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Reel Six: The Blueprint

Planning Plumbing for a Bathroom Renovation

A good bathroom renovation starts with a plan for the water, not the tile. Here is the order of decisions that keeps a project on track.

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The short version

Decide the layout first, then choose fixtures, then plan pipes, then book trades. Keep fixtures in their current spots if budget is tight. Replace old pipe while the walls are open. Get a permit when drains or vents move.

A white bathtub beside a sink and mirrors
A white bathtub beside a sink and mirrors.

Step by step

  1. Map the existing room. Note where the toilet flange, tub drain, sink and stack are. The stack is the large vertical drain pipe, and moving away from it adds work.
  2. Settle the layout. Keeping the toilet close to the stack is the single biggest cost saver. Moving a shower a short distance is often manageable.
  3. Choose fixtures early. Wall-hung toilets, freestanding tubs, rain heads and body sprays all need specific rough-in measurements and sometimes larger supply lines.
  4. Check the water heater. A big soaker tub or multiple shower heads can outstrip a standard tank. Consider capacity or tankless options.
  5. Plan for the hidden. Older Oakville homes may reveal galvanized supply, cast iron drains or Poly-B. Budget a contingency for replacing them.
  6. Sort permits. The Town of Oakville building department handles permits for plumbing changes. Condos also need board approval.
  7. Schedule trades. Demolition, rough-in plumbing, inspection, waterproofing, tile, then finish plumbing.

Use a pressure-balancing or thermostatic shower valve. They protect against sudden temperature swings when another tap is opened elsewhere in the house.

Keep this kit by the main shut-off

  • Flashlight or headlamp
  • Bucket and old towels
  • Adjustable wrench and slip-joint pliers
  • Flange plunger for toilets, cup plunger for sinks
  • Label on the main valve so anyone can find it

Mistakes to avoid

  • Buying the vanity after rough-in. Drain and supply heights depend on it.
  • Setting the shower valve body at the wrong depth for the finished wall. The trim will not fit.
  • Neglecting access panels for valves and tub drains.
  • Skipping the vent. A drain without proper venting gurgles and drains slowly.
  • Leaving old supply lines in place to save a little money. The new tile will have to come off when they fail.
  • Choosing a curbless shower without planning floor slope from the start.

Budgeting tips

Plumbing costs rise with each change to the layout, with fixtures that need special rough-in, and with the condition of what is behind the walls. Keep a contingency for surprises in older homes. Buy fixtures before rough-in, not after, and keep the boxes until the job is finished in case a part is missing. Ask for an itemized plan so you can see which choices drive cost, then decide where to save and where to spend. A plain, well-placed shower valve often beats an elaborate system that is hard to service.

Stop and phone a plumber when

  1. 1A ceiling or wall starts dripping
  2. 2More than one drain backs up at once
  3. 3You smell gas or sewage indoors
  4. 4A valve will not turn or drips when touched

When to call

Call before demolition, when the plan is still on paper. A plumber can tell you what layout changes cost the most, what the existing pipes look like and whether a permit is needed. We handle renovation plumbing, shower valves, toilets and repiping. Condo owners should also read condo and townhouse plumbing.

Straight answers to common calls

Does moving a toilet need a permit in Oakville?

Moving a toilet usually means changing drains and venting, which generally requires a building permit.

How long does rough-in plumbing take?

It depends on the scope. Keeping fixtures in place is quick; relocating several fixtures takes longer and needs an inspection.

Should I replace old pipes during a reno?

If walls are open and the pipe is galvanized, Poly-B or near the end of its life, replacement is usually the smart move.

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