# Roof-Deck Problems in Tacoma's Century-Old Homes | Tacoma Roofing

> The roof-deck issues commonly found under original roofing on pre-1930 Tacoma homes in North Slope and Stadium-Seminary, and what they mean for a re-roof project.

URL: https://tacomaroofing.net/guide/century-home-roof-deck-problems-tacoma/

Common roof-deck problems on Tacoma homes built before 1930 include original board decking with gaps or delamination, moisture damage from decades of rain exposure, and multiple layers of roofing added over time. These typically aren't visible until the existing roofing is torn off, which is why we recommend a full tear-off rather than layering on these homes.

Original roof decking on a century-old Tacoma home carries a genuinely different risk profile than modern sheathing — here's what's actually commonly found once the old roofing comes off.

## Why this comes up specifically on Tacoma's oldest homes

Roughly **80% of homes in Tacoma's North Slope Historic Special Review District were built before 1930**, across three distinct construction booms — **1888-1893, 1902-1915, and 1919-1929** — in a mix of Stick Style, Queen Anne, Craftsman, American Foursquare, Tudor Revival, and Mission Revival architecture. The Stadium-Seminary National Historic District, on the Register since 1977, adds roughly 400 more buildings from a similar era on the bluff above Commencement Bay. Homes from these construction booms were built to the framing and decking standards of their time, and have carried roughly a century of Tacoma's roughly 39-43 inches of annual rain since.

## What's commonly found under the original roofing

- **Original board decking** — many homes from this era used individual wood boards (skip sheathing or plank decking) rather than the plywood or OSB sheets used in modern construction. Board decking can have gaps, warping, or delamination that isn't visible until it's exposed.
- **Moisture damage accumulated over decades** — even a well-maintained roof develops small leak points over a century of service; moisture that reached the deck years or decades ago and dried can leave weakened wood that isn't obvious from the surface.
- **Multiple prior roofing layers** — some homes have had roofing material added over existing layers across past decades rather than torn off and replaced, which adds weight to the structure and can trap moisture between layers.
- **Rafters and framing sized to older standards** — framing from this era wasn't engineered to current structural codes, and while it's often performed adequately for a century, any modification (like adding a layer, or extending a roofline) needs to account for the load it's actually carrying.

## Why we tear off rather than layer on these homes

Layering new roofing over existing material on any home skips the chance to see and address deck condition — but on a home built before 1930, that's a meaningfully bigger risk, given how likely some degree of deck wear is after this many decades. A full tear-off lets us actually inspect the deck, address any damaged sections with new sheathing, and confirm the structure underneath is sound before new roofing goes on top of it.

## What this means for your project timeline and cost

Deck condition genuinely can't be fully assessed from the outside — it's one of the few things that's confirmed only once the old roofing comes off. This is why we build the possibility of deck repair into how we scope these projects from the start, rather than treating it as a surprise change order. Localized damage typically adds a defined, itemized repair cost; widespread damage is a stronger signal that full replacement, addressed properly from the deck up, is the more sound long-term investment.

## How this connects to material choice

If your property sits inside North Slope or Stadium-Seminary and the project triggers a permit, Landmarks Preservation Commission review under Tacoma Municipal Code 13.05.047 will look at the finished roofing material and pitch — separate from the deck work itself, but worth planning together. Our historic-district guides cover what that review evaluates.

## Bottom line

Original decking, accumulated moisture damage, and prior roofing layers are common, real findings on Tacoma's century-old homes once the roof is opened up — and they're far cheaper to address during a planned re-roof than discovered later as an emergency. Call **(253) 201-1336** and we'll give you an honest assessment before and during the project.

## FAQ

**Will deck problems always show up as a visible leak first?**

Not necessarily — some deck issues, like localized delamination or minor rot in a small section, can exist without an active interior leak, especially if the roofing surface above is still intact. This is part of why deck condition often isn't known until tear-off, regardless of whether you've noticed a leak.

**Does finding deck damage mean the whole roof needs replacing, not just a repair?**

Not automatically — localized deck damage can sometimes be addressed as a repair with new sheathing installed in that section. Widespread deck damage across the roof is a stronger signal toward full replacement. Our repair-vs-replace guide covers how that decision generally gets made.

**Does finding deck damage add significant cost to a project?**

It adds a real, line-item cost for the sheathing replacement itself, but it's far cheaper to address during a planned re-roof — when the deck is already exposed — than to discover it later as a structural or water-damage emergency.