Flood water entry through weep holes in brick walls:
Area flooding sends water and mud through weep openings and into veneer wall cavities. What problems ensue and what should homeowners in areas subject to flooding do about venting brick veneer walls?
This article series explains the purpose of drainage openings & rain screens in solid brick walls and in some brick veneer walls: brick wall weep holes and recommends their use in new construction and in some brick wall repairs or retrofits.
Weep holes in building exterior masonry walls (brick or stone) are a drainage system that is used in cavity wall or rain-screen wall construction methods to get rid of water that has penetrated the outer wall skin or surface.
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Carson Dunlop Associate's sketch at left [Click to enlarge any image] illustrates an improper backfill that will certainly direct surface runoff or flood waters towards the building wall cavity, almost assuring water entry, rot, insect damage over time.
Carson Dunlop Associates, a Toronto home inspection, education & report-writing tool firm, notes in their educational mateiral that in-slope grade and burying veneer wall vents is improper.
But even when the lower edge of a veneer wall and its vents are a foot or more above ground level, area flooding is likely to cause water entry into the veneer wall cavity, leaving mud behind and risking clogging of the veneer wall vent system.
Even after flood-waters reside a blocked veneer wall vent system risks future damage to the building if water is trapped in the wall cavity.
2017/08/31 Sarah said:
@Rob, we have the same issue in Houston so I am anxious to here the responses.
No water in our house but some of the marble tiles at front of house showed darker along the grout lines extending out from the walls.
We have not done any moisture testing but our real estate neighbor has warned of dangers of mold so we don't want to ignore but are not sure what to do or how quickly we need to act.
2017/08/31 Rob said:
We had flood water get right to, and maybe an inch above the brick weep holes. In one location we had a small section of baseboard damage.
No other baseboard damage but we get a higher moisture reading in several other locations using a cheap 2 pin meter from the hardware store. Do we need to remove all of the baseboards, insulation, and sheetrock or will those dry out by themselves?
The water was at that level for several hours but less than a day. Most of the readings were in the green and less than 12% on the wood scale when checking the drywall right above the baseboard. Thanks for any help you can give.
Sarah and Rob,
I may be able to give better, and more economical advice when I know more details, have see photos, and have details of what you found when exploring for wet areas as I will describe, but here is what I recommend as some initial steps for homes that were NOT subject to deep flooding that sent water inches or higher into finished building interiors.
In my experience even a half-inch of water on floors that just wets baseboard trim will, especially if left for hours or days, seep upwards in the wall cavity, by capillary action, following wood and drywall higher in the wall cavity.
IF water has wet floors in a building such that it went behind even just the bottom inch or so of floor-trim baseboards and drywall, wetting those spaces then you really want to take the following steps:
1. Remove floor trim baseboards in wet areas: AS SOON AS POSSIBLE pull off the floor trim baseboards, wipe them dry and place them in a dry location to finish drying. If you can work carefully (I use pairs of small flat prybars) to remove the trim it can usually be dried and re-used in the same rooms, saving time on buying, cutting, painting new trim boards.
2. Remove wet drywall up 12" or more: Cut off & remove the bottom 12" of drywall in any areas where the drywall was wet, even if only its bottom inch was wet. Remove any wet insulation, let the wall cavity dry.
3. Speed dry-out if possible: Fans and dehumidifiers can speed the drying process if you have safe electrical power. If we get these materials dry in 24-48 hours after soaking we can usually avoid a more serious mold cleanup job . A combination of fan to stir air circulation and a dehumidifier to remove moisture will help dry out a building interior much more quickly than either of those appliances will do on their own.
If you have already removed and tossed out wet wall-to-wall carpets and carpet padding and then do the tasks above, quickly enough then you can avoid a more costly mold problem.
Watch out: for "mold prevention" fraudsters: If you do not open wet wall bottom cavities, there is absolutely no magic system like "water extraction" by dehumidifiers alone, nor by blowing air through little holes cut along a wall that has ever worked successfully in my (more than 40) years of experience.
I have pulled off baseboard trim weeks after a room appeared "dry" to find that there was still visible water on the trim back side, and by then, a mold colony happily blooming away on both sides of the drywall low on the walls.
If you can establish by observation or by measurement using a simple pin type moisture meter that water didn't go all the way around a room, just pull off the wet baseboards and open the wet areas.
Usually wet wood and drywall will peg the moisture meter over into the red area.
Moisture under 18% in wood is acceptable UNLESS you have reason to think the moisture meter can't see far enough into the wall - eg if you waited too long to make these measurements (days) and the outer surface is dry but back side of trim and hidden drywall behind the trim are actually still wet.
In that case explore the most-suspect area as I describe here.
Go to the most-suspect-wet area, (look at water marks and debris), open that by pulling off trim and removing wet drywall, and keep going until you find dry baseboard and drywall and wall cavities. Stop there.
Check the back side or previously-hidden side of drywall and wood floor trim that you remove. If it's moldy more cleaning is needed. You don't need to "kill" mold. Simple cleaning wood with detergents or spray cleaners followed by drying is enough.
If drywall back side is moldy, cut more off up another foot or more as needed until you can see that the remaining drywall and any insulation in walls is dry.
Keep me posted. You can also send photos and details along with follow-up questions by email using our page top and bottom CONTACT links.
See FLOOD DAMAGE REPAIR PRIORITIES where we issue safety warnings and provide links to articles discussing specific flood damage control, demolition, flood damage repair articles.
Watch out: for safety, before entering a building that has been flooded review BUILDING ENTRY for DAMAGE ASSESSMENT
2016/03/25 S Schneider said:
We had severe flooding in a brick town home in Tyler Texas recently, for the third time. The contractor recommended sealing up the weep holed. He said that's where the water was flooding in.
We have French drains already. Reading your site, I'm concerned sealing the weeps is a bad idea?
I agree that water entering a brick veneer wall in flood conditions is a serious concern. Brick veneer walls are built to shed water from wind-driven rain but not to resist standing floodwater. Floodwater will pass through the veneer and enter the wood framed wall cavity wetting insulation, drywall, and other components, inviting costly mold damage too.
Ultimately homes flooded in this manner need to gut the wall to framing, replacing insulation and drywall.
I would not normally advise sealing weep holes in a brick wall unless you are changing the wall structure, design, insulation and drainage system to a flood-resistant wall that prevents water entry in the first place. We describe that approach at BRICK VENEER WALL REPAIRS in FLOOD PRONE AREAS
Otherwise, while sealing vent or drain openings in a veneer wall might slow water and mud entry into the wall cavity during flooding, it will also trap more frequent wind-driven rainwater that will enter the wall and be unable to drain out.
The result will be a catastrophe: water trapped in the building wall and ensuing damage beyond mold to include rot and insect attack.
Let me offer more general comments, gripes, worries about building flood resistance: no normally-constructed home is built to work like a boat: that is, slab, foundation, and wall structures as well as roofs may be water-resistant but only roofs are water-proof and even roofs rely on shedding water to keep water out.
That is, except for membrane roofs, if a roof were under-water it would leak. Similarly, foundations and walls of most buildings cannot resist the forces of standing water against the building exterior and certainly that's also true for a building's exterior walls above-ground. Those walls are designed to shed water not to be waterproof if inundated.
And if we *did* build a building exterior that was totally waterproof we'd have moisture and mold problems indoors from interior generated water and moisture - those long hot showers and spaghetti cooking on the stove.
What all this means, I'm sorry to say, is that flood-proofing a home in an area that is frequently inundated, that is flood-proofing a home located where water frequently rises up along the exterior walls, will require raising the home above the flood level - on a higher pier or other foundation system - or moving.
2016/06/21 Shayne said:
What is the min distance a concrete path can be from the bottom of the weep hole
Interesting question. I've not seen a ground-clearance specification for brick veneer weep holes. But you're quite right that water entering such openings from the ground could cause building damage.
Schneider's question and answer in the article above discusses Texas flood water entry into structures through wall weep openings.
A subtle component of just what that damage risk is depends on how the veneer wall is constructed, the height above grade of the bottom masonry lip or steel rail on which the veneer wall sits, and the in-wall height of the in-wall flashing at wall bottom that directs any in-wall-cavity water out through he weep holes.
My OPINION is that the weep hole should be high enough that it won't pick up surface water runoff during rain or periods of melting snow; that may vary by individual situation from an inch upwards.
Sandbagging against weep holes around base of veneer wall: When you anticipate floodwaters around the home, dense packing of sandbags around the wall bottom can slow water penetration into the veneer wall cavity and should also reduce the volume of clogging mud that will enter those openings from flooding
The topic of repair and reconstruction options to reduce future flood damage to brick and brick veneer wall homes has moved to a new, expanded article now found at BRICK VENEER WALL REPAIRS in FLOOD PRONE AREAS. Please see that article for details and an ongoing discussion of flood damage repair and reconstruction for homes built with brick or brick veneer walls.
Continue reading at BRICK VENEER WALL REPAIRS in FLOOD PRONE AREAS - repairs to reduce future flood damage, or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.
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(Mar 13, 2012) WEill said:
if water enters the weep holes during a spell of high water, and allows some water into the building. if the sheet rock is not wet, will mold still grow inside the wall? if so how should i dry it out?
(Feb 18, 2013) Levertis Steele said:
Water rises above the weep holes when it rains in my backyard for several hours. Water seeps in from somewhere and covers most of the room it enters. After the rain stops and the water level outside recedes, the water drains from the room in the same direction from where it came. I thought that it was coming through the weep holes. What is wrong?
Even with a lot of experience with mold detection and remediation in buildings I can't say for certain that mold will or won't grow at a specific location on a house I've never seen. But certanly drywall is very mold friendly. If drywall is wet or even if it's not, if there is water inside a wall cavity that sends moisture higher in the wall cavity to where drywall is located, you can expect problematic mold growth to show up.
You can explore the suspect area for visible mold by making a test cut into the most-suspect location. Check the cavity side of the drywall for visible mold and also check nearby wood framing and insulation.
Periodic area flooding that is submerging a building wall to heights above the top of the foundation wall suggests some more serious steps are needed to control floodwaters, or if that's not going to be reasonable or reliable, to live with water entering the property, structural design changes are needed.
In an area of very limited water and rot problems on a flat site in New York, I addressed a water entry and related rot/insect damage problem by chopping off the bottom two feet of a wood frame wall and building up the wall base with a couple of courses of solid concrete block.
(Sept 11, 2012) Anonymous said:
I have weep holes located on the 2nd floor of my house. above and below a window and also a few towards the base of the 2nd floor. Can these be covered up?
Closing off weep openings in a masonry wall, presuming that they were properly located, installed, and flashed in the first place, risks trapping wind-blown rain or other water inside the wall cavity, inviting structural damage, rot, or mold contamination.
(Sept 22, 2012) dena said:
we have water after a blowing rain coming over the brick ledge which sits on the basement foundation .the water did not drain out due to the builder installing the flashing wrong it is on the outside of the tyvak.the moisture caused the vapor barrier to condense and now we have a mold problem. can we remove several couses of brick to repair the flashing?
a builder wants to remove all the brick around the house which is very expensive and money we don't have as we are senior citizens and in bad health.
a masonary man says he can remove several courses by leaving some of the bricks every 5 feet.can this be done?
I think your mason may have more experience with brick veneer than the builder, and his suggestion is worth a try. But be careful. 5 feet as the drainage opening interval may be too big a gap.
An unknown is the number and spacing of ties to the wall structure. If the wall is not supported enough and thus cracks you'll end up removing it all. Try working on just one segment at a time and perhaps leave more bricks loose but in place, removing the temporary support ones just briefly during repair and re- flashing. Send me some photos and perhaps we can comment further.
(Feb 17, 2014) Sal said:
I have round weep holes along my brick retaining wall that are not working. Is there anything I can use to unclog them?
Sal, possibly - it depends on the problem. If the weep holes are clogged from insects, such as mud dauber wasps who love those openings, a careful routing with a suitably-sized tool and maybe using a shop vac to draw out as much debris as possible may be enough.
For a retaining wall (as opposed to a brick veneer or structural brick wall) it's also most likely fine to try jamming a rod back into the soil behind the wall, through the weep opening.
But if the weep holes never worked because they are blocked by dense mud, lacked gravel backfill, are clogged by concrete, or some other snafu, you'd need to take a different approach, possibly involving a long masonry bit. Perhaps if you use the CONTACT link to send me some photos I can comment further.
4-17-2014 Ted said:
I have weep holes above my windows and door. The rear of the house is exposed to blowing wind and rain. I have leaks in three windows, one easily seen dripping from the top window frame the others I suspect are running down around the edge of the window and coming out below the window from the lower trim, running down the inside walls.
I had the windows caulked and as an add on the contractor, as a favor, added metal wrap to the lentil and caulked around that too. First really heavy wind and rain storm came and now the leaks seem worse. I suspect the flashing must have been run out through the lentil and that wrap and caulk job are the reason it's worse. Am I correct in that thought? Should I take the wrap off of the lentils? How should I check for proper flashing as I had leaks before the wrap and caulk job?
Ted, I agree that it sounds as if the flashing above windows and doors was omitted or not properly installed or punched or damaged during construction. I can't see how to fix this easily without some exploring into the wall cavity to see what's going on. Check out Carson Dunlop Associates' page top sketch (click to enlarge any image) to see what the flashing position should be.
Keep in mind that even if the flashing is properly installed, if a lot of water is leaking into the wall from higher-up, the water might be running down the wall sheathing and behind the flashing and out from underneath it. That diagnosis is what's needed before we try to fix anything.
Watch out: Certainly we don't want to just close off weep openings or caulk in the wrong place or we risk either water accumulation in the wall or severe rust and lintel damage.
4/18/2014 Rodney Thompson said:
Have you ever heard of a weep hole extending in a straight verticle line from the foundation to the roof?
A weep opening in a brick veneer wall is placed at intervals and at one or more location heights always including the wall bottom and possibly at higher points in the wall depending on how the wall is constructed.
The open space behind a brick veneer wall is typically intermittently partially obstructed by extrusions of mortar in the veneer, depending on how the wall was built, but hopefully nowhere is the air space totally obstructed across the whole width of the wall - so moisture can find its way to a weep opening for exit.
SO yes the air space behind a veneer wall extends, though irregularly, from wall base to wall top. But no, not explicitly in a "straight line".
The "wall top" may not extend to the roof line - that depends on how the building is designed and how high the veneer wall extends.
(June 1, 2014) Kathryn Mundy said:
dirt is coming out of retaining wall weep holes in patio. I have tiny patio that abuts earth -- the top of the wall is at ground level of a row of neighbors that live up a hill behind me. I had this home 15 years. In last month I now have large piles of Dirt at openings of the 3 weep holes (I have photos) .
We recently had 3 days torrential rain; also possible there are mice (I live very near a river in a small town and river redraws rats and mice) also last year neighbor behind me built picket fence at top of wall (the earth behind wall is a dirt path with landscaping that leads out to parking area. What would suddenly be forcing so much dirt to come out of the weep holes at bottom of my retaining wall?
It's common for soil to wash through drain holes in a retaining wall, especially after heavy rains. If the wall has not moved, bulged, cracked, then it sounds as if the drainage openings are doing their job.
I'm not sure why there would be a sudden change, perhaps settlement or a surge in water behind the wall.
To avoid confusing other readers, a retaining wall is NOT part of a building structure, it is a wall built to hold back earth.
(June 4, 2014) Virginia P. said:
I am converting my front porch into a room. The contractors says we can leave the existing brick walls with the weeping holes in place. He wants to keep the wall, and built over it. Some people tell me we should have the brick wall removed so moisture will not built up and create mold. The contractors says its not necessary. I don't know what is correct. What should I do?
I don't understand how your existing porch is constructed nor where the weep holes are located in it. If you are describing drain openings in a masonry wall that is earth filled, over which a porch slab was poured, leaving them in place is harmless. In any event the intent of drain or weep openings is to allow rain or other water penetration to exit the structure. Sealing them, in general, risks future trapped water and a moisture problem or in freezing climates, frost damage.
(July 22, 2014) Anonymous said:
Stucco Tec / I am a brick mason we are laying 60000 brick and using weep tube the home owner has been running water behind are brick to see if the weep tub is working 80% of them are working the others are plugged with mortar that has fallen behind the brick which will happen I am now going to make my tubes longer what do you think is a good idea. Thank You Stucco Tec
I think the owner is not doing a very good thing to pour water in volumes far greater and at a greater rate than the brick veneer wall design would anticipate - a result risks leaks into the wall cavities, floors below, mold, insulation damage.
It is common for some weep hole openings to become clogged with fallen mortar. If it's just a very few and if weep openings are frequent enough along the wall bottom, it's not likely to be a concern. More important is proper flashing at the wall base to be sure that water is directed out to the weep openings.
However if you detect a clogged weep opening before the mortar is hard-set you might be able to just clear the existing opening or cut it bigger and insert one of the retrofit weep opening products in this article.
Longer tubes at weep openings may still become mortar clogged and certainly you don't want the end of the tube to be jammed up against the sheathing of the exterior wall.
What do you think about using some of the other weep opening products shown in the article above. There are products for both original installation and for retrofit.
(Sept 1, 2014) Susanora said:
What can I do to stop the wall rot (interior crumbling plaster & also some crumbling of interior ferrocement) behind my 1938 brick - lath walls?
The brick frame house has no weep holes, and the problem is only on the west side along about a 15 feet section, all above grade. I think condensation may be part of the issue - this is in Salt Lake City and driving rains are not frequent.
I have had the house for 24 years and the problem has been continuous - I repaired the interior plaster several times, then gave up & hung cloth over the mess. No mildew or mold, but it is a significant cosmetic problem. Is there any way I can add ventilation from the inside of the house to the airspace behind the brick? It is so arid here (average humidity 15% - 20%) wouldn't it be possible to ventilate the cavity from inside of the wall?
Rot, which refers to organic materials like wood, is caused by a combination of water and wood destroying fungi, often basidiomycetes, sometimes more serious Meruliporia.
The right epair is to stop the source of water entry and to determine if structural repairs are needed.
I'd also look for insect damage in the same areas.
If you think condensation is occurring in the wall from indoor humidity I'd look for and fix any sources of indoor moisture and I'd seal penetrations into the wall such as around receptacles.
I would not try venting the wall cavity to the indoors - you may invite IAQ problems.
I would look at some of the brick veneer drain retrofit products we describe in this article.
(Sept 6, 2014) JJ said:
Why is there both weeping holes AND flashing? Can't water get out through flashing alone? I am not understanding the logic: do they both perform the same function? Thanks!
No the flashing would be sealed by the mortar course.
The weep holes are the water exit; the flashing is the water director.
7 January 2015 Anonymous said:
I have a long brick exterior wall. Near the end of the wall is a double door and then just a few more lengths of brick prior to the termination of the wall into hardi-plank. Is it needed to install a weep hole in the brick in this short length. There isn't one currently.
I feel there is plenty of weep holes on this wall on the other side of the door to allow for air pressure equalization, but I don't see how moisture could escape between the door and the end of the wall (moisture can't go up and over the door opening to the other side to travel out of those weep holes).
The weep holes' job is less air pressure equalization and more water drainage.
Obviously we don' t need continuous weep openings at the bottom of a masonry wall, the openings are spaced at intervals. However an individual wall section bordered by other structural elements, that is not connected to drained wall sections, should have its own weep openings even if only one is fitted.
Having a weep hole in even that short wall section would reduce the chances of water accumulation therein and thus related building damage.
You can make a further risk or needs assessment if you can inspect the building interior walls below the section you are talking about - e.g. from a basement or crawl space where you'd look for leak signs, and you can also assess risk by noting conditions outside that increase the risk of leaks into that section of wall cavity such as an un-flashed or leaky window, door, or cracks in the brickwork.
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