Structural Exclusion in Roslyn

Which exclusion work needs a certificate, and which does not?

Most of it does not, and knowing that in advance is worth more on a Roslyn job than any material choice.

Roslyn incorporated as a village on 11 January 1932 and runs its own mayor, board of trustees, Architectural Review Board and Historic District Board. The Historic District Board issues certificates of appropriateness: any construction, alteration, change, move or demolition within the Historic/Scenic Overlay District — delineated on the village zoning map dated 13 February 1997 — needs board approval before a permit issues. Criteria for review run to general design, character and appropriateness; scale against the property and its neighbors; texture, materials and color; how windows and other openings are proportioned and arranged; roof shape; and historical and architectural value.

Then comes the sentence this whole discipline turns on: ordinary maintenance or repair, with like materials of similar quality and color, does not require approval.

Sort a typical exclusion scope against that and the result is unexpectedly favorable.

Exempt. Repointing an open mortar joint in a rubble or early block foundation with a matching mortar. Replacing a decayed section of clapboard with clapboard of the same profile. Refitting a soffit board that has dropped. Closing a gap at a fascia corner in matching material. Packing and sealing an existing service penetration. Rebedding a flashing. Refitting a dropped threshold in like material. Rescreening an existing vent behind its original grille. Cutting back a planting bed. Extending or clearing a leader line.

Needs a certificate. Cutting a new vent where none existed. Substituting a different cladding or roofing material. Fitting a visible metal closure on a street elevation. Altering the size or arrangement of an opening. Changing a roof profile. Rebuilding a terrace or wall to a different height.

The reason this matters practically is that exclusion work reveals things. A soffit return opened to close a squirrel entry turns out to have decayed framing behind it. A sill section behind a planting bed turns out to be gone. Where the honest repair can be executed in like materials, the work continues. Where it changes the appearance, it stops until a certificate issues. Establishing the category before the job is priced is a ten-minute task; discovering it in the middle costs weeks.

The scale of what is covered: the Roslyn Village Historic District, listed in 1987, incorporates the earlier Main Street Historic District listed in 1974, and the 1986 multiple resource nomination covers 111 contributing resources — 90 contributing buildings, 19 contributing structures and 2 contributing objects — with a period of significance running from about 1680 to 1936. The district occupies roughly 65 acres, of which all but 25 are the Main Street district. Individual properties outside the district can also be designated as historic sites, so the boundary question is worth asking rather than assuming.

What does “like materials of similar quality and color” actually rule out?

Most of the standard exclusion kit on a visible elevation — and, usefully, most of the things that were going to fail anyway.

The exclusion trade has a default toolkit: mesh, sheet metal, expanding foam, mortar mix, sealant, rigid closures. One item on that list we have taken out permanently, and two more need thinking about on a two-hundred-year-old clapboard house inside a historic district.

Mortar. A hard modern mix in a soft rubble wall does not just look wrong; it does damage. Old masonry moves and takes water, and it relies on a mortar softer than the stone so that the mortar sacrifices itself rather than the stone face. Repointing with a hard cement mix concentrates stress and moisture into the stone and spalls it, which produces more openings in five years than were closed. Matching mortar is simultaneously the exempt option and the correct one.

Sheet metal. Legitimate where a chewable timber edge needs protecting, and where it is concealed — behind a soffit line, inside a void, at a hidden bearing. A visible metal patch fixed across a street elevation is both a certificate matter and a poor repair, because it fails at its edges as the timber behind it moves and it traps water underneath.

Expanding foam. This is the one we removed, and we removed it outright rather than restricting it to some supporting job. Mice chew straight through cured foam, and its worse failure is presentational — a foamed opening looks closed, so nobody checks it again. In a historic district there is an additional objection: it is visible, it is the wrong color, and it is impossible to remove cleanly from old timber and stone.

What is left is the correct approach for this building type anyway. Timber repaired with timber of the same species and profile. Masonry repointed in a compatible mortar. Concealed rigid closures fitted behind original material rather than over it. Screening in a durable, corrosion-resistant metal fitted behind an original grille or vent frame rather than replacing it. Mechanical fixings into sound substrate, with the substrate repaired first where it is not sound.

That is slower and it is not cheaper. It is also the only version that lasts on a building of this age, which is why the board’s rule and good practice arrive at the same place.

Where is the opening on a clapboard house, and why is it never one hole?

At the sill line, and it is a line rather than a hole because of how the wall was built.

The district is predominantly wood frame with clapboard siding, from the circa 1680 Van Nostrand-Starkins house through Colonial Revival work of the early twentieth century. Village-wide, about 261 units — 18.3 per cent — predate 1940, with a further 173 from the 1940s.

Three properties of that construction decide where the work goes.

Clapboard is a lapped, ventilated cladding. Every course has an edge and a joint. It was never intended to be an air barrier and it is not one. Behind it on a house of this age there is typically no sheathing membrane in the modern sense and frequently no insulation.

The sill bears directly on early masonry. Rubble, fieldstone or early block, with mortar that was never a continuous seal and has had two or three centuries of freeze-thaw cycling to open its joints, and a hand-cut sill sitting on top of it. Settlement widens that junction, and on the valley floor settlement is ongoing.

The junction runs the full perimeter. That is why it is a line. On a modern house you find four or five discrete openings and close them. Here you find a continuous condition of variable severity, and the work is a length of wall rather than a count of holes.

So the survey has to get a hand on that line, all the way round, which means moving soil and cutting back planting on every elevation. On a village lot with two hundred years of gardening against the walls, that is genuinely the most productive hour of the job and it is the hour most often skipped.

The closure itself is repointing in a compatible mortar and, where the timber has gone, replacing the timber. Sealant across the face of the junction is not closure; it is a cosmetic treatment applied over a structural condition, and it will part from at least one of the two materials within a couple of seasons.

What does a stud bay running sill to top plate do to this job?

It separates the symptom from the cause by two floors, which is why the reported location is so often the wrong place to look.

On a frame house of this period, a stud bay can run uninterrupted from the sill to the top plate. There is no fire blocking, no insulation and no draft stopping. That is a vertical shaft the height of the wall, and it connects the ground line to the eaves.

Practically, that produces three patterns.

Noise upstairs, entry downstairs. Scratching reported from a first-floor bedroom wall is entirely consistent with an opening at the base of that same wall, outside, at ground level. Treating the bedroom achieves nothing.

Activity in an attic with no attic entry. An animal that came in at grade can reach a roof space without ever going outside again.

Evidence that appears in the middle of a wall. Where a later alteration blocked a bay — a plumbing run, a piece of blocking, an insulation retrofit that reached partway — animals stop where the bay stops, which is somewhere nobody would have predicted.

The consequence for scope is that closure at the base of the wall is worth more than closure anywhere else on this construction. It is also why the internal detail matters: where finishes are being opened for other reasons, closing a bay at floor level with rigid material is a small addition to the work and it permanently shortens every route in the building.

The animal most often involved is the house mouse, which needs roughly a quarter of an inch and works at an edge rather than through a face.

Why does the roof plane cost more here than the walls?

Because nineteenth-century architecture put a great deal of edge into a small area of roof, and every edge is a junction.

The village’s rooflines are unusually elaborate for their size. Within a few hundred yards of East Broadway the whole range is on show: a Colonial Revival library of 1921, a Second Empire house of 1876 under a mansard roof, and a Queen Anne house of 1895. A mansard, a gable end and a dormer cheek all make valleys.

The items that recur:

Soffit returns. The small boxed return at the base of a gable is, on a great many houses of this period, a void with a board across it. It is the most common wildlife entry on this stock and it is invisible from the ground unless you are looking for it.

Dormer cheeks. Where a dormer wall meets the main roof plane there is a flashing joint, a change of material and frequently a gap at the bottom of the cheek.

Valleys. Every intersection concentrates water and debris and carries a flashing joint that has been repaired more than once.

Mansard junctions. A mansard has a near-vertical lower slope meeting a shallow upper one, with a transition detail that was made by hand and has moved since.

Chimney flashings and stack penetrations.

Gable and roof vents, which have to stay working and therefore get screening rather than closure.

Cornell notes that bats and flying squirrels typically enter the upper part of a building while other species come in around the foundation, and that many animals reach roofs by natural bridges from branches touching the structure — which on mature canopy over steep ground is most of the roofline. The animals arriving there are a wildlife management question rather than a rodent one.

The cost driver is access and detail rather than material. Steep old roofs, restricted village lots with nowhere to put a ladder or a tower, and a large number of small individual items. The efficient approach is to do every roof-line item in one visit — returns, cheeks, valleys, flashings, vent screening, terminations — rather than returning three times for one opening each.

What has to stay open on a building at the valley floor?

Everything that is moving air, and here the rule is stricter than usual because the water table is not going anywhere.

A permanent five-acre impoundment at the low point of a steep-sided valley keeps soil moisture high on every property near the valley floor, year-round, and below it the head of Hempstead Harbor is shallow with a tidal range of approximately seven feet.

On ground like that, ventilation is doing structural work.

Cellar and crawlspace vents get a durable, corrosion-resistant screen fitted so it can be inspected, never blocking. Closing a vent in a wet cellar puts moisture into the sill and joist ends above it, and decay in a sill on a historic frame building is a far more expensive problem than the animal that prompted the work.

Attic and roof ventilation, including gable vents and any ridge detail, screened rather than filled. Blocking attic ventilation produces condensation on the underside of the sheathing in winter, which produces the damp timber carpenter ants look for.

Appliance terminations — dryer, bathroom, kitchen — each with a correct terminal and a working flap rather than mesh over a duct.

Combustion air openings, which belong to the heating trade and are not available for closure.

Areaway and yard drainage, which is a functional opening even though nobody thinks of it as one, and which on this relief receives runoff from uphill.

There is a historic-district overlay on all of this. Where an original vent, grille or louvre is a character feature, the right move is screening fitted behind it so the original stays visible and the opening keeps working. That is exempt maintenance and it is also the better repair.

What does the multifamily half of the village need instead?

Compartmentation rather than perimeter work, and a different person to address it to.

Only 633 of Roslyn’s roughly 1,423 units — 44.5 per cent — are detached single-family houses. Some 238 units, 16.7 per cent, sit in buildings of 50 or more, 162 in buildings of 10 to 19 and 165 in three- and four-unit buildings, with roughly 514 units, 36.8 per cent, renter-occupied. Count the flats over the Main Street shops and a large part of the village lives in a building somebody else owns.

A nineteenth-century Main Street building was built with trade at street level and accommodation above, and the connection between them is a stair, a chimney chase and — after a century of upgrades — a plumbing riser, a cable bundle and a duct or two, all passing through floor structures that were never fire-stopped and certainly never pest-stopped.

Closing those is the scope:

The stair void at each landing, where the stringer meets the floor structure and the trimming was framed for load rather than closure.

The chimney chase, closed at each floor with non-combustible material fitted to allow the masonry and the timber to move differently — never with foam, never with anything that could contact a live flue.

The plumbing riser, with proper escutcheon plates where supply pipes pass through finishes. It is a five-minute item and it is almost never done.

Cable and conduit penetrations, closed rigidly with a metal facing.

Joist pockets where a floor structure bears into a party wall, closed around the joist rather than packed solid. The end grain of a joist is the most absorbent surface on the member, and burying it in damp masonry trades a rodent problem for a decay problem that shows up years later as a sagging floor.

The extract run from a ground-floor kitchen, warm, greasy and continuous through the structure.

All of that is an owner, board or managing agent decision. Portfolios run through property management pest control and boards through co-op and condo pest control, with food premises at restaurant pest control inside the commercial program. Anyone tendering should read choosing a pest control contractor on what the documentation has to contain.

In what order does this run, and what does the record have to show?

Ground, then base, then roof — and the record has to answer the board’s question years later.

The consent question first. Which proposed items are exempt maintenance in like materials, and which will need a certificate. This is the item that reorders everything else.

Then the ground. Cut back planting to expose the base of the building on every elevation. Reduce the grade where it has buried the skirt. Take roof water away from the base of the wall and open any leader line that has stopped working. On a hillside lot, deal with the uphill face first, because that is where the deterioration is.

Then the base of the wall. Repoint the open joints in compatible mortar, replace decayed timber in like material, and close every existing service penetration properly around the sleeve.

Then the compartments, on a shared building — stair, chase, riser, joist pockets, floor by floor.

Then the roof line, in one visit: returns, cheeks, valleys, flashings, vent screening and terminations.

Then the canopy. Pruning branches back from the roof line removes the access rather than closing it, and it is the cheapest item on the list.

Then re-check in the cold. December and January on an old frame house show where warm air is leaving, and those are the same openings.

One further sequencing point applies here and almost nowhere else nearby. Because so much of this work is exempt maintenance, it can be done incrementally without a permit cycle interrupting it — which makes a phased scope genuinely practical on a building where the whole job would be a large single expense. A sensible phasing runs: the ground and the base of the wall in one autumn; the roof line the following season; the compartments during any refurbishment or void period. What that phasing must not do is stop after the visible half. A building whose roof edge has been closed and whose sill line has not is still open at the point that matters most.

The record should read as a set of located items, each with a description of what was found, the material used and a photograph, with anything unreachable named and explained. On a listed building there is a second reason for that discipline: a future owner, a future contractor or the board itself may need to know what was done to a contributing structure and in what material. A dated record with photographs answers that. A memory does not.

For the discipline itself, see structural exclusion. The reduction side is rodent control in Roslyn, and the same wet ground and clearance corrections are what stop a contributing building’s sills staying soft enough to be worth excavating; the insect half of that is ant control, specified in materials the board will accept on a visible elevation. For the village across every service, pest control in Roslyn, with the Long Island hub and the coverage list. For the same discipline under different rules, Glen Cove is a city with its own registry, Locust Valley has no review board at all, and Commack answers to two towns at once.

If you own a contributing building here and want the work specified so it stays exempt, tell us which elevations concern you.

Related

• Structural Exclusion — how we approach it
• All pest control in Roslyn
• Rodent Control in Roslyn
• Ant Control in Roslyn