Building a house

What it does

Understand which work must be complete before the next trade can proceed.

Follow the reference house from survey through groundwork, frame, enclosure, services and finishes.

When it fits

Learning the dependencies in a small house build.

The trade-offs

The illustrated durations and sequence belong to this house; actual logistics and approvals vary.

Context. An educational model. Geometry, material assumptions and the reference building are described in the illustrated study.

A house goes up in an order that is not a matter of habit. Each stage waits for what it will bear on, for what will brace it, and for the inspection of whatever it is about to hide. Follow those three rules from the surveyor’s first stake to the last shovel of topsoil and the nineteen stages in the figure fall into place, along with the reason a crew never does them in another order.

What bears on what

Load runs down, so construction runs up. The footing must be in the ground before the wall that stands on it, the wall before the sill bolted to its top, the sill before the joists that bear on it, the deck before the walls framed on it, the walls before the trusses that sit on their top plates. Nothing in the figure arrives before the thing it rests on; that is the load path built in the order it will later be used.

The ground goes first for the same reason. Before a footing is placed, the soil under it has to be known: a boring and a test pit on this lot found stiff silty clay good for 2,000 psf, groundwater about 14 ft down and frost reaching 42 in. Those three facts chose the foundation, set the footing’s width, and put its bottom 8 ft 2 in below grade, far under the frost.

What braces what: why backfill waits

The clearest case of a stage waiting to be braced is the backfill. Soil pushed against a basement wall presses on it like a fluid that grows heavier with depth: for a clay backfill, about 60 lb per square foot for every foot down. Over the 7 ft 4 in of soil against this wall that is roughly 1,600 lb on every foot of wall.

Backfill before the first floor is on and the wall has nothing at its top: it must stand as a cantilever off the footing, bending about 3,900 ft·lb per foot of wall at its base, right at the 4,000 ft·lb at which a plain 8 in concrete wall cracks. Wait for the slab to brace its foot and the floor deck to brace its head, and the same wall spans between them like a beam stood on end, and the bending falls to about 1,600 ft·lb, less than half. That is why the figure pours the slab and builds the deck (stages 8 and 9) before the backfill, and why the anchor bolts, set in the wet concrete a week earlier, matter: they are what ties the deck to the wall it is bracing.

Bracing runs through the frame the same way. Walls are held plumb by temporary 2×4 braces until the floor above ties their tops together; trusses are held upright by a temporary restraint and diagonals until the sheathing turns the whole roof into a stiff plane. Each temporary piece in the figure comes off exactly when something permanent takes its job.

What hides what: the hold points

An inspection comes just before something is buried, because afterwards no one can see it. The footing is inspected in its open forms, before the concrete hides the steel and the soil under it. The drain and coating are checked before backfill covers them; the plumbing under the slab is tested before the stone goes over it; the frame, pipes, ducts and wires are inspected together before insulation fills the walls; the insulation is checked before the board closes them. The work stops at each of these points until the inspector signs off, which is why they mark the ends of stages.

Hold point	Before	What is checked
Footing	The pour	Depth, width, firm undisturbed soil, steel
Foundation and drain	Backfill	Wall, bolts, dampproofing, drain and stone
Under-slab plumbing	Stone and slab	Pipe, fall, a water or air test
Framing and rough-in	Insulation	Structure, connectors, holes and notches; pipes, ducts, wiring
Insulation	Drywall	R-values, air sealing, vapour control
Final	Moving in	Everything, and the certificate of occupancy

Dry before anything that water ruins

A wood frame shrugs off a few days of rain; insulation, gypsum board, finished floors and wiring do not. So the building is dried in before the inside work begins: the roof sheathed and shingled, the walls wrapped, the windows and doors set into their flashing. Only then do the trades bring in what water would spoil. On the outside, by contrast, siding can wait; the wrap behind it already sheds the rain, so the cladding runs alongside the interior work rather than ahead of it.

The ground in and out

The figure measures its own earthwork from the surfaces it draws. Stripping the work area took about 100 cu yd of topsoil, piled behind the house. The basement hole took about 540 cu yd out of the ground, 9.3 ft deep at the uphill back and 7.0 ft at the front; its sides lie back at 1:1 because below 5 ft an unsupported trench in clay can collapse on whoever is in it. About 205 cu yd went back against the walls, in compacted lifts; the rest was spread to shape the ground or hauled away. At the end about 100 cu yd of topsoil went back on, the ground falling 6 in in the first 10 ft from the house on every side, with a swale uphill to carry the water coming down the lot round it. Cut and fill works through the same lot in detail.

Trades and the critical path

A house is built by a relay of trades, each handing a finished stage to the next: surveyor, excavator, foundation crew, framers, roofers, plumber, heating contractor, electrician, insulators, drywall crew, finish carpenters, painters. The stages that must wait on each other form the critical path: ground, foundation, frame, dry-in, rough-in, inspection, insulation, board, finishes. A day lost on any of them is a day lost on the house. Work off the path (the siding, the driveway, the landscaping) can slide without delaying the move-in. For this house a competent crew needs about six months; weather in the groundwork, inspections and materials are where the time goes.

Every stage

Before the ground is brokenKnow the land, lay the house on it, protect what stays.

01Survey and soils
A surveyor finds the lot corners, measures the ground into contours and sets a benchmark that every height on the job is taken from. A boring and a test pit show what is under the topsoil, how much it can carry, how deep frost goes and where the water sits. With those, the house is placed, its floor height set and its foundation chosen.
Who
Land surveyor, Geotechnical engineer, Designer
Takes
2–6 weeks, mostly waiting on the permit
Before going on
Plans approved and the building permit issued.
Decides
Where on the lot does the house go, and which way does it lie? · What does the house stand on? · How does the house meet a sloping lot?
Drawn in
Contours and the house's floor height · Soil, frost and water decide the foundation
02Stake out
The surveyor stakes the house's corners. Because the stakes will be dug away, the crew sets batter boards a few feet outside each corner, all at one height taken from the benchmark, and stretches strings between them on the lines of the foundation. Equal diagonals prove the rectangle is square.
Who
Surveyor, Excavator
Takes
1 day
Before going on
Corners and setbacks checked against the site plan.
Drawn in
Batter boards and strings
03Clear and protect
Before any machine works, the site is protected: silt fence along the downhill edge, a gravel entrance so trucks do not track mud into the street, and a fence at the drip line of every tree that stays. Then the footprint is cleared, underground utilities are marked, and the topsoil is stripped and piled to be spread back at the end.
Who
Excavator, Utility locators
Takes
1–2 days
Before going on
Erosion controls inspected; utilities located.
Drawn in
Stripping the topsoil

GroundworkDig, pour and drain the substructure, deck it over, then give the soil back.

04Excavate
The excavator digs the basement: down to the underside of the footings and 2 ft beyond the walls on every side, room to form, waterproof and drain them. Below 5 ft a trench can bury a worker, so the sides are laid back at a slope the soil can hold, benched, or shored. On this lot the uphill back is the deepest cut; the spoil is piled clear of the edge for backfill.
Who
Excavator
Takes
2–3 days
Before going on
Bottom checked for depth and for undisturbed, firm soil.
Decides
How do the sides of the dig stay up? · How does the house meet a sloping lot?
Drawn in
Digging the basement · Where the dirt goes
05Footings
Forms are set on the bottom of the hole, steel bars laid in them on chairs, and a keyway formed down the middle so the wall cannot slide. Square pads go in under the future basement columns. The inspector sees the open forms and the bare soil before any concrete is poured.
Who
Foundation crew, Concrete supplier
Takes
2–3 days
Before going on
Footing inspection, before the pour.
Drawn in
How wide, how deep · Forms and steel
06Foundation walls
Wall forms rise on the footings, tied through with steel at a set spacing; bucks frame the basement windows and sleeves leave holes for the pipes. The wall is poured in one go, anchor bolts are set in the wet concrete along the top, and the forms are stripped a day or two later.
Who
Foundation crew
Takes
4–7 days
Before going on
Wall height and bolt layout checked; forms stripped once the concrete has gained strength.
Decides
What are the basement walls made of?
Drawn in
Forming and pouring the wall · The other ways to stand a house
07Dampproof and drain
The outside of the wall is coated against soil moisture, or membraned where groundwater can press on it. A perforated pipe is laid in washed stone beside the footing, wrapped in filter fabric, and run to daylight or a sump, so water around the house is led away before it can build up against the wall.
Who
Waterproofer, Foundation crew
Takes
1–2 days
Before going on
Foundation and drain inspection, before backfill.
Decides
How is water kept out of the basement?
Drawn in
Coating, drain and stone · The footing drain
08Under-slab work and slab
The plumber lays the building drain under the basement floor and brings it out through the footing toward the sewer. Then come 4 in of stone, a radon vent pipe, a heavy vapour retarder and, here, rigid insulation, before the 4 in concrete slab is poured and its control joints cut.
Who
Plumber, Concrete finisher
Takes
2–3 days
Before going on
Under-slab plumbing tested and inspected, before the stone covers it.
Drawn in
The building drain · Slab layers
09Sill and first floor
A treated sill on foam sealer is bolted down to the wall. Steel columns stand on their pads and carry the glulam girder down the middle; joists bear on sill and girder, a rim closes their ends, and the subfloor is glued and nailed on. The deck is the crew's working platform, and it braces the top of the foundation wall.
Who
Framers
Takes
3–4 days
Decides
What are the floors framed with?
Drawn in
Sill, joists and deck · The girder · The steel columns
10Backfill and rough grade
Only now, with the slab bracing the bottom of the wall and the deck bracing the top, is soil pushed back against it. Backfill goes in layers of 8 to 12 in, each compacted, with clean material near the wall. The ground is shaped to fall away from the house on every side, and a swale uphill turns the water coming down the lot around it.
Who
Excavator
Takes
1–2 days
Decides
How does the house meet a sloping lot?
Drawn in
Backfilling in lifts · Cut, fill and the slope away

FramingWalls, floor and roof go up as one braced, tied structure.

11First-floor walls
Walls are framed flat on the deck, headers over every opening, then sheathed, stood up, nailed down through the subfloor into the rim, and braced plumb. The doubled top plate laps every corner and tee, tying the walls into one box.
Who
Framers
Takes
3–5 days
Decides
What are the outside walls built of? · What keeps the walls from racking?
Drawn in
Framing the walls · Why the sheathing matters
12Second floor and walls
The second floor repeats the first: rim and joists on the top plates, a subfloor deck, walls framed and raised on it. The stair opening is framed with doubled headers and trimmers before the deck goes down.
Who
Framers
Takes
4–6 days
Drawn in
Platform on platform · The stair opening
13Roof framing
Trusses are craned or hand-set onto the top plates 24 in apart, each tied down with a hurricane tie and braced as it goes up, because a row of unbraced trusses falls like dominoes. Permanent bracing follows the truss maker's drawing, and the gable ends are framed and sheathed.
Who
Framers, Crane operator
Takes
3–5 days
Before going on
Truss bracing checked against the truss drawings.
Decides
What holds up the roof?
Drawn in
Setting the trusses · Tying them down · Rafters, the other way

Closing inShed the water, run the services, hold the heat.

14Dry in
The roof is sheathed, its panel edges gapped and clipped, the temporary braces coming off as it goes on; then drip edge, underlayment and shingles. Housewrap laps down the walls like shingles, and windows and exterior doors are set over flashing laid in the right order, so every sheet sheds water onto the one below it. From here the house keeps the weather out, and the inside work can begin.
Who
Framers, Roofers
Takes
1–2 weeks
Decides
What goes on the roof? · What keeps water and air out behind the siding?
Drawn in
Housewrap and window flashing · Sheathing and roofing
15Rough-in
With the frame open, the trades run everything that will hide in it. The plumber runs supply lines and the drain, waste and vent pipes; the heating contractor sets the furnace and ducts; the electrician sets the panel and boxes and pulls cable through bored studs. Each hole is drilled within limits that keep the joists and studs strong, and steel plates guard pipes and wires near the faces.
Who
Plumber, HVAC contractor, Electrician
Takes
2–3 weeks
Before going on
Rough-in and framing inspections; pipes pressure-tested.
Decides
What carries the water to the fixtures? · How is the house heated and cooled? · How does power reach the house?
Drawn in
Supply, drain and vent · Furnace and ducts · Service, panel and circuits
16Insulate and air-seal
Every gap between inside and out is sealed: plates to subfloor, around windows, every hole the trades drilled. Batts fill the stud bays, foam lines the rim joists, and after the ceiling board is up, loose fill is blown deep into the attic.
Who
Insulation contractor
Takes
3–5 days
Before going on
Insulation inspection; later a blower-door test of airtightness.
Decides
What insulates the walls?
Drawn in
The four control layers

FinishingSkin, surfaces and ground: the house as it is lived in.

17Siding and trim
Outside, corner boards and window casings go on first, then the siding laps up to them; soffit and fascia close the eaves, and gutters hang from the fascia. This runs alongside the inside work.
Who
Siding crew, Gutter installer
Takes
1–2 weeks
Decides
What is the house clad in?
Drawn in
The rainscreen behind the siding
18Drywall and finishes
Gypsum board is screwed to ceilings, then walls, its joints taped and coated three times and sanded. Then the finishes: primer and paint, doors and trim, flooring, cabinets and counters, and the trades come back to set fixtures, registers, switches and outlets.
Who
Drywall crew, Finish carpenters, Painters, Flooring, The trades again
Takes
6–10 weeks
Before going on
Final plumbing, mechanical and electrical inspections.
Drawn in
Board in the house · The finished stair
19Final grade and landscape
The stockpiled topsoil is spread back, the final grade checked to fall away from the house, downspouts led out onto splash blocks or into drains, the driveway and walks laid, and the ground seeded before it can wash. The final inspection closes the permit, and the house can be lived in.
Who
Excavator, Landscaper, Paving
Takes
1–2 weeks
Before going on
Final inspection and the certificate of occupancy.
Drawn in
The finished grade