Wood Frame vs Concrete: How Building Type Changes Your Maintenance Plan

Two strata buildings sit on the same street and take the same rain. One is a four-storey wood frame building, the other a concrete tower. On the same day, a resident in each reports a stain on an interior wall.

These are not the same problem, and treating them the same way is a mistake that costs one of those buildings considerably more than the other.

The difference is not about which construction type is better. Both are used across the region and both perform well when maintained. It is about what happens after water gets in, and that difference should shape how each building is inspected, budgeted, and managed.

The core difference: what water does

In a concrete building, water is a durability problem operating on a long timeline. Moisture and dissolved chloride migrate into the concrete and eventually reach the reinforcing steel, where they break down the protection the concrete provides and start corrosion. Rust expands, cracks the concrete from within, and eventually shows as spalling. It is a serious and expensive process, and it is also slow, measured in years, and the concrete itself is not consumed by it. The mechanism is set out in the guide on rebar corrosion and concrete delamination.

In a wood frame building, water attacks the structure directly. Wood that stays wet supports decay fungi, and the material that carries the building’s loads is the material being degraded. Given sustained moisture and moderate temperatures, structural framing can suffer meaningful damage within a single wet season. Mould can establish faster than that.

That difference in timeline is the whole point. Concrete gives you time to notice a problem, investigate properly, and plan a repair. Wood frame gives you much less.

What this means for response, not just inspection

The usual conclusion drawn from this is that wood frame buildings need more frequent inspections. The more useful conclusion is that they need faster response.

Inspection interval is a schedule. Response time is what happens when something is found, and that is where the two building types genuinely diverge.

On a concrete building, a new stain or a damp patch warrants investigation on a reasonable schedule. Getting an investigator out in a few weeks is fine. The chloride and moisture reaching the steel in that period is not materially different from what reached it last month.

On a wood frame building, the same finding warrants investigation before the next stretch of sustained wet weather. The question is not whether the building will tolerate the delay, but how much wetting the framing takes during it.

This also changes what deferral costs. Postponing a sealant repair on a concrete tower for a season shortens service life slightly and does not create an immediate structural issue. Postponing the same repair on a wood frame building can add framing replacement to a scope that was previously just sealant. The repair grows while you wait, which is why the guidance on emergency leak response matters more acutely on wood frame construction.

Why the wall assembly matters more on wood frame

Wood frame construction in BC carries a specific history that is worth understanding, because it still determines how many buildings behave.

Buildings from a particular era were commonly built face-sealed. The exterior finish, often stucco, was expected to be the complete water barrier, with no drainage cavity behind it. The theory was that if the outer surface is continuous and sealed, water never gets in.

In practice, exterior finishes develop cracks, sealants fail, and penetrations leak. When the outer seal on a face-sealed wall failed, water reached the framing with no path to drain out and no ventilation to dry the assembly. In a climate with the rainfall of coastal BC, water accumulated and stayed. The result was the widespread rot damage that led to the remediation programs still working through the building stock, described in the post on the rainscreen and leaky condo legacy.

The response was the rainscreen: a wall with a drained and vented cavity behind the cladding, so water that gets past the outer surface runs down and out through weeps, and air movement dries what remains. This accepts that the cladding will leak and manages the consequence rather than trying to achieve a perfect seal. How it works is covered in the guide on how a rainscreen works, and the comparison between the two approaches in rainscreen versus face-sealed.

For an owner or council, the practical question is which type of wall your building has. Buildings built after the requirement came in generally have a rainscreen. Older buildings may have been retrofitted during remediation, or may not have been. Visible weep openings at the base of cladding are one indicator, but the drawings or an assessment give a definitive answer, and the guide on is my building rainscreened walks through the signs.

A face-sealed wood frame building that has not been remediated is carrying a risk that a concrete building of the same age simply is not.

What each building type actually spends money on

The maintenance budgets look different because the elements at risk are different.

A concrete building’s recurring envelope costs concentrate in a few places. Concrete repair, which arrives when corrosion has progressed enough to cause delamination and spalling. Protective coating renewal, which slows the ingress driving that corrosion and needs periodic recoating. Sealant maintenance on glazing, which on a tower with large glazed areas represents substantial linear metres of joint. Parkade and podium waterproofing, since concrete buildings usually have structured parking below.

A wood frame building’s costs sit elsewhere. Cladding maintenance and eventual replacement. Roofing, which on a low-rise is a larger proportion of the total envelope than on a tower. Deck and balcony waterproofing, which on wood frame construction protects framing directly rather than protecting concrete. Sealant at penetrations, windows, and transitions. And, if water has got in, framing repair, which is the item that turns a routine budget into a large one.

Neither type is uniformly cheaper. A wood frame building that stays dry can be inexpensive to maintain, because its elements are accessible and its scale keeps access costs low. A wood frame building with a compromised wall assembly can be extremely expensive. Concrete buildings have a more predictable cost profile, generally higher in absolute terms because of scale and access, but with fewer catastrophic outcomes from a single missed leak.

Access and scale

Building type correlates with height, and height drives access cost.

Wood frame construction is limited by code to a certain number of storeys, so wood frame strata buildings are low-rise. Much of their envelope can be reached from ladders, lifts, or modest scaffolding, and the cost of getting to the work is a smaller share of the project. What that involves is covered in the post on envelope work on low-rise three-storey buildings.

Concrete towers require rope access, swing stages, or mast climbers, and the access component becomes a significant line item. It also means work tends to be batched: because mobilizing access is expensive, a tower benefits from grouping several tasks into one campaign rather than making separate trips for sealant, coating, and concrete repair.

Height brings a second effect. Wind-driven rain loading increases with height, so the upper floors of a tower face harder water exposure than a low-rise ever does, as explained in the guide on wind-driven rain. A concrete tower’s envelope is dealing with more severe conditions even though the structure tolerates water better.

Concrete buildings still contain wood

One qualification worth stating. A concrete building’s structural frame does not rot, but concrete buildings routinely contain wood in interior partitions, in balcony assemblies, in finishing, and in some deck constructions.

Persistent water in a concrete building still causes damage: to those wood elements, to drywall and insulation, to flooring, and through mould growth affecting residents. The structural frame is protected from rot, which is the important difference, but nobody should read that as water being tolerable in a concrete building.

What to take into a depreciation report

The practical output of all this belongs in the reserve plan.

A concrete building’s report should carry concrete repair, protective coating renewal, and glazing sealant as significant recurring items, with realistic access costs attached to each and with a note about whether they can be batched into combined campaigns. Cover depth and chloride findings, where they exist, should inform the timing.

A wood frame building’s report should emphasize cladding, roofing, and deck and balcony waterproofing, and should state clearly whether the walls are drained or face-sealed. If face-sealed and unremediated, that is the dominant risk on the building and the report should say so, because it determines whether the strata is planning maintenance or planning for a remediation project.

Both reports should say something about response capability: who residents report water to, how quickly it gets investigated, and whether there is a standing arrangement with a contractor. On a wood frame building, that answer is worth more than an extra inspection on the calendar.

The one-line version

Concrete buildings give you time. Wood frame buildings do not.

Both need the same fundamentals: working drainage, maintained sealants, sound cladding, and someone paying attention. The difference is in how much a delay costs, and on wood frame construction, it costs more.

Sources and further reading

• BC Building Code, Division B Part 5 (Environmental Separation) and Part 9, referenced 2026
• BC Housing, Building Enclosure Design Guide, Wood Frame Multi-Unit Residential Buildings, referenced 2026
• Canada Mortgage and Housing Corporation, Survey of Building Envelope Failures in the Coastal Climate of British Columbia, referenced 2026
• Homeowner Protection Act (British Columbia) and associated warranty regulation, referenced 2026
• Allweathercoating field records on low-rise and high-rise strata buildings, Metro Vancouver, 2026