Swell Sport · Practical guide

Protecting existing waterproofing during sauna installation

Where a proposed sauna sits on a balcony or waterproofed terrace, make protection of the existing building a separate work package. The key deliverable is an agreed sequence for access, supports, any penetrations and inspection—not a promise that a sheet of padding or a bead of sealant will protect everything.

Swell Cedar Cube 2 in a home setting.

Identify the existing system before covering it

Collect available drawings, membrane information, previous repairs, warranties and inspection records. Ask the owner or building manager who is responsible for the waterproofing and who can approve work affecting it. Photograph the accessible surface, junctions, outlets and any existing marks before installation activity begins.

Write unknown beside missing records rather than naming a membrane from appearance. The visible paving or tile finish is not a sufficient project record of the concealed system. Ask a suitable waterproofing professional what investigation is needed and keep that separate from the structural review of whether the terrace can support the proposal.

Use a no-penetration-until-reviewed hold point

Ask each trade to identify proposed drilling, fastening, cutting or service penetrations, including temporary works. Mark them on one drawing and do not release that part of the work until the responsible designer, waterproofing professional and relevant owner approval have been coordinated. This is a project control, not a claim that all penetrations are prohibited.

QBCC’s published account of a Queensland deck failure describes water-entry points that relied solely on sealant and subsequent deterioration allowing water ingress into wall framing. It is not a terrace membrane specification, but it is a concrete reason not to accept “we will just seal it afterwards” as the entire detail. ^[1]

Review non-penetrating proposals too

An arrangement described as non-penetrating still needs review for how it bears on the surface, what materials contact the existing system and how access to outlets and inspection points will be maintained. Ask the professionals to document any protection layer and its compatibility rather than selecting an improvised pad from this guide.

Give the installation contractor a route for bringing components and equipment onto the terrace, along with the agreed staging locations. Identify what must not be dragged, stacked or temporarily fixed without review. Have the appropriate professional resolve construction loads and handling restrictions; this article gives no allowable loads.

Agree the inspection sequence before work starts

Write the stages in order: existing-condition record, reviewed details, any preparatory works, inspection before concealment, installation, and final handover. Name who attends each stage and who can release the next one. If work changes on the day, return to the relevant reviewer instead of treating the timetable as permission to proceed.

For example, a hypothetical electrician needs a service route different from the one shown on the accepted plan. The useful response is to stop that affected work, revise the detail and coordinate its waterproofing treatment. Filling the new opening afterwards without an agreed detail would bypass the very review the project arranged.

Keep a record that survives the installation

At handover, retain photographs of concealed details, the agreed protection arrangement, any new installation records and the names of the contractors responsible. Ask how the remaining accessible parts are to be inspected and what must happen before the sauna is moved or later work occurs nearby.

No waterproofing warranty outcome is promised here. Seek written confirmation from the relevant parties about the proposed works and any conditions. If the existing system cannot be identified or a necessary detail remains unresolved, keep that item on hold rather than presenting the terrace as ready simply because the cabin fits.

Your practical checklist

Collect existing waterproofing records and condition photographs.
List temporary and permanent penetrations from every trade.
Review bearing, contact materials and inspection access even without drilling.
Assign inspection hold points and retain concealed-detail photographs.

Is a non-penetrating installation automatically safe for a membrane?

That label does not answer compatibility, support, drainage or access questions. Have the actual arrangement reviewed before accepting it.

Can the installer guarantee the original warranty remains unchanged?

Do not assume that. Ask the parties responsible for the existing system and proposed works to confirm their position in writing; this guide makes no warranty promise.