# How Beams, Joists, and Piers Are Repaired | Guide > The mechanics of pier-and-beam restoration: beam shimming and replacement, sistering joists, pad-and-block work, re-leveling, and restoration. URL: https://sanantoniofoundationrepair.net/guide/how-beams-joists-and-piers-are-repaired/ Last-Modified: 2026-09-16 Homeowner guide # How Beams, Joists, and Piers Are Repaired The mechanics of pier-and-beam restoration: beam shimming and replacement, sistering joists, pad-and-block work, re-leveling, and restoration. Published September 16, 2026 · 6 min read ![Worker sistering a new joist alongside an old one in a crawlspace](/images/featured/worker-fastening-a-new-sister-joist-alongside-an-o.webp) ## Why Access Changes Everything On a slab foundation, reaching anything beneath the middle of the house means tunnelling or cutting the floor. On a pier-and-beam home, someone crawls to it. That accessibility is the reason these repairs are generally more targeted and less expensive than slab work. It also means the findings can be specific: this girder, at this bearing point, needs this repair. Our pier-and-beam repair [/pier-and-beam-repair/ →](/pier-and-beam-repair/) page covers how the assessment produces those findings, and our guide on signs of pier-and-beam foundation problems [/guide/signs-of-pier-and-beam-foundation-problems/ →](/guide/signs-of-pier-and-beam-foundation-problems/) covers what typically prompts the inspection in the first place. ## Beam Shimming **What it addresses:** a girder sitting low over a pier that is itself sound and stable. **How it works:** a shim of treated hardwood or steel is placed between the pier cap and the underside of the beam, restoring contact and correcting the local elevation. Where a small lift is required, a screw jack takes the load briefly while the shim goes in. **When it is right:** when the pier and its footing are sound and the gap is the whole problem. This is the lightest correction available and, applied correctly, a durable one. **When it is not:** when the pier has settled or its footing has failed. Shimming a beam over a sinking pier restores contact today and loses it again as the pier continues down. The findings should distinguish between the two conditions rather than shimming everything. ## Sistering Joists **What it addresses:** a subfloor joist that has lost capacity through rot, termite damage, splitting, or over-notching for plumbing runs. **How it works:** a new joist is positioned alongside the existing one and fastened to it along its length, so the two act together. The new member must bear properly at both ends, which sometimes means extending it past the damaged zone to reach sound bearing. **Why not just replace it:** removing a joist means disconnecting everything attached to it, including subfloor, plumbing, and wiring, and often disturbing more of the floor than the problem warrants. Sistering restores capacity with far less disruption. **Detail that matters:** the sister has to be the same depth and it has to bear at the ends. A short sister spanning only the damaged section, not reaching bearing, does not carry load. ![New concrete pad and block supporting a beam under a raised home](/images/content/new-concrete-pad-and-block-support-installed-benea.webp) ## Girder Replacement **What it addresses:** a beam where damage runs through the section rather than sitting at the surface. Rotted bearing ends, extensive termite tunnelling, or a structural split along the grain. **How it works:** 1. Screw jacks and temporary cribbing take the load from the beam. 2. The joists bearing on it are temporarily supported. 3. The old member is removed. 4. New material, typically treated southern yellow pine sized for the span, is installed. 5. Joists are reconnected and load is transferred back. **Why it is a bigger job:** temporary support has to be adequate and properly positioned, and the working space in a crawlspace makes handling long members awkward. The scope should state the length involved rather than describing it as beam work. ## Pier and Footing Work **What it addresses:** a pier that has settled, a footing that was never adequate, or masonry that has deteriorated. **How it works:** the load is taken temporarily, the failed support is removed, and new support is built. That may be a concrete footer poured to depth with a new pier above it, or a rebuilt pad-and-block assembly where that is appropriate. **Footing sizing:** follows the load carried at that point and the bearing conditions there. This is why one property can need different footing details in different locations, and why a proposal listing a pier count without describing the footings is incomplete. ## Re-Leveling Once individual repairs are complete, or as part of the same operation, the structure can be brought back toward level. Screw jacks are positioned at the support points and the structure is raised in controlled increments, with readings taken between stages. Shims and pier heights are adjusted to hold the new position. The realistic objective is recovery toward level within practical limits. A structure that settled over decades has adjusted around its position, and pushing for absolute flatness produces more damage than benefit. Our house leveling [/house-leveling/ →](/house-leveling/) page covers the process and its limits in more detail. > **What you will notice** > > Some sheetrock or plaster relief cracking, particularly above door and window openings. Some trim gaps opening or closing. Some doors operating better immediately and others needing adjustment once the structure settles. All normal, all discussed before work starts, and the scope should state which cosmetic repairs are included. ## Sequencing and Moisture One point worth stating: repairing decayed wood while the moisture source is still active means doing the work twice. Where crawlspace moisture is a factor, the sequence usually runs: address the exterior drainage and grading, install or repair the vapor barrier, then repair the damaged framing. Sometimes the structural work is urgent enough to come first, in which case the moisture work follows immediately rather than being left to a later project. ## Finishing Up On completion, the crawlspace should be left clean, with materials removed and the access properly closed. The findings record, the scope as performed, and any elevation readings taken before and after form the project documentation. Keep that record. On a raised home it is genuinely useful years later, because it tells the next assessor which members have already been addressed and which have not. Quick answers ## Questions About This Topic ### What is sistering a joist? expand\_more Fastening a new joist alongside an existing one that has been weakened, so the new member carries load alongside the old. It restores capacity without removing the original, which matters because full replacement would often require dismantling more of the floor than the problem justifies. The new member has to bear properly at both ends to do its job. ### How are pier-and-beam homes re-leveled? expand\_more Screw jacks and temporary cribbing take the load, then support is adjusted in controlled increments through shimming and pier work until the elevation profile improves toward the agreed target. The lift is deliberately gradual, because moving a wood-framed structure quickly transfers stress into plaster, trim, and door frames all at once. ### Can shims come loose over time? expand\_more Yes, and finding loose or fallen shims in an older crawlspace is common. It usually means the support beneath has settled, the wood has shrunk, or vibration has worked them out. Simply replacing them treats the symptom; establishing why they came loose is what determines whether the repair holds. ## Related Guides ### Crawl Space Moisture and Wood Rot in San Antonio Homes Crawlspace humidity, wood rot, and moisture mitigation in older San Antonio homes: sources, risks, vapor barrier concepts, and what an assessment checks. Read guide arrow\_forward [Crawl Space Moisture and Wood Rot in San Antonio Homes →](/guide/crawl-space-moisture-and-wood-rot-san-antonio/) ### Pier-and-Beam vs. Slab: How Repairs Differ How repair differs by foundation type: construction and method differences, access and disruption, and why foundation type shapes the scope. Read guide arrow\_forward [Pier-and-Beam vs. Slab: How Repairs Differ →](/guide/pier-and-beam-vs-slab-how-repairs-differ/) ### Signs of Pier-and-Beam Foundation Problems How pier-and-beam home owners recognize problems: bouncy or sloping floors, gaps, moisture indicators, and when to request an evaluation. Read guide arrow\_forward [Signs of Pier-and-Beam Foundation Problems →](/guide/signs-of-pier-and-beam-foundation-problems/) ### What Pier-and-Beam Repair Involves The scope of pier-and-beam repair: construction basics, common repair scope like shimming and sistering, pier work, and crawlspace access. Read guide arrow\_forward [What Pier-and-Beam Repair Involves →](/guide/what-pier-and-beam-repair-involves/) Browse all guides [/guide/ →](/guide/)