Q&A for How to Attach Roof Felt on a Shed

No, you only use that for applying the large sheet of granular roofing rolls. Install the first row along the edge of the house and then add the drip edge flashing. Continue up to the top with each each new row overlapping at least three inches. Then you can roll on the peel and stick underlay that will act as a vapor barrier and ice shield and finally, the shingles.

It has to go rougher side up, but there is no specific top or bottom. Make sure the felt placed higher up overlaps the lower piece.

You don't need to apply any tar before laying the felt, however it depends on your needs. You can go whole hog by sanding and priming the roof decking and then using a bituminous paint to stick the underlay felt down. Then use a second layer of top felt, again with bituminous paint, without having to use any clout nails. Of course, this could limit your options for replacing the felt at a later stage.

Roofing felt has a smooth side and a rough side; the side that needs to face the elements is the rough side.

No. The nails should be shorter than the combined thickness of the boarding material and the felt.

Never, as the water will work it' way under the join. For an apex roof, start at the bottom and lay it horizontal, the next should overlap {as in video}, so the water runs over the join as it runs off the roof, finishing at the apex or top of roof. The last layer should go over both sides of the roof, overlapping both side covered in felt. For a flat roof, the same applies––start at the lower end first, working to the higher end, and this should resemble tiles on a roof. Hence, this is why tiles are fitted on top of each other rather than sideways.

Any clout nails will work, so long as they are galvanized. Bituminous paint should always be used to make the felt last longer, this also prevents the wind from ripping up the joins, and helps to prevent small leaks and preserve the wood. For OSB board, this is a must.

There isn't one really, But if it's really hot, it does become soft and harder to cut. If you cannot use a hook blade, just use a straight one.

It's best to start again. The old felt is likely to have rips or holes. Also, you don't want to re-felt over existing nails. Removing all old felt and ensuring all old nails are removed (they can be used again) means you'll have a flat surface to lay the new felt.

No. The roof has to be totally dry prior to fitting new felt to prevent rotting.

No, because the wood roof decking needs to breathe in order to prevent rot. Humidity finds its way through any wood, be it painted, stained, or not. It's best to use good quality felt tar paper or ice shield underlayment as per the instructions, carefully sealing all nails used to install said underlayment.