Before anything else: confirm you actually need one
A WPI-8 is required for structures in TDI-designated catastrophe areas — the Tier 1 coastal counties and the designated portion of Harris County east of SH 146. New construction, re-roofs, additions, and major remodels in those areas all qualify. If you are not sure whether your property is in a designated area, call us with the address and we will verify it against TDI records before you spend a dollar.
Step 1: Appoint a qualified engineer (the WPI-1)
Only a TDI-appointed qualified engineer or inspector can produce a valid WPI-8. Your roofer cannot issue one, and neither can the city building department. The engineer opens your project with TDI by filing the WPI-1 form — this is the formal appointment that tells the state who is inspecting your project. This step should happen before work begins: appointing an engineer early means every stage of construction can be documented properly.
Step 2: In-progress inspections (the WPI-2 filings)
As construction proceeds, the engineer inspects at the stages TDI requires and files WPI-2 inspection reports. For a typical re-roof, that includes the dry-in stage (underlayment and deck attachment) and fastener checks; for additions and new builds it extends to framing, strapping, and opening protection. Each report documents that the installed work matches the windstorm building standards TDI has adopted. Missing a required stage is the most common reason projects end up on the more expensive WPI-8E path — schedule inspections before the phases get covered up.
Step 3: Final inspection and the WPI-8 certificate
When the work is complete, the engineer performs the final inspection. If everything passes, the engineer submits the compliance paperwork to TDI and your WPI-8 Certificate of Compliance is issued — the document TWIA and private windstorm insurers require. You will typically need it at closing if you are selling, at renewal if you are insuring, or at permit close-out if you are a contractor.
What it costs and how long it takes
Residential re-roof certification starts at $500 plus a per-square-foot component, with new construction starting at $1,000; commercial projects start at $800. Rush service (5 days from deposit to TDI submission, next-day inspection available) adds $500. Standard turnaround is about 14 days. The single most important tip: engage the engineer before construction starts — retroactive certification of finished work always costs more than inspecting it as it happens.