An 1800s three-family in Mystic that the owner is renovating in phases with Tidal Build: the basement first, then a new roof with a raised third-floor ceiling and dormers, then the first and second floors. He asked for three things, and the letter is organized around them. What condition the house is in as a whole. A specification for the basement framing work that he could hand to a framer and start from. And a structural opinion on whether the third-floor plan can be carried, written so the basement work prepares for it.
Matt Williston at Tidal brought me the job, sent his schematic basement plan and twenty photographs of the basement ahead of time, and met me there for part of the visit.
A three-story wood-frame house about 45 ft along the street and about 22 ft deep, with a wrap-around porch, a gable roof with the ridge running parallel to the street, and a chimney at the left gable end. The foundation is brick over a band of stone, whitewashed inside, with brick piers built against the walls and a slab floor. The basement ceiling had already been opened to the framing, so all of it was there to see.
The first thing the basement tells you is that the house is balloon framed. The sill does not sit on top of the foundation wall. It runs against the inner face of the brick and bears on the piers. That matters later, when a ridge-beam post needs somewhere to land at each gable end.
The first floor is rough-sawn joists on 6x6 girders that run front to back across the basement, from eave wall to eave wall, each one about ten and a half feet from the wall to a support at mid-depth. Those mid-depth supports are the story. The original ones are two tapered granite posts, a single stone each; post 2 is 9 in at the base and about 5 in at the top. Everything else is a later generation of repair: a built-up wood post beside one granite post, two posts carrying a makeshift header of two pieces of wood and a stack of shims under one girder, a 6x6 and more shims bearing on another beam under a second, and at one pier a girder end sitting on a shim that does not fully cover the pier. None of the later supports stands on a footing I could see and none is fastened top and bottom.
On the letter’s assumptions, a 6x6 under this floor wants supports about five feet apart or less. Where it is more, the girders have sagged over the life of the house. Along two of the girders, on the front half of the house, where the joists are joined with mortise and tenon and no hangers, the tenons have pulled part way out of their mortises as the girders dropped away from them. Every floor above slopes inward toward the middle of the house, which the owner confirmed and which I walked.
The wood itself is fine. Pin readings at the girders were 9 to 13 percent, dry for a basement, and I found no active rot anywhere in the basement framing, no decay at any support, and no sign of water coming in. The only damage of note is a big old notch in the sill beside one pier, probably cut for a pipe, with a hole in the floor above it, and what may be old insect damage in one or two joists beside it. The piers are sound, the chimney stands on a mass of concrete, and the foundation walls show nothing worse than minor spalling. Stone does not creep. The sag is in the wood between the supports, not in the posts, and nothing in the basement suggests the foundation is moving.
The fix is support and connection, not replacement. Give every girder a permanent post on a real footing at close enough spacing that it cannot sag further, take the load off the shims and the improvised headers, replace the shims with steel plates, and put a hanger on every joist that has walked out of its mortise. Done in that order the floor stops moving and the joints stop opening.
The specification is nine numbered items a framing contractor can price from the letter, and the post layout was then set girder by girder in Addendum 1, signed and sealed November 8, 2026, from the measurements the contractor took on November 6. The addendum replaces the letter’s items 1 and 3 and governs where the two differ; everything else in the letter stands. Each girder is checked first. A brick pier or a granite post is its middle support only if it stands under the girder near its middle, the girder sits right on it and not on a header or shims, and it is sound, plumb, with no crack through it and hard mortar; every other girder gets a new middle post. Then the side posts, from each eave wall to the middle support, with no gap longer than the girder’s largest gap. The letter’s five feet took each girder as 6 in square with the bays unmeasured; the addendum, set from the contractor’s tape of the girders and the bays between them, gives each girder its own largest gap: 6 ft 6 in on girder 1, 6 ft 0 in on girder 2, 4 ft 6 in on girder 3 and 5 ft 6 in on girder 4, numbered from the chimney end, and no gap over 3 ft 6 in on a girder whose joist pockets are cut open through its top. At the lengths on the plan that is 10 to 14 side posts in all, plus the new middle posts.
Each side post is the letter’s item 2: a 3-1/2 in Schedule 40 steel pipe with welded plates, or a manufactured adjustable column listed for permanent use, on its own footing cast below the slab, 24 in square by 12 in thick with three #4 bars each way, set with a temporary shore beside it, the girder lifted only until it bears on the post, then the shore released. Where a girder gets a new middle post, the middle is carried before the slab is cut: a temporary beam under the girder across the area to be dug, with a shore at each end outside the cut, sized by the contractor to carry 21,000 lb, the same load as the new post, and whatever props the girder there comes out only once that beam carries it. Then the footing, 48 by 48 by 14 in of 3,000 psi concrete with seven #4 bars each way, dug to undisturbed soil or cleaned ledge and never fill; then the post, a 3-1/2 in adjustable steel column with a 0.216 in wall, rated for at least 21,000 lb at its installed height, under an 8 by 10 by 5/8 in steel plate lagged to the girder. No post takes load until its footing is 7 days old, and the work goes one girder at a time.
At every pier or post top where a girder bears on wood shims, the shims come out and a 1/2 in steel plate the full width of the girder goes in on a bed of non-shrink grout, so the girder bears on steel on grout on solid masonry. At every joist whose tenon has pulled, a face-mount hanger listed for 2 in rough-sawn lumber, every hole filled, installed after the girder is on its new posts with the joist drawn tight so the hanger carries it from the day it goes in.
The joists are a separate question. They are reported as about 2x6 at about 24 in, and I did not measure them. Rough 2x6 joists at 24 in are, by calculation, lighter than today’s code wants for a residential floor at spans of ten feet and more; in the narrower bays toward the chimney end they are closer to it. The contractor’s tape on November 6 later put them at 2 by 6-3/4 in at 24 in on center. The house has stood on them, and left exposed and watched they are acceptable as they are. If the basement is to be finished with an insulated ceiling under rented bedrooms, I recommended sistering every joist with a 1-3/4 by 7-1/4 in LVL, full length, which brings the floor to a modern stiffness and costs mostly labor, and the letter sizes it so the contractor can price it. The contractor has since measured the bays; every one is under 12 ft, so no sister needs the 9-1/4 in LVL.
The historic slope is accepted on purpose. Jacking the house back toward level after a hundred years would crack plaster and finishes on three floors for no structural gain.
The third floor. The owner intends to take the roof off, raise the ceiling to about 10 ft, keep the front gable dormer and add two more beside it, build two gable dormers joined by a shed dormer on the rear slope, and keep the front facade as it is. Structurally this works. The way to do it is a continuous ridge beam between the gable end walls on three posts: one at each gable end and one intermediate post near the middle of the house. With a ridge beam the rafters hang from the ridge instead of pushing on the eave walls, so the knee walls and ties that hold an ordinary gable together are no longer needed and the ceiling can open up. Without the middle post the beam would span about 45 ft and be deep and expensive. With it, each span is about 22 ft and the beam is a reasonable engineered lumber or steel member.
On a planning basis, under Connecticut snow, each gable-end post carries on the order of 5,000 lb and the intermediate post on the order of 16,000 lb. The end posts can land on the existing masonry, on the pier at the right gable end and in the space behind the chimney at the left, about 9 in clear, through a steel plate on the brick in each case. Whether the ridge falls exactly over that pier and the chimney, or a foot or two off, is a survey question for the design phase; if it is off, a new pier beside the existing one takes the post. The intermediate post is the one to plan for. It has to pass through the third, second and first floors to a footing of its own in the basement, about 4 ft square, on the centerline of the house where the girders’ mid-depth supports stand. It must not land on a girder between posts and it must not land on the slab. The new middle footings and columns of the basement work carry the floors only; the ridge post does not land on them without a new design. The obvious place to hide it is the stair and closet stack at the middle of the house, which is why the third-floor stair and this post should be settled together in the design. That is also why the new basement partition on the plan, which sits about two feet off the centerline, is a partition and not a bearing wall. If the owner wants it to carry the ridge post, it moves to the line of the supports and the post gets its own footing there.
Tidal Build designs and builds its own work out of Mystic and keeps no engineer on staff. Matt draws, with a good feel for how a frame carries its load, and the calculations and the seal are mine. On this one the owner wanted the whole house looked at and a specification he could build from before Tidal’s drawings existed, so the letter is written to be built from directly and to hand the design phase a basement where the ridge post has somewhere to land.
If you own an old house along the shoreline and the floors have gone soft or the plan has a bigger roof in it, this is a job I do. One visit, a letter that says what is sound and what is not, a specification your framer can price, and the design after it when you are ready.
| Item | Detail |
|---|---|
| Building | Three-story wood-frame three-family house from the 1800s, about 45 ft along the street and about 22 ft deep in its main block, with a wrap-around porch, a gable roof whose ridge runs parallel to the street, one gable dormer on the front slope, and a chimney at the left gable end |
| Framing | Balloon framed. The sill does not sit on the foundation wall but runs against its inner face and bears on brick piers. Rough-sawn first-floor joists, reported as about 2x6 at about 24 in on center and not measured, on 6x6 girders spanning front to back across the basement, each about ten and a half feet from the eave wall to a support at mid-depth. A plank subfloor |
| Foundation | Brick over a band of stone, whitewashed inside, with brick piers built against the walls, two tapered granite posts as the original mid-depth supports, and a concrete slab floor |
| Existing condition | The basement ceiling opened to the framing. Girders sagged between supports spaced too far apart, the joist tenons pulled part way out of their mortises on two of them, several generations of shim stacks and makeshift headers added to stop it, and every floor above sloping inward toward the middle of the house |
| Scope | Three things in one letter. The structural condition of the house as a whole. A nine-item specification for the basement framing work the owner intends to start from this letter, written so a framing contractor can price and build it. And a planning-level structural opinion on whether the raised third floor with its dormers can be carried, written so the basement work prepares for it |
| Girder span, eave wall to mid-depth support | About 10 ft 6 in, on 6x6 timbers |
| New post spacing, by the sealed Addendum 1 of November 8 | Set girder by girder from the contractor's tape of the girders and the bays between them, where the letter's 5 ft took each girder as 6 in square with the bays unmeasured. The largest gap on girder 1 is 6 ft 6 in, on girder 2 6 ft 0 in, on girder 3 4 ft 6 in and on girder 4 5 ft 6 in, counted from the chimney end; 10 to 14 side posts in all, plus the new middle posts |
| Lift at each side post | Only until the girder bears on the post, with a temporary shore beside it. The historic slope is accepted |
| Moisture in the girders | 9 to 13 percent by pin meter, dry for a basement |
| Granite post 2 | A single tapered stone, 9 in at the base to about 5 in at the top, standing on the basement fireplace |
| Chimney at the left gable end | About 21 by 34 in, standing about a foot inside the gable wall with about 9 in clear behind it, no firebox, a duct through it |
| Future ridge beam | About 45 ft between the gable ends. With one intermediate post, two spans of about 22 ft |
| Planning loads for the new roof | On the order of 5,000 lb at each gable-end post and 16,000 lb at the intermediate post, under Connecticut snow |
| Side posts under every girder | 3-1/2 in diameter Schedule 40 steel pipe columns with welded top and bottom plates, or a manufactured adjustable steel column listed for permanent use, each on its own footing cast below the slab, 24 in square by 12 in thick, 3,000 psi, three #4 bars each way, base anchored with two 1/2 in expansion anchors, top lagged to the girder; set from each eave wall toward the middle support with no gap longer than the girder's largest gap in the addendum's table |
| New middle posts | Where a girder has no brick pier or granite post that passes the addendum's check as its middle support: a 3-1/2 in adjustable steel column with a 0.216 in wall, listed for permanent use and rated for at least 21,000 lb at its installed height, under an A36 steel plate 8 by 10 by 5/8 in lagged to the girder with two 1/2 in lag screws 4 in long, on a footing 48 by 48 by 14 in, 3,000 psi, seven #4 bars each way at the bottom with 3 in of cover and a 90 degree hook at both ends of every bar, dug to undisturbed soil or cleaned ledge, never fill. The girder is carried on a temporary beam and two shores rated for 21,000 lb before the slab is cut, and no post takes load until its footing is 7 days old |
| Bearing plates in place of shims | 1/2 in steel plate the full width of the girder and the full depth of the pier, on a 1 in bed of non-shrink grout, so the girder bears on steel on grout on solid masonry |
| Joist hangers where the tenons pulled | Face-mount hangers listed for 2 in rough-sawn lumber (Simpson Strong-Tie U26R or equal), allowable download not less than 700 lb, every hole filled, installed after the girder is on its new posts with the joist drawn tight |
| Sisters, if the basement ceiling is to be finished | One 1-3/4 x 7-1/4 in LVL 2.0E beside every first-floor joist (the addendum lets the 64 in bay at the chimney end differ), girder to girder, two rows of 1/4 x 3-1/2 in structural screws at 12 in staggered with adhesive, the screws doubled over the last 24 in at each end. The contractor measured the bays on November 6; every bay is under 12 ft, so no sister needs the 9-1/4 in LVL |
| Granite posts | Ornamental once the new posts carry the girders, and may be left as they are. A granite post kept as a girder's middle support, where it passes the addendum's check, gets a 6 by 10 by 1/2 in steel cap plate on two epoxy-anchored 1/2 in rods |
| Footing for the future ridge post | About 4 ft square on the centerline of the house, where the girders' mid-depth supports stand, sized to carry the roof and, where it falls on a girder, that girder too; never on a girder between posts and never on the slab. The new middle footings and columns of the basement work carry the floors only; the ridge post does not land on them without a new design |
| Load path | Today the first floor runs from the joists to the 6x6 girders, out to the brick piers at the eave walls and in to the granite posts, the chimney base, or a collection of later shim stacks and makeshift headers at mid-depth. After the work, every girder bears on permanent steel posts on their own footings, spaced girder by girder to the sealed addendum's gaps, with steel on grout where it meets masonry, and every pulled joist hangs in a hanger. For the new roof, the rafters hang from a continuous ridge beam to a post at each gable end on the existing masonry and to one intermediate post that passes through the third, second and first floors to its own footing on the centerline of the basement |
| Loads carried | the first floor, on the girders and their new posts, the planned roof under Connecticut snow, at planning level, on the ridge beam and its three posts |
| Code basis | An existing house from the 1800s, not required to meet today's code and evaluated for condition and behavior. The basement specification and the planning loads for the new roof are by calculation, with the existing girders and joists evaluated as No. 1 grade eastern softwood |
No. The slope is a hundred years of girders sagging between supports that were too far apart, and the house is otherwise sound. Lifting it back to level would crack plaster and finishes on three floors for no structural gain. The fix is to put a permanent post on a real footing under every girder at close spacing, lift each one only until it bears on its new post, and let the slope be.
Because the joists are joined to the girders with mortise and tenon joints and no hangers, and the tenons have pulled partly out of their mortises as the girders dropped away from them. A face-mount hanger at each one, installed after the girder is on its new posts with the joist drawn tight, carries it from the day it goes in.
This one, yes. The right way is a continuous ridge beam between the gable ends on three posts, one at each end on the existing masonry and one in the middle of the house. With a ridge beam the rafters hang from the ridge instead of pushing on the walls, so the knee walls can go and the ceiling can open up. The middle post is the one to plan for, because it has to pass through three floors to a footing of its own in the basement, which the basement work leaves room for. The floor's new middle posts carry the floors only; the ridge post does not land on them without a new design.
Independent review and stamped calculations for a rear addition where 44 ft of first-floor bearing wall came out in two spans on a four-ply 20 in LVL, plus a sealed revision when the framing changed.
A gutted timber frame in Bristol, sound where examined, its three 6x6 second-floor beams stripped of most of their partitions and about to lose a chimney.
A buyer's structural assessment of a timber-frame house from about 1790. Temporary posts doing permanent work in the basement, a girt the inspection report called a split joist, and a sound old frame.
Call or text Travis at (860) 519-6009, or send the details below. Stamped letters follow within a few business days of the visit, and you always talk to the engineer who stamps it.
Repairs to a timber-frame house that is on the State or National Register may qualify for Connecticut's historic homes tax credit; how that works.
This page describes engineering performed for a specific structure under conditions verified on site. Spans, member sizes, and connection details are particular to that building and its loading. Nothing here is a design for any other structure. Every project requires its own analysis by a licensed engineer.
