Partial Tear-Off and Overnight Dry-In

Purpose

On a multi-day reroof the underlayment left overnight is a roof. It has to shed driven rain and hold against gusts with nobody on site to watch it, over a family asleep underneath.

The failure this prevents: a temporary edge sealed with a bead of mastic instead of lapped and fastened, which lifts at 2 am and delivers the whole slope's water into the ceiling below.

Scope

Covers planned multi-day steep-slope tear-off and reroof on occupied residential and light commercial buildings, from the day's end line through the overnight tie-in and wind check to the morning re-entry.

Does not cover a single-day tear-off and dry-in or an unplanned mid-job weather stop, both owned by their own SOPs, nor the finished shingle course above the underlayment, nor low-slope membrane, where a partial-day tie-in is an adhesive or hot-work detail rather than a lap.

Roles and responsibilities

Where the day ends is chosen in the morning

An end line is a feature of the roof plane, not a point the crew reached. Good lines: under an existing shingle course that has not been stripped, over the ridge onto the far slope, into a valley center, or against a wall. Bad lines: mid-field on open sheathing, halfway up a valley, or across a penetration. Water arriving from above has to run OVER the temporary top edge, and only a lap under an existing course or a run past the ridge gives you that.

The other half is fastening, and every manufacturer publishes two patterns: a covered-application pattern for material shingled the same day, and a tighter exposed-application pattern with a stated maximum exposure duration. Read both off the roll and use the exposed one, tightest at perimeter and laps. Cap fasteners, not staples - a staple in synthetic underlayment tears through under uplift and leaves the sheet flying with the fastener still in the deck. Where the overnight material is felt rather than synthetic, it meets ASTM D226 or D4869, and a self-adhered ice barrier meets ASTM D1970, in whichever your adopted code and the shingle manufacturer both accept.

Procedure

1. Choose and write the end line at the huddle, then size the day back from it. Walk the slope, pick the plane feature the day will finish on, mark it, and set the strip target as what can be stripped, dried in, detailed and wind-checked before the leave time. Acceptance: a named end line and a leave time, both written on the ticket before anything comes off. Wrong looks like a square target with no line, which ends the day wherever the crew ran out. Stop rule: no plane feature within reach of a realistic day means the day is shortened to the previous feature, not extended to the next one. Hazard: walking and marking a slope is roof work, so fall protection is on before anyone leaves the ladder, including for a two-minute look, under 29 CFR 1926.501(b)(13) on residential construction and 1926.501(b)(11) for steep-slope work outside it, which is where a light commercial reroof lands.

2. Strip to the line and stop there. Work ridge down in bounded sections, keep the strip line straight and parallel to the eave, and stop at the marked feature. Acceptance: the strip line coincides with the marked feature along its whole length, with no fingers of stripped area running past it. Wrong looks like one section pushed two courses further because the shingles were loose there. Stop rule: any area stripped past the line is dried in tonight regardless of the day's plan, and the leave time moves. Hazard: nails standing proud on freshly exposed deck are the trip surface, so they are pulled or driven flush inside each section before anyone walks it, not at the end of the day.

3. Finish every deck repair inside tonight's area before the line is closed. Sound each exposed sheet, replace what is soft, delaminated or sagging, and land every replacement on rafter centers to the fastening schedule. Acceptance: no unrepaired sheet anywhere inside tonight's dried-in area, every replacement photographed with a tape in frame before it is covered. Wrong looks like a soft sheet covered because the light was going. Stop rule: a repair that cannot be completed before the leave time means the end line moves down-slope of it and that area is dried in as open deck under a full temporary cover rather than left. Hazard: cutting sheathing releases wood dust and whatever was on the old felt, so the saw runs its dust shroud into a vacuum or the cut is made wet, with eye protection on and any filtering facepiece worn only under a written respirator program per 29 CFR 1910.134, never as a loose dust mask; with neither extraction nor water the cut waits. An unexpected friable or suspect board product stops the cut and goes to identification rather than through the saw.

4. Terminate the top edge so water runs over it, never into it. Either run the underlayment up under an unstripped existing course by the manufacturer's stated lap, or carry it over the ridge and fasten it down on the far slope. Acceptance: no exposed horizontal top edge anywhere on the slope, and a measured lap or over-ridge distance recorded. Wrong looks like a top edge nailed flat on old shingles, which is a funnel pointed at the deck. Stop rule: a section that cannot be lapped under a course gets a full-width temporary cover strip carried past the line and battened, which is logged as temporary and removed in the morning. Hazard: this work happens at the highest point of the slope late in the day, so the anchor is re-verified into exposed framing before the pair moves up to it, because its substrate changed when the layers came off.

5. Fasten to the exposed-application pattern and measure it. Set cap fasteners to the pattern printed on the roll for exposed application, tightest at the perimeter, the rakes and every lap. Acceptance: a spot check of at least ten fasteners on each perimeter run measuring at or under the printed exposed spacing, recorded as a number. Wrong looks like a pattern spaced by eye, which drifts wide exactly at the rake where uplift is worst. Stop rule: any measured run over the printed spacing is re-fastened before anyone leaves, not noted for the morning. Hazard: fastening at the rake puts a knee near the edge with nothing under it, so the work is done from upslope, and a cap gun is set down closed and never left loose on the slope.

6. Detail the ends: valleys, walls, penetrations and the eave. Every valley center, wall termination, pipe boot and skylight inside tonight's area gets its underlayment detail before the leave time, and the eave gets drip edge with the underlayment lapping over it. Acceptance: no open penetration, no unlapped valley and no bare eave edge anywhere inside the dried-in area. Wrong looks like a chimney left with underlayment cut short because the crew ran late. Stop rule: a detail that cannot be finished means that section is covered full width and the whole area above it is treated as temporary, rather than left partly detailed. Hazard: crews step on their own fresh membrane around a penetration, so work outward from the pipe and keep boots off the course just laid.

7. Run the wind check against tonight's forecast, then decide whether to leave. Pull the overnight forecast, compare the gust figure against what the material and pattern are rated for, and walk the whole perimeter for a lifted cap, a fishmouth or an unfastened lap. Acceptance: a recorded overnight gust figure, a recorded perimeter spacing, a clean perimeter walk, and a named person reachable overnight. Wrong looks like a crew driving off at the leave time without walking the edge they just fastened. Stop rule: a gust forecast the pattern was not rated for means battens over the rakes and ridge before anyone leaves, and if it still cannot be made secure the crew stays. Hazard: if the tie-in fails overnight the customer is inside with water coming in, so the call-out plan is real - who is called, who drives out, and the occupant instruction is specific: switch on nothing that is wet, open the breaker feeding any light or outlet in a wet ceiling rather than reaching for its switch, and if a ceiling is sagging, bulging or dripping over a bed or a walkway, get everyone out of that room and call from outside it.

8. In the morning, inspect and measure before adding any load. Look at the tie-in from the ladder before stepping onto it, check for lifted or torn caps, wind-flipped laps and ponding, then meter the deck under any temporary strip and remove every temporary strip and batten as the permanent work catches up. Acceptance: no lifted or torn fastener left, deck moisture at or below 19 percent everywhere metered, and the count of temporary items removed matching the count logged the night before. Wrong looks like permanent underlayment run over a temporary strip somebody forgot, which is a hard edge under the shingles forever. Stop rule: deck above 19 percent stays uncovered and is re-metered later. Hazard: overnight dew makes synthetic underlayment far slicker than yesterday, so it is tested underfoot from an anchored position before anyone walks it and before any bundle lands on it.

The record this produces

One overnight tie-in entry per day on the job ticket: the end line chosen and why, leave time planned and actual, squares stripped and dried in, deck sheets replaced with locations and photos, the termination method with the measured lap or over-ridge distance, the exposed pattern read off the roll and the measured perimeter spacing, the overnight gust figure, temporary strips and battens with a count, the call-out name, and the morning inspection with moisture readings.

Worked pass: 34 square gable, three days, day one on the south slope

Seventeen squares a slope. Day one's end line was set at the huddle as the ridge, with the underlayment carried 12 in onto the north slope and fastened there, leave time 5:30 pm. The roll's printed exposed-application pattern was read as caps at 6 in on center at laps, rakes and perimeter, and 12 in in the field, with a stated maximum exposure of 30 days.

Steps 2 to 4 ran clean: 17 squares stripped and dried in, four delaminated sheets replaced over the west rafters and photographed with a tape before covering, the top edge carried the measured 12 in past the ridge.

Step 5 fails on the west rake. Ten fasteners spot-checked on that run measured about 9 in apart against the 6 in printed for exposed application at a perimeter, wide by 3 in on center. The stop rule fired at 5:10 pm. The rake was re-fastened to 6 in and re-checked at ten fasteners before anyone left, costing 25 minutes against a 5:30 leave time.

The 4 pm forecast had moved from 25 mph gusts at the huddle to 40 mph overnight, so battens went over both rakes and the ridge lap: two temporary battens and one temporary cover strip logged. The perimeter walk found one fishmouth at the east rake, re-fastened on the spot, and the lead left the office a reachable number.

Next morning the tie-in was clear, the deck under the temporary strip metered 12 percent against the 19 percent gate, and all three logged temporary items came off before the first bundle landed on the slope, so none ended up under the finished roof.

References

• The underlayment manufacturer's printed instructions for the exposed-application pattern, lap dimensions and maximum exposure duration, which are a warranty condition.
• The International Residential Code, in the edition your jurisdiction has adopted, for underlayment, ice barrier extent and drip edge.
• 29 CFR 1926.501(b)(13) for residential construction and 1926.501(b)(11) for steep roofs outside it, both at the 6 ft trigger; 1926 Subpart M generally; 29 CFR 1910.134 for the written respirator program.
• See related: roofing-tear-off-and-dry-in-the-same-day and roofing-weather-hold-and-dry-in-decision-mid-job.