to fix. Condensation from inside may or may not be easy to find and fix, depending on level of completion and complexity of causes.
Thanks for answering. It is not condensation. The interior is still stud walls. This is bulk water intrusion during rain There is no window above this one. There are windows above some of the other leaking first floor windows. Seems clear that the water is getting behind the majvest. I dont know how - either thru saturation or the fact that the top edge was not taped and the membrane isnt well adhered. Siding is on at various portions of the house. I hired a local expert to build me this high performance house and this is what I got. THere are no experts to investigate this and help. Do you know any who will come to Redding, CT?
Is the interior heated? What makes you sure it's not a condensation issue? Why are you focusing on the windows if the leaks are happening throughout the membrane? Is the wetting spread over the entire wall or is it limited to specific areas?
There is no interior heat. The leaks happen when it rains.
I wonder if there is a problem with the membrane itself. If you were seeing leaks only under the windows, that would suggest a problem with the window detailing, but the fact that you have leakage elsewhere suggests another cause. It would be worth removing a section of membrane and testing it to see if it sheds water.
Here is a picture of what is above that particular window
It looks like there is a roof to wall intersection there. Can you take some more picutres there as most likely the issue is with the roof.
It also doesn't help that the flashing tape is reverse lapped at the top of the window. This is wrong but unfortunately very common, usually it doesn't create big issues though unless there are some large fish mouths in the tape.
Reverse lapping with European products like Siga and Pro Clima is not my favorite detail but it's not wrong, and usually works just fine. In fact the installation looks almost exactly like Siga's instructions: https://performancebuildingtapes.com/wp-content/uploads/2018/01/siga-majvest-500-sa-system-guideline_en.pdf.
The fact that the membrane and plywood is wet ABOVE the windows make me think that the window installation details are not the problem.
You’ll notice they do another sheet of SA over the window top flange tape. I think they realize the reverse lap is not ideal. Henry requires an addition of caulk/LF at reverse lap joints. I think LF is a better alternative for this reason.
They show one detail with an extra flap on page 18. Pages 16-17 show other details without the extra flap.
Micheal,
I don't know what the cause of the water ingress is, or how much relying on adhesion rather than lapping has contributed, but broadening out the discussion, I'm not at all surprised any house left exposed with just the WRB installed experiences some moisture damage. You can find videos of well installed Zip and Tyvek leaking to the interior when subjected to water spray testing (here is one: https://www.youtube.com/watch?v=p3q09-Thebs ). They are WRBs not cladding, and are designed to deal with incidental wetting, not as a primary barrier against bulk water intrusion.
With that in mind, the solution I would be comfortable with would be to flash the windows as Akos suggests in post # 16, make sure the intersection of wall and roof was sealed, and put the siding on.
yes, I mostly just meant that I think even siga knows that the reverse lap is not ideal. I also think that leaving a horizontal surface flashed with only wrb Is waiting for a leak, this is where metal head flashing is required.
Replying to #27
Malcom,
That test used 240PA negative pressure. 50MPH wind does happen but how often. I bet you if it the seams of the CDX under the house wrap were taped, no water would have made it through.
With a house with overhangs, I have found that reasonably installed house wrap does not leak. Small sample, so take it with a grain of salt.
Akos might have the key here. I think he's referring to a roof/wall intersection that is just out of the frame to the right. The diagonal tape is, I think, and attempt to protect that transition area. If there is no kickout flashing here, that's a very common source of leakage. A photo just to the right of this one would help. Water leaking in here could easily run across the top of the window and buck, beneath the Majvest and Wigluv tape.
But that's just this window. If there's leakage at many windows, it is reasonable to look for something more systemic. Or, the builders made different unique errors in many places. It's been known to happen.
I'm not a builder and even I know that's wrong.
Shingle style layering is not happening on that tape. Builder is clearly treating the SA WRB as sufficient on its own and then applying tape above it (top of window flashing)
Tape material doesn't matter, that's a place for fish mouthing where water is held in physical place. European means it will vapor breath, not water drain?
Look at Benjamin Obdyke instructions. Even on their SA house wrap with their European perm rated tape, they cut above the window/fold up like traditional WRB, tape underneath, then fold down the SA layer.
European membranes are typically monolithic, vs. woven or perforated WRBs common among North American products. European tapes have high-quality acrylic adhesive, which if installed properly--usually meaning applied with pressure and with time for the adhesive to bond with the substrate--they become chemically bonded to the substrate, vs. other adhesives which rely on mechanical means to remain attached.
Pro Clima Mento, one membrane I'm very familiar with, is tested to remain waterproof for 24 hours under a 30 foot water column. I have seen it leak when used in a horizontal application where it remain saturated for several days, but in normal use it shouldn't leak.
Where a lot of people go wrong with acrylic tapes is that they don't apply pressure. Think of it as little beads of acrylic--you have to pop the beads for the adhesive to fully work, and you need to give it time for the chemical reaction with the substrate to occur. The tape will stick without pressure, it just won't perform as intended.
Yep. Benjamin Obdyke UV Plus tape is also European perm rated. They still have their tape under the SA Hyrdogap in their install instructions
Chistine,
"I believe I still have to remove the window(s) and reflash the RO since there is leftover majvest behind the flange"
This is not an issue, you can leave it there as long as the window is re-flashed properly. Since all the re-flashing is adding layers on top it should not be an issue.
" also need to peel layers of tape off the flanges"
Existing is fine there, you are just putting another layer on top. No need to peel it off.
"The water is getting behind the majvest which is poorly adhered leaving pathways for travel down the wall"
Once the window top (at least the one in the first picture set) is flashed properly, water won't get behind the WRB. The key to good water management is shingling. An upper layer always goes over a lower layer so water is always channeled out. Of course if the water is getting behind the WRB further up, say from the roof to wall intersection or a badly flashed upper story window, you need to fix those first. Properly installed house wrap is weather tight except in the most extreme weather.
Small sample, but I have left walls exposed with just house wrap well past their best by date with without any water getting in.
Replying to #27. Malcom, I'd love to flush out this discussion with you as this has come up in the past. This is also a bit of a sidebar from the topic at hand, so apologies in advance.
The cladding/siding is the 'water shedding' layer, not the primary bulk water control layer. The WRB is the primary bulk water control layer. I think part of the issue is semantics. Primary indicates that it is the first thing water 'sees' in a colloquial sense. The intent of determining the primary water control layer is to determine which is the 'ultimate' or 'control layer of concern' when assessing an assembly. Water gets behind siding. This is why there is a rainscreen, flashings and a membrane behind it. Siding sheds most of the water. The rainscreen reduces driving forces and the membrane (SA, mechanical or liquid applied) is the 'primary control layer of concern'. This is the one that gets drawn on the plans across the details to make sure it is a continuous and comprehensive system. We cannot rely on siding alone to be the 'primary' water control layer.
One thing that didn't get mentioned was the conditions outside when the membrane and tapes were applied. Cold, wet weather, damp or dusty surfaces can affect adhesion of even great products such as Siga. It does seem to me that water is getting behind the membrane and this needs to be the focus to find the solution. Luckily, considering the stage the project is in, this is completely fixable.
One thing to note, the SA was wrapped into the RO primarily to act as the air barrier. This is what brings the primary air barrier into the window and will get connected from the interior to the frame of the windows. By cutting this out, the AB has been compromised. If this isn't addressed (just cutting the flap and sticking flashing under it) then the long term durability of the building may be compromised. One would need to continue the AB into the RO plus flash the top of the window appropriately. All four control layers need to be continuous and comprehensive and this should be drawn out on the detail prior to any fix (it is helpful to use different colors for the different control layers).
There is no issue with putting Siga Wigluv tape directly on top of the SA membrane. Michael Maines correctly points this out. The biggest issue with intrusion is the driving forces and most of this has been taken care of with a fully ventilated rainscreen. With the asterisk of making sure that the tapes and membranes were installed correctly and under the correct conditions.
The good news is that this issue is absolutely solvable for long term durability.
I don't think two points are accurate.
Benjamin Obyke HydroGap SA house wrap and Hydro UV+ tape is European. Their instructions are only for the tap to go under on the horizontal window top, and treat vertical stretches on the bottom as consealed. Unlike Tyvke, BO states many times on their website to never vertically tape with any tape because of fish mouths and their tape is perm rated like SIGA. Vertical fish mouth seems the likely problem.
I received a ton of not unfriendly, but "move on" when asking if "cut back" or "fold in" where mechanically superior at windows. Why not ask since the labor and material is nothing when you're doing it--as the pros which is best.The stock response to me and many other threads on this forum is "you're sweating the details." That tells me that folding in is 100% fine and shouldn't be blamed here.
For example, Benjamin Obdyke install instructions show 4 methods: Cut back with tape, cut back with liquid applied, fold in, and windows first.
The folding in wasn't the problem. I would guess.