Inside face of brick frozen/frosted over in new historic brick remodel
I am an architect by training. I mostly practice in the LEED/PHIUS world now on the consulting side. I’m looking for some insight on these discovered house issues.
We bought a home in July 2020, a historic brick home, that was gutted and fully renovated on the interior. We are in climate zone 5. We are under limited warranty until July 2021. The typical wall assembly was: existing historic brick wall, 2×4 wood stud, fiberglass batt with kraft paper facing inside, gyp. Roof was not newly constructed during remodel, rather patched/repaired in various areas as required. All new windows installed, some old openings, some new openings.
Starting in December 2020, we’ve noticed visible wetting/discoloration on pieces of drywall in a few locations, mostly around windows and 1 point in the ceiling beneath the flat roof. We had water dripping at the head of a sliding door, pooling on the floor beneath it. I did a thorough pass through the house with an IR camera, finding a lot of very cold spots in the drywall partitions near window openings, some random cold spots in the walls/ceiling, and the typical thermal bridging at all corner/connections. We took a surface moisture meter to various drywall sections near windows and it did come back with readings of 50%+. All visible wet drywall areas giving moisture readings of 90%+.
We requested from the builder that they address the water infiltration issues and they started by looking at the limestone window sills, some of which were pitched back towards the house. When they came to pull them out and re-pitch them, I saw that there was NO flashing at the window opening, with the limestone sill out, you could see right through to wood studs and fiberglass batt.
After seeing how poorly the window openings were handled, we called out 3rd party consultant to cut a few holes in drywall in a few key sections to see what was going on inside. We expected some very saturated fiberglass batt sections (due to virtually no flashing at windows), but it was visibly dry from the interior side. We did not cut holes closer to the floor, which seems like it could provide a bit more insight…. What we did discover though, was the interior face of the historic brick wall was frozen/frosted over. All batts that were pushed up against the brick were wet to the touch as well. The consultant pushed a moisture probe through the drywall in other sections of the house and it surprisingly did not trigger high levels of moisture, however we think that could be due to the frozen sections reducing conductivity vs. an actual wet material. We are assuming that pretty much every interior brick face is frosted over across the entire home. Over the months, we’ve noticed on the exterior, brick/mortar crumbling off and accumulating at the ground around the perimeter of the house.
Too long/Didn’t Read – Major issues observed:
1. Water infiltration visibly showing up at on interior drywall in a handful of places in the house. Those areas now discolored/bubbled/paint chipping away.
2. Very poorly installed windows that are not flashed/sealed and allowing air & water infiltration at practically every opening.
2. Lots of moisture trapped between the brick and interior stud wall, that is freezing in cold temperatures, and wetting materials over time practically throughout the entire house
Our main question:
1. Is this would you would expect to happen with this wall assembly? To me this seems like a serious issue as there is continual wetting of insulation. I’m also concerned what will happen when things thaw out…where is all that water/moisture going to go from the frozen brick?
2. Should we be concerned about potential mold growth? We set a few of those petri dishes mold tests on some flat surfaces throughout the house and they grew mold just from airborne contact. No swabbing.
3. What does this mean for the longevity of the brick?
Any thoughts would be greatly appreciated!!
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There are a bunch of articles here at GBA and also some very good ones on the Building Science Corporation website on how to properly insulate historic masonry buildings. Your builder did just about everything wrong. Yes, this behavior is expected. The installation of insulation on the interior of the brick reduces energy flow through the wall, making the inside face of the brick colder. If it is cold enough outside, the face of the brick will drop below the dewpoint of the interior air. Without at least a continuous Class II vapor retarder on the interior of the wall, damp interior air will reach the cold brick and condense. This is exactly what you are seeing. When it warms up, the ice will melt. Either the meltwater will be soaked up by the brick and eventually dried out to the exterior and/or interior, or if there is excess water, it will pool at the bottom of the wall and soak/rot the wood studs.
You are correct in your concern about the stone sills. There should be a continuous water barrier behind the brick. This is difficult to achieve with an existing brick wall. Even a pan flashing under the sill and integrated with the window would have helped. Your leakage is probably inevitable.
Finally, there are some pretty well done studies showing that, once the wall is insulated and the heat flow reduced, the brick stays wetter in winter and is exposed to more freeze/thaw cycling and damage. The fact that you are already seeing brick/mortar crumbling is not a good thing. In a historic building the mortar should be softer than the brick, and most of the crumbling would be confined to the mortar. If the brick faces are spalling off, then someone might have repointed the wall using cement mortar. That would be another mistake.
Hi Peter, thanks for the reply.
I've been reading through the various articles on how insulating and building the wall assembly like they did was a big no no. Shouldn't the kraft face on the fiberglass batt act as a class II vapor retarder? We all know it won't truly be a continuous barrier though in this application... We also don't have a lot of conditions that help keep water off the walls. No overhangs, bad window details, etc.
I wouldn't put it past the builders to have used cement mortar to band-aid fix the brick. It looks like they applied an additional layer on top of all the mortar joints and its just been peeling/crumbling off these past 6 months+. It isn't just the mortar though, because there is red colored content involved as well. Likely some spalling.
At this point we are trying to figure out how to approach the builder and these issues. They have been receptive, so to speak, but they are moving slow and likely trying to stall on any major fix until the warranty period is up. They obviously won't want to entertain the idea of removing all the drywall and insulation in order to redo the assembly correctly. I feel like this is the only true fix though (along with properly installing all the windows).
In a perfect world, I'd love to see the following happen:
1. proper maintenance to tuck/re-point the exterior (possible water sealant on exterior if advised)
2. reinstall all windows with flashing a proper sealing
3. reconstruction the interior side of the exterior wall assembly per Martin's article
Sorry to hear about your situation.
I think these are some of the articles Peter is referring to:
475 High Performance Supply has documented how to do masonry retrofit projects successfully:
You can fix it from the outside or the inside, but either way it's going to be expensive.
Are you working with a larger builder with a reputation worth protecting, or a smaller business owner?
Was there a home inspection completed prior to your purchase? If yes, did they note any water, mold, or brick issues anywhere in the home?
Hi Eric, thanks for the reply and the links.
I do not think an exterior solution is in the cards. As I mentioned, we are still under warranty, so coming up with solid argument to get the builder on board to remediate these issues is our best path at the moment.
The 475 solution aligns to what I was thinking, but this will require the building to agree to rebuilding the entire interior side of the exterior wall assembly.
I think it's clear to me at this point that I need good documentation of the freeze/thaw conditions with resources showing what happens to the durability of the home overtime when subdued to this phenomena. We need to make a clear case that this will have long term repercussions that could impact our health and the integrity of the structure.
We did have an inspection done, by a reputable source, one who does focus on building performance, however inspections are a snapshot in time. It was performed during the summer during a hot/dry spell. The temperature differential wasn't there to pick up any issues with IR imagery. There were some typical builder shortcomings, but nothing red flag level.