Article Post

A Closer Look at Wood Balconies and Decks

April 13, 2023

Construction deficiencies are among the most common issues affecting homeowners. Wood decks and balconies are no exception as they can be quite challenging to construct. This is typically due to their exposure to the elements. Poor construction can lead to performance issues and, when left unchecked, cause further deterioration of the surrounding structure.

A homeowner may first realize there is an issue with their deck or balcony after experiencing a water related loss or water related deterioration of the structure. To avoid further deterioration, it is important for homeowners to be aware of the performance and maintenance issues that can occur over time.

Common Performance Issues with Balconies and Decks

Elements of Wood Decks and Balconies

Figure 1: Elements of Wood Decks and Balconies

  1. Water Ponding

Water ponding occurs when the deck or balcony surface is not properly sloped to accommodate proper drainage or there are obstructions to the drainage path (i.e. clogged or limited drains). On a membraned surface, water ponding can lead to the degradation of the membrane or moisture ingress at points of discontinuities.

  1. Poor Ledger Attachment

Ledger attachments are fastened to the building structure to provide support to the deck. If inadequately installed or designed the deck or balcony may not be able to accommodate the required design loads, leading to failure. Another issue with ledger attachments is when they are not properly protected from moisture, leading to rot and decay.

  1. Deterioration of Trim and Fascia Board

It is important that trim and fascia boards are protected from the elements with proper detailing of membranes and edge flashing. If not, deterioration can occur due to excessive moisture exposure.

  1. Unsafe Guards and Railings

Inappropriate material choices and poor design can lead to unsafe guards and railings. It is important for wood materials to be decay-resistant and metal fasteners to be corrosion-resistant. To ensure proper support of design loads, components must be adequately sized, attached, and suitable spaced.

  1. Deterioration of Columns and Posts

Wood columns and posts face common moisture related issues. If untreated wood is used there is an increased risk of decay and insect attack. Proper base drainage and a separation between concrete footings must be incorporated into design. Unprotected bases can wick moisture, leading to rot and deterioration.

  1. Unsafe Stair Stringer Attachment

Stair stringers must be properly secured to the horizontal wood-framed structure. It is important for corrosion resistant fasteners and treated wood products to be used to avoid metal corrosion and wood decay.

  1. Deterioration of Framing and Sheathing

If the deck or balcony framing and sheathing is exposed to moisture, the assembly can experience wood decay. This most commonly occurs when there is a deterioration of the waterproofing membrane due to poor installation or unsealed fasteners.

Location of Common Performance Issues

Figure 2: Location of Common Performance Issues

Signs of Balcony and Deck Damage

Oftentimes, there is little that can be done to prevent damage caused by construction errors. However, a homeowner can ensure that damage, especially related to leakages, does not have far reaching consequences by  identifying issues early and reaching out to professionals. Below are some common signs to watch out for.

  • Staining of interior and exterior balcony finishes
  • Leaking at windows, doors, or door thresholds
  • Difficulty opening and closing windows or doors due to swelling of wood
  • Peeling, blistering, or splitting paint at critical areas
  • Exterior wood trim deteriorating, splitting, soft, or with biological growth
  • Weakened joints, especially critical at balcony railings and structural posts

The Investigation Process of Water Damage

It is common that deck or balcony related issues can lead to water ingress inside the home. In the event this occurs, a forensic investigation can help determine the location or reason for the water loss. A typical investigation will include:

  1. Visual Observations

A visual investigation will be performed where problem areas reported by the owner will be inspected as well as the entire balcony and surroundings. This will help determine if concerns of structural damage are visible. This initial investigation will employ non-evasive tactics to determine the root cause of the water ingress. This can include a moisture meter to determine the level of wood saturation and/or infrared camera to assist with identifying leaks.

  1. Complex Evaluation and Destructive Testing

If initial investigation methods are unable to uncover the root cause and location of water ingress, more extensive testing and evaluation tactics can be used. Such tactics include destructive testing involving opening up selective areas to examine components that are not visible.

  1. Plan to Repair or Replace

Based on the site investigation, recommendations will be made to either repair or replace the assembly. If the cause and location of the leak was identified, a remediation plan to repair the issue will be recommended. However, there are cases where narrowing down the specific location of water ingress is proving to be very time consuming and costly. Water can and will make its way through any discontinuity in the balcony assembly. Sometimes, water damage can be the result of two or more different issues allowing water to leak into the home making identification a lengthier process. There are numerous potential locations for water ingress to occur but simply identifying that water damage is related to the balcony assembly is enough to solve the issue. In these circumstances, it is often best to replace the assembly instead of spending more time and money locating the source.


Emma Ledo Inácio, M.Eng., P.Eng.
Forensic Structural Engineer

Emma is a structural engineer specializing in the investigation, assessment and restoration of existing buildings. Her experience also consists of the design and analysis of steel and concrete structural systems, including the design of transportation, healthcare and government structures. She holds a Master of Engineering degree from the University of Toronto and is a Certified Associate in Project Management./