In brief
- A lintel carries the wall above an opening, so it needs level bearing on solid masonry, not on loose blocks or rubble fill.
- Cracks above doors and windows appear when the lintel sits unevenly, bears on too little wall, or has gaps packed instead of bedded.
- Catch the defect before plastering by checking level, bearing length and joint fill, with a straightedge and a level on the lintel soffit.
Contents
Lintel installation skills gaps in Burao show up as diagonal or stepped cracks above doors and windows weeks after the blockwork is finished. The work looks simple: a beam over an opening. The failure is usually at the bearing ends, where the lintel meets the masonry. Check bearing, level and fill before plaster goes on.
What goes wrong at the bearing ends?
A lintel spans an opening and carries the wall above it, so each end must sit on solid, level masonry over enough length. General practice is to seat each end on a full mortar bed over enough masonry to spread the load, but the length depends on the span, the load above and the lintel type. Confirm the required bearing with the project's engineer or specification before work starts. Where bearing is short, the block under the lintel crushes or tips, and the wall above settles on one side. That shows as a diagonal crack running from the lintel corner into the wall. It also happens when the mason beds the lintel on mortar that is too stiff to level, or packs a gap with broken block and mortar after the lintel is already in place.
How does workmanship create cracking above openings?
The crack is not caused by the lintel alone; it is caused by how the lintel sits, how it is filled and when it is loaded. If a rubble or block infill is used to make up a gap between the lintel and the wall, that infill compacts under load and the wall drops. If the lintel is laid out of level, the wall above follows that slope and the mortar joints open at one end of the opening. If formwork for a cast in situ lintel is struck too early, the concrete sags before it has gained strength, and the top of the opening bows. Ask the site supervisor what mix, what cover and what striking time the engineer specified, and check the answer against the approved drawings rather than against what the crew usually does.
How do you check a lintel before plastering?
Walk the floor while the lintel is exposed, before any plaster or skim coat hides it. Use a spirit level or a straightedge on the lintel soffit and check it in both directions. Tap the bearing ends of the lintel and listen for a hollow ring, which can point to a gap under the beam. Look at the mortar bed under each end: it should be full and even, not a wedge of broken pieces. Ask the engineer or check the specification for the sequence it requires: whether the masonry above the lintel is built after the lintel is bedded, and what support the wall above needs before that masonry starts. If the lintel is cast in situ, ask to see the concrete cube or test records if the engineer required them, and ask the municipal engineer's office what record it expects on file for the structure. Write what you find with the date, with a photo and a note of the opening reference.
For a homeowner in Burao, the practical protection is the same. Agree at the start that the lintel stays exposed until the supervisor signs off the bearing and the level. A short checklist on site, filled in per opening, stops a plasterer from covering a defect that will reappear as a crack in the finish. If a crack has already appeared, do not fill it immediately; note its width, its direction and whether it moves with the seasons, and show the record to the engineer before any repair.
What to do next
Pick one door or window opening on the site and check it today before plastering: level along the soffit, bearing length at each end, and a tap test for hollowness. Record the result with a photo and the opening number. Then ask the engineer to confirm the required bearing and fill for the rest of the openings, and hold the plaster until each lintel is signed off.
Frequently asked questions
Do cracks above doors always mean the lintel is wrong?
No. Cracks above openings can also come from foundation movement, thermal movement or a weak wall above the opening. Check the lintel bearing and level first because it is the easiest to see and record, then ask the engineer to look at the wider wall and foundations.
How long should a lintel bearing be?
The required bearing depends on span, load and lintel type. Confirm it with the project's engineer or specification before you accept the work.
Local reporting: this article is written for building work in Burao and Somaliland. Ground conditions, prices and rules differ between places; confirm the details for your own site.