When should I consider deck waterproofing?

Consider deck waterproofing such as TimberTech DrySpace when you want to turn the area beneath an elevated deck into a dry, usable outdoor space rather than simply allowing rainwater to fall through the decking.

For Snohomish County, this can be especially useful because of the long rainy season. But whether it is worth the investment depends on the deck's height, how you plan to use the space below, and whether you're building a new deck or retrofitting an existing one.

TimberTech DrySpace

An under-deck drainage system such as DrySpace collects water that passes between the deck boards and channels it toward a gutter or drainage outlet.

It can help you create a sheltered area below for:

• Outdoor seating and entertaining.
• Storing patio furniture or gardening equipment.
• A covered patio with lighting or fans, where appropriately installed.
• Keeping the area below the deck more comfortable during wet weather.

Important: DrySpace is an under-deck drainage system, not a substitute for the deck's structural waterproofing, house-wall flashing, or a roof designed to keep all wind-driven rain out.

When is DrySpace worth considering

Strong reasons to install it

• Your deck is elevated enough to create usable space below.
• You want a sheltered seating, dining, or storage area.
• You are already rebuilding the deck and can plan the drainage details.
• You want a finished underside rather than exposed joists and dripping water.

Reasons to skip it

• Your deck is at ground level with no useful space beneath it.
• You only need water to drain into the yard.
• The deck is very low, leaving little clearance for installation and maintenance.
• Your primary goal is a completely enclosed, weatherproof room beneath the deck. DrySpace alone is not designed for that purpose.

TimberTech describes DrySpace as suitable for new decks and many existing decks, but the framing dimensions and installation details must be compatible.

If you're building a new elevated deck in Snohomish County and want to use the space underneath, decide on under-deck drainage before finalizing the framing plan. That gives you the best opportunity to coordinate the joists, beams, flashing, and water outlet. However, DrySpace can be successfully installed on existing elevated decks for a new outdoor space.