Weep Holes in Chicago Brickwork: Why Yours Are Pointed Shut

By Affordable Tuckpointing Pros, a Chicago tuckpointing and brick repair company in business since 1996. License number MC6337.

Direct answer

A weep hole is the opening left in a mortar joint directly above through-wall flashing so that water which has already entered the wall can drain back out. The Brick Industry Association designs drainage walls on the assumption that wind-driven rain will penetrate the outer wythe of brick, collect on the flashing, and exit through the weeps. [1] Weeps get pointed shut because an open head joint looks exactly like a defect to anyone repointing a wall, and BIA says so directly: it recommends screens in open head joint weeps partly to emphasize their purpose and “reduce the risk of sealing during future maintenance work.” [1] A sealed weep does not stop water entering the wall. It only stops it leaving.

TL;DR

• Weeps are required at the level of the flashing at all locations. Putting them one or more courses of brick above the flashing is not recommended, because water then has to pond on the flashing before it can drain. [1] [3]
• BIA recommends open head joint weeps no more than 24 in. (610 mm) apart. Most building codes permit up to 33 in. (838 mm), which BIA calls out as the looser number. [1] [3]
• The preferred weep is an open head joint, formed by simply leaving mortar out of a vertical joint, at least 2 in. (51 mm) high. [1] [2]
• Weep tubes are not recommended. The small opening drains less and clogs more. [1] [2] [3]
• BIA explicitly anticipates that later maintenance work will seal weeps shut, and suggests screens or vents in open head joints partly to stop that happening. [1]
• Mortar droppings during original construction are the other main way weeps get blocked, along with debris pushed into the air space during brick replacement. [3] [4]
• Landscaping and new sidewalks bury weeps. BIA wants flashing and weeps no more than 10 in. (254 mm) above finished grade, and says the elevation should account for planting beds and ground coverings. [1]
• BIA lists “missing or clogged weeps” on its own inspection checklist, and again as a potential cause of masonry distress. [4]
• Clogged weeps can often be reopened by probing with a thin dowel or stiff wire. Where weeps were never spaced properly, supplemental ones can be drilled. Both risk cutting the flashing sitting immediately behind. [4]
• Not every Chicago wall should have weeps. A solid mass masonry wall is a different system, and drilling holes in one is not a repair. [1]

One liner: Weeps are the only designed exit for water that is already inside a drainage wall, which is why closing them converts an ordinary wet wall into a trapped one. [1]

What is a weep hole, and why does a brick wall need one?

In short: Because brick walls are not designed to keep all water out. They are designed to let it back out, and the weep is where it leaves. [1]

Most homeowners assume a brick wall works like a boat hull: keep the water on the outside and everything is fine. That is not how the Brick Industry Association designs a modern wall, and it is not how the wall on your house behaves. BIA is blunt about where water actually gets in. When water passes through brick masonry walls, it typically does so through minute separations between the brick units and the mortar joints. Under normal exposures, BIA says, it is virtually impossible for significant amounts of water to pass directly through the brick units or through the mortar themselves. [1] The brick is not the leak. The hairline gap between the brick and the mortar is the leak, and there are thousands of them on any elevation.

Because that cannot be eliminated, the wall is designed around it. BIA calls the modern assembly a drainage wall, and the category covers cavity walls and anchored veneer walls. The guiding principle, in BIA’s words, assumes that a heavy, wind-driven rain will result in moisture penetrating the exterior wythe of brickwork. When that happens, the wall is designed to collect this moisture and redirect it out of the wall assembly. The water runs down the drainage cavity, typically on the interior face of the outer brick wythe, where it is collected on the flashing and exits the wall system through the weeps. [1]

Read that sequence again, because the whole argument of this article is in it. Water gets in. Water runs down. Water lands on flashing. Water leaves through weeps. Four steps, and only the last one is visible from the sidewalk. If step four is closed, steps one through three still happen. You have not built a waterproof wall. You have built a bathtub with a lid.

The cavity itself has to be a real cavity for this to work. BIA requires a minimum 1 in. (25.4 mm) air space, and notes that the IRC treats that as a nominal dimension while the IBC treats it as a specified dimension, which is a tolerance distinction rather than a different wall. [1] Where continuous insulation sits in the cavity, that 1 in. clearance has to be maintained between the back of the brick and the face of the insulation, not measured to the backing behind it. [1] A cavity choked with mortar is not a drainage cavity, and weeps at the bottom of it cannot drain a space that water never reaches.

Flashing is the other half of the pair, and it is not optional or generic. BIA wants the flashing wide enough to start outside the exterior face of the brick wythe, extend across the cavity, and turn up vertically against the backing or inner wythe at least 8 in. (203 mm). Sections lap at least 6 in. (152 mm) with the lap sealed, discontinuous runs terminate in an end dam turned up at least 1 in. (25.4 mm) into a head joint, and in no circumstances should the flashing be stopped behind the face of the brickwork. [3] That last rule matters to you as an owner: flashing that stops short of the face dumps its water back into the wall instead of onto the world.

Which Chicago walls should have weeps, and which genuinely should not?

In short: Drainage walls need weeps. Solid mass masonry walls are a different system entirely, and the absence of weeps on one is not a defect. [1]

This is the question that separates an honest inspection from a sales pitch, and it is the reason we will not simply tell every caller their wall is missing weeps.

BIA describes the historic condition plainly. Masonry walls once functioned as both the structural system and the exterior skin of the building, and those walls were massive, ranging in thickness from 12 in. (305 mm) up to 6 ft (1.83 m) of solid brick. Because of their thickness and their state of constant compression under structural load, they worked quite well at keeping water out of the interior. The large volume of masonry prevented moisture reaching the inside through sheer mass, and the wall acted as a reservoir for absorbed moisture which was later released as vapour. Many were also built with roof overhangs, cornices and other ornamentation that helped protect the wall face. [1]

BIA calls that family barrier walls, and the category includes mass masonry multi-wythe walls with mortar or grout-filled collar joints, composite brick and block or brick and structural clay tile walls, reinforced brick masonry, and adhered veneer. The system relies on the thickness of the masonry and the integrity of the mortar or grout to prevent moisture reaching the interior during the rain event, with that moisture slowly evaporating during drier weather. [1] There is no cavity in that wall. There is nothing for a weep to drain.

What is critical in a barrier wall is the collar joint, the vertical space between the wythes, along with the bed and head joints between units. BIA says these must be solidly filled with grout or mortar, because gaps create pathways that direct water to the interior and bypass the storage capacity of the wall assembly. Grouting is the most effective method of filling collar joints, though spaces less than 3/4 in. (19.1 mm) should not be grouted; in those cases the face of the inner wythe is parged and the back of the brick in the outer wythe buttered. Slushing, which means troweling mortar into the collar joint after the wythes are laid, does not produce completely filled joints and is not recommended. [1]

Single-wythe walls sit in between. BIA treats them as a variation on the barrier wall, usually thicker than a nominal 4 in. (102 mm) veneer wythe, with grouted cells helping resist penetration. BIA is candid that single-wythe walls are inherently not as resistant to water penetration as drainage walls or multi-wythe barrier walls and may not be appropriate for some severe exposures, though careful detailing and good construction can make them perform well. [1]

So the practical Chicago question is not “where are my weeps” but “which wall do I own”. A post-war brick veneer bungalow or a newer two-flat with a cavity behind the face brick is a drainage wall and should have weeps. An older solid masonry building is a barrier wall, and the correct work on it is keeping the joints and the collar joint sound, not drilling a row of holes into brick that has no cavity behind it. Anyone who offers to add weeps without first establishing which system you have is guessing with your wall. Our masonry repair assessments start with that question because the answer changes every recommendation that follows.

Where should weeps be, and how far apart?

In short: At flashing level, never above it, with open head joints no more than 24 in. apart. Codes allow 33 in.; BIA prefers tighter. [1] [3]

BIA states the location rule without hedging: in order to adequately drain any water collected on the flashing, weeps are required at the level of the flashing at all locations. The practice of placing weeps in one or more courses of brick above the flashing will allow water to accumulate and is not recommended. [1] Technical Note 7B puts the same rule in the installer’s language and explains the physics: specifying weeps one or more courses above the flashing is not recommended, as it requires a head of water to accumulate on the flashing before drainage can occur. [3]

That is the single most useful thing an owner can know. A weep one course too high is not “close enough”. It guarantees a standing reservoir of water sitting on the flashing at all times, against the back of your brick, through every freeze the city can produce.

On spacing, there are two numbers and they are not the same number. BIA recommends spacing of open head joint weeps at no more than 24 in. (610 mm) on centre. Most building codes permit weeps to be spaced up to 33 in. (838 mm) on centre. [1] Technical Note 7B names the gap between the two directly, describing the recommended spacings as closer than the 33 in. o.c. spacing permitted by most building codes, and saying plainly that the tighter spacing improves drainage. [3] Code-compliant and well-drained are different standards, and you are entitled to ask which one a quote is pricing.

If wicks are used instead, the spacing tightens again: BIA recommends no more than 16 in. (406 mm) on centre for wick or tube weeps. [1] [3] And the minimum opening permitted by most codes is a diameter of 3/16 in. (4.8 mm), which BIA cites as the code floor rather than as a recommendation. [1] [2]

Weeps are not just a wall-base item. BIA requires through-wall flashing, and therefore weeps, at a specific list of locations: wall bases, window sills, heads of openings, shelf angles, tops of walls and roofs, parapets, above projections such as bay windows, balconies and decks, at changes in grade, and at transitions with other cladding materials. [1] Over openings the requirement is explicit, with weeps required immediately above the flashing at lintels over all door and window heads, and the flashing turned up at each end of the lintel to form end dams. [1] Technical Note 31B reinforces it from the steel side: regardless of whether flashing is used, weepholes should be provided in the facing at the level of the lintel to permit the escape of any accumulated moisture. [5] We covered what happens when that is missing in our piece on rusting steel lintels.

Sills follow the same logic. BIA wants window sills sloped to shed water at a minimum of 15 deg from horizontal, with through-wall flashing placed under all sills and turned up at the back and at the ends to form a pan. [1] Where flashing is stepped, as around curved or sloped openings, BIA wants weeps to direct water out of the wall installed at each level of the stepped flashing, with higher courses overlapping the layer below by at least 4 in. (102 mm). [1] A wall can have perfectly good weeps at the base and still be trapping water at every window head above it.

At the bottom of the wall the constraint is grade. BIA says the elevation of flashing and weeps should be no more than 10 in. (254 mm) above finished ground level, and that the elevation should take account of planting beds, ground coverings and sidewalks placed immediately adjacent to the wall. It also warns that once the designer has set the flashing level against the grading plan, care should be taken that field modifications do not leave any section of flashing below grade. [1] Technical Note 46 records the same requirement as a code matter, noting that model building codes require base flashing to be installed within 10 in. (254 mm) of final grade. [4] For drainage away from the wall, BIA cites the IRC requirement that lots be graded to drain surface water away from foundation walls, with a minimum slope of 6 in. (152 mm) within the first 10 ft (3.05 m). [1]

What do the different types of weeps look like on the wall?

In short: An open head joint is the preferred type and the easiest to spot. Wicks and tubes exist, and BIA does not recommend tubes. [1] [2]

There are three things you might see, and knowing which is which tells you a lot about who built the wall and who has worked on it since.

The open head joint is the one BIA wants. It is formed by simply leaving mortar out of a vertical joint, and BIA calls it the preferred type of weep. It should be at least 2 in. (51 mm) high. [1] [2] [3] On a wall this reads as a short vertical slot between two bricks, usually in the course directly above a horizontal line of flashing. Noncorrosive metal, mesh or plastic screens or vents can be installed in open head joint weeps if desired. [1] [2] [3] Technical Note 7A gives a second reason to like them: such weeps serve a dual function of allowing water to drain while also allowing air to enter the cavity, producing more drying action and helping to keep insects out. [2] A weep is a vent as well as a drain.

Wick weeps are a rope. BIA describes rope wicks as at least 16 in. (406 mm) long, made of cotton sash cord or other materials that wick, extending through the brick wythe into the air space and along the back of the brick wythe. [1] [2] At the face, Technical Note 7B wants the rope flush with, or extending 1/2 in. (12.7 mm) beyond, the face of the wall to promote evaporation. [3] If you can see a short length of cord protruding from a joint near the base of a wall, that is not debris and it should not be trimmed off flush and pointed over.

Weep tubes are the ones to be sceptical about. BIA says weep tubes are not recommended due to an increased risk of clogging. [1] [2] Technical Note 7B is more specific about why: the smaller opening results in reduced drainage capability and increased risk of clogging, and therefore the use of tube weeps is discouraged. [3] A row of plastic tubes is common on walls, and their presence is not a crisis, but they are the weep type most likely to be doing nothing at all by the time the wall is twenty years old.

Whatever forms the weep has to survive being in a wall. BIA states the requirement simply: items used to form weeps should not easily deteriorate or stain the brickwork. [2] That rules out a good deal of improvised site material.

Behind the weeps, on newer work, there may be a drainage material or mortar collection device. BIA recommends using them, and sets out the principles for any such material: it should fill the entire width of the air space, should not absorb water, and should not transmit moisture to the backing. [1] [2] They come either full height of the air space or as a low-height product sitting immediately above the flashing, and where the product is not full height, BIA prefers a two-level mortar collection device to a single-level one because it better maintains a path for moisture to reach the flashing. [2] Technical Note 7B notes that using a mortar collection device together with good workmanship to maintain an unobstructed cavity is becoming standard practice in the industry, while adding the caveat that it does not eliminate mortar bridging or absolve the mason from minimising mortar droppings in the cavity. [3] BIA makes the same point twice: drainage media should not preclude good workmanship. [1] [2]

Why are so many Chicago weeps pointed shut?

In short: Because an open head joint looks like a missing joint, and BIA says outright that it expects future maintenance work to seal them. [1]

There are five documented ways a weep stops working, and only one of them is anybody acting in bad faith.

The first is the original build. Technical Note 7B is direct about it: in a drainage wall it is essential that the air space be kept as clear of mortar droppings as possible, because if it is not, mortar droppings may clog the weeps, protrusions may span the air space in what BIA calls mortar bridging, and water may penetrate to the interior. [3] BIA is also realistic, conceding that it is unreasonable to expect a mason to maintain a cavity completely clear of mortar droppings or protrusions, and that an air space providing drainage is permitted to contain mortar from construction. [1] [3] The trade has techniques for this. Beveling the bed joint away from the cavity means a minimum of mortar is squeezed out when the brick is laid, and the squeeze-out can be troweled back onto the unit. Another method leaves access: every third or so brick in the course above the flashing is omitted during construction, mortar droppings are cleaned out of the base of the cavity once the brickwork is complete, and the omitted brick are then laid with weeps provided. [3] Whether any of that happened on your wall in 1958 is not something you can see now, but its consequences are.

The second is repointing, and it is the big one. Consider what an open head joint weep looks like to a crew working a scaffold: a vertical joint with no mortar in it, in an otherwise continuous wall, at exactly the height where mortar erodes worst. It looks like a defect. It looks like the thing they were hired to fix. BIA anticipates precisely this. Its stated reason for recommending screens or vents in open head joint weeps is that they may be beneficial to discourage insect entry and to emphasise the purpose of the open head joints in order to reduce the risk of sealing during future maintenance work. [1] A trade body does not write a sentence like that unless the failure mode is common. Technical Note 7B leaves the corresponding instruction for whoever is holding the trowel: ensure that weeps are clear of all mortar to allow the wall to drain. [3]

This is where weeps intersect with tuckpointing in a way most quotes never mention. Repointing is a legitimate and necessary repair, and BIA sets out how to do it: use prehydrated Type N, O or K mortar, install it in multiple quarter-inch lifts, and tool each lift when it is thumbprint hard. [4] The National Park Service adds the preparation standard, requiring mortar cleaned out to a uniform depth rather than the ragged partial removal it illustrates as incorrect. [6] None of that guidance says anything about weeps, because it is guidance about joints. The weeps are the exception a crew has to already know about. If nobody on the scaffold knows which joints are supposed to be empty, they will all be full by Friday.

The third is brick replacement. Technical Note 46 warns that when units are removed from the exterior wythe of a drainage wall, care must be exercised to prevent debris from falling into the air space, which could block weeps and interfere with drainage. [4] A spall repair on the third course can close a weep two courses below it.

The fourth is coatings and sealants. Technical Note 46 states the principle: water repellents and coatings should not replace or be considered equivalent to essential, code-required details that resist water penetration, such as flashing and weeps. [4] It also warns that using coatings outside their intended application rarely reduces water penetration and may lead to more serious complications with the brickwork, and that only vapour-permeable products such as siloxanes and silanes should go on exterior brick, never film-forming coatings. [4] We took that argument apart in more detail when we wrote about brick sealers. The short version for weeps: a product sprayed across the face of a wall does not know which openings were deliberate.

The fifth is the ground. Weeps live within 10 in. (254 mm) of finished grade at the wall base, and BIA specifically says that elevation must account for planting beds, ground coverings and sidewalks placed immediately adjacent to the wall, warning that field modifications should not leave any section of flashing below grade. [1] In practice this means a raised bed, a new walk poured an inch or two high, or twenty years of mulch topped up each spring will quietly bury the drainage path of a wall that was detailed correctly. Nobody sealed anything. The wall simply sank into the yard.

What does a blocked weep actually do to the wall?

In short: It keeps water inside the assembly, which is the condition that drives efflorescence, corrosion, freeze damage and interior finish damage. [1] [4]

BIA lists the consequences of a wall carrying a disproportionate amount of water, and the list is the table of contents for most masonry repair work in this city. Dimensional changes. Efflorescence on exterior surfaces. Cracking, crazing, spalling or disintegration due to repeated freeze-thaw cycling. Corrosion of metals. Insulation losing its effectiveness. Interior finishes deteriorating. On susceptible elements, enough moisture for mould growth. [1]

Technical Note 46 makes the causal link explicit rather than leaving it implied. Its Table 3, listing possible causes of masonry distress, puts “missing or clogged weeps” in the same column of potential causes as incompletely filled mortar joints, plant growth, deteriorated or torn sealant, capillary rise, missing or damaged flashing and differential movement, set against observed conditions including cracked units, spalled units, deteriorated mortar, efflorescence, moisture-related stains, corrosion of concealed materials and damaged interior finishes. [4] A clogged weep is not a cosmetic footnote in BIA’s own diagnostic table. It sits alongside missing flashing.

The same document puts it on the inspection checklist. Table 2, the Brick Masonry Inspection Checklist, lists “missing or clogged weeps” as an above-grade item to be recorded elevation by elevation, alongside cracked units, loose units, spalled units, hairline cracks in mortar, deteriorated mortar joints, plant growth, deteriorated or torn sealants, out-of-plumb conditions, efflorescence, stains and water penetration. [4] If a condition report on your building does not mention weeps at all, it has skipped a line on BIA’s own form.

BIA also ties persistent efflorescence specifically to unresolved water. Its maintenance guidance says to investigate and determine moisture sources before attempting repairs to correct water penetration issues, and to scrutinise masonry with persistent efflorescence for unresolved water penetration issues. [4] It adds that efflorescence will simply return if the water ingress behind it is not resolved first. [4] A white bloom that keeps coming back after cleaning is a wall telling you its drainage is not working.

The freeze angle is what makes this a Chicago problem rather than a general one. BIA names repeated freeze-thaw cycling as a mechanism of cracking, spalling and disintegration in walls carrying too much water. [1] We are not going to put a cycle count on a Chicago winter here, because we have not read a primary source that establishes one. What the sources do support is the direction of the relationship: more trapped water means more damage per freeze, and a sealed weep is a mechanism for trapping water. That is the claim, and it is enough.

The corrosion consequence is the one that gets expensive. BIA includes corrosion of metals among the effects of excess water in a wall, and corrosion of concealed materials among the observed conditions in its distress table. [1] [4] Concealed materials means ties, anchors, shelf angles and lintels. Water that cannot leave a wall finds the steel in it.

How do you find your weeps from the sidewalk?

In short: Look for a horizontal line near the base of the wall and check the vertical joints just above it, then repeat at every window head. [1]

You can do a useful first pass yourself in about ten minutes, and BIA endorses the general approach: it recommends periodic inspections, preferably each season, using binoculars and adjacent roof areas or balconies to permit close-range observation of conditions at upper floors. [4] The same document suggests supplementing the checklist with photographs, sketches and notes, and keeping inspection and repair records to reference during future inspections. [4] Photographs matter more than most owners expect, because the useful comparison is against the same wall three years ago.

Start at the base of the wall, within roughly 10 in. (254 mm) of finished grade, since that is where BIA puts base flashing and weeps. [1] [4] Look along a single course for a repeating pattern of vertical joints that are open rather than filled. At the recommended spacing of no more than 24 in. on centre you would expect roughly one every two feet; at the code-permitted 33 in. you would see fewer. [1] Open head joint weeps should read as slots at least 2 in. high. [1] If you find screens or small plastic vents set into some joints, those are weeps that somebody deliberately protected. [1] [2]

Then go up. Check the course directly above every window head and door head, since BIA requires weeps immediately above the flashing at lintels over all openings. [1] Check above shelf angles if the building has them, above bay windows, balconies and decks, at changes in grade, and where the brick meets a different cladding material, because those are the flashing locations BIA lists. [1] Check under sills. [1] A wall can pass at the base and fail at every opening.

What you are looking for is any of four findings. No weeps at all where the wall type says there should be some. Weeps present but spaced much wider than 24 to 33 in. Weeps sitting a course or more above the flashing line rather than immediately on it. Or weeps that exist and are packed with mortar, paint, sealant, soil or debris. BIA treats the first two as a spacing problem warranting supplemental weeps and the last as a clogging problem warranting cleaning. [4]

One honest caveat on doing this yourself: you may not be able to tell from the face of the wall whether there is flashing behind a weep at all, and on an older building there may be neither. BIA notes that a designer may encounter masonry-bonded hollow walls in historic applications, and its maintenance guidance contemplates installing flashing in existing walls as a distinct and substantial repair, to be done in alternate 2 to 5 ft (610 mm to 1.52 m) sections with temporary bracing used for longer runs. [1] [4] Where flashing is missing entirely, opening a weep drains nothing, because there is no collection surface feeding it. That distinction is worth paying someone to establish before you pay anyone to drill.

How are clogged or missing weeps repaired?

In short: Clogged weeps get probed clear; missing ones get drilled. Both operations are performed inches from flashing that must not be cut. [4]

Technical Note 46 has a section titled Opening Weeps, and it is short enough to be worth following closely.

BIA starts with the diagnosis. Weeps should be inspected to ensure that they are appropriately spaced and not clogged, so that moisture within the walls is drained to the exterior. If the original weeps were not appropriately spaced, then drilling new supplemental weeps may be necessary, and BIA points back to Technical Note 7 for the types and spacing to use. [4] So the repair is defined by the standard: you are not drilling holes wherever seems reasonable, you are bringing the wall to no more than 24 in. on centre. [1] [4]

For clogged weeps, the method is deliberately gentle. If weeps are clogged, BIA says, they can be cleaned out by probing with a thin dowel or stiff wire. [4] Not a drill bit, not a masonry blade. A dowel.

The reason for the caution is the flashing. BIA warns that when cleaning or installing weeps, care must be exercised not to damage the existing flashing located immediately below and behind the weeps, and suggests using a stopper to limit the depth of penetration of the probe or drill bit as an effective way of reducing the possibility of damaging the vertical leg of the flashing in the drainage cavity. [4] This is the whole risk of the job in one sentence. The flashing is the surface that collects the water. It sits directly behind the weep. A drill run too deep turns a drainage repair into a flashing breach, and the second problem is far more expensive than the first. Ask whether the crew uses a depth stop. It is a fair question and the answer tells you a great deal.

BIA’s summary of retrofit work reads as a sequence, and it is a useful frame for a scope of work. When weeps are clogged, carefully open them to ensure that existing flashing is not damaged. When weeps do not exist, carefully drill new weeps, again ensuring existing flashing is not damaged. In cases of rising damp, consider replacing base flashing or installing a dampproof course. Repair or replace damaged flashing in alternate 2 to 5 ft (610 mm to 1.52 m) sections, using temporary bracing to install longer sections. Where anchors or ties are damaged or missing, install remedial anchors and ties per manufacturer recommendations and confirm performance by in situ testing in a mock-up. [4]

Rising damp deserves a word, because it is the failure that looks like a weep problem and is not. BIA describes it as the movement of moisture up a wall through the brickwork by capillary action, appearing as a rising water line or tide mark on the wall caused by soluble salts in the groundwater, and says a dampproof course should be installed to reduce the potential for it. [4] It also notes that model codes require dampproofing or waterproofing material on masonry wall surfaces below grade. [4] If the stain on your wall has a tide line and stops at a consistent height, opening weeps above it will not touch the cause.

And one note of proportion from BIA itself: all buildings are unique and may require different levels of maintenance, a solution for one project may not remedy similar issues on all buildings, and the repair method should suit the particular building rather than being based solely on maintenance performed on other buildings. BIA suggests that consulting a design professional experienced in building repair may be beneficial in systematically identifying sources of deterioration. [4] On a large or complicated facade, that is the right first call.

What should a tuckpointing quote say about weeps?

In short: It should say something. A repointing scope that never mentions weeps is a scope that may close them. [1] [3]

This is the practical reason we wrote this article rather than another one about mortar.

Repointing and weeps are performed on the same joints, by the same crew, in the same afternoon. The guidance for repointing is about filling joints completely and properly. BIA specifies prehydrated Type N, O or K mortar, applied in multiple quarter-inch lifts, each tooled when thumbprint hard. [4] The National Park Service requires the joint prepared to a uniform depth and explains why the mortar matters, showing a wall where hard portland cement mortar less permeable than the soft brick trapped moisture that could not evaporate through the mortar, until water pressure eventually popped the surface off the brick. [6] NPS records the ASTM strength hierarchy that sits behind those type letters as Type M at roughly 2,500 psi, Type S at 1,800, Type N at 750, Type O at 350 and Type K at 75. [6]

All of that is about making joints right. Weeps are joints that are supposed to be wrong. They are the one place on the elevation where the correct action is to leave the joint empty, and nothing in general repointing guidance flags them. That is why the instruction has to be explicit and why BIA writes it as its own line: ensure that weeps are clear of all mortar to allow the wall to drain. [3]

So when you read a quote, look for four things. First, that somebody has identified which wall system you have, because a drainage wall and a barrier wall get different work. [1] Second, that existing weeps are identified and protected before repointing starts, rather than discovered afterwards. [1] [3] Third, that where weeps are missing or badly spaced, the scope says what spacing it is working to and how it will avoid the flashing. [1] [4] Fourth, that flashing condition is addressed as a separate question from weep condition, since a weep with no flashing behind it drains nothing. [1] [4]

A quote that prices square footage of repointing and says nothing about drainage is not dishonest. It is just incomplete in the specific way that tends to show up three winters later as spalled brick. BIA’s own position is that water resistance depends on four factors together and that failure to properly address any one of them can result in water penetration problems: design including detailing, materials, construction, and maintenance. [1] Weeps are where maintenance most easily undoes design.

Frequently asked questions about weep holes

Should I fill the holes in the bottom of my brick wall?

No. If they are evenly spaced vertical gaps in the course above a flashing line, they are weeps, and they are the designed exit for water inside the wall. BIA designs drainage walls on the assumption that wind-driven rain will penetrate the outer wythe, run down the cavity, collect on the flashing and exit through the weeps. [1] Filling them stops the last step only.

How far apart should weep holes be?

BIA recommends open head joint weeps no more than 24 in. (610 mm) on centre, while noting that most building codes permit up to 33 in. (838 mm) on centre. [1] Technical Note 7B says the tighter recommended spacing improves drainage compared with the code maximum. [3] If wick weeps are used, the recommendation tightens to no more than 16 in. (406 mm) on centre. [1] [3]

How big does a weep hole need to be?

An open head joint weep should be at least 2 in. (51 mm) high. [1] [2] [3] Where a drilled or tube opening is used, most building codes permit a minimum diameter of 3/16 in. (4.8 mm), which BIA reports as the code floor rather than as a recommendation. [1] [2]

My weeps are one course above the flashing. Is that a problem?

Yes. BIA says weeps are required at the level of the flashing and that placing them one or more courses of brick above it will allow water to accumulate, which is not recommended. [1] Technical Note 7B explains that the arrangement requires a head of water to build up on the flashing before drainage can occur. [3]

Are plastic weep tubes acceptable?

They exist widely, but BIA does not recommend them. Technical Note 7 and 7A both say weep tubes are not recommended due to an increased risk of clogging. [1] [2] Technical Note 7B adds that the smaller opening results in reduced drainage capability as well as increased clogging risk, and that their use is therefore discouraged. [3] The preferred weep is an open head joint. [1] [2]

My brick wall has no weep holes at all. Is that always wrong?

No, and this is the most common misunderstanding. Weeps belong to drainage walls, meaning cavity walls and anchored veneer. [1] A solid mass masonry wall is a barrier wall, relying on the thickness of the masonry and the integrity of the mortar and collar joints rather than on a drainage cavity. [1] BIA describes historic mass masonry walls as ranging from 12 in. (305 mm) up to 6 ft (1.83 m) of solid brick, acting as a reservoir for absorbed moisture released later as vapour. [1] Establishing which wall you have comes before any discussion of adding weeps.

Can I just clean out a clogged weep myself?

BIA says clogged weeps can be cleaned by probing with a thin dowel or stiff wire, so the method is not exotic. [4] The risk is what sits behind them. BIA warns that care must be exercised not to damage the existing flashing located immediately below and behind the weeps, and recommends a stopper to limit how deep a probe or drill bit can penetrate. [4] Damaging the flashing is a much larger repair than the blockage.

Will screens in the weeps keep bugs out?

That is one of two reasons BIA gives for them. Noncorrosive metal, mesh or plastic screens or vents can be installed in open head joint weeps, and BIA says they may be beneficial to discourage insect entry and to emphasise the purpose of the open head joints in order to reduce the risk of sealing during future maintenance work. [1] Technical Note 7A adds that such weeps let air into the cavity as well as letting water out, giving more drying action. [2]

Does a water repellent or sealer make weeps unnecessary?

No. BIA states that water repellents and coatings should not replace or be considered equivalent to essential, code-required details that resist water penetration, such as flashing and weeps. [4] It also warns that coatings used outside their intended application rarely reduce water penetration and may lead to more serious complications with the brickwork. [4]

Does new landscaping affect my weeps?

It can close them. BIA puts base flashing and weeps no more than 10 in. (254 mm) above finished ground level and says that elevation should account for planting beds, ground coverings and sidewalks placed immediately adjacent to the wall, warning that field modifications should not leave any section of flashing below grade. [1] Technical Note 46 records the same 10 in. figure as a model code requirement for base flashing relative to final grade. [4]

Stats box

Definition bank

Entity cards

Weep hole

Drainage wall system

BIA Technical Note 7

BIA Technical Note 46

Through-wall flashing

Getting your drainage path back

In short: Ask which wall system you have and whether your weeps are open, spaced and sitting on flashing. Those three answers decide whether repointing helps or hurts. [1] [4]

Weeps are the cheapest working part of a masonry wall and the easiest to lose. They cost nothing to build, since the preferred type is simply mortar left out of a joint. [1] They are invisible in any photograph of a finished building. And BIA itself anticipates that ordinary maintenance will close them, which is why it suggests marking them with screens or vents to reduce the risk of sealing during future maintenance work. [1]

If you are booking tuckpointing this season, the single most valuable thing you can do is ask the contractor to walk the base of the wall and every window head with you before the scaffold goes up, and to say out loud which joints are weeps. That conversation takes fifteen minutes and it is the difference between a wall that drains after the work and one that does not. BIA’s instruction to the trade is one line long: ensure that weeps are clear of all mortar to allow the wall to drain. [3]

We do this as part of every masonry repair assessment, because the drainage question changes the scope. If you have a drainage wall with clogged weeps, the fix may be a dowel and an afternoon. If the weeps were never spaced correctly, supplemental weeps are drilled to BIA’s spacing with a depth stop to protect the flashing. [1] [4] If there is no flashing behind them at all, that is a larger and more honest conversation, and BIA sets out how flashing is retrofitted into existing walls in alternate 2 to 5 ft sections. [4] And if you own a solid mass masonry wall, we will tell you that drilling weeps into it is not the repair. [1]

To have someone look at your wall and tell you which of those four situations you are in, get a free quote from our team.

Sources

1. Brick Industry Association, Technical Note 7, “Water Penetration Resistance: Design and Detailing”, November 2017. https://www.gobrick.com/media/file/7-water-penetration-resistance-design.pdf
2. Brick Industry Association, Technical Note 7A, “Water Penetration Resistance: Materials”, November 2017. https://www.gobrick.com/media/file/7a-water-penetration-resistance-materials.pdf
3. Brick Industry Association, Technical Note 7B, “Water Penetration Resistance: Construction and Workmanship”, November 2017. https://www.gobrick.com/media/file/7b-water-penetration-resistance-construction-and-workmanship.pdf
4. Brick Industry Association, Technical Note 46, “Maintenance of Brick Masonry”, December 2017. https://www.gobrick.com/media/file/46-maintenance-of-brick-masonry.pdf
5. Brick Industry Association, Technical Notes 31B, “Structural Steel Lintels”, revised, reissued May 1987. https://www.gobrick.com/media/file/31b-structural-steel-lintels.pdf
6. National Park Service, Preservation Brief 2, “Repointing Mortar Joints in Historic Masonry Buildings”, Mack and Speweik, rev. 1998. https://www.nps.gov/orgs/1739/upload/preservation-brief-02-repointing.pdf