Masonite & Hardboard Siding Replacement in Portland
Hardboard lap siding from the 1980s and 1990s swells at its lower edges once water gets past the paint. Here is how to tell if you have it, and your options.
Masonite siding replacement in Portland, Oregon is one of the most common re-side jobs on houses built or re-sided in the 1980s and 1990s. Hardboard lap siding, much of it sold under the Masonite name, and LP Inner-Seal OSB siding were both widely installed in those years, and both fail the same way: water gets past the paint at cut edges and nail holes, the wood fibers swell, and the lower edges of the boards flare out and soften.
Lake Oswego’s median home was built in 1982 and Gresham’s in 1981 (Census ACS 2020-2024), which puts a large share of both cities’ houses in that era. See the Lake Oswego and Gresham pages.
Portland Siding Pros passes hardboard replacement requests to independent siding contractors, who inspect and quote directly.
Hardboard, OSB, wood or fiber cement? Four checks
- Look at an exposed edge. Hardboard has a dense, brown, papery fiber core with no grain; LP OSB shows flat wood strands pressed together.
- Check the texture. Hardboard lap usually has an embossed wood-grain pattern that repeats more regularly than real cedar.
- Check the date. A house sided between about 1980 and the late 1990s is a candidate.
- Look for a stamp. Board backs, visible in an attic or unfinished garage, sometimes carry the maker’s name.
If you cannot tell, a contractor can identify it in a few minutes.
Is there any settlement money left?
No. The class-action settlements covering Masonite hardboard siding and LP Inner-Seal OSB siding have closed to claims. If you are buying a house with this siding, it is worth pricing its replacement into the purchase.
Swapping boards vs. a whole-house re-side
A few swollen boards on one wall, with the rest in good shape and well painted, can be swapped out. Hardboard itself is mostly no longer made in the original profiles, so the replacements are fiber cement or engineered wood cut to match the exposure, then painted. When swelling shows on most walls, siding replacement is the durable fix, and it lets the contractor check and repair the sheathing and add proper flashing and wrap.
Replacement materials for Masonite-era houses
- Fiber cement lap siding is the most common choice, because it will not swell or rot. Window and door trim often has to be built out for its extra thickness.
- Vinyl siding costs less and needs no paint.
- Engineered wood lap siding such as LP SmartSide is the product line that followed the older OSB sidings, with resin and treatments designed to resist moisture, and should be installed and sealed exactly to the maker’s instructions.
Common finds under old hardboard
Expect some sheathing repair below windows and at the bottom of walls, missing or torn building paper, and windows set with little flashing. Ask for the quote to price sheathing replacement per sheet, so the surprise is a known unit cost. Related failures: water behind siding and T1-11 damage.
Budgeting for a hardboard re-side
The siding cost page lists regional averages for a full fiber cement or vinyl re-side and per-square-foot installed ranges for each material, each with its source and date, plus tear-off and disposal.
What you may notice
Lap boards whose lower edges have swollen, flared or "mushroomed" outward.
Soft, spongy spots around nail heads, sometimes with the nail pulling through.
Paint flaking off in sheets, exposing a brown, fibrous board.
Boards that have cracked, buckled or started to crumble at the ends.
A regular embossed wood-grain pattern that looks too even to be real wood.
What causes it
Hardboard siding, much of it sold under the Masonite name, and LP Inner-Seal OSB siding are wood-fiber boards that swell once water gets past the paint at edges and nail holes. Both were installed widely in the 1980s and 1990s, and both class-action settlements have long since closed to claims.
Hardboard and OSB siding are made from wood fibers or strands pressed with resin, and absorb water through unsealed cut ends, bottom edges and nail holes.
Paint that has worn thin or cracked, so the board is no longer sealed.
Low clearance to soil, patios and roofing, keeping the bottom course wet.
Missing flashing at windows, doors and roof edges.
How soon it needs attention
Swelling does not reverse. A board that has mushroomed keeps absorbing water every winter and softens further. If swelling is limited to a few boards, repair and repainting can buy time; once it appears on most walls, it is usually time to price replacement before the sheathing behind is affected.
Services that fix it
Siding Replacement
Tear-off to the sheathing and a complete new wall skin: rot repair, house wrap, flashed windows, a drainage gap where it is required, new trim and new siding.
Fiber Cement (Hardie) Siding
James Hardie and other fiber cement lap, panel and shingle siding, primed or factory-finished, installed to the maker's clearance and fastening rules.
Vinyl Siding
Vinyl lap, board-and-batten and shake-profile siding, and repair of panels that have buckled, cracked, melted or slipped out of their channels.
Common questions
How do I know if my siding is hardboard?
Look at a cut edge, such as at a corner, a vent or behind a downspout. Hardboard shows a dense brown fiber core with no grain or layers; OSB shows flat wood strands pressed together; real wood shows grain; fiber cement is grey and hard. Hardboard is also noticeably softer than fiber cement when pressed with a screwdriver at a swollen edge. Sometimes a stamp on the back of a board, visible from an attic or garage, names the maker.
Can I still get paid by the Masonite or LP class actions?
No. The class-action settlements over Masonite hardboard siding and LP Inner-Seal OSB siding closed to new claims years ago. Replacement today is at the owner's cost. Home insurance generally does not cover gradual deterioration either.
Can swollen hardboard boards be repaired?
Individual boards can be replaced, but hardboard is no longer made in most of its original profiles, so replacements are usually fiber cement or engineered wood cut to the same exposure. That works for a few boards; when swelling is on every wall, piecemeal repair usually costs more over time than replacement.
Start My Siding Quote
Describe the siding job once and we pass it to an independent local siding contractor, who quotes you directly. Free, with no obligation.