Seed Home 2 Roof
- EPDM can be installed directly over EPS. 
Parameters for assessing cost and practicality:
- Materials: EPDM, TPO or PVC
- Installation method: fully adhered, mechanically fasteners + heat welded (seams only) or mechanically fastened + glued (seams only)
- Form factor: all of these materials come in a variety of sizes - but none is a perfect fit for our roof size - so we need to pick the one that leads to the least waste (cut ends)
Suppliers that sell directly to the public.
Roofkit (EPDM only, I think):
- Product line at menards: 45 mil EPDM, latex adhesive, primer, seam tape. This comes out to around $1.15/sq ft - but that doesn't include the cost of seams (which use primer and seam tape) nor waste due to form factor.
- Installation manual
- Website - with installation videos and FAQ
WeatherBond (EPDM, TPO and PVC)
- Comes in a variety of sizes (for example). Can also be acquired by the foot.
- Fastener plates
- Installation videos
- Loads of technical and how-to details (if you can make sense of them):
Installing mechanically fastened TPO seems relatively straightforward up to a point (you unroll the membrane, fasten the edges to the deck with screws and plates, overlap the next sheet and heat-weld the seam). But on the written instructions they keep talking about "perimeter sheets" - but I can't find out what perimeter sheets are, how many we need, how much they cost nor how to install them (are they glued?). It's like a ghost material :)
They also make a weld-free TPO, but I can't find it for sale online (we may need to contact the manufacturer). Weld-free means Seam Tape.
One more thing: Elijah says he doesn't know whether TPO can still be heat-welded after prolonged exposure to UV. So this is a question for the manufacturer - as it would affect if and how we could reuse the membrane.
Mechanically fastened roofing membranes:
See also Roofing Membranes