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Fascia and Soffits
The fascia is the 1”x8” wood that runs around the exterior of the roof and helps to tidy things up. The fascia is another piece of wood helps protect the wood frame. The soffit is the wood you install underneath the roof to get rid of gaps and make everything airtight. There is no reason to get too fancy with the soffits. I tried to do a nice soffit made from tongue and groove cedar, but it just made the cuts more difficult, was more expensive than regular plywood, and ended up looking pretty similar to plywood, after it was stained, anyway.
Don’t make the mistake of installing the roof membrane before the fascia and soffits since the roof membrane needs to go over the outside of the fascia. I made this mistake and it was no fun redoing the roof membrane!
Tools Needed for Fascia and Soffits
| Circular Saw | Level | Tape Measure | Drill |
 |  |  |  |
Materials Needed for Fascia and Soffits
| Item | Description | Quantity |
|---|---|---|
| Fascia Boards | 1”x8” Fascia Board | Approx 34’ |
| Soffit Plywood | 4’x8’ at 19/32” thick | 1 |
| Fascia and Soffit Screws | 2” Exterior Screws | 30 |
You will want to do the soffit first since the fascia will end up covering the edge of the soffit after the soffit is installed. To do this, simply measure from the front siding to the bottom edge of the roof rail and make your cuts. Since the sauna roof is 8’ 6” wide, you will not be able to cover the entire width in one cut. After you have made the cut, you will attach with the brad nailer. Follow the same process for the back. If you used tongue and groove cedar for the siding, then side soffits will not be required but if there is a gap there that needs to be covered, then you can do that now.
After you have installed the soffits, you will attach the fascia board around the perimeter of the roof. For the front fascia board, you will want a board that is at least 8’ 6” so it covers the entire span of the front of the roof. When you are done, the soffit and fascia will look similar to the photo below (without the roof trim).
Rubber Membrane Roof
Once you get the rubber roof membrane installed, your sauna will become pretty much waterproof, at least for construction purposes, which is a great relief if you are working in wet weather. I considered using metal or shingles for roof but found a rubber membrane roof to be the best solution for the sauna. The rubber roof is easy to work with and does not require any special tools or skills like metal roofs. Also, the rubber roof is ideal for a lower angle sloped roof such as what you are building with the sauna.
Tools Needed for Rubber Membrane Roof
| Utility Knife | Paint Roller | Tape Measure | Drill | Circular Saw |
 |  | | | |
Materials Needed for Rubber Membrane Roof
| Item | Description | Quantity |
|---|---|---|
| Roofing Membrane | 10’x10’ RubberGard 60-mil EPDM Roof Rubber | 1 |
| Rubber Glue | EPDM Bonding Adhesive | 1 Gallon |
| Metal Trim Screws | Everbuilt Self-drilling Roofing Screws #10x 1″ | 1lb box |
| Roof Edge Metal Trim (Drip Edge) | Gibraltar Building Products 1-1/4 in. x 2-1/4 in. x 10 ft Hemmed Galvanized Steel Drip Edge Flashing (in Black or your preferred color) | Approx 34’ |
The hardest part of the rubber roof install is getting the right materials. However, with the list that I have provided above, it should be easy. Just keep in mind that Home Depot does not usually have all these items in stock. For the 10’x10’ RubberGard 60-mil EPDM Roof Rubber, I was able to order this off of Amazon.com. Be sure to get a piece that is large enough to cover the entire roof without cutting. The EPDM bonding adhesive I was able to find from a local website where someone had a half gallon left over. But it looks like Amazon also has the EPDM bonding adhesive available. Finally for the metal trim, I was able to find the Gibraltar Building Products 1-1/4 in. x 2-1/4 in. x 10 ft Hemmed Galvanized Steel Drip Edge Flashing (in Black) at my local Home Depot.
Application is easy. You simply roll on the bonding adhesive onto the roof sheathing with a paint roller. Then you roll out the rubber onto the roof. You will press out all the air bubbles using a wood roller from the center moving to the edges. You will then cut the edges CAREFULLY with about a 3-4” overhang from the roof. Then, cut and attach the drip edge . The drip edge we like is the Gibraltar Building Products 1-1/4 in. x 2-1/4 in. x 10 ft hemmed galvanized steel drip edge flashing which can be attached using the metal screws, spacing about 2 feet apart. The drip edge helps to hold the edge of the roof membrane in place and also helps water flow away from the fascia, protecting it from water wear. Finally, remove the excess rubber material using a razor blade, being careful not to cut the fascia.