"Commander Kinsey" wrote in message
newsp.0d1qmig1wdg98l@glass...
On Tue, 07 Jan 2020 23:19:33 -0000, Rod Speed
wrote:



"Commander Kinsey" wrote in message
newsp.0d1n3vgmwdg98l@glass...
On Tue, 07 Jan 2020 21:55:04 -0000, Rod Speed
wrote:

Commander Kinsey wrote
Rod Speed wrote
Commander Kinsey wrote

Why secure a loft trapdoor in a storm?

And what's the roof pitch to do with anything?

In theory you can get a suction effect similar to
what you get with an aircraft aerofoil section.

In practice it isnt seen often enough to matter.

I wonder what the roof pitch has to do with it.

That's what determines whether you get the aerofoil effect.

When the pitch is too high, you don't.

But how can that get to the loft hatch?

The suction effect in the roof space sees air moved
out of the house into the roof space, lifting the hatch.

how could that happen? Surely aerofoil works on the roof itself, lifting
the tiles off.

The tiles arent an airtight surface like an aircraft
wing so you do get considerable movement of
air out of the roofspace before the tiles come off.

And my hatch is made of wood, way too heavy to lift like that.

You're wrong when the roof is of lower slope.

And hardly the end of the world if it opened, it might give me a fright
that's all.

Sure, but that's just as true of the other stuff like
shutters that it suggests should be shut and secured.

"Close and secure loft trapdoors with bolts, particularly if roof
pitch is less than 30°"

https://www.metoffice.gov.uk/weather...afe-in-a-storm