Replacing a staircase mid renovation: when to measure and what goes wrong

A staircase has to fit the finished house exactly, and during a renovation the levels keep changing. Guest author Nima Gerani of RealDream Contracting explains when to measure a replacement stair and what goes wrong when you measure too early.

A staircase is the one part of a house that has to fit exactly. Not close. Exactly.

Cabinets get scribed to the wall. Trim covers a gap. Drywall hides a lot of sins. A stair does none of that, because the dimension that matters is the height from one finished floor to the other, and that dimension has to divide evenly into risers that are all the same.

Which creates a problem specific to renovations, and it is the reason I am writing this. During a renovation, the house does not hold still. Floors come up. New floors go down. Levels change. And the stair gets measured somewhere in the middle of all that, by someone who assumed the numbers were final.

They were not final. That is how you end up with a beautiful staircase that does not fit.

The measurement that ruins stairs

Total rise is measured from finished floor to finished floor. Finished floor. Not subfloor.

So the fabricator needs to know, before they cut anything, exactly what is going on top of the subfloor at the bottom of the stair and exactly what is going on top of the subfloor at the top.

Engineered hardwood is one thickness. Tile with a mortar bed is another. Tile over an uncoupling membrane is another again. Carpet with underlay is different from all of them. And here is what actually goes wrong: those two floors are frequently different from each other. Hardwood in the upstairs hall, tile in the downstairs entry. That difference goes straight into the total rise, and if the fabricator was told “hardwood” without being told about the tile downstairs, every riser in the flight is now slightly wrong.

Slightly wrong is not a small problem. The building code requires risers in a flight to be consistent with each other, and an inspector will measure them. A stair that is out by enough gets rejected, and the fix is usually a new stair.

So the rule I work to is simple. The flooring selections have to be locked before the stair gets measured. Not chosen loosely. Locked, including the underlayment and setting bed, with the actual product thickness written down.

If the client is still deciding between tile and hardwood at the entry, the stair is not ready to measure. It does not matter how far behind schedule that puts you. Measuring early to save a week costs you the entire stair.

Old houses do not cooperate

The second thing that goes wrong is specific to the housing stock most of us are renovating on the North Shore and across the older parts of Vancouver.

Nothing is square. Nothing is level. Nothing is plumb.

A house built in the 1950s has settled for seventy years. The floor at the top of the stairwell is not necessarily at the same height across its width. The walls flanking the stair opening are probably not parallel to each other. The opening itself is often not a consistent width from top to bottom.

A stair built to a single clean set of numbers will not sit properly in a hole like that. Which means the site measure needs to record the variation, not just the nominal dimensions, and someone needs to decide how the stair deals with it. Some of it gets absorbed in the install. Some of it has to be corrected in framing before the stair arrives.

This is worth paying attention to because it is a sequencing question more than a stair question. If the framing correction has to happen first, it has to be in the schedule ahead of the delivery date, and it usually is not.

You still have to get upstairs

Easy to overlook when you are planning on paper. There is a period between the old stair coming out and the new stair going in, and during that period the second floor has to remain reachable.

For a full gut where nobody is living in the house, this is a minor inconvenience and you build a temporary stair or use a ladder. For an occupied renovation, which is most of the work I do, it is a real constraint. Families are living upstairs. There may be one bathroom and it may be on the wrong floor.

The way to handle it is to make the gap as short as possible, and that means the new stair should be fabricated and physically on site before the old one comes out. Not ordered. On site, inspected, ready to install.

That single decision, ordering early enough that the new stair waits for the demolition rather than the demolition waiting for the stair, removes most of the pain from this part of a renovation. It also costs nothing. It is purely a scheduling choice.

Where the stair fits in the order of operations

Rough sequence that works, for anyone planning one of these:

Structure first. If a wall is coming out beside the stairwell, or the opening is being widened to bring light down through the house, that structural work has to be resolved before anyone measures anything. The opening is not final until the framing is final.

Then lock the flooring. All of it, both levels, with real thicknesses.

Then site measure, recording the actual variation in the opening, not the idealised version.

Then fabricate, with enough lead time that the finished stair is waiting on site.

Then remove the old stair and install the new one.

Then finishes, and the guard, which will have its own code requirements to satisfy.

Rushing any step earlier in that list to save time only moves the delay later, where it costs more. The stair is the least forgiving element in the house. Give it the sequence it needs and it goes in cleanly.

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Nima Gerani is the founder of RealDream Contracting, a renovation company working across North Vancouver and West Vancouver, with select projects in Vancouver, New Westminster and White Rock. Reach them at info@realdream.ca or (604) 401-4849.