Remove Old Siding or Install New Siding Over It?
Leaving old siding in place can reduce tear-off and disposal, but an overcladding proposal is not automatically the lower-cost or lower-risk project. The existing wall, the new product, and the details around openings must be compatible.
What tear-off buys you
Removing cladding exposes more of the wall for inspection. A contractor may identify failed flashing, wet sheathing, rot, missing drainage layers, or poorly detailed windows before the new finish hides them. Those conditions are possibilities, not automatic findings.
Tear-off adds labor, disposal, temporary protection, and sometimes replacement of trim or accessories. Ask whether concealed repairs are priced by unit rate, allowance, or a separate authorization.
What overcladding changes
An approved system may be designed over a particular substrate, but no material can be assumed compatible with every existing siding. Added thickness can affect window and door jambs, sill and head flashing, corners, vents, penetrations, trim, and roof-edge transitions. A wall that is not flat or is already holding moisture may be a poor candidate.
Request the exact product and its current installation details. Do not rely on a generic statement that siding can go over siding.
Older paint and siding
In U.S. pre-1978 target housing, EPA says paid renovation can remain subject to the RRP Rule when newer siding was installed over older lead-painted siding unless the affected components are documented lead-free through an accepted qualified process. This is a federal U.S. context, not Canadian law.
Health Canada and Government of Canada guidance also make older Canadian paint and suspect asbestos-containing siding screening relevant to renovation planning. That guidance does not identify a particular property or establish one province-wide work method. Arrange qualified assessment and confirm local requirements before disturbing suspect material.
Compare complete scopes
Ask both options to state inspection access, removal, disposal, wall preparation, flashing, drainage layers, transitions, trim, hazard screening, permits, and change-order rules. Choose overcladding only when the complete system and details are suitable.