Proper Location for Weep holes in Brick or other Masonry Veneer Walls:
Here we explain the proper location for weep or drain openings in brick or other masonry veneer walls. We warn against blocking weep openings by placing them below grade or below an abutting sidewalk or patio.
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. We explain how these weep or vent openings in brick walls work, where and how they should be installed, and what special products such as opening screens & flashings are available. Page top photo: properly-located but probably too small and clog-prone brick weeps at the bottom of a veneer wall. [Click to enlarge any image].
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Where do the brick wall weep holes go? At the wall bottom, but above ground level. The spacing of weeps, typically no more than 33" apart, is given in the first article of this series, beginning at BRICK VENEER WEEP HOLE & VENT SPECIFICATIONS.
[Click to enlarge any image]
In the image above you'll see that when the brick veneer is supported by a steel lintel, the weep openings are immediately over the wall bottom flashing that is in turn immediately over the upper surface of the supporting steel lintel. - adapted from Figure 3, "A Typical Section of a Brick Veneer Wall with Steel Stud Backup Wall" - Arumala (2007)
Below is a BIA design detail for draining a brick veneer that sits atop a foundation wall projection.
[Click to enlarge any image]
Above: Brick veneer wall construction details showing weep openings immediately above flashing that is in turn atop bottom brick course of a brick veneer wall constructed over a steel stud cavity wall. These details are for a brick veneer wall that rests atop a masonry foundation on a projecting lip. I'm not sure about that bottom course of brick under the bottom flashing unless the space between the brick and the wall sill is filled-in and waterproof.
This illustration is adapted from BIA Technical Notes 28B, Figure 1 as used in Arumala 2007 cited below. Critical wall bottom flashing is shown in red, brick veneer weep opening locations above the horizontal portion of that flashing are shown in green, and house-wrap / water barrier fabric(s) are shown in dark gray.
In a brick veneer wall resting on the foundation, typically the weep openings and flashings are at the bottom of the brick veneer atop the foundation wall projection, or in some illustrations we see the openings installed one brick course up from the very bottom of the wall.
In a brick veneer wall that rests on a steel lintel, the weep openings are made immediately above the horizontal projection of wall bottom flashing. That flashing itself is above the upper surface of the steel lintel and extends up the wall at least 8" where it is either behind the wall water and air barrier or is sealed to it at the flashing upper edge (for example using flashing tape).
At BRICK VENEER WEEP HOLE & VENT SPECIFICATIONS we provide detailed specifications for the spacing, intervals, and flashing at veneer wall weep openings, drain holes, and vents.
Watch out: do not block the drain opening at brick veneer wall weep openings by back-fill, concrete sidewalk, patio blocks or anything else. Weep openings need to be above grade and un-blocked to function properly.
Carson Dunlop Associates sketch (below) illustrates that it's a bad idea to backfill against a building so that the wall's weep openings are below grade.
This mistake traps water inside the wall inviting frost damage, building water entry, and insect attack on the building sills and floor framing.
Hi there i am a real estate broker and my client has an accepted offer on his house conditional to an inspection the inspector determined that the bottom weep holes of the bricks have been covered by pave unit block terrace by about 3 bricks high (above grade), although the paving people left an air space between blocks the inspector claims it isn't enough, how much empty space must one give to the weep holes for them to function properly - R. by private email to editor 2016/05/03
I can only guess as I have seen nothing about the home in question, but in concept, no amount of space between paving blocks will fix the problem you describe, and much worse, building up a patio against or above the weep holes means that rainfall or melting snow on the terrace is being directed ***into*** the wall structure. There is a distinct probability of water problems including leaks, mold, insect damage, and rot in the home you describe, more so if you're talking about a brick veneer over wood framing.
Any problem can be corrected, it's more a question of urgency, cost, and defining the proper solution.
Missing from your note is information about what evidence the inspector found (if s/he did) of actual effects of the improper construction you describe. It's not the case that every mistake always leads to a catastrophe. If they did, we'd learn more from and pay more attention to good construction practices.
4/19/2014 Rich said:
A new construction question. The mason contractor installed a brick veneer wall with the appropriate flashing and weep holes at top of foundation.
The bottom two courses of the brick veneer, including weep holes, are below the top of the concrete stoop, when the front door concrete stoop was built.
Should the weep holes have been placed above the finished grade of the concrete stoop a the front door entrance?
Is this a critical issue, having some of the weep holes covered by the concrete stoop?
I need to see some photos or a sketch to understand the question more clearly (use our CONTACT link if you like). Generally if the concrete stoop abuts a brick veneer in a location where the veneer wall is already interrupted by an entry door it may be that those particular weep holes don't have much to do anyway.
I infer from the design you suggest, however, that there may be a concrete entry platform or "stoop" abutting what is basically a wood-framed structure - a design that in some locations may invite termite damage.
Continue reading at BRICK VENEER WEEPS BLOCKED or MISSING 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 buiding 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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