Case 1

Blistering on Ceiling

Introduction

Blistering of paint is evident on the ceiling. Blistering on the ceiling develops as moisture simply cannot escape from beneath the paint film when it passes through a porous masonry substrate that is sealed at the exposed surface by paint.

Blistering occurs when pockets of trapped air and moisture expand and displace the membrane to form a small blister. Air and moisture passing through the dense concrete ceiling at a slow flow rate allow blisters to form. Under high surrounding temperatures, the vapour pressure rises too quickly for the trapped air and moisture to escape through the dense deck. Pressures will then develop, causing a displacement and stretching of the paint when the air pocket increases in size.

Preventive Measures

Design:

Specify the use of a breathable paint system to reduce trapped moisture and to avoid wetness and dampness of basement walls. Fungi resistant paint is also required. Avoid the use of Alkyd-based paint on concrete surfaces that may lead to saponification. (i.e. the formation of oily patches)

Construction:

Ensure adequate curing of the substrate before paint application to avoid shrinkage cracks. Moisture content should not exceed 6%. Clean surface and use clean tools. Avoid prolonged storing, inadequate stirring, use of incompatible thinner/solvent, or mixing with leftover paints from previous batches.
Ensure proper surface preparation of concrete using mechanical or chemical cleaning. Ensure that the substrate is dry, so as to avoid blistering of nonbreathing waterproofing material.
Allow for good ventilation and check with a moisture meter.

Corrective Measures

Regular inspection is important to detect or identify the defects immediately so that corrective maintenance could be carried out at the early stages to prevent further complexities. Visual inspection techniques or instrumentation techniques can be used for regular inspections.

Diagnostics of Defects:

Visual Inspection

Inspect at reasonable intervals to identify any blistering of paint.

Use of Moisture Meter

A Moisture meter can be used to measure the reduced resistance between two probes when they are embedded in damp materials. It can be used to trace areas of walls affected by rising dampness or rain penetration. Measurements should be taken at regular intervals to distinguish between surface dampness or dampness within the wall.

Remedial:

The steps for remedial are as follows:

Repair loose caulking and improve ventilation of the building to prevent a recurring problem.
Remove the blisters by scraping or sanding down to the bare surface.
Prime all bare areas with a high-quality primer.
Repaint the surface with a high-quality paint in the desired finish.

Standards

Paints:

BS EN 1504-2 Products and systems for the protection and repair of concrete structures. Definitions, requirements, quality control and evaluation of conformity. Surface protection systems for concrete

BS 6150 Painting of buildings. Code of practice

SS 542 Code of practice for painting of buildings

SS 150 Specification for emulsion paint for decorative purposes

SS 554 Code of practice for indoor air quality for air-conditioned buildings

BS EN ISO 12944-4 Paints and varnishes. Corrosion protection of steel structures by protective paint systems. Types of surface and surface preparation

BS EN ISO 1513 Paints and varnishes. Examination and preparation of test samples

ASTM C33/C33M-16e1 Painting of buildings. Code of practice

ASTM E1667-95a Paints and varnishes. Corrosion protection of steel structures by protective paint systems. Types of surface and surface preparation

ASTM E903-12 Paints and varnishes. Examination and preparation of test samples

BS 4873 Code of practice for painting of buildings

Waterproofing:

SS 637 (formerly CP 82) Code of practice for waterproofing of reinforced concrete buildings

AS 3740 Waterproofing of domestic wet areas

BS 5427 Code of practice for waterproofing of reinforced concrete buildings

Repair Works:

BS 8221-1 Code of practice for cleaning and surface repair of buildings. Cleaning of natural stone, brick, terracotta and concrete

BS 8221-2 Code of practice for cleaning and surface repair of buildings. Surface repair of natural stones, brick and terracotta

SS 509-1 Code of practice for cleaning and surface repair of buildings – Part 1 : Cleaning of natural stone, brick, terracotta, concrete and rendered finishes

SS 509-2 Code of practice for cleaning and surface repair of buildings – Surface repair of natural stones, brick, terracotta and rendered finishes

BS 8000-0 Workmanship on construction sites. Introduction and general principles

ASTM C1496-18 Eurocode 2: Design of concrete structures. General rules and rules for buildings

BS 8298-1 Code of practice for the design and installation of natural stone cladding and lining. General

References

[1] Dunn-Edwards. (n.d.). Paint Blistering: How To Fix. Dunn-Edwards. Retrieved from https://www.dunnedwards.com/explore/how-to/paint-problem-solver/blistering/

[2] Wilson, C. (2022). Interior Wall Bubbling and Moisture Control. Renaissance Development Blog. Retrieved from https://blog.rendevdc.com/interior-wall-bubbling

[3] Rebori, K. (2020). How to Fix Paint Bubbling. Paintzen. Retrieved from https://www.paintzen.com/blog/how-to-fix-paint-bubbling

[4] SS652:2019 Singapore Standard Maintainability of Facilities

[5] QBM. (2016). Bubbling paint on asbestos cement sheeting. QBM. Retrieved from https://qbm.com.au/bubbling-paint-on-asbestos-cement-sheeting/