Which direction to lay felt

[beatts]

I am felting my summerhouse roof tomorrow.

It's is 5m long x 3m wide and slopes down the long side.

I have raised it 100mm higher at one end, so it is a very gradual 1 in 50 slope

My question is

Which orientation should I lay the felt?


In 3 or 4 pieces following the slope down the long edge

Or

In Several pieces 90 degrees to the slope?

Ta

 

[r896neo]

What type of felt are you using?

A 1:50 slope is really not enough to use a basic nail on felt.

Did you build this structure yourself?

 

[beatts]

It's a summer house. The felt came with it, it's your standard capping felt.

The roof had no slope so I added firrings to create one.


Why wouldn't felt work?

 

[Burnerman]

There's going to be a fair bit of movement in the summer.....I'd go for across the length, I think.
I had to do a similar thing for someone once - it was one of those occasions where felt shingles in strips helped with the movement.
Of course, there's always the possibility of water being blown upwards with a minimal slope.
John

 

[beatts]

Ah, I see so the Problem is the potential for water getting pushed back up the slope.

I'll make sure I put two layers down well sealed and see how that fares over the next year. If no good ill Board and EPDM it next spring, I just don't have the finances this year, besides I have 4 rolls of felt to use up.

 

[r896neo]

Torch on felt might work ok but nail on is nowhere near well enough sealed at joints to deal with so small a fall. Driving rain could easily push rain under laps.

Nail on felt is designed for shed roofs with a pitch, with such a small fall you need to use a higher spec felt as would be used on a small flat roof .

You should use a torch on felt and possible use a base layer too.

Who on earth made a summer house with no fall on the roof?

As john said the expansion and contraction is worth considering which is a good reason for a 2 layer system.

If you already have the felt and can't return it you could use cold adhesive rather than nailing it.

 

[beatts]

I agree, no fall is ridiculous but I wasn't aware that was the case till I'd constructed it. Shoddy company!!!

I was going to nail the first layer down (for movement) and then bond the second layer to the first using cold adhesive.


Do you think it's worth putting a small batten (under the felt) down either edge down the slope to form a lip and prevent water flowing over the sides?