---
title: "Retrofitting a brick masonry building"
subject: "Building Technology"
chapter: 11
key: "semester_6/building_technology:retrofit-brick-masonry"
source: https://www.bctengineer.com/q/semester_6/building_technology/retrofit-brick-masonry
site: BCT Engineering
---

# Retrofitting a brick masonry building

Building Technology · Chapter 11: Earthquake protection & Retrofitting in building

- Asked in: 2076 Baisakh, 8 marks
- Video: [Retrofitting a 1970s Brick Veneer Home — Airtightness, Insulation & Ventilation](https://www.youtube.com/watch?v=8ZrzGjXTRAo) — ecoEVO - Efficiency Matrix
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/building_technology/retrofit-brick-masonry
- Whole chapter: https://www.bctengineer.com/md/semester_6/building_technology/chapter-11

## Question

Why retrofitting in existing building is important? How would you retrofit a brick masonry building?

## Short answer

Retrofitting is important because many older brick buildings are seismically deficient and strengthening them prevents collapse at low cost. Retrofit methods include crack injection, repointing, ferrocement jacketing with through-wall ties, adding RC bands, vertical corner bars, strengthening openings, anchoring roof, and improving foundation.

## Answer

#### Importance of retrofitting
- Many older buildings in Nepal were built without engineering design or seismic code (NBC 105), so they can collapse in a moderate earthquake (as in Gorkha 2015).
- Retrofitting saves lives and property at a cost much lower than demolition and reconstruction (typically 10-30% of new construction cost).
- Seismic codes are revised; buildings built to old codes become deficient.
- Change of use, added floors, or deterioration (corrosion, cracks, aging) reduces capacity.
- Heritage and important buildings (hospitals, schools, temples) must be preserved.
- Damage from a past earthquake must be repaired and the building made safe against the next one.

#### Retrofitting a brick masonry building
Steps: (1) condition survey and NDT of the walls, mortar and foundation; (2) selection of method; (3) execution; (4) quality check.

1. **Crack repair:** inject cement or epoxy grout into cracks; stitch large cracks with steel dowels or staples.
2. **Replace damaged parts:** remove crushed bricks and re-lay in rich mortar (1:4).
3. **Re-pointing:** replace weak mud mortar with cement mortar to a depth of 20 mm.
4. **Ferrocement / mesh jacketing:** weld mesh or chicken mesh fixed on both faces of walls with through-wall ties at 450-600 mm, covered with 20-30 mm cement plaster (1:3). Improves in-plane strength and out-of-plane stability.
5. **Adding RC bands:** insert plinth, lintel and roof-level bands (in lengths) or provide external steel bands.
6. **Vertical steel at corners and jambs:** drill holes through walls, insert bars, and grout.
7. **Strengthening openings:** put RC frames or steel angles around large openings; close unnecessary openings.
8. **Tying of floors and roof:** anchor roof and floor to walls; provide diagonal bracing in flexible roofs; add an RC topping to make a rigid diaphragm.
9. **Adding buttresses or shear walls** at weak walls; replace heavy mud roof with a light roof.
10. **Improving foundation:** underpin or widen the foundation, add a plinth beam.

```text
   mesh + plaster on both faces
   |#|   wall   |#|
   |#|----------|#|   <- through tie every 450-600 mm
   |#|          |#|
```

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Why did many older buildings in Nepal need retrofitting?
   A. They were all built with steel frames
   B. Built without engineering design or seismic code, so they can collapse in moderate earthquakes
   C. They had too many bands
   D. They were too light
   Answer: B. Non-engineered buildings without NBC 105 compliance are vulnerable, as seen in Gorkha 2015. (Key point: Importance)

2. What is the correct order of retrofit steps?
   A. Condition survey and NDT, method selection, execution, quality check
   B. Execution, survey, quality check
   C. Plastering, then survey
   D. Method selection before any survey
   Answer: A. Retrofit starts with assessment of walls, mortar and foundation. (Key point: Retrofit sequence)

3. How is ferrocement/mesh jacketing of a brick wall done?
   A. Mesh on one face only without ties
   B. Mud plaster over chicken mesh
   C. Mesh on both faces fixed with through-wall ties at 450-600 mm and covered with 20-30 mm cement plaster
   D. Paint applied over cracks
   Answer: C. Mesh on both faces, tied through the wall and plastered, improves in-plane strength and out-of-plane stability. (Key point: Mesh jacketing)

4. What is done with weak mud mortar and cracks?
   A. Leave it, and just paint
   B. Fill with more mud mortar
   C. Remove whole walls
   D. Re-point with cement mortar to 20 mm depth; inject cement/epoxy grout into cracks
   Answer: D. Re-pointing replaces weak mortar and grout injection restores cracked masonry. (Key point: Re-pointing and cracks)

## Related in Building Technology

- [Retrofitting techniques; why it is important](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Aretrofit-techniques-importance) — Building Technology, chapter 11, asked 3×
- [Techniques of retrofitting a building](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Aretrofit-techniques) — Building Technology, chapter 11, asked 3×
- [Making brick masonry earthquake resistant](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Aeq-brick-masonry) — Building Technology, chapter 11
- [Specifications of brick masonry work](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Abrick-masonry-specs) — Building Technology, chapter 3, asked 2×
- [Types of bonds in brick masonry](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Abrick-bonds-types) — Building Technology, chapter 3
- [Conventional strengthening and innovative-material retrofit](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Aretrofit-strengthening-innovative) — Building Technology, chapter 11

## Related in other subjects

- [Quantity method for load bearing brick building](https://www.bctengineer.com/question.md?key=semester_7%2Festimating_and_costing%3Aquantity-method-load-bearing-brick) — Estimating and Costing, chapter 2
- [Brick masonry infill walls in RC frames](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Amasonry-infill-walls) — Concrete Technology and Masonry Structure, chapter 7, asked 3×
- [Use of masonry; types of brick bond](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Amasonry-uses-bond-types) — Concrete Technology and Masonry Structure, chapter 7, asked 2×
- [Flat-jack test for brick masonry wall](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Aflat-jack-test) — Concrete Technology and Masonry Structure, chapter 10, asked 2×