The Hardwood Refinish Job SOP

Purpose

Run a sand and refinish from the estimate to the day the customer moves back in, with the same result whoever is on the crew. Refinish jobs go wrong in ways that are expensive and hard to undo: a floor sanded through its wear layer, a customer walking on a coat in socks four hours too early, a dog across wet finish, a pile of oily rags in a bag in the garage. Almost none of those are sanding skill problems. They are handoff problems between the estimator, the sander, the finisher and the office, which is what this SOP fixes.

Scope

Covers full sand and refinish of site-finished and sandable prefinished wood floors in occupied homes. The sanding technique itself is in How to Sand and Refinish a Hardwood Floor and the machines in Sanding Machines and Grit Sequences; choosing a finish system is Hardwood Floor Finishes for Refinishers. A floor that only needs a fresh coat is How to Screen and Recoat a Worn Floor Finish. In a home built before 1978, The Lead-Safe Floor Work SOP runs alongside this one and its controls win where the two differ.

Roles and the handoffs

The handoff that matters most is sander to finisher: the finisher does not open a can until the sander has walked the floor with them and both agree it is ready.

The procedure

1. Estimate: settle what the floor can take before any price. Record the year the home was built; before 1978, flag the lead SOP. Pull a register or look at a threshold to tell solid from engineered and measure the wear layer above the tongue, note face nails and earlier refinishes, and test the existing finish for wax or a silicone polish that would ruin a recoat. Acceptance: species, construction, wear layer measured, finish history and home age on the sheet. Wrong looks like a quote for a full sand on an engineered floor nobody measured. Stop rule: a wear layer below the shop's minimum for a full sand, 3 millimeters as a common shop floor unless the maker says otherwise, is not drum-sanded; it is quoted as a screen and recoat or declined. Hazard: none at this step, but no sanding or scraping to "check" a finish in a pre-1978 home.

2. Office sends the prep letter and confirms the plan. The letter tells the customer which rooms must be empty and by when, who moves the furniture, that pets and people stay out of the work area for the whole job, which days they cannot cross the floor, and that the HVAC will be off while the crew sands and back on at normal settings for the finish coats. For an oil-modified or other solvent-based finish, it says that pilot lights and other ignition sources in the open area must be off, turned off by the customer or their service company. Acceptance: letter sent and a reply confirming the dates. Wrong looks like the customer learning on day two that they cannot reach the kitchen. Stop rule: no confirmation, no start. Hazard: the solvent vapor is flammable; the ignition-source instruction is in writing, not a verbal aside.

3. Day before: confirm the house is ready for machines. The sander confirms the rooms are empty, the power source for the big machines, and the containment and protection plan per The Flooring Job Site Protection SOP. A 240-volt drum sander runs from the dryer receptacle with the machine maker's cord, or from a power source an electrician provided, never a homemade adapter. Acceptance: rooms empty, power source identified, protection plan ready. Wrong looks like a crew arriving to a full living room. Stop rule: rooms not empty means the crew does not start that room. Hazard: keep sander cords off the path and out of the drum's travel, and check the cord and plug for damage before each use.

4. Set up containment and protection. Dust walls at the work area's openings, HVAC off during sanding with registers and returns in the zone covered, doors and stair rails protected, and a sign at each entry. Acceptance: zone sealed, system state recorded. Wrong looks like a running furnace pulling sanding dust through the house. Stop rule: no machine starts with an open return in the zone. Hazard: wood dust is an inhalation hazard, so the crew wears respirators suited to it and runs the sanders' dust collection, emptying bags before they are full.

5. Sand, then walk it with the finisher. Sand per How to Sand and Refinish a Hardwood Floor and the NWFA sanding and finishing guidelines through the grit sequence chosen for the species and condition, edge, and blend the field and the edges to the same final grit. Then the sander and finisher walk the whole floor together in normal light, followed by a low-angle light to look for edger swirls, chatter and missed finish. The low light is a pre-finish check only; the finished floor is judged standing, in normal light. Acceptance: no old finish left, no chatter or drum stop marks, field and edges scratch-matched. Wrong looks like a halo of edger marks at the walls. Stop rule: the finisher refuses the floor until it is corrected; no finish goes over a sanding defect. Hazard: empty sander dust bags into a metal can and take it outdoors at the end of each day, because fine wood dust with finish residue can self-heat.

6. Finish, and keep the floor closed between coats. Once the sanding dust is vacuumed up, uncover the registers and returns, change a dust-loaded filter, and restart the system, confirming it runs at the settings the finish maker calls for. Vacuum and tack the floor. If stained, lay a test patch the customer approves before the field goes down. Apply each coat per the finish maker's spread rate and recoat window, abrading between coats when the maker requires it. Lock or block every entry and keep the sign up. Acceptance: each coat applied inside its window, temperature and humidity at each coat recorded, nobody on the floor between coats. Wrong looks like footprints in a coat, or a coat applied outside the window. Stop rule: a coat that fails to dry, blushes or shows contamination stops further coats until the cause is found. Hazard: ventilate as the finish maker directs, and for solvent-based finishes wear respirators with organic vapor cartridges under the shop's respirator program (29 CFR 1910.134, applied to construction by 29 CFR 1926.103); no ignition source in the area.

7. Deal with rags and waste every day. Rags and applicators wet with oil-modified finish, stain or penetrating oil go into a water-filled, closed metal can, which leaves the house at the end of the day and is disposed of by local rules. Acceptance: no finish-wet rag anywhere but the can, can out of the house overnight. Wrong looks like rags in a trash bag in the garage. Stop rule: none; this step is never skipped. Hazard: oil-wet rags heat as the oil cures and can ignite on their own.

8. Hand back the floor with a schedule, in writing. After the last coat, the office sends the return-to-service letter taking every date from the finish maker's sheet: when socks are allowed, when shoes, when furniture can go back with felt pads, lifted not slid, and when rugs can go down, which is usually the longest wait. Acceptance: letter sent with the last-coat time and each date. Wrong looks like the crew telling the customer "a day or so" at the door. Stop rule: if the finisher did not record the last-coat time, the office calls them before sending the letter. Hazard: the customer or their service company relights any pilot or ignition source turned off for the job once the area has ventilated, following the appliance's own instructions.

9. Follow up. The office calls once the rugs date passes and asks about sheen, smell and any marks. Acceptance: call logged. Wrong looks like the first contact being a complaint. Stop rule: any finish complaint goes to The Flooring Callback and Claim Inspection SOP. Hazard: none.

The record this produces

The estimate sheet with wear layer and home age, the prep letter and the customer's reply, the sand-ready check signed by sander and finisher, a coat log with time, temperature and humidity for each coat, the finish maker's sheet, and the return-to-service letter. It lands in the job file. The finisher's coat log is what the finish maker will ask for if the finish fails; the return letter is what settles "nobody told us" later.

Worked pass: a main floor in a 1984 house

The house: built 1984, so no lead flag. Living room, dining room and hall in 3/4-inch solid red oak, about 520 square feet, plus a family room in an addition.

Step 1 triggered its stop rule in the family room. At the floor register the estimator found engineered oak, not solid, and measured a wear layer of about 2 millimeters, under the 3-millimeter floor in this SOP. The stop rule triggered: the family room was quoted as a screen and recoat, not a full sand, and the customer was told why with the register out and the edge in their hand. The solid oak passed, with a full wear layer above the tongue and one earlier refinish.

Step 2: letter sent, customer replied, two-component water-borne finish chosen, so no ignition-source instruction applied. Step 3: rooms empty, the drum sander on the dryer receptacle with its own cord. Step 4: dust walls at the kitchen and stairs, system off, three registers covered.

Step 5: sanded 36, 50, 80 then 100 grit. At the walk, the finisher found edger swirls along the hall's east wall. The floor was refused; the sander re-edged and blended that wall with a multi-head sander, and the second walk passed.

Step 6: three coats, each inside its window, recorded at 68 to 70 F and 44 to 47 percent humidity. Step 7: the few rags used with the water-borne finish went in the can anyway, which is the shop's rule. Step 8: the finish maker's sheet for this product gave socks at 24 hours, furniture at 72 hours and rugs at two weeks from the last coat, and the letter gave dates from the recorded last-coat time. Step 9: the follow-up call found no issues; the family room recoat was scheduled separately.

References

• The finish maker's application instructions and return-to-service schedule for the product used
• National Wood Flooring Association sanding and finishing guidelines, current edition
• OSHA 29 CFR 1910.134, respiratory protection, which 29 CFR 1926.103 applies to construction work
• See related: How to Sand and Refinish a Hardwood Floor; Hardwood Floor Finishes for Refinishers; The Lead-Safe Floor Work SOP; How to Screen and Recoat a Worn Floor Finish